Fermi Paradox Special Issue

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Journal of the British Interplanetary Society

VOLUME 71 NO.6 JUNE 2018 Fermi Paradox Special Issue

THE ORIGIN OF THE “FERMI PARADOX” Anthony R. Martin FERMI AND LOTKA: the Long Odds of Survival in a Dangerous Universe Kent A. Peacock SCENARIO BLOCK DIAGRAM ANALYSIS of the Galactic Evolution of Life Stephen Ashworth EXTREMOPHILES: The Resilience of Life under “Adverse” Conditions Robert O. J. Weinzierl LIFE BEFORE FERMI – Back to the Solar System David L. Clements ALIEN AIRCRAFT: Have they been observed on Earth? Alan Bond

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198 Introduction 200 THE ORIGIN OF THE “FERMI PARADOX” Anthony R. Martin

207 FERMI AND LOTKA: the Long Odds of Survival in a Dangerous Universe Kent A. Peacock

212 SCENARIO BLOCK DIAGRAM ANALYSIS of the Galactic Evolution of Life Stephen Ashworth

216 EXTREMOPHILES: The Resilience of Life under “Adverse” Conditions Robert O. J. Weinzierl

222 LIFE BEFORE FERMI – Back to the Solar System David L. Clements

225 ALIEN AIRCRAFT: Have they been observed on Earth? Alan Bond

OUR MISSION STATEMENT The British Interplanetary Society promotes the exploration and use of space for the benefit of humanity, connecting people to create, educate and inspire, and advance knowledge in all aspects of astronautics.

JBIS Vol 71 No.6 June 2018 197 INTRODUCTION

Introduction

by GERRY WEBB FBIS, President of the British Interplanetary Society

he idea that there are worlds outside Earth which and extremophiles. I therefore thought it useful to return to may be inhabited has existed throughout history. the topic of the Fermi Paradox, review the new and improved However, Enrico Fermi was the first to voice the data and see if the topic can be freshened and tightened in any problem posed by the absence of evidence of intel- way. Accordingly, to test whether this could be done, and ably Tligent aliens on Earth clearly and with some reason. assisted by Alistair Scott I put together a symposium which was Since he had been a major player in bringing about the nu- run on the 28th November 2017. It was generally agreed that clear age, the first time in history that humans could see how this symposium was a success and produced much interesting the power necessary for interstellar travel could be generated, discussion. Four of the papers presented have been prepared it was but a short step for a man of his calibre to spot the vital for publication in this special JBIS issue and others may follow question ‘where is everybody?’ in future editions. The term ‘Fermi Paradox’ was not coined until later when The papers cover a broad range of topics within the Fermi the ‘evidence for absence’ had begun to build and a conven- Paradox envelope and I am pleased to say that Bond and Mar- ient way of referring to the problem was needed. Stated without tin are represented. The first two papers, by Martin and Pea- frills the paradox is: there should be evidence of (intelligent, cock respectively, were not presented at the symposium, but starfaring, communicative) aliens and there is not. Martin’s paper was stimulated by it and provides an excellent, The paradox usually provokes ‘why’ and ‘how’: Why should even necessary, introduction. Peacock’s paper was submitted there be aliens? How do we know there are no aliens? The first when this edition of JBIS was taking shape and fits perfectly is mainly addressed by pointing to human civilization as a typi- into its theme. cal development of intelligent star-faring life and the second by Radio telescopes were evolving at the same time as nucle- the increasing amount of astronomical evidence which, at first ar power but, because it was clearly much simpler to envisage, glance, would seem to indicate that the conditions necessary interstellar communication by signals was discussed (and at- for the development of civilisations such as our own are com- tempted) first, in the 60s and 70s, to a much greater extent than mon throughout the universe. physical transportation. I will not digress on what, in my opin- We cannot say for sure that intelligent technically capable ion, are the limitations and naivety of the former, save to say beings do not exist elsewhere in the universe, but the evidence that I remember arguing against any form of advertising our for their absence increases every year since Fermi first posed presence during the panel discussion at the 1977 BIS confer- the question in 1950. Nearly 70 years of increasingly sophis- ence referred to by our first author, Anthony R Martin, who ticated data on everything from extremophiles to extrasolar fixes very well the evolution and use of the term ‘Fermi-Par- planets has shown nothing so far. adox’ at about this time. The understandable reason for this In the 70s and 80s the BIS published much pioneer work early bias against physical transport is what are perceived as on Interstellar Studies such as ‘Project Daedalus’, World-ships the large timescales required for interstellar transport. How- and the Fermi Paradox. The main inspirers and leaders of this ever, these timescales are large only in terms of human life and work were Alan Bond and Tony Martin. In the intervening not at all a problem on the cosmic scale. decades no evidence for even primitive life outside the Earth Other intelligences could have a completely different per- has been found despite the vast amount of data that has been spective on such timescales from differences in lifespan, life- accumulated on the habitability of the cosmos and the resil- style, sociability, culture or ideology. Even within the human ience of life on Earth, with the discovery of extra-solar plants race there have been cultural/ideological groups, such as the

198 Vol 71 No.6 June 2018 JBIS INTRODUCTION

Spartans, who probably had the group rather than individu- ourselves or becoming unable to colonise space, ever. The possi- al commitment necessary to undertake interstellar flight. No bility of this scenario, no matter how slight, is why, in my opin- doubt, if we ever make it to colonising the solar system, the ion, the Fermi Paradox is the paramount question to answer. stimulus of the diversification and evolution of our ways of life There is a third class of scenario with many variants, none of will lead to many alternative cultural/ideological views enabling which pass the ‘Occam’s Razor’ test of simplicity that can be ap- some of these societies to be willing and able to face the task. plied to the first two. This group assumes that alien civilisations Cosmic religions may evolve to frame these enterprises. The are present but not communicating with us for various reasons, ideas of the inspiration behind Tsiolkovsky, Nikolai Fyodorov, such as the zoo hypothesis. In spite of, or perhaps because of, ‘Cosmism’, are an example. They led Tsiolkovsky to believe that it fostering the careers of science fiction writers and pandering colonising space would lead to human perfection, immortality to all sorts of weaknesses in human nature and psychology, this and the ideal human life. Many of my Russian colleagues in class of scenario cannot be ruled out. the space business, particularly the older generation from the Each of these scenarios are subject to the proposition of some Soviet Regime, still cling to views of this kind. sort of machine intelligence take-over. There is no evidence for The string of organisms along the evolutionary path to the this any more than there is for extra-terrestrial organic life and, human race has already passed through many ‘filters’ which despite being supported by many very distinguished authori- could have eliminated us altogether. More filters, many self-in- ties, the proposition does not, to my knowledge, satisfactorily duced, may await us before we achieve even the colonisation address the question of motive. I am hoping that someone will of the solar system, let alone the galaxy. Other intelligences in attempt this soon. the galaxy will have faced a similar obstacle-race to interstellar The fourth paper by Robert Weinzierl discusses extremo- civilisation. The second paper in this issue, by Kent Peacock, philes, one of the fields of study that has grown considerably discusses this question of the ‘filters’ that we or others may have in importance since the ‘fixing’ of the Fermi Paradox term in to pass. How severe these obstacles are will dictate how rare 1977. The fifth paper by David Clements shows that, in spite of these civilisations are or whether they can exist at all. The third the expansion in the possibility of habitable sites as shown by paper, by Stephen Ashworth, questions whether we have, as yet, extremophiles and the recently confirmed cosmic abundance enough data to assess if we are alone or not. If we are indeed of planets and water that there may be quite subtle filters that alone in the galaxy then there would seem to be two straight- will prevent intelligent life becoming space-faring. Both of forward if disturbing alternative scenarios. these papers increase the Paradox from the point of view of the The first is that the human race is the first (potentially) ‘we are alone’ first two scenarios. The last paper, by Alan Bond, star-faring life-form in the galaxy to evolve so far. Arguments is the only one that addresses an aspect of the third scenario, for this scenario focus on the unlikelihood of either our habitat UFOs, a tricky thing to do properly. As you would expect, some or evolutionary path. If we can make it through the next few interesting ideas emerge. decades and begin to colonise the solar system this would seem Of course the papers presented here only address a tiny frac- to be good news even if a little biblical ‘chosen race’ in nature. tion of the data and research that, added together, make up the The second scenario is the bad news that we may be alone Fermi Paradox. There is, therefore, plenty of motivation to have because no intelligent life emerging in the galaxy makes it as far another symposium sometime in 2019. I am sure that it will as the stage when it can communicate or colonise. This would be as enjoyable and informative as the last. I look forward to it imply that we have only a short while to go before destroying with pleasure. GW

JBIS Vol 71 No.6 June 2018 199 JBIS VOLUME 71 2018 PAGES 200–206

THE ORIGIN OF THE “FERMI PARADOX”

ANTHONY R. MARTIN, The Cleaver Archive, Building C2, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB, UK

If life is common in the Galaxy, and the development of intelligent, technical civilisation is not unique to Earth, then why do we see no signs of this life? This conundrum prompted the famous “Fermi Question” – “Where is everybody?” – and the subsequent “Fermi Paradox”, both referring to the Italian physicist Enrico Fermi. This paper is not concerned with aspects of the “Fermi Paradox” as such, but rather it attempts to document the origin and evolution of the “Fermi Question” and the “Fermi Paradox” itself. The history of the first – the “Question” - is now (relatively) straightforward. That of the latter – the “Paradox” – is not.

Keywords: Fermi Paradox, Fermi Question, Extraterrestrial Intelligence

1 INTRODUCTION lution of what should correctly be termed the “Fermi Ques- tion” – “Where is everybody?” – and the subsequent “Fermi In the field of Interstellar Studies and, in particular, when dis- Paradox” itself. cussing the issue of the existence or otherwise of extra-terrestrial intelligence and the possibilities or searching for and The history of the first – the “Question” – is now (relatively) detecting signals from, or other evidence for the existence of, straightforward. That of the latter – the “Paradox” – is not. intelligent life other than that on Earth, the topic referred to as the “Fermi Paradox” frequently arises. 2 THE ORIGIN AND THE EVOLUTION OF THE “FERMI QUESTION” The attribution is to the Italian physicist Enrico Fermi born in Rome on 29 September 1901. Fermi won the Nobel Prize The definitive origin of the “Fermi Question” has been docu- for physics in 1938 in connection with his work on the atomic mented by careful research carried out by Eric Jones at the Los nucleus and radioactive decay. He moved to work in the Unit- Alamos National Laboratory in New Mexico, USA [2, 3]. ed States shortly afterwards. He was the leader of the group which first achieved self-sustaining nuclear fission in an atomic According to Jones’ work, a conversation took place at Los reactor, or pile, in December 1942. He was a member of the Alamos during the summer of 1950 before and during lunch Manhattan Project to develop the atomic bomb at Los Alamos one day when Enrico Fermi was visiting in his role as consult- during the Second World War. After the war Fermi returned to ant to the ongoing research programme at the Laboratory. As academic life, but still retained links with Los Alamos and the well as Fermi, the lunch time companions were Emil Konopin- post-war activities there. Fermi died on 29 November 1954, at ski, Edward Teller and Herbert York. All three of Fermi’s lunch the tragically early age of 53. partners on that day were able to provide Jones with accounts of the incident. Definitions vary, but the “Fermi Paradox” may be stated, following Stephen Webb [1]: In a universe populated with many According to Edward Teller: extra-terrestrial civilisations – I remember having walked over with Fermi and others to the “if the universe is teeming with aliens” – there could right now be Fuller Lodge for lunch. While we walked over, there was a conver- a million civilisations trying to communicate with us. So why do sation which I believe to have been quite brief and superficial on a we not hear from some of them? In fact, why are they not already subject only vaguely connected with space travel…we talked about here? If some of the civilisations are extremely long-lived, then we flying saucers and the obvious statement that the flying saucers are might expect them to colonise the Galaxy – and have done so be- not real…flying saucers might be due to extraterrestrial people fore multicellular life even developed on Earth. The Galaxy should (here I believe the remarks were purely negative), partly because be swarming with extraterrestrial civilisations. Yet we see no sign exceeding light velocity would make interstellar travel one degree of them. We should already know of their existence, but we do not. more real. Where is everybody? Where are they? This is the Fermi Paradox. We then talked about other things…the discussion had nothing to do with astronomy or with extraterrestrial beings. I think it was This paper is not concerned with aspects of the “Fermi some down-to-earth topic. Paradox” as such, on which a large literature now exists (and Then in the middle of this conversation, Fermi came out with which a comprehensive bibliography of such is surely long the quite unexpected question “Where is everybody?”…The result overdue). Rather, it attempts to document the origin and evo- of his question was general laughter because of the strange fact that

200 Vol 71 No.6 June 2018 JBIS THE ORIGIN OF THE “FERMI PARADOX”

in spite of Fermi’s question coming from the clear blue, everybody was musing, why have we seen no sign of them – by a visitation to around the table seemed to understand at once that he was talking Earth, for example? about extraterrestrial life. In passing, no criticism is made of Sagan misreporting the According to Emil Konopinski: date as “during the Second World War” and “1943”. The present author in a much later 1984 contribution [9] referred to “the There ensued a discussion as to whether the saucers could mid 1940’s”, irritatingly (but perhaps inevitably) one year be- somehow exceed the speed of light and it was after we were at the fore Jones’ definitive work [2, 3]. Also, the “apocryphal” remark luncheon table that Fermi surprised us with the question: “But is disproved even before Jones’ work by the comments in 1976 where is everybody”. of Stan Ulam, a colleague and personal friend of Fermi at Los Alamos and afterwards, that [10]: According to Herb York: Fermi used to ask: “Where is everybody? Where are the signs Fermi said, virtually apropos of nothing: “Don’t you wonder of other life?” where everybody is?”…we all knew he meant extra-terrestrials. He then followed up with a series of calculations on the probability of In a special issue of JBIS Interstellar Studies, on the top- earthlike planets, the probability of life given an earth, the prob- ic of the “Development of intelligence and civilisation in the ability of humans given life, the likely rise and duration of high Universe” in November 1975, Sebastian Von Hoerner wrote technology, and so on. in connection with the evolutionary development of Karda- shev-type civilisations [11]: The evolution of the “Fermi question” into the mainstream discussion of the possible existence of extra-terrestrial intelli- WHERE IS EVERYBODY? gence and the search for it appears to have begun (as with many The Question… things connected with these subjects) with a mention in a paper by Carl Sagan in 1963 [4]. As a footnote to the suggestion of As far as we know, all this is technically well possible. Interstel- the “possibility that contact with an extraterrestrial civilisation lar activities of this scale do not violate any laws of physics. They has occurred within historical times” Sagan said: just need determination and time…Why, then, do we see no interstellar activity, not a single sign of life, among the billions of stars in This possibility has been seriously raised before; for example, by our own Galaxy, among the billions of other galaxies visible in our Enrico Fermi, on a now rather well-known dinner table discussion telescopes? This, indeed is a very serious question. at Los Alamos during the Second World War, where he introduced the problem with the words “Where are they?” Again, no attribution was made for the question.

A short time later Stephen Dole commented in 1965 [5]: In the same JBIS issue, Krafft Ehricke wrote [12]:

One argument against the occurrence of other intelligent life The conclusion is that the probability of another star-faring civ- forms is implied by the question, “If there are so many advanced ilisation or even superior technological civilisation existing within forms of life around, where is everybody?” 20 light years is vanishingly small…the probability that manipu- lative intelligences exist somewhere between Hominid level and However, Dole made no attribution for this quote. stone age may be just a bit higher; the probability that life-sustaining planets exist may be low…the probability of other planetary In the seminal “Intelligent Life in the Universe” Shklovskii systems within 20 light years may be considered fairly high; and, and Sagan in 1966 headlined a chapter in the book with the finally, that the comparatively most promising stars to which to lis- note [6]: ten or direct signals inside the 20 light year limit or beyond are in the late F and the early G class stars… Where are they? In this sense, Fermi’s classical question “Where is everybody?” Enrico Fermi (1943) may be answered with “where the late F stars and the early G stars a r e”. but did not amplify, and made no further reference. This, then, has traced the origin of the “Fermi Question” and A further mention of “Fermi’s Question” occurred in 1971 its evolution up to the mid 1970s. However, the references all in the Project Cyclops report, edited by Barney Oliver and John relate to the “Question”. What of the “Paradox”? Billingham [7]: 3 THE ORIGIN AND THE EVOLUTION OF THE “FERMI If, on the other hand interstellar travel is much easier than we PARADOX” predict, we would argue that to maintain radio silence is no real protection, for in this case a galactic survey would not need to de- In 1975 Michael Hart published a paper [13] which, according pend on beacons. The question to be answered in this case is En- to Stephen Webb [1], “sparked an explosion of interest in the rico Fermi’s Where are they? paradox”. In “An explanation for the absence of extraterrestrials on Earth” Hart wrote: Sagan again in 1973 [8]: Are there intelligent beings elsewhere in our Galaxy? This is In a by now much quoted and possibly even apocryphal story, the question which astronomers are most frequently asked by lay- the nuclear physicist Enrico Fermi asked during a luncheon con- men. The question is not a foolish one; indeed, it is perhaps the versation at Los Alamos in the middle 1940’s, “Where are they?”. most significant of all questions in astronomy. In investigating the If there are vast numbers of beings more advanced than we, he problem we must therefore do our best to include all relevant ob-

JBIS Vol 71 No.6 June 2018 201 ANTHONY R. MARTIN

servational data. within the Galaxy, and that consequently there could have been Because of our training, most scientists have a tendency to dis- no visitations to this solar system by other civilisations.’ regard all information which is not the result of measurements… In the present matter, however, that policy has caused many of us to The present author agrees with this attribution by Gray of disregard a clearly empirical fact of great importance, to wit: There the appearance in the archival literature, but would argue that are no intelligent beings from outer space on Earth now…’Fact A’. this does not equate to the origination of the “Fermi Paradox” Once this is recognised, an argument is suggested which indi- itself. David Stephenson was well aware of Viewing’s contri- cates an answer to our original question. If, the argument goes, there bution, quoting it as the second reference in his 1977 paper were intelligent beings elsewhere in our Galaxy, then they would [16] (the first reference being to Hart). Gray briefly mentions have eventually achieved space travel, and would have explored and Viewing’s paper, but without quoting any of the relevant text, as colonized the galaxy, as we have explored and colonized the Earth. done above in the present paper. However, (Fact A) they are not here; therefore they do not exist. As an aside, the present author acknowledges Gray’s work, Hart makes no mention of Fermi, does not ask the “Ques- his paper having been one of the catalysts for the present study. tion”, and makes no inference regarding the existence of a “Par- Gray covers some, but not all, of the history of the “Question” adox”. Nevertheless, this paper is now seen as a seminal contri- as outlined above. However, it is thought that the present au- bution and “led to a vigorous debate” [1]. thor’s recollections (even if from a period over 40 years ago) of events (even if only in the United Kingdom) should at least be However, also in 1975, in the third paper appearing in the on the record of the origin and evolution of the “Paradox”. special issue of JBIS Interstellar Studies referred to above, another contribution appeared which led to just as vigorous a de- There was in the United Kingdom in the early 1970s an in- bate, at least initially within the United Kingdom. In “Directly teractive discussion taking place among people with an interest interacting extra-terrestrial technological communities” David in Interstellar Studies (mainly, but not exclusively, members of Viewing wrote [14]: the British Interplanetary Society). The “New Frontiers” series of papers on futuristic topics, organised by Ken Gatland, had If there are no other civilisations nearby, in a few millions of been appearing in Spaceflight. The Project Daedalus Starship years our descendants might have established thriving colonies on Study was ongoing (January 1973 – May 1978) and the mem- most of the suitable planets in our part of the galaxy – millions of bers of the Study Group met frequently for discussions, both worlds. An eventual limit might be as high as 10 percent of the on Daedalus and on other topics of relevance and interest. stars in the galaxy with planets carrying human communities – ten JBIS Interstellar Studies (the “Red Cover” issues of JBIS), edit- thousand million worlds! ed by the present author, started appearing in April 1974. Dis- However, we are unlikely to be first. Someone – a naturally cussions and debates took place on a continual basis, and old evolved biological intelligence produced by natural selection and concepts and new ideas were examined and aired. The present having all the instincts of survivability, expansion and propagation author was there, and participated in what was an exciting and that we possess – must have already made these points, billions of productive time in the evolution of Interstellar Studies. years ago. Only – they were first. It is said that Enrico Fermi first asked the question, many years As specific instances relating to the paper by Viewing: ago, which lies at the core of this problem. It is simply: “Where are they?” • Th e present author has on file a correspondence (“Dear This argument presents, in my view, a paradox. Shklovskii has Carl”/“Dear Tony”) during December 1974 to February coined the phrase “Cosmic Wonder” to denote a manifestation of 1975 with Carl Sagan, prior to the publication of the pa- intelligent activity on the cosmic scale which can be observed from per, on the subject of Viewing’s paper and relating details afar. However, no such observations have apparently been made to of a visit paid by Alan Bond and Tony Martin to The Ex- date, despite the considerable sensitivity of modern astronomical tra-terrestrial Society’s laboratory in Peterborough, UK techniques… (formed by Viewing and his associates to carry out prac- This, then, is the paradox: all our logic, all our anti-isocentrism, tical research). assures us that we are not unique – that they must be there. And • A lan Bond was one of the people acknowledged for yet we do not see them. “many helpful comments and encouragement during the preparation of this paper” [14]. It is the present author’s contention that this contribution of • B ob Parkinson made reference [17], in the fourth paper Viewing should be regarded as the origin of the “Fermi Para- in the November 1975 special issue of JBIS Interstellar dox”, even though that exact phrase was not used in the paper. Studies referred to above, to Viewing’s paper having seen Webb is in agreement with this when he writes [1]: a preprint prior to publication. • Harry Langton [18], in a contribution published in the Viewing acknowledges that Fermi was first to ask the important July-August 1976 issue of JBIS Interstellar Studies, notes: question – “Where are they?” – and that this question leads to a paradox. To my knowledge, then, this paper is the first that refers It is often deduced that the galaxy should contain an abundance directly to the Fermi paradox. of civilisations at a technological level equal to or greater than our own. If this is the case, the question as to why these other civili- In a recent paper Robert Gray notes that [15]: sations have not been detected appears to present a paradox, as mentioned by Viewing. The question “where is everybody?” has The phrase ‘Fermi Paradox’ seems to have first appeared in recently been discussed by von Hoerner…and by Parkinson…The print in March of 1977, referring to Fermi’s question “where is purpose of this paper is to attempt an explanation which may be a everybody?” Stephenson (1977): possible answer to this paradox. The first and simplest answer to ‘Fermi’s paradox’ has been put forward by Hart …mankind is the first intelligent species It is argued that this documented evidence indicates an ac-

202 Vol 71 No.6 June 2018 JBIS THE ORIGIN OF THE “FERMI PARADOX” tive and lively interaction and discussion of Viewing’s paper session in April, 1977 (Martin, et al, 1979), and the phrase began around the time of its appearance and afterwards. appearing frequently in the early 1980s – cited in 19 places in one SETI symposium (Papagianis, 1984)… On the afternoon of 5 April 1977, the month after Stephen- son’s paper [16] was published, a discussion session was held The Martin reference is [19] and the Papagianis reference as part of the 2nd. BIS Conference on Interstellar Travel and is [20]. The index to the Symposium notes citations to “Fer- Communication in London, UK. The session was entitled “The mi Paradox” in 19 places in the contributions. Actually, two of Fermi Paradox – A Forum for Discussion” [19]. This Confer- the citations are to “Fermi’s Paradox” and four of the “Fermi ence, organised by the present author, had been in the planning Paradox” citations refer to editorial material by Mike Papagi- for about one year, with the first announcement being made anis and so should properly be ignored. On the other hand one in Spaceflight in November 1976. The provisional programme other citation (at least) was missed by the indexing, so this cer- was published in Spaceflight for April 1977, which was actually tainly represents frequent use of the phrase. Gray thus implies published on 25 March 1977, and included “Panel discussion that between 1977 and 1984 (the date of the Symposium; pub- on “The Fermi Paradox””. Thus the appearance of the term in lication was a year later) little happened to the “Fermi Paradox” the non-archival literature (the programme was printed on the until the latter date saw its entry into mainstream literature. magazine cover, rather than in the magazine proper) coincided precisely with the use by Stephenson. The present author notes this attribution by Gray of the frequent appearance in the archival literature, but would argue The Forum format was for four speakers (Tony Martin, Da- that this does not equate to the start of the widespread usage vid Viewing, Alan Bond, Gerry Webb) to give a presentation, of the term and discussion of the topic. It is argued that this followed by comments by other participants in the discussion was, in fact, occasioned by the appearance in print of the pro- from the audience. “Each of the four was asked to present a ceedings of “The Fermi Paradox – A Forum for Discussion” particular aspect of the topic” [19]. in 1979 [19]. Here “Fermi’s Paradox” occurs four times, “the Fermi Paradox” appears fifteen times, and there are twenty two It is argued that between the publication of Viewing’s pa- references to “the paradox”. per in November 1975 and the Conference in April 1977 (16 months) the expression “the Fermi Paradox” had become well- To quote from the introduction by Martin [19]: known, widespread and in common usage, at least in the UK, as a result of discussions and interactions between the Inter- THE “FERMI PARADOX” – if life is common in the Galaxy, stellar Studies community. This allowed four people to prepare and the development of intelligent, technical civilisation is not remarks for presentation in advance of the Conference, for unique to Earth, then why do we see no signs of this life – is be- four others (Enrico Coffey, Bob Parkinson, Ian Ridpath, David coming one of the most frequently discussed topics in Interstellar Speed) to make lengthy contributions to the discussion at the Studies in view of its fundamental importance. Conference, and for the Conference audience of about 40 peo- Although many possible resolutions to the paradox have been ple to be aware of and understand the expression “the Fermi proposed, no completely adequate solution has yet been given. The Paradox”, and to participate in the general discussion following Oxford English Dictionary defines a paradox as “A statement seem- the above contributions (the present author has on file a tape ingly self-contradictory or absurd, though possibly well-founded recording of the session). or essentially true. (b) often applied to a proposition that is actually self-contradictory, and so essentially absurd or false”. In the first It should be emphasised that the present author makes no case we have not found the resolution to the paradox; in the sec- claim for originating the expression “the Fermi Paradox”, only ond, the premises upon which the paradox lies must be false, but that he participated in the wide discussions of the topic that led we have not identified where the fault lies. to the organic development of the phrase in the UK. During the 2nd BIS Conference on Interstellar Travel and Com- munication, held in London on 4-5 April 1977, one complete after- That this was the case in North America, and certainly Can- noon session was devoted to the discussion of the Fermi Paradox… ada, as well can be inferred from a comment by David Stephen- It is our hope that the publication of this material will stimulate son in 2014, quoted by Gray [15]: thoughts and discussion…and that we will be able to publish further contributions to this topic… At the time the word paradox was used in conversation to de- If even a few civilisations are stable over relatively long periods scribe the problems facing SETI researchers and Carl Sagan’s story of time (relative, that is, to the age of the Galaxy) then even very about Fermi and “Where is everybody” was often mentioned. I put slowly progressing colonisation is sufficient to populate the whole single quotes around ‘Fermi’s Paradox’ … as an apology for using of the Galaxy. a short convenient two word label for a large and indistinct field of For long lifetimes of a few races of intelligent beings, then, the conjecture. Universe should be teeming with intelligent life – communicating, visiting, colonising, using energy, engaging in large scale engineer- The evolution of the “Fermi Paradox” into the mainstream ing activities, tripping over each others feet, and generally making discussion of the possible existence of extra-terrestrial intelli- their presence felt. gence and the search for it is now examined. How did events But, we look into the night sky, we listen with our radio tele- unfold between March 1977 and June 1984? The relevance of scopes, our radars scan the skies, we keep our minds and our eyes the latter date is that this was when the 112th Symposium of the open – and yet we see no signs of them at all. International Astronomical Union took place, on the subject of Enrico Fermi first put explicit expression to the Paradox- “The Search for Extraterrestrial Life: Recent Developments” [20]. “Where is Everybody?”

Gray notes [15]: That this was the point where the “Fermi Paradox” saw its entry into the mainstream literature can be illustrated by a brief The Fermi paradox appeared as the subject of a conference review of activity between this date and 1984.

JBIS Vol 71 No.6 June 2018 203 ANTHONY R. MARTIN

First, Stephenson’s “Fermi’s Paradox” [16]. Stephenson him- we believe quite logical, conclusion has profound implications for self used this wording in a further contribution in 1979 [21]: the search for CETI. Unfortunately, the full import of this conclusion does not seem to be widely appreciated. The goal of this paper If the concept of mankind as a unique being is seen to run coun- is therefore to reanalyse in greater depth the implications of Hart’s ter to the modern philosophy and experience of science Fermi’s and Viewing’s observations on interstellar travel. paradox becomes apparent – “Where is everybody?”…The process of refining the accepted models for the behaviour of an advanced Also in 1982 Tang published a paper [25] which noted: interstellar culture must continue as the search for alien intelligence advances. Of the two models presented here Fermi’s paradox seems …the plurality of life-bearing planets in our Galaxy is asserted to question the virus model of interstellar expansion…The struc- by modern science…the expected number of indigenous galactic ture of an advanced interstellar culture must be far different from civilisations…is still commonly reckoned as large…Nevertheless, any that has existed on Earth. Unless great care is taken simplistic we have had no sight of them, in particular no substantive evi- models of such cultures will exhibit paradoxes such as Fermi’s… dence of visitations past or present. The resolution of this conflict between observation and expectation, sometimes called the Fermi It must be noted that the “Question” was still being asked at Paradox, is the purpose of this paper. this time. A symposium on “Where are They? A Symposium on the Implications of Our Failure to Observe Extraterrestrials” In 1983 the present author, together with long-time friend was held in November 1979. In the written proceedings of the and colleague Alan Bond, entered the fray [26, and in a short- symposium Ben Zuckerman wrote (in December 1980) [22]: ened form in 27]:

Where are they? Enrico Fermi is reputed to have asked this The “Fermi Paradox” – if extraterrestrial intelligent beings exist question at the dawn of the atomic age. He must have been won- elsewhere in the Galaxy, then we should see signs of their presence dering why, having discovered and tamed nuclear energy sources, – has remained unresolved for over 35 years. This paper presents advanced extraterrestrials were not in evidence here on Earth or some simple arguments which appear to rule out the possibility of out in the skies. a highly populated Galaxy, and which suggest instead that Man- During the 1960’s and early 1970’s, Fermi’s question was largely kind may in fact live in an otherwise uninhabited Galaxy. forgotten or ignored… The absence of advanced extraterrestrials on the Earth and, very This paper was followed up in 1984 by a paper [9] which the probably, in the solar system has been interpreted by various sci- authors regard as their definitive contribution on the subject: entists…as evidence such creatures may not exist anywhere in our Milky Way galaxy. Thus, Fermi’s question has now reemerged to If intelligent life is a common occurrence in the Galaxy, then haunt our minds. many civilisations should have arisen which by now are far in ex- cess of mankind in both their age and their capabilities. It is to It is interesting that in the following 17 contributions to the be expected on technical grounds that some of these should have symposium there was no further mention of Fermi. crossed the threshold of their home planetary system and ventured out into interstellar space. In a time that is short when measured In a paper by Kuiper in 1980 he wrote [23]: against astronomical timescales such civilisations could have colonised the planets orbiting every suitable star in the Galaxy. This brings us to the famous paradox attributed to Enrico Fer- As the Solar System is relatively young in the Galaxy, there should mi, which asks “Where are they?”… never have been a time in our history when mankind was not aware It seems to be very difficult to remove anthropocentrism from of the presence of such civilisations. And yet, we apparently see no our considerations of Mankind’s status in the Universe. In the “Fer- signs of intelligent life in the Galaxy other than ourselves! mi Paradox”, for example, lies buried the assumption that Mankind This paradox, now well known, was first expressed by Enrico must be so interesting a phenomenon that a galactic civilisation… Fermi 40 years ago, and today is still as relevant to discussions on is compelled to establish contact with us, or alternatively, that the the possible existence of intelligent life in the Universe and the earth is so desirable an environment that this civilization would methods of searching for signs of such life as it was then. have colonized it long before Mankind ever evolved. Since neither The authors have reviewed the many aspects of the Fermi Par- of these has happened, therefore Mankind must be a unique phe- adox for the last decade, and have recently entered the debating nomenon in the Galaxy (if not the Universe)! chamber. This present paper is an attempt to further contribute to that debate by exploring some of the arguments prompted by the Cliff Singer published a paper in 1982 [24] which, while not Paradox in more detail than we have previously commented on. mentioning the “Fermi Paradox”, was motivated by it. He ref- We emphasise that we are participating in a debate which has been erences (among many other sources) Hart, Viewing and “The underway for several years now, and which has well-developed ar- Fermi Paradox – A Forum for Discussion”. He uses the phras- guments covered in depth in the literature. It is our conclusion that es “resolve our paradox” and “resolution of the paradox”. The all of these arguments have only one self-consistent resolution – present author was one of the people acknowledged for “help- mankind is unique in the Galaxy. It is our hope that, by elaborating ful discussions” (Singer was working in London at the time) some of the key concepts which we find persuasive, we will cause and can attest to the connection. the debate to refocus on the Paradox that Fermi identified so many years ago. If indeed the Galaxy has been populated by a large number of ETI capable of broadcasting CETI, then some of these ETI may In 1983 Robert Frietas made two early contributions [28, also have undertaken direct interstellar exploration. If interstellar 29], of many which were to follow, specifically motivated by exploration is feasible, then at least one of the ETI undertaking the Fermi Paradox. To quote from [28]: such exploration might have undertaken interstellar settlement, possibly instigating a wave of settlement which would reach even- The Fermi Paradox, attributed to a question from Enrico Fermi tually to the farmost confines of the Galaxy. This remarkable, but after a discussion on the possibility of extraterrestrial life during

204 Vol 71 No.6 June 2018 JBIS THE ORIGIN OF THE “FERMI PARADOX”

the 1940’s, is traditionally formulated as follows: If there are intel- maintained that this selection is more than sufficient to substan- ligent beings elsewhere, then in time they must achieve the tech- tiate the claim that the appearance in print of the proceedings of nology of nuclear power and spaceflight and would explore and “The Fermi Paradox – A Forum for Discussion” in 1979 repre- colonise the Galaxy, as humanity has explored and colonised the sents the real point in time of the entry of the “Fermi Paradox” Earth. Thus they should have been able to travel to Earth, but we into the literature of Interstellar Studies, and not at a later date. see no evidence of such visitations, ergo they cannot exist. Fermi’s question “Where are they?” implicitly construes the absence of ex- It should be noted that the above literature selection is con- traterrestrials on Earth as positive evidence of their nonexistence fined to contributions that make specific reference to the “Fer- elsewhere in the Universe. mi Paradox”. Many other papers were written which were mo- Dormant for many decades, recently the Fermi Paradox has re- tivated by discussions of various aspects of the Paradox. As a emerged as a modern challenge to the existence of extraterrestrial personal example, the present author together with Alan Bond intelligences (ETI)… examined various aspects of the Paradox, publishing the results in papers which did not refer to Fermi, but were driven by at- In 1985 Paul Birch wrote [30]: tempts to grapple with the issues which they perceived to be raised by the “Fermi Paradox”. A somewhat different objection to indefinite population growth is that migration would be too costly or too slow, even if enough Neither does it deliberately set out to discount or ignore the new territory could be found. In the field of interstellar colonisa- many other studies published during that period, but which tion (von Hoerner) purported to show that exponential population did not directly make mention of the “Fermi Paradox”. Perhaps growth must cease, because of the limited speed of migration pos- the best example of this is the paper by Frank Tipler [34]. This sible from a growing sphere of influence. This idea has been used had an impact similar to that of Viewing [14] and Hart [13] by CETI supporters as a rationalisation of the Fermi Paradox (“if when it was published, and “poured oil on the fires of the de- extraterrestrials exist, where are they?”)… bate and led to a further round of argument” [1]. Tipler made In this paper we shall argue that such considerations are mis- reference to the Fermi Question quote of [4], but nothing guided, and that there is every reason to believe in the potential for more, and therefore is not included here. This does not mean indefinite population growth. that his arguments were not appreciated at the time. In a later paper [35] Tipler notes “The article…was circulated in the It must be pointed out that not everyone acknowledged Fer- form of a preprint amongst various people who are interested mi. In a classic review of the topic in 1983 David Brin noted [31]: in the question of extraterrestrial intelligence”. Among the people who Tipler was “grateful for extensive discussions on the Recent discussions concerning the likelihood of encountering subject” was “A. R. Martin”. extraterrestrial technological civilisations have run into an apparent paradox. If, as many now contend, interstellar exploration and 4 CONCLUSIONS settlement is possible at non-relativistic speeds, then reasonable calculations suggest that space-faring species, or their machine This paper has attempted to follow the origin of the “Fermi surrogates, should pervade the Galaxy. The apparent absence of question” – “Where is everybody” in relation to the apparent evidence for extraterrestrial civilisations, herein called ‘the Great absence of any signs of extra-terrestrial civilisations in our Gal- Silence’ places severe burdens on present models. axy – and its subsequent evolution into the “Fermi Paradox”.

This is a concise statement of the “Paradox” but, although The origin of the “Question” has been carefully and con- Brin referenced “The Fermi Paradox – A Forum for Discussion”, vincingly documented by Eric Jones and traced to a lunchtime no reference to Fermi was made. That the two are one and the conversation at Los Alamos in the summer of 1950. This paper same was soon after acknowledged by, for example, Vallee [32]: has reprised some of this evidence and followed the subsequent usage and evolution of the “Question” to 1975. A summary is made of a program to scan slowly a band of sky in search of strongly linearly polarized radio signals from E.T.I. com- Between 1975 and the appearance in print, in both the archi- munication relays. Despite this and numerous other observational val and non-archival literature simultaneously in March 1977, searches, no signals have been found. An optimist approach to this the phrase “the Fermi Paradox” gained widespread usage in the great silence (Fermi’s paradox) is developed. United Kingdom. This paper associates the first appearance of the linking of “Fermi” and “paradox” (though, admittedly, not and Papagiannis [33]: the use of the exact phrase) with a paper by David Viewing published in November 1975. After this, it is argued, interac- The absence of any scientifically verifiable past or current -con tive wide discussions of the topic taking place among people tacts with extraterrestrials on Earth has become known as the “Fer- with an interest in Interstellar Studies (mainly, but not exclu- mi Paradox” and is also referred to as “The Great Silence” sively, members of the British Interplanetary Society) resulted in the organic development of the phrase “the Fermi Paradox” This brings the account of the evolution of the “Fermi Par- in the UK. There is evidence that this was also the case in North adox” up to the date of the publication of the IAU Symposium America, and certainly Canada, leading to the use of the phrase [20], which Gray [15] implies was the date that the “Fermi Par- “Fermi’s Paradox” by David Stephenson in 1977. adox” entered into mainstream literature. Tracing the further evolution of the “Fermi Paradox” in the The present author makes no claim about the completeness literature, it is then argued that the appearance in print of the of this selection of literature contributing to the discussion of proceedings of “The Fermi Paradox – A Forum for Discussion” the “Fermi Paradox”. It has been compiled with reference to in 1979 represents the real point in time of the entry of the the files which still exist in his records. As already mentioned, “Fermi Paradox” into the literature of Interstellar Studies, and most of this work took place 40 or more years ago. However, it is not at a later date.

JBIS Vol 71 No.6 June 2018 205 ANTHONY R. MARTIN

REFERENCES 1. S. Webb, If the Universe is Teeming With Aliens…Where is Everybody? Journal of the British Interplanetary Society, 32, 424 – 434 (1979). Fifty Solutions to the Fermi Paradox and the Problem of Extraterrestrial 20. M. D. Papagianis (Ed.), International Astronomical Union Symposium Life, Copernicus Books, 2002. No. 112, The Search for Extraterrestrial Life: Recent Developments, D. 2. E. M. Jones, “’Where is everybody?’ An account of Fermi’s Question”, Reidel Publishing Company, 1985. Los Alamos National Laboratory LA-10311-MS, March 1985. 21. D. G. Stephenson, “Extraterrestrial cultures within the Solar System?”, 3. E. M. Jones, “Fermi’s Question”, pp. 298 – 300 in B. R. Finney and E. Quarterly Journal of the Royal Astronomical Society, 20, 422 – 426 M. Jones (Eds.), Interstellar Migration and the Human Experience, (1979). University of California Press, 1985. 22. B. Zuckerman, “Preface”, p. vii in M. H. Hart and B. Zuckerman (Eds.), 4. C. Sagan, “Direct contact among galactic civilizations by relativistic Extraterrestrials: Where Are They?, Pergamon Press, 1982. interstellar flight”, Planetary and Space Science, 11, 485 – 498 (1963). 23. T. B. H. Kuiper, “Galactic-scale civilization”, pp. 35 – 43 in M. D. 5. S. H. Dole, The search for a rational for interstellar communication”, Papagianis (Ed.), Strategies for the Search for Life in the Universe, D . RAND Paper P-3296, Symposium on “Communication with Reidel Publishing Company, 1980. Extraterrestrial Life”, 132nd. Annual Meeting of the American Association 24. C. E. Singer, “Galactic extraterrestrial intelligence I – The constraint on for the Advancement of Science, Berkeley, California, December 1965. search strategies imposed by the possibility of interstellar travel”, Journal 6. I. S. Shklovskii and C. Sagan, Intelligent Life in the Universe, p. 448, Dell of the British Interplanetary Society, 35, 99 – 115 (1982). Publishing Company, 1966. 25. T. B. Tang, “Fermi Paradox and C.E.T.I.”, Journal of the British 7. B. M. Oliver and J. Billingham, p. 31 in Project Cyclops: A Design Study Interplanetary Society, 35, 236 – 240 (1982). for a System for Detecting Extraterrestrial Life, NASA CR-1114445, 1971. 26. A. R. Martin and A. Bond, “Is Mankind unique? – The lack of evidence 8. C. Sagan, The Cosmic Connection, p. 229, Anchor Press, 1973. for extraterrestrial intelligence”, Journal of the British Interplanetary 9. A. R. Martin and A. Bond, “Is mankind unique in the galaxy?”, Paper Society, 36, 223 – 225 (1983). IAA-84-239, 13th International Academy of Astronautics International 27. A. R. Martin and A. Bond, “Is Mankind unique?”, Spaceflight, 25, 254 – Review Meeting on Communication with Extraterrestrial Intelligence, 256 (1983). 35th. International Astronautical Federation Congress, Lausanne, 28. R. A. Freitas Jr., “Extraterrestrial intelligence in the Solar System: Switzerland, October 1984. Resolving the Fermi Paradox”, Journal of the British Interplanetary 10. S. M. Ulam, Adventures of a Mathematician, p. 302, Charles Scribner Society, 36, 496 – 500 (1983). Sons, 1976. 29. R. A. Freitas Jr., “The search for extraterrestrial artifacts (SETA)”, 11. S. von Hoerner, “Population explosion and interstellar expansion”, Journal of the British Interplanetary Society, 36, 501 - 506 (1983). Journal of the British Interplanetary Society, 28, 691 – 712 (1975). 30. P. Birch, “Can population grow forever?”, Journal of the British 12. K. A. Ehricke, “A long-range perspective and some fundamental aspects Interplanetary Society, 38, 99 – 105 (1985). of interstellar evolution”, Journal of the British Interplanetary Society, 28, 31. G. D. Brin, “The ‘Great Silence’: the controversy concerning 713 – 734 (1975). extraterrestrial intelligent life”, Quarterly Journal of the Royal 13. M. H. Hart, “An explanation for the absence of extraterrestrials on Astronomical Society, 24, 283 – 309 (1983). E a r t h”, Quarterly Journal of the Royal Astronomical Society, 16, 128 – 135 32. J. P. Vallee, “Search for strongly polarized radio emission from E.T.I., (1975). and an optimist approach to the great silence”, pp. 321 – 325 in M. D. 14. D. Viewing, “Directly interacting extra-terrestrial technological Papagianis (Ed.), International Astronomical Union Symposium No. communities”, Journal of the British Interplanetary Society, 28, 735 – 744 112, The Search for Extraterrestrial Life: Recent Developments, D. Reidel (1975). Publishing Company, 1985. 15. R. H. Gray, “The Fermi Paradox is neither Fermi’s nor a paradox”, 33. M. D. Papagiannis, “An infrared search in our Solar System as part Astrobiology, 15, 195 – 199 (2015). of a more flexible search strategy”, pp. 505 – 511 in M. D. Papagianis 16. D. G. Stephenson, “Factors limiting the interaction between (Ed.), International Astronomical Union Symposium No. 112, The Search twentieth century man and interstellar cultures”, Journal of the British for Extraterrestrial Life: Recent Developments, D. Reidel Publishing Interplanetary Society, 30, 105 – 108 (1977). Company, 1985. 17. B. Parkinson, “The starship as a philosophical vehicle”,Journal of the 34. F. J. Tipler, “Extraterrestrial intelligent beings do not exist”, Quarterly British Interplanetary Society, 28, 745 – 750 (1975). Journal of the Royal Astronomical Society, 21, 267 – 281 (1980). 18. N. H. Langton, “The probability of contact with extra-terrestrial life”, 35. F. J. Tipler, “Additional remarks on extraterrestrial intelligence”, Journal of the British Interplanetary Society, 29, 465 – 468 (1976). Quarterly Journal of the Royal Astronomical Society, 22, 279 – 292 (1981). 19. A. R. Martin (Ed.), “The Fermi Paradox – A forum for discussion”,

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206 Vol 71 No.6 June 2018 JBIS JBIS VOLUME 71 2018 PAGES 207–211

FERMI AND LOTKA: the Long Odds of Survival in a Dangerous Universe KENT A. PEACOCK, Department of Philosopy, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta, Canada T1K 3M4 email [email protected]

Fermi’s Paradox is the contradiction between the fact that it would seem to be highly probable that there are other technologically advanced species beyond the Earth, and the fact that there is no generally accepted evidence for their existence. Hanson and Bostrom have proposed that there may be a Great Filter, a survival challenge so lethal that it prevents virtually all species from evolving to an advanced stage. This paper argues that the Great Filter would be not one single factor, but rather simply the statistics of survival in an always-dangerous universe. The frequency of species that survive multiple existential threats would likely obey a power law such as Lotka’s Law, such that the frequency of survivors would diminish as an inverse power of the number of threats. Since any species that advances to the point at which it is detectable on an interstellar scale likely must survive a large number of existential threats, by Lotka’s Law the number of such survivors would be a very small fraction of the candidate species that evolve on various planets. Some sobering implications of this picture are outlined.

Keywords: Fermi’s Paradox, Lotka’s Law, extinction, Great Filter

1 FERMI’S PARADOX AND THE GREAT FILTER Great Filter as follows:

This paper will argue that a well-known statistical principle Th e Great Filter can be thought of as a probability barrier. called Lotka’s Law could provide some insight into Fermi’s It consists of one or more highly improbable evolutionary Paradox (also called the Fermi Problem). This problem is the transitions or steps whose occurrence is required in order contradiction between the fact that there is little or no reliable for an Earth-like planet to produce an intelligent civiliza- or generally agreed-upon evidence that humanity has detect- tion of a type that would be visible to us with our current ed or has been visited by extraterrestrials, and the fact that it observation technology [2]. seems to be virtually certain, on general physical and biological grounds, that intelligent life must exist on many other worlds The question that worries Bostrom is whether the Great Fil- throughout the universe. ter has already operated in the past or will operate in the future. If it tends to operate at some fairly early stage in the evolution This paper will not exhaustively review the numerous at- of life, then, Bostrom suggests, humanity can breathe a cau- tempts to resolve the Paradox. (Webb [23] presents a useful tious sigh of relief, since we would be on one of the very few survey of the possibilities, while Heinlein and Robinson [8] planets if not the only planet to have dodged the celestial bullet provide a sobering alternative perspective.) Nor will this paper and we would therefore have a chance of a comfortably long attempt a calculation of the probability of life on other worlds future ahead of us. And we would have reason to believe the in our galaxy, except to note that recent dramatic results from Filter has already done its lethal work in the past if we were to the Kepler probe and other astronomical observations have find absolutely no evidence of life elsewhere in the universe. If, only made the Fermi Problem more acute by vastly increasing on the other hand, we find evidence of extinct or primitive life the probable number of exoplanets in the Galaxy [12]. Instead, on other nearby worlds such as Mars, but continue to fail to de- the aim here is to understand why highly advanced life is (ap- tect evidence of advanced civilizations, that would suggest that parently) rare given that simple life must be rather common the Great Filter tends to act at later stages in the evolution of throughout the universe. complex life, and that it therefore likely awaits us in our future. Bostrom (perhaps with tongue in cheek) therefore suggests A paper by Nick Bostrom [2] adds an intriguing twist to that we should be glad if we do not find any evidence of life, ei- the debate over Fermi's Paradox. Following Robin Hanson ther extant or extinct, on planets within our own solar system. [7], Bostrom suggests that a reason why life, or at least very advanced life, might be scarce in the universe is that there is One problem with the Great Filter hypothesis is that we a Great Filter that every species encounters at some point in presently are not aware of any physical or biophysical basis its evolution, some survival challenge so lethally effective and for any single type of lethal effect that could operate with near- universally pervasive that almost no life can pass through it 100% efficiency at the same stage in the development of life on its evolutionary path from simplicity to complexity. This on virtually every habitable planet. Chopra and Lineweaver [3] survival filter has to be something that would operate with argue that there may be ‘Gaian’ bottlenecks in the development near certainty throughout the universe. Bostrom explains the of a planetary biosphere: life on many planets may not evolve

JBIS Vol 71 No.6 June 2018 207 KENT A. PEACOCK quickly enough to develop the ability to regulate greenhouse gasses and albedo so as to maintain climate within habitable limits. However, even this proposed survival challenge would probably not act universally enough to serve as Hanson and Bostrom’s Great Filter; after all, we know of at least one planet (ours) that so far has (narrowly) evaded the Gaian bottleneck, and it is not plausible that our planet is unique or even all that rare on a large enough scale. Possibly the closest thing presently known that could amount to a Great Filter would be gamma ray bursts (GRBs). Piran and Jimenez [17] argue that there is an appreciable probability that GRBs could harm or even extinguish complex life on Earth (by damaging the ozone layer) and a near-certainty that GRBs would have prevented the evolution of life in the early universe and in the star-dense percentage of authors central regions of galaxies in the present epoch. Again, though, despite the dangers they pose, it is not clear that even GRBs could be as universally lethal as the Great Filter hypothesis de- mands; furthermore, they could impact a species at any stage in its development.

Of course, we cannot rule out the possibility that there are other survival challenges as yet unknown that could act with number of publications the high frequency and lethality necessary to count as a Great Filter. This paper, however, will outline the possibility that if Fig.1 Lotka’s Law of Scientific Publication. (Adapted from Lotka [9]) there is anything like a Great Filter, it lies not in some single but presently unknown physical or biophysical principle, but simply in the statistics of survival in a generally dangerous uni- kills, submarine kills, and tank-combat kills follow Lotka-like verse. The proposal outlined here would demand revision of power distributions [1]. Ormerod [14] argues that while new some of the factors in the Drake Equation, with the effect of corporations may proliferate rapidly in the right conditions, the significantly lowering the probability of contact with extrater- relatively small number that survive a large number of business restrial intelligence even if primitive life is abundant. cycles is described, again, by a power law. As Ormerod puts it, most things fail. 2 THE LOTKA CURVE Lotka’s Law is one of several power laws, including Pare- In 1926 the mathematical biologist A. J. Lotka published a study to’s and Zipf’s Laws, that are found to occur widely in nature of the statistics of scientific publication [9]. Based on two large [4,13,14]. The physical and mathematical basis of power laws databases of publications in chemistry and physics, Lotka found is still not fully understood, despite their simplicity and wide- that there is an inverse relation between the number of papers spread occurrence. (See Newman [13] for extensive review.) published and the number of people publishing them; that is, Murray argues that Lotka-like outcomes will show up most a rather small number of scientists were publishing most of the strongly (that is, the curve will peak more sharply to the right) papers. Lotka showed that the relationship between the num- in fields in which high accomplishment is exceptionally diffi- ber of publications n and the frequency f(n) with which authors cult [11, pp. 90–106]. However, even though we lack a com- have n publications is well-approximated by the power law pletely satisfactory general explanation of power laws, all of the cases where Lotka-like curves have been found to apply do (1) have one feature in common: they involve series of trials with binary outcomes. Lotka’s original example of scientific publication is an illustration: a paper is either published or it is not, where a and C are constants. As shown by Lotka himself [9] and with no in-between. The numerous kinds of citations studied in Newman [13], C is a normalization constant that appears in by Murray possess the same rudely binary quality; a book, an any typical power law of this form. The physics is in the exponent artwork, a scientific paper, or a piece of music is either cited a; in Lotka’s Law it possibly represents, in part at least, complex or not. Murray also shows that several kinds of win-or-lose and hard-to-analyse weighting factors having to do with the in- sporting events follow a Lotka curve. Professional golf is an nate talent of the individual authors, their varying circumstanc- example: a golfer either wins a tournament or does not, tertium es, and possible correlations between successive publications. non datur. Murray shows that only a very small number of (Successful authors tend to publish more often, partially as a outstanding players won most of the PGA (Professional Golf- result of their success: ‘Those who have, get’.) Takinga = 2 and ers Association) tournaments held up to 2001. By contrast, the C = 0.6 (i.e., 60%), close to the values found by Lotka in his tab- distribution of quantifiable golfing skills, such as how accu- ulation of scientific publications, we get the familiar Lotka hy- rately a player can putt or how far he can drive a ball, tends perbola showing the relationship between the number of publi- (according to Murray) to follow something close to a normal cations and the number of authors with that many publications (Gaussian) distribution. (Fig.1). Charles Murray [11] carried out an extensive study of eminence in many fields of human activity from the arts to the There are, to be sure, obvious disanalogies between some of sciences. He showed that if frequency of citations can be taken these cases. The ecology of professional golfing is much more as a measure of excellence, then accomplishment in many fields forgiving than the ecology of wartime dogfights; we do not ex- also follows a Lotka curve (though with some variation in the ecute professional golfers who fail to win a tournament, while values of the exponent). There also is evidence that combat pilot fighter pilots who lose a dogfight rarely fly again. In order to

208 Vol 71 No.6 June 2018 JBIS FERMI AND LOTKA: the Long Odds of Survival in a Dangerous Universe maintain a supply of competitors, the PGA allows runners-up Existential risks to a species can be roughly classified into to earn enough money to stay in the game. But the statistics those due to external factors and those that are self-induced. of tournament wins is uncompromisingly Lotkan. It does not External risks can be further subdivided into astronomical make any difference to the statistics of winning whether the risks, terrestrial/tectonic risks, and biological risks. losing competitors get a second chance or have to be replaced after every round. Astronomical risks could include instability of a planet’s home star, massive solar flares, impacts by asteroids or com- In sum: while no attempt will be made in this paper to pro- ets, nearby supernovas, gamma ray bursts (as noted above), vide a general analysis of Lotka’s Law or similar power laws, or other factors of which we presently have no knowledge. we will take it as a working hypothesis that such behavior is Terrestrial and tectonic risks could include massive volcanism, frequently manifested in cases where there are a succession of Gaian bottlenecks, or other sorts of natural climate change trials with binary outcomes. Now it will be argued that, given perhaps due to lethal nonlinearities in oceanic-atmospheric or this assumption, Lotka’s Law has an obvious application to the ecosystem dynamics. It is worth noting that most of the major Fermi Problem. and medium-sized mass extinction events throughout Earth’s history have been climatological, often (though not always) 3 LOTKA MEETS FERMI trigged by greenhouse emissions due to massive volcanism. (A major impact played a role in the terminal Cretaceous extinc- A species will be subject, from time to time, to existential threats: tion 66 mya). Biological risks could include epidemic disease some factor or event that threatens either its biological survival due to emergent pathogens, hostile actions by a technological- or at least its continuance as a possible ‘galactic’ species (a spe- ly superior extraterrestrial species (highly unlikely, one hopes, cies that has the technology and wherewithal to be noticeable but not inconceivable), or (again) some factor of which we by other suitably equipped species on an interstellar scale). The presently have no knowledge. key point is that the survival of such a threat is binary: a species either survives the threat or it does not, and if it does not, it is The factors mentioned so far could threaten life at any stage out of the galactic game, likely permanently in most cases. Thus in its development on a planet. If and when a species final- it is reasonable to investigate the possibility that the statistics of ly achieves a complex technological culture, it becomes sub- survival of candidate galactic species would be subject to Lotka’s ject to a long list of possible self-inflicted existential threats. Law or a similar power law. It is unclear how often existential These are the most immediately interesting because they are threats would occur in the career of a species; the Law by itself the threats that necessarily dominate humanity’s attention cannot tell us that. All we can be reasonably certain of is that a now, and also the ones that we have the best chance of do- species would have to get through several such threats before it ing something about (although we do by now have a limited can be a player on the galactic scale. Thus, by Lotka there would ability to deflect possible impactors given sufficient warning be only a very small number of such multiple-threat survivors, and political will). A list of such threats includes various kinds and thus a very small number of galactic species, even if the in- of ecocide by means of the degradation of supporting ecosys- itial candidate pool (the number of planets where life evolves) tems, leading to factors such as runaway greenhouse warming, is quite large. It would be as if a PGA player had to win a very loss of biodiversity, loss of topsoil, deforestation, exhaustion large number of tournaments before becoming eligible for a of critical resources, or the triggering of emergent disease due special, once-every-few years tournament. to ecological disruption. A recent study by Motesharrei, Rivas and Kalnay [10] shows that under certain conditions economic If this hypothesis is correct, there is no need to invoke a parasitism by elites can also be sufficient to cause the collapse mysterious ‘Great Filter’; the universe is rife with existential of a complex society independently of resource exhaustion or risks (some of which are reviewed below), and Lokta guaran- environmental degradation (although it would rarely occur in tees that only a few candidate species (relative to the initial isolation from those factors). size of the ‘applicant pool’) will survive enough of these win- lose challenges to be noticeable on the galactic scale. Indeed, A number of possible existential risks could be classified, it is not out of the question that no species (no matter how at least prima facie, as behavioural: they include the risk of promising) survives to become much more advanced than we nuclear war, the tragedy of the commons (in which a game-the- are now. Thus, one could agree with Bostrom that the Great oretic ‘grid-lock’ forestalls effective cooperative action even Filter is a sort of ‘probability barrier,’ but it is one that is due when that is physically possible and to greater mutual advan- not to any one single survival challenge or hazard acting at a tage [19]), and conceivably fanatical religion (as suggested by particular stage of a species’ career but rather the cumulative Arthur C. Clarke [15]). statistics of on-going survival hazards in an always-dangerous universe. Thus, we should, in fact, be glad if we find evidence It might be argued that behavioural factors such as lack of of extraterrestrial life, especially relatively complex life, be- foresight in the use of resources are peculiar to humans and cause that means there is a better chance that advanced life can thus not relevant in a discussion of the Fermi problem. In fact, survive the multiple hazards of the universe. ecology suggests that there is a general tendency for organisms to behave in ways that undercut their own survivability (some- 4 POSSIBLE EXISTENTIAL RISKS, AND POSSIBLE times, though not always, counterbalanced by symbiotic ten- RESPONSES TO THEM dencies [16]). Such self-destructive tendencies are unlikely to be peculiar to human beings, even if they manifest in humans It is worth considering a list of possible existential risks that in ways that are peculiarly human. Rather, it is the tendency could be encountered by a species roughly like ours, on a plan- of all organisms to foul their nests or overshoot their resource et roughly like ours. This list is by no means exhaustive. We base under certain circumstances, and any species that sur- humans would be guilty of potentially fatal hubris if we were vives long enough to be noticeable on a galactic scale must to presume that we are presently aware of all of the possible have found some way of transcending or sidestepping these survival threats that our species could face. self-undermining tendencies.

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The nature of the crises faced and surmounted could also biology, unfettered proliferation and radiation are exponential, play a role in determining the probability of future wins, in while long-term survival is described by power laws. The same ways that would be very difficult to analyse in detail. As Ron- would likely apply to von Neumann probes: even if their pro- ald Wright notes [24], a species may overcome one survival liferation is in principle exponential, the probes will be subject challenge by means of an innovation, only to fall into a ‘pro- to all sorts of survival challenges and their spread throughout gress trap’ — a further survival challenge caused by the unin- the universe would be limited to Lotkan-type power laws just tended side-effects of that very innovation. Humanity’s present as with the spread of species of biological origin. This does dependency on fossil fuels is a good example of a progress trap not guarantee that no von Neumann probe could succeed in in Wright’s sense. spreading itself rather widely throughout a galaxy. However, it could be almost or just as difficult for a von Neumann probe No attempt is made here to guess the number of existential to spread itself widely in space as it would be for a biological crises that a species might be expected to face, or how often species. Therefore, it is by no means a given that we should such crises would be likely to occur. There is no reason to think have seen von Neumann probes by now, even if someone out that they would occur at regular intervals, so some species there is producing them. (such as H. sapiens) might be lulled into a false sense of security by a long (say, 10,000 year) period of relatively benign 6 CONCLUSION AND SOME CAUTIONARY IMPLICATIONS and supportive ecological conditions. Thus, failure to exercise and implement intelligent foresight must be listed among the If there is a Great Filter, then the most natural account of it is most significant of the possible self-induced existential risks. that it is nothing more than Lotka’s Law or some similar power law that drastically limits the number of species that survive a Existential threats to the evolution of advanced life include long succession of survival challenges. What matters the most not only challenges to the survival of a particular advanced to survival in the long run is not the type of survival challenge, species, but also thresholds that must be passed before it is but the number of them. The number of species that can be even possible for a biosphere on a planet to harbour complex expected to survive n survival trials will go roughly as an in- life. For example, if a planet becomes locked permanently verse power of n. This implies that the Filter is something that into a phase where its anaerobes are dominant, then complex is neither strictly before us nor strictly after us, but rather a technological life might never evolve [22]. Several such evo- factor which operates all the time. The universe will never cease lutionary thresholds have to be surmounted (again, a binary to be a dangerous place in which to live — although it seems process) before there is any possibility of the appearance of a likely that a species that has contrived to disperse itself widely radio-emitting species on a planet. throughout space would, all things being equal, have a greater chance of long-term survival. 5 LOTKA AND VON NEUMANN Lotka’s Law, or some similar power law, is therefore one Several authors have observed that von Neumann self-repli- of the factors that very likely must be taken into account when cating automata could be used as the basis for an automated trying to estimate the probability of encountering an advanced interstellar probe. As Bostrom, citing Tipler [20], explains [2], species. This could be done via a modification of the Drake Equation, possibly by revising downward the parameters fi (the A von Neumann probe would be an unmanned self‐rep- fraction of life-bearing planets on which advanced life emerg- licating spacecraft, controlled by artificial intelligence, -ca es), fc (the fraction of planets that develop civilization detecta- pable of interstellar travel. A probe would land on a planet ble at interstellar distances), or L (the length of time such civi- (or a moon or asteroid), where it would mine raw ma- lizations release signals or artifacts) [21]. While it is generally terials to create multiple replicas of itself, perhaps using understood that these quantities must be relatively low, if the advanced forms of nanotechnology. These replicas would hypothesis suggested here is correct then they must to be fur- then be launched in various directions, thus setting in ther, and perhaps drastically, reduced by a ‘Lotkan’ discount. motion a multiplying colonization wave. It is to be emphasized that pointing out the possible role of Since the multiplication of the probe would be exponential, it a Lotka-like law in limiting the probability of long-term sur- would seem that such a probe could colonize a whole galaxy vival does not by itself solve the Fermi Problem in an abso- (or perhaps infect is a better term) in a time that is very short lutely conclusive way. If the Great Filter is nothing other than compared to the time required for the biological evolution of the grim statistics of survival, there might indeed only be a intelligent species. If a technological species were to send out very small number of civilizations in our galaxy or even our a von Neumann probe, the offspring of the probe might sur- Local Group that have survived long enough for us to have vive much longer than the species itself. Even if it is technically a chance of detecting them (despite the enormous number of more difficult to produce a von Neumann probe than we cur- possible life-bearing planets). However, it is still conceivable rently imagine, it would only take one successful effort in order that at least one such very long-lived species would have had to fill the whole universe with them. The fact that we have so far sufficient time to spread either their signals, their artifacts, not detected any extraterrestrial von Neumann probes can be or themselves throughout a very large volume of space. The taken as especially compelling evidence, therefore, that there is probability of detecting another advanced species cannot be reno other technological species than ourselves within some very duced to zero; any “solution” to the Fermi problem can only be great distance. probabilistic. However, the fact that long-term survival likely exhibits power-law behaviour suggests that this probability The problem with the von Neumann probe hypothesis may well be much smaller than we have so far appreciated. is that the spread of the probes could well be subject to the same Lotkan limitations as the long-term survival of ordinary Another important implication of the picture outlined here biological organisms. Although this requires more study, it is is that any advanced species that we do happen to encounter probably safe to say (at least to a coarse approximation) that in would likely be very far out on the right-hand tail of the Lot-

210 Vol 71 No.6 June 2018 JBIS FERMI AND LOTKA: the Long Odds of Survival in a Dangerous Universe ka curve. Any such species would possess formidable survival because he is a good golfer; although luck always plays a role, capabilities and thus would be potentially very dangerous to good golfers generate their own luck. (We may define a piece humanity in ways that would be hard for us to predict, even of luck as a favourable statistical fluctuation.) The fact that if it harboured no hostile intent as such toward us. Therefore, humanity has so far dodged more than one existential chal- should we ever encounter other advanced species, extreme re- lenge could indicate that we might have the qualities it takes spect and caution are advised. to beat the odds for quite some time to come. But it should be a wake-up call, a caution against arrogance, complacen- In summary: If the hypothesis advanced here is correct then cy, and over-confidence. (The fact that humanity has so far the reason that we have not yet encountered advanced alien life dodged nuclear annihilation may indeed be a matter of dumb is simply that it is far more difficult than we have so far appre- luck [5,18].) In particular, humanity should take the very im- ciated for a technological civilization to survive a long time mediate existential risks implicit in anthropogenic climate — not because of any one particular hazard, but because the change with utmost seriousness [6]. No doubt many species odds are so high of a species’ luck running out when faced with do survive a few extinction threats more or less by sheer luck. a succession of hazards. Indeed, it seems likely that planetary Sooner or later, though, intelligent foresight and creativity life will typically have to run a gauntlet of multiple survival must become the dominant factors that permit a technolog- challenges before it can produce species that can even count as ical species to survive repeated threats, and humanity’s best technological. This is certainly consistent with the history of long-term bet for survival is to promote whatever social and life on earth; it has taken about 3.8 billion years for our plan- economic conditions tend to foster those virtues. et to evolve life capable of sending radio emissions to deep space, while we have had that limited capability for only about Acknowledgements 100 years. By Lotka, the number of planets that reach even For helpful discussion and advice, the author is indebted to this modest threshold must be a tiny fraction of the number of James Byrne, Thomas Heyd, David McDonald, Andrew Pat- life-bearing planets throughout the universe. terson, Evan Peacock, Norm Sleep, John Vokey, Byron Willis- ton, members of the Philosophy through Science Fiction class This need not be an occasion for despair, however; it will at the University of Lethbridge (Fall 2017), an anonymous not usually be a matter of pure luck whether or not a species referee, and discussants at the 2015 Meeting of the Canadian surmounts an unusually large number of survival trials, any Society for the History and Philosophy of Science. He is grate- more than it is pure luck when a particular author publishes ful to the University of Lethbridge for support. None of these an unusually large number of papers. To revert to Murray’s individuals or organizations are responsible for any errors or golfing example: a professional golfer who has won multiple omissions in the present work, which is entirely the responsi- events has done so in important part (though never entirely) bility of its author. No competing financial interests exist.

REFERENCES 1. J.J. Bolmarcich, "On the Distribution of Combat Heroes", in Human 12. NASA Exoplanet Archive, California Institute of Technology. Retrieved Behavior and Performance as Essential Ingredients in Realistic Modeling June 1, 2018, from https://exoplanetarchive.ipac.caltech.edu/ of Combat – MORIMOC II, Vol. 2, Military Operations Research 13. M.E.J. Newman, "Power laws, Pareto distributions and Zipf’s law", Society, Alexandria, VA, pp. 658–691, 1989. Contemporary Physics, 46(5), pp. 323–351, 2005. 2. N. Bostrom, "Where Are They? Why I hope the search for 14. P. Ormerod, Why Most Things Fail: Evolution, Extinction, and extraterrestrial life finds nothing", MIT Technology Review, (May/June), Economics, Faber and Faber, London, 2005. pp. 72–77, 2008. 15. P. Parsons, "Arthur C. Clarke: Interview", BBC Knowledge, (Sept/Oct), 3. A. Chopra, and C.H. Lineweaver, "The Case for a Gaian Bottleneck: The pp. 41–43, 2008. Biology of Habitability", Astrobiology, 16(1), pp. 7–22, 2016. https://doi.org/10.1089/ast.2015.1387 16. K.A. Peacock, "Symbiosis in Ecology and Evolution", in K. deLaplante, B. Brown and K. A. Peacock (eds.), Philosophy of Ecology, Handbook of 4. B. Drossel, "Biological evolution and statistical physics", Advances in the Philosophy of Science, Vol. 11, Elsevier, Amsterdam, pp. 219–250, Physics, 50(2) 2001, pp. 209–295. 2011. www-tandfonline-com.ezproxy.uleth.ca/toc/tadp20/50/2?nav=tocList 17. T. Piran and R. Jimenez, "Possible Role of Gamma Ray Bursts on Life 5. D. Ellsberg, The Doomsday Machine: Confessions of a Nuclear War Extinction in the Universe", Physical Review Letters, 113(23), 231102, Planner, Bloomsbury, New York, 2017. 2014. https://doi.org/10.1103/PhysRevLett.113.231102 6. J. Hansen, Storms of my Grandchildren: The Truth About the Coming 18. E. Schlosser, Command and Control: Nuclear Weapons, the Damascus Climate Catastrophe and Our Last Chance to Save Humanity, Accident, and the Illusion of Safety, Penguin Press, New York, 2013. Bloomsbury Press, New York, 2009. 19. P.G. Sekeris, "The tragedy of the commons in a violent world", The 7. R. Hanson, "The Great Filter", 1998. Retrieved June 1, 2018, from RAND Journal of Economics, 45(3), pp. 521–532, 2014. http://mason.gmu.edu/~rhanson/greatfilter.html https://doi.org/10.1111/1756-2171.12060 8. R.A. Heinlein and S. Robinson, Variable Star, Tom Doherty, New York, 20. F. Tipler, "Extraterrestrial Beings Do Not Exist", Quarterly Journal of the 2006. Royal Astronomical Society, 21, pp. 267–281, 1980. 9. A. J. Lotka, "The frequency distribution of scientific productivity", 21. D.A. Vakoch and M.F. Dowd (eds.), The Drake Equation: Estimating Journal of the Washington Academy of Sciences, 16(12), pp. 317–323, the Prevalence of Extraterrestrial Life through the Ages, Cambridge 1926. University Press, Cambridge, 2015. 10. S. Motesharrei, J. Rivas, and E. Kalnay, "Human and nature dynamics 22. P.D. Ward, The Medea Hypothesis: Is Life on Earth Ultimately Self- (HANDY): Modeling inequality and use of resources in the collapse or Destructive? Princeton University Press, Princeton and Oxford, 2009. sustainability of societies", Ecological Economics, 101, pp. 90–102, 2014. https://doi.org/10.1016/j.ecolecon.2014.02.014 23. S. Webb, If the Universe is Teeming With Aliens ... Where is Everybody? (Second Edition), Springer, Cham, 2015. 11. C. Murray, Human Accomplishment: The Pursuit of Excellence in the Arts and Sciences, 800 B.C. to 1950, HarperCollins, New York, 2003. 24. R. Wright, A Short History of Progress, Anansi Press, Toronto, 2004.

Received 7 June 2018 Approved 7 September 2018

JBIS Vol 71 No.6 June 2018 211 JBIS VOLUME 71 2018 PAGES 212–215

SCENARIO BLOCK DIAGRAM ANALYSIS of the Galactic Evolution of Life

STEPHEN ASHWORTH 49 Princes Street, Oxford OX4 1DE, UK email [email protected]

The current ignorance of science concerning the abundance and nature of life on a galactic scale allows a number of possible scenarios to exist. These may be organised using a Scenario Block Diagram. This approach may be used to inform discussions on the Hart–Tipler Argument, also known, incorrectly, as the Fermi Paradox. Due to the continued popularity of the idea that a paradox exists, the observations to be made in the coming centuries which are required to establish that such a paradox does indeed exist are broadly indicated.

Keywords: Fermi Paradox, Hart–Tipler Argument, Extraterrestrial life, Block diagram analysis

1 THE MULTIPLE SCENARIO APPROACH tury molecular biology to the holistic system-level approach required by studies of the integrated organisation of a complete In a paper published in 2014, the present author discussed the cell, tissue, organism, ecosystem or planetary biosphere. Our weaknesses of the Drake Equation and the Fermi Paradox, and intention here is therefore broadly to extend a similar holistic attempted to move away from them to find a more illuminating approach to looking at life on a galactic scale. method for analysing the possibilities of discovering extraterrestrial life, intelligence and technological civilisation [1]. The Unlike those other examples of the use of block diagrams, less well-known Bond Equation for the prevalance of life in the however, the scenario block diagram is used in a slightly dif- universe was also critically examined. ferent way in that it shows alternative scenarios consistent with existing scientific knowledge. Most of the scenarios it presents Since then, Robert Gray has argued that the so-called Fermi may be expected to be ruled out by observation over the next Paradox should not be attributed to Enrico Fermi, and neither is few centuries to a millennium of detailed surface and subsur- it a genuine paradox [2]. Gray proposed instead the more accu- face observation of exoplanets in the solar galactic neighbour- rate term “Hart–Tipler Argument”. More recently still, Anders hood with suitable instrument packages. Sandberg, Eric Drexler and Toby Ord have demonstrated in detail that the supposed paradox is an artefact of a mathematically Despite much recent excitement over the discovery of incorrect interpretation of the Drake Equation, in which spec- large numbers of exoplanets, with speculation and modelling ulative values are confidently assumed for variables whose true of their surface conditions directed especially at planets not range of uncertainty spans many orders of magnitude [3]. too dissimilar from Earth in size and orbital location in their respective star’s surface liquid water (“Goldilocks” or “habit- There remains therefore a need for a new conceptual frame- able”) zone, it is worth remembering that the study of extra- work for the whole question of analysing the abundance and terrestrial life is still in its infancy. In particular, the number nature of life on a galactic scale. of planets with surface or subsurface conditions arguably hospitable to life as we know it which are known either definitely In the present author’s 2014 paper, the framework offered to have or definitely not to have indigenous life still stands at was a parameter space of alternative scenarios. The present pa- one (i.e. Earth itself). per offers a visual overview of the alternatives in terms of the block diagram shown in Figure 1. Rather than rush to the conclusion that life is or is not common in the Galaxy, the correct procedure at this stage is to iden- Block diagram analysis is widely used in hardware and tify the full range of different scenarios consistent with current software engineering to show the functional relationships of knowledge, and then to specify the observations we would parts of a system, or the flow of information or material prod- need to make in order to falsify each one. Without real-world uct from one process to another. In recent decades it has also observations of the frequency of extraterrestrial life, even the found application in systems biology, where the need has been best theoretical models and laboratory simulation cannot give to move on from the reductionist approach of mid-20th-cen- a reliable answer. Clearly, science stands or falls through observation, to which theory must always give way.

This paper is based on a presentation by the author at the “Fermi At the lowest level of resolution, the evolution of life as we Paradox” Symposium on 28 November 2017 at the BIS in London. know it falls naturally into three phases. Firstly, there is a pe-

212 Vol 71 No.6 June 2018 JBIS SCENARIO BLOCK DIAGRAM ANALYSIS of the Galactic Evolution of Life

Scenario Block Diagram for the galactic evolution of life

Fig.1 The Scenario Block Diagram riod of time and a set of circumstances in which biogenesis humans could develop a form of it being confined to economic, takes place: the emergence of the earliest living creatures from sociological or psychological issues. inanimate matter. It is currently known that this occurred at least once and at least four billion years ago, but any further 2 SCENARIOS FOR BIOGENESIS details than those remain speculative. Secondly, a futher period of time and allotment of circumstances are required for Beginning on the left-hand side of Figure 1, the question to those simple organisms to develop into metazoa: muticellular be addressed is how often and under what circumstances life creatures with differentiated tissues, and therefore the potential emerges from non-living chemistry. Of all the factors in the to develop means of both manipulating their environment and Drake equation, this is the one whose value is least constrained thinking about it. So far as is currently known, this requires by current knowledge. According to Paul Davies, the probabil- uniquely Earthlike surface conditions, with a mixture of oce- ity of the emergence of life in any given hospitable location per anic and land surface areas, an Earthlike gravity level, atmos- unit time may be infinitesimal, or it may be inevitable, or it may phere, insolation and so on. There has however been specu- be anywhere in between [4, 5]. lation about the possibility of developed forms of life existing in the global subsurface oceans of smaller worlds such as the Similarly, Sandberg, Drexler and Ord have stated: “As noted larger satellites of the outer giant planets. by Carter and McCrea, the evidential power of the early emergence of life on Earth is weakened by observer selection effects, The third development stage is that of technogenesis: the allowing for deep uncertainty about what the natural timescale emergence of a technological form of life which is no longer of life formation is. By their argument one cannot assume it lies dependent upon or confined to a single planet, but which can within the habitability span of Earth” [3, §3.1]. These authors survive and prosper in a wide range of locations in the astro- find that the current scientific uncertainty in the rate of abio- nomical universe where raw matter and energy are available genesis events per unit volume conservatively spans 200 orders to it. Again, this would appear to require a planet with high- of magnitude. ly Earthlike surface conditions; ice- or atmosphere-covered ocean worlds would not be suitable. Scenarios are therefore possible in which single-celled life emerges relatively quickly, and other scenarios in which it The existence of technological life is currently speculative emerges relatively slowly. Clearly, a continuous range of values but is well grounded in the recent history of human civilisation, is possible, but for simplicity the two extremes are considered which shows a rapid trend towards acquiring the scientific and here, namely Rare Biogenesis and Common Biogenesis. engineering capabilities and the social organisation that will enable such a level of life to branch out from it. The specula- Let it be assumed firstly that the emergence of life is a rare tion is also well grounded in the sense that technological life event, taking place no more often than, say, once per galaxy per is clearly physically possible, with any doubts about whether ten billion years.

JBIS Vol 71 No.6 June 2018 213 STEPHEN ASHWORTH

Is it possible that that rare event took place on Earth? It is tific knowledge. logically possible. Many would argue that because life is known to have started so soon after the formation of our planet, such The modern default assumption, however, is Common Bio- a unique biogenesis would be inconsistent with the view that genesis, based on the fact that microbial life was present very it was a natural event. On the other hand, Brandon Carter and early on Earth, and the belief, which may or may not be correct, Robin Hanson have shown that if the average time required that Earth life is indigenous to either Earth or Mars. Given this for biogenesis on an Earth-analogue planet is far greater than assumption, as also the known abundance of planets, the in- the average habitable lifetime of such planets, but if life devel- ferred abundance of Earth-analogue planets and their inferred ops on one such planet and, as a fluke occurrence, appears so existence for approximately 8 billion years before the formation early that there is time for its evolution to intelligence, then the of the Solar System, the result must be that microbial life is and pattern of life’s development would match what we observe on has long been common throughout the Milky Way Galaxy (and Earth (particularly if that biogenesis event actually took place indeed all galaxies). on Mars a little earlier than was possible on Earth, and viable microbes were later transferred to Earth) [6, 7]. If Common Biogenesis is combined with a low-gravity origin of life, the expected result is still that microbial life will This is the famous Great Filter argument, subsequently pop- be common on Earth-analogue bodies, due to the high rate at ularised by Nick Bostrom, though he changed the perspective which matter infalling from space is added to them. But, as not- from Hanson’s original sequence of about nine improbable ed above, if the genesis of life is difficult in low-gravity bodies steps to focus on one difficult step in particular, which then (and impossible elsewhere), then these two scenario elements had to be located in the future or the past of a species at our may prove to be mutually incompatible. own level of development [8]. 3 SCENARIOS FOR TECHNOGENESIS A second rare genesis scenario is that life has emerged on multiple Earth-analogue planets, but only after a gestation pe- If technogenesis is common, then the absence of observed in- riod of at least 8 billion years per planet. It would then be scat- dustrial alien societies nearby requires either that technological tered at rare intervals around the Galaxy at the present day. In civilisations are always unstable and destroy themselves once this scenario our own existence would require a further step, they reach our own level of development, or that they never in which the star for one such planet produced a nova, which expand into space and instead always adopt an introverted ze- blew viable microbes off into space at a time when that star ro-growth economy. (Clearly, many highly speculative varia- was close to the star-forming region in which our Solar System tions on these ideas have been proposed over the years.) The condensed, thus seeding the planets of our system during their first of these options is obviously highly unpleasant for us to formation with single-celled organisms. An alternative pos- contemplate, the second contradicts the dynamism still evident sibility would be an act of directed panspermia by intelligent in modern human society, and both suffer from the drawback inhabitants of the original planet, if they were only marginally that sociological arguments need to be applied to all possible capable of spaceflight (as humanity is at present) at the time civilisations in defiance of what is allowed by physical reality, when solar or other astronomical changes render their planet as Michael Hart first pointed out [10]. no longer inhabitable. Either way, on this scenario, a rare biogenesis event is followed by an even more unlikely, though But even if biogenesis is common, technogenesis may still be still perfectly possible, transference event from the location of rare. For what period of time do Earth-analogue planets typi- biogenesis to the newly forming Earth. cally maintain comfortable conditions for land-based surface life? A great deal of computer modelling has been focused on A third rare genesis scenario is possible which completely this question, but it is impossible to know for sure until de- decouples the origin of life from the evolution of industrial civ- tailed explorations have been made covering a representative ilisation. Thanks to experiments carried out on the ISS, it has sample of planets in our galactic neighbourhood. now been stated: “microgravity [in comparison with terrestrial gravity] has been demonstrated to have profound effects at the Planetary habitability may be disrupted in two different cellular and molecular level, including changes in cell mor- ways (shown together in one box in the diagram). Firstly, the phology, proliferation, growth, differentiation, signal trans- astronomical environment may damage habitability through duction and gene expression” [9]. Given this fact, it is not yet gamma-ray bursts, changes in the planet’s home star and possible to rule out the scenario in which biogenesis requires a planetary system, and asteroid impacts. Changes in the galac- different gravity level from the evolution of life to higher forms, tic radiation environment in particular may occur as a gal- and ultimately to technogenesis. axy evolves, leaving open the possibility that the surfaces of Earth-analogue planets may have been regularly sterilised by If the origin of life is constrained to be on a low-gravity body, events such as gamma-ray bursts in the Galaxy’s youth, with for example subsurface on a comet, then it may be a low-prob- the onset of milder conditions beginning only around four bil- ability event due to the short periods of time when water on lion years ago. such bodies is in the liquid state. In order for technogenesis to occur, there then needs to be a low-probability transfer of Secondly, planetary habitability may be disrupted by inter- viable microbes from the interior of such a comet to the surface nal factors such as volcanism or plate tectonics, or simply by of a suitable Earth-analogue planet, or to the accretion cloud the mathematical chaos inherent in any complex system. A re- of a newly forming planetary system. In this scenario, Earth lated issue is that of a planet’s initial composition: an otherwise could well be the first planet in the Galaxy to have experienced Earth-analogue planet may have too much or too little surface animal evolution, followed by industrialisation. water to allow the kind of surface conditions conducive to development of land-based multicellular animals, or it may be There are thus three possible Rare Biogenesis scenarios depleted in the concentrated metal ores or fossil fuels needed consistent with the loose constraints given by current scien- to begin the process of industrialisation.

214 Vol 71 No.6 June 2018 JBIS SCENARIO BLOCK DIAGRAM ANALYSIS of the Galactic Evolution of Life

These points taken together amount to the Rare Earth ar- Hart’s reasoning published in 1975 [10], and Tipler’s extension gument proposed in 2000 in a book of that title by Peter Ward of this reasoning in 1980 to embrace machine intelligence [14]? and Donald Brownlee [11]. A recent new spin on the thesis was given by Aditya Chopra and Charles Lineweaver, who in- Firstly, it would be necessary to demonstrate that biogenesis is troduced the idea of a Gaian bottleneck again restricting de- a common event, not a rare one, in our Galaxy. This will require velopment from microbiota to metazoa [12]. The Rare Earth at least one other genesis of life to be found in our galactic vi- hypothesis has been highly controversial, and was most re- cinity. It must be analysed in sufficient microbiological detail to cently challenged by Dirk Schulze-Makuch and William Bains prove that it cannot possess a common ancestor with Earth life. in 2017 [13]. Secondly, it would be necessary to demonstrate that favour- Nevertheless, at the current state of scientific knowledge, able surface conditions on Earth-analogue planets commonly scenarios in which surface habitability of Earth-analogue plan- endure for periods on the order of four billion years, and have ets is typically sustained for multi-billion-year periods of time been doing so for a significant period of time prior to the for- must be balanced against those in which they typically deteri- mation of the Solar System. This will require detailed study of orate after less than one or two billion years, preventing tech- the geology of one or more Earth-analogue planets in our ga- nogenesis from occurring. In the latter case, Earth’s continued lactic vicinity. long-term surface habitability would be a rare outlier. These studies will necessarily occupy the attention of an ex- Figure 1 therefore channels its scenario pathways through panding human civilisation over the next few centuries. They boxes labelled Stable surface conditions and Unstable surface will depend upon sufficient mastery of interstellar spaceflight to conditions. In the latter of these, given a planet which is an explore Earth-analogue and other exoplanets to better than the Earth-analogue in its gross properties of mass, composition level of detail yet achieved on Mars over the past half century and orbit, either Earth-analogue surface conditions do not of close-up spacecraft observations. Therefore the act of mak- arise at all, or else they do arise but do not endure long enough ing those observations will in itself demonstrate that industrial to allow an initial endowment of microbial life to go all the way civilisations are not universally intrinsically unstable, and not to spacefaring industrial civilisation. universally confined to their home planets, ruling out the two sociological branches deriving from the realisation of common At the same time one should bear in mind Stephen Jay technogenesis in the bottom-right-hand corner of the diagram. Gould’s view that, even granted the multi-billion-year tenure of life on Earth, the emergence of intelligence depended upon a se- Assuming that all these observations have been made, it will quence of chance events which, had they gone differently, might have been demonstrated that a paradox does indeed exist. But not have led to anything resembling human intelligence [15]. it remains possible that different conclusions will be reached.

4 RELEV ANCE TO THE HART–TIPLER ARGUMENT (“FERMI Further work will be helpful in refining the scenarios PARADOX”) sketched briefly here, and in specifying in more detail the exact criteria which need to be observed, for example the precise Is it possible to establish that there does indeed exist a paradox biochemistry which would allow the conclusion that an inde- based on Fermi’s “where is everybody?” question from 1950 [2], pendent origin of life has been found.

REFERENCES

1. S. Ashworth, “A Parameter Space as an Improved Tool for Investigating Extraterrestrial Life Finds Nothing”, MIT Technology Review, May-June Extraterrestrial Intelligence”, JBIS, 67, pp.224-231, 2014. 2008, pp.72-77. 2. R.H. Gray, “The Fermi Paradox is Neither Fermi’s Nor a Paradox”, 9. Cora S. Thiel et al., “Rapid adaptation to microgravity in mammalian Astrobiology, 15(3), pp.195-199, 2015 (https://doi.org/10.1089/ macrophage cells”, Nature, Scientific Reports 7, Article number: 43 ast.2014.1247). (2017); doi:10.1038/s41598-017-00119-6; published online: 27 February 3. A. Sandberg, E. Drexler and T. Ord, “Dissolving the Fermi Paradox”, 2017 (https://www.nature.com/articles/s41598-017-00119-6). preprint available online at arXiv:1806.02404v1, 8 June 2018. 10. M.H. Hart, “An Explanation for the Absence of Extraterrestrials on 4. P. Davies, The Eerie Silence: Searching for Ourselves in the Universe E a r t h”, Quarterly Journal of the Royal Astronomical Society, 16, pp.128- (Allen Lane, 2010), p.37. 135, 1975. 5. P.C.W. Davies, “Bio-Signatures and Techno-Signatures beyond Earth”, 11. P. Ward and D.E. Brownlee, Rare Earth: Why Complex Life is Uncommon presented at the three-day symposium entitled “Exploring Exoplanets: in the Universe (Copernicus, 2000). The Search for Extraterrestrial Life and Post-Biological Intelligence”, the 12. A. Chopra and C.H. Lineweaver, “The Case for a Gaian Bottleneck: The John Templeton Foundation’s Humble Approach Initiative, September Biology of Habitability”, Astrobiology 16(1):, pp.7-22, 2016 (https://doi. 2015, held at the Royal Society, Chicheley Hall, near London, UK. org/10.1089/ast.2015.1387). 6. B. Carter, “The Anthropic Principle and its Implications for Biological 13. D. Schulze-Makuch and W. Bains, The Cosmic Zoo: Complex Life on Evolution”, Philosophical Transactions of the Royal Society of London, Many Worlds (Springer, 2017). vol.A 310, pp.347-363, 1983. 14. F.J. Tipler, “Extraterrestrial Intelligent Beings Do Not Exist”, Quarterly 7. R. Hanson, “The Great Filter: Are We Almost Past It?”, 15 Sept. 1998, Journal of the Royal Astronomical Society, 21, pp.267-281, 1980. online at http://mason.gmu.edu/~rhanson/greatfilter.html, last accessed 15. Stephen Jay Gould, “The Evolution of Life on the Earth”,Scientific 10 July 2018. American, special issue: “Life in the Universe”, October 1994, p.64. 8. N. Bostrom, “Where Are They? Why I Hope the Search for

Received 32 July 2018 Approved 19 October 2018

JBIS Vol 71 No.6 June 2018 215 JBIS VOLUME 71 2018 PAGES 216–221

EXTREMOPHILES: The Resilience of Life under “Adverse” Conditions ROBERT O.J. WEINZIERL Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, United Kingdom.

Email [email protected]

Biochemical studies on organisms occupying a wide variety of ecological niches on Earth have revealed the unexpectedly wide range of external conditions carbon-based life can adapt to. Extremophiles (organisms that thrive in environments most other organisms would not survive in) use numerous adaptations that preserve the structural and functional integrity of their cellular structures even under highly adverse conditions. Some of the lessons learned from extremophiles may help us to understand better the probability of life emerging and evolving on planets that are similar to Earth but may differ in certain aspects (such as temperature, pressure, salinity). One important takeaway lesson from terrestrial extremophiles is that they are all microbial organisms. This observation casts a considerable doubt on the question whether higher life forms – and ultimately intelligence – could arise elsewhere in the universe under circumstances other than the mostly moderate conditions found on Earth.

Keywords: Archaea, Bacteria, Drake equation, Molecular interaction forces, Evolution

1 INTRODUCTION the mutual control of and flow of information between sepa- Biochemical research carried out over the last few decades has rate functional entities (Fig. 1). reshaped our thinking about the environmental conditions capable supporting life. The majority of animals, plants and mi- It is easy to see, how such delicate non-covalent interactions crobes that we come into daily contact with live under what critical for the most central biological functions, can be dis- we define as “moderate” or “mesophilic” conditions in terms turbed, or even abolished, if the temperature of the environ- of exposure to radiation, acidity/alkalinity, temperature and ment rises (or falls), or the intracellular environment exceeds pressure. When biochemists analyse the various chemical con- appropriate ionic concentrations or pH values. The discovery stituents of organisms, it becomes apparent that many of the and subsequent analyses of organisms living under more unu- most basic components, such as proteins, nucleic acids, carbo- sual conditions, such as in the presence of saturating salt, or on hydrates and lipid membranes, appear quite delicate; exposure ocean floors in high temperature/high pressure environment, to higher temperatures, acidic and basic conditions, radiation therefore came as a considerable surprise and findings derived and/or high salt concentrations typically damages such mo- from such organisms have dramatically reshaped our under- lecular assemblies in an irreversible manner or destroys them standing of conditions under which terrestrial life is feasible. altogether. Here, I will provide a brief overview about the physi- The physico-chemical reasons for this structural sensitivi- co-chemical adaptations that have allowed terrestrial life to ty of molecules involved in basic biochemical processes, such function under a wide range of apparently hostile – or ex- as replication of DNA and numerous other cellular enzymatic tremophile – conditions. These observations have a distinct processes, are well understood. Although the most important impact on discussions of the Fermi paradox because they al- – information-processing – biological macromolecules are co- low us to assess more accurately the possibility of life forms valently bonded polymers of simpler polymeric units (proteins based on the biochemical components we are familiar with, are polymers of 20 different amino acids, nucleic acids are pol- and thus lead to a more accurate estimation of the frequency ymers of four nucleotides) that are chemically relatively stable, of life forms within our galaxy (and from there, extrapolating the key aspects of biological functions only emerge when such to other regions of the known universe). Attempts to quanti- molecules fold into distinct three-dimensional shapes guided tate such probabilities are mostly based on the Drake equa- by noncovalent bonds (hydrogen and “hydrophobic” bonds, tion, which defines the probability of detecting intelligent life van der Waal’s and electrostatic interactions). For example, as the product of seven parameters: such noncovalent forces are necessary for proteins acting catalytically (enzymes) to configure a precisely shaped “active N = R* fp ne fl fi fc L site” that can carry out a chemical transformation of a specific metabolite. Non-covalent forces also dictate the affinity and In this equation, N is the number of detectable higher civ- specificity of interactions between different biological macro- ilization in the Milky Way, R* is the rate of star formation, ne molecules, which constitute one of the key aspects of biology: the number of earth-like planets, fl represents the fraction of

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Fig.1 Structure of the human nucleosome. DNA, the genetic material, is a thin long molecule that needs to be stored in a spatially organized manner in the cell nucleus. Nucleosomes consist of eight individual proteins that associate with each other into a disc-shaped complex that can associate with DNA through an extensive array of noncovalent forces (predominantly electrostatic bonds between the negatively charged phosphodiester backbone and positively charged amino acid residues [lysine, arginine, histidine] on the surface of the nucleosome. When particular genes are required for cellular processes (such as transcription, repair and replication), the DNA can be reversibly detached from nucleosomes. The structure above contains around 28,500 atoms linked by covalent bonds (indicated as lines), but the overall conformation depends extensively on labile noncovalent bond interactions to form a specific three-dimensional structure.

planets with life forms, fi the fraction with life evolving intelli- mesophilic life forms as extremophiles. The terms “extremo- gence, fc is the fraction of civilizations that are detectable (and phile” is the most generic one and extremophilic organisms are ideally contactable) and L represents the average survival time then further subdivided according to the precise environmen- of such civilizations. As can be seen from this equation, a pre- tal adaptations (see Table 1 for a brief overview). As discussed cise estimate of the fl parameter that represents the fraction of in more detail below, it should be noted that all these extremo- planets with life forms, is critically dependent our understand- philes are almost exclusively represented by microorganisms ing of what kind of environmental conditions are capable of (Bacteria and Archaea). There are certain eukaryotes that fall supporting the emergence, evolution and subsequent support into the less demanding end of the range of the conditions of any type of life. specified in Table 1, but it appears that higher (especially multicellular) organisms cannot adapt successfully to any extremo- 2 EXAMPLES OF EXTREMOPHILIC ADAPTATIONS OF LIFE philic environment (this observation may affect the assessment of the fi parameter of the Drake equation representing the frac- As already mentioned in the Introduction, we consider organ- tion with life evolving intelligence [which, we assume, depends isms growing under “moderate” conditions as mesophiles, and conventionally on the evolution of higher multicellular life other organisms living in environments that do not support forms]).

TABLE 1 Classification of Various Types of Extremophiles

Piezophiles organisms living in high pressure (20 to 130 mPa) environments

(Hyper-)thermophiles organisms living in high temperature (55-122oC) environments

Halophiles organisms living in high salt (for example, 0.5-5.0 M NaCl) environments

Psychrophiles organisms living in cold (0° to 15°C) environments

Acidophiles organisms living in acidic pH (lower than pH 4.0) conditions

Alkaliphiles organisms living in alkaline ph (higher that pH 8.0) conditions

Next to the names, a brief description of the extreme conditions. Note that these conditions are considered to be more or less permanent and not just brief deviations from an otherwise mesophilic life style. Also, some extremophiles are able to cope with more than one extremophilic deviation. For example, Archaea living in vulcanic thermal vents on ocean floors are both hyperthermophiles and piezophiles.

JBIS Vol 71 No.6 June 2018 217 ROBERT O. J. WEINZIERL

Below I will discuss briefly some of the biochemical adap- heat-mediated chemical degradation [3]. Intracellular salt con- tations of some of these extremophiles and I will focus par- centration stabilizes DNA and special enzymes (“reverse gyras- ticularly on Hyperthermophiles and Halophiles. This is at least es”) appear to have specifically evolved in hyperthermophiles partially due to the fact that such organisms have been studied to promote the repair of DNA at elevated temperatures. Other in considerably more depth than some of the other extremo- nucleic acids in hyperthermophiles essential for key cellular philes and we are therefore in a better position to understand activities, such as the transfer RNAs (tRNAs) and ribosomal the molecular details of their adaptations. Another reason RNAs (rRNAs), increase their structural integrity by employing for this choice is that these two conditions, high temperature chemically modified bases to restrain conformational flexibil- during the early stages of the formation of planets/subsequent ity at crucial points [4]. Some hyperthermophilic species also vulcanic activity and the presence of concentrated salt lakes, contain a high intracellular concentration of various polyvalent respectively, may be more relevant on other planets than some cations (polyamines) that help with the thermostabilizition of of the other terrestrial extremophilic adaptations. The recent all types of nucleic acids (DNA and RNA) [5]. It is therefore discovery of a sizable salt lake under ice on the southern polar clear that different hyperthermophiles have evolved a series of plain (Planum Australe) of Mars is a particularly poignant ex- independent molecular mechanisms to stabilize the structure ample of the potential relevance of studying and understanding of their nucleic acids at high temperature. ecosystems for halophilic organisms [1] Similar considerations apply to another class of important 2.1. Thermophiles and Hyperthermophiles macromolecules in hyperthermophiles, which are the proteins. Proteins depend even more distinctly on weak non-covalent Thermophilic (55-80oC) and hyperthermophilic (80-122oC) or- interactions to take up their three-dimensional structure, ganisms were essentially unknown until the 1970s when such which – especially for enzymes acting catalytically – has to habitats were considered sterile and incompatible with life. The be very precise and stable. Biochemical and structural studies isolation of microorganisms (later identified as various archaeal have revealed that proteins and enzymes from hyperthermo- strains) from the hot springs of Yellowstone National Park philes remain – in contrast to their counterparts from meso- (Wyoming) showed, however, that such environments support philes – fully folded and catalytically active at the high temper- their own, specialized biosphere. Subsequent research revealed atures of their natural habitats. It is therefore clear that these additional hot environments, especially the vulcanic vents on proteins, although they are built from the same standard set the deep ocean floor, to support a rich variety of hyperthermo- of 20 different amino acids as in every other organism, are in- philic life (for example, the East Pacific Rise, near the western trinsically more stable and temperature resistant in the absence coast of Mexico). One of these hyperthermophiles, Methano- of any external factors. Various genome sequencing projects of caldococcus jannaschii (M. jannaschii), was the first non-bacte- hyperthermophilic archaea carried over the last two decades rial organism whose genome was sequenced in 1996 [2]. These have revealed their entire proteome and the primary sequences data, in conjunction with numerous other studies on other hy- of all proteins encoded in such organisms in abundance. In- perthermophiles, have provided numerous insights into vari- terestingly, no distinct “hyperthermophilic signature” uniquely ous extrophilic adaptations. The environment ofM. jannaschii identifying thermostable proteins has thus far been discov- typically is pressurized to 20 MegaPascal at a temperature up ered. Given the primary amino acid sequences of a mesophilic to 94oC and thus requires unique adaptations for survival and enzyme and its hyperthermophilic counterpart, even experts growth at both high temperature and high pressure. As already would not be able to identify which is which. Closer structural mentioned in the Introduction above, biochemical macromol- investigations of their three-dimensional shapes reveal many ecules from mesophilic organisms cannot function under such subtle differences: hyperthermophilic proteins contains a high- conditions and would become irreversibly damaged within er proportion of amino acids supporting the three-dimension- fractions of a second due to the loss of their three-dimensional al folding through the formation of hydrophobic bonds (ex- shape reliant on weak, noncovalent interactions. The hydrogen clusion of water molecules) that provide a substantial degree bonds keeping the two polynucleotide strands of double-helical of internal stability. Other observables include the presence of DNA together are mostly destroyed at temperatures above 75oC. ion-pair networks connecting large parts of such protein and The precise melting point depends on the composition of the the absence of loosely folded polypeptide loops on the protein four different bases (the sequence of which determines the ge- surface or poorly structured N- and C-termini. netic information stored in DNA). DNA rich in A-T basepairs denatures above 70oC, whereas DNA rich in G-C basepairs is In summary, a series of relatively minor changes in the pri- heat-resistant up to 95oC. A possible adaptation to life at high mary amino acid sequence of a protein add synergistically to temperature would therefore be for an organism to employ cause substantial increases in thermostability of proteins so mostly G-C basepairs in the DNA to encode their genetic in- that even very sophisticated molecular mechanisms, such as formation (this is actually feasible, because the redundancy of transcription of DNA into RNA, requiring a careful coordina- the genetic code allows codons of various base composition to tion of a series of precise conformational changes with catalytic substitute for each other). Interestingly, the genome of M. jan- activity, are fully functional at elevated temperatures [6]. naschii is not unusually enriched for G-C basepairs and therefore other mechanisms must be employed to stabilize DNA at One other major question that remains currently unan- high temperatures. One solution is that many hyperthermo- swered is whether true thermophilic higher organisms ex- philes use enzymes that supercoil their DNA in a way to stabi- ist. The answer currently seems to be “no”, but it is not clear lize the doubles-helical form of DNA by introducing additional why this should be the case. If individual cells (or small cell twists (a helix can be made tighter by twisting it in one direction clusters) have managed to adapt their biochemistry to life in [“positive supercoiling”], or looser by twisting it in the opposite boiling water, why do we not see examples of higher plants or direction [“negative supercoiling”]. animals that can do the same? There are reports of various in- vertebrates, such as worms (Ridgea piscesae, Riftia pachyptila, It appears that the major challenge faced by DNA in hyper- Alvinella pompejana), gastropods amd shrimps (Rimicaris ex- thermophilic conditions therefore is not strand separation, but oculate) that live near thermal vents, but it appears that they

218 Vol 71 No.6 June 2018 JBIS EXTREMOPHILES: The Resilience of Life under “Adverse” Conditions only tolerate higher temperatures for very short periods, or at amino acid composition. The high concentration of phosphates distances from vents where mixing of vent streams with cool- within the phosphodiester backbone of DNA allows DNA to er water already causes a significant drop of temperature [7, remain fully soluble under these conditions, and the high ionic 8]. For example, the bristle worm Alvinella pompejana builds concentration stabilizes the base-pairing between the comple- tube-like projections on deep-sea thermal vents where its tail mentary strands. Extreme halophiles are typically exposed to ends are occasionally exposed to temperature spikes as high as high UV-radiation in the shallow salt lakes, so organisms such 80°C, while their heads are typically surrounded by cooler wa- as H. salinarum evolved highly effective DNA-repair mecha- ter (22°C) [9, 10]. There are no reports, however, that such bris- nisms to cope with UV-induced damage. Additional damage tle worms would be able to survive for a considerable length control mechanisms include polyploidy (multiple copies of the of time when submerged continuously in temperatures above genome in each cells) making such organisms highly resistant 55oC. A similar species found in the Northern Pacific,Paralv - to radiation [15]. inella sulfincola, withstands temperatures of 50-55oC, but pre- fers to live at lower temperatures ranging from 40 to 50oC [11]. 3 IMPLICATIONS FOR EXTRATERRESTRIAL LIFE FORMS These observations agree with biochemical data on recombi- AND THE FERMI PARADOX nantly produced enzymes from such organisms. A comparison of A. pompejana DNA polymerase η (Pol η) with its human ort- The Fermi Paradox poses the question why we appear to be holog demonstrated that the A. pompejana enzyme maintained alone in the Universe that may be teeming with life, including high activity following incubation at temperatures up to 49°C. intelligent life capable of being detected by its technological In contrast, the upper limit for the human Pol η was 43°C. At footprint, or even civilizations reaching out to communicate 52°C, both enzymes lost most of their activity [12]. We con- with other civilizations across planetary and galactic borders. clude that even the most “promising” candidates of a higher The Drake equation attempts to provide a scientifically justi- organism display, at best, only very moderate thermophilicity fiable answer to that question. Unfortunately, for many of the in stark contrast to the microbial counterparts. parameters within that equation we only have poor estimates. This review attempted to shed some light on the components Other resilient higher organisms are the tardigrades which feeding into the fl parameter that attempts to quantitate the survive exposure to extreme temperatures, extreme pressures fraction of planets with life forms. Apart from numerous radiation, dehydration, and starvation, but are unable to grow non-biological (astronomical, geological) factors influencing under such adverse conditions [13]. There are therefore no the likelihood of life evolving on a planet in the first place, the higher life forms known that can sustain their existence and value of fl critically depends on our understanding of terrestrial reproduction in a genuinely extremophile environment over biology and the limits of the chemistry giving rise to all known prolonged periods. terrestrial organisms.

2.2. Halophiles Research on extremophiles over the last few decades had a major impact on our understanding of the resilience of the car- The second extremophilic example that we will investigate in bon-based biochemicals found in all known life forms here on more detail here are the halophiles. As the name implies, halo- earth. The universal building blocks of life (nucleotides, amino philes (“salt-loving”) live in high salt environments where salt acids, lipids, carbohydrates etc.) found on earth are capable of is dissolved up to close to its saturation level (up to 6 M for supporting life over a substantially larger environmental range NaCl). Natural salt lakes are landlocked bodies of water were than was suspected previously. As illustrated in the preced- the evaporation rate exceeds the efflux rate, resulting in the ing sections, the extension of biological processes outside the accumulation of high concentrations salt (typically NaCl from “moderate” range relies merely on a series of modifications on the concentration of sea water). In solution, high salt concen- the molecular level that can be selected and optimized through trations compete very effectively for the hydrogen bonding the evolutionary process and allows organisms to expand into with water molecules and therefore make it more difficult for ecological niches that are not extensively populated by most biological macromolecules to dissolve. Nevertheless, salt lakes other organisms. No exotic new compounds or chemical ele- contain usually high concentrations of halophilic archaea and ments not found in other organisms are required to build ex- bacteria that not only survive but thrive under such adverse tremophiles. In many cases, such as the adaptations of keeping conditions. Although it is, at least in principle, possible for DNA intact in hyperthermophilic environments, it appears organisms to survive under such conditions by actively main- that there are several independent ways of achieving that goal; taining a substantially lower intracellular ionic concentrations, different hyperthermophiles use different strategies for the extreme halophiles choose a different strategy. Microbes, such same result. In other cases, such as keeping proteins soluble as Halobacterium salinarum (this species was named mislead- in high-salt environments or stabilizing proteins internally to ingly before it was classified as an Archaeon), maintain a high withstand elevated temperatures, relatively minor adaptations intracellular salt concentration that mirrors the external envi- in the primary amino acid sequence are sufficient to achieve ronment and thus reduces osmotic stress (the main difference such a goal. We can therefore conclude quite confidently that is that the extracellular anion is Na+, whereas the intracellu- the biochemical components on which terrestrial organisms lar anion is mostly K+ which is maintained by active transport are all based, are perfectly adaptable to a broad range of envi- mechanisms across the cell membrane) [14]. This high concen- ronments typically found on earth and other earth-like planets. tration of intracellular potassium requires a specific adaptation At this stage, this is the only type of biochemistry we are fa- of protein primary sequences that allow these proteins to re- miliar with, but it is needless to point out that there have been tain their solubility. Proteins from extreme halophiles typically speculations about radically different chemistries that may also contain a significantly higher proportion of acidic amino acid be capable of supporting life forms and may extend the phe- residues, such as aspartic and glutamic acid. In contrast to the nomenon of life in its most abstract definition to locations that previously mentioned proteins from hyperthermophiles, align- would – even with terrestrial biochemistry pushed to its limit ing of equivalent (orthologous) proteins from mesophiles and – be considered uninhabitable. Speculations about such alter- halophiles are thus clearly distinguishable just based on their native biochemistries range from minor modifications (altered

JBIS Vol 71 No.6 June 2018 219 ROBERT O. J. WEINZIERL chiralities of amino acids) to biomolecules including elements, environment, or vice versa. such as silicon, that are barely (or only in special circumstances) used in terrestrial organisms. Life forms based on altered Currently, most evidence appears to be compatible with the chiralities of asymmetric precursor molecules (D-amino ac- “Hot Earth Biogenesis” model. It is well established that early ids and L-sugars, instead of the L-amino acids and D-sugars) planets form in protoplanetary disks, before “collapsing” into would be different and biochemically mostly incompatible with more stable spherical structures that, even after solidification conventional organisms, but the underlying chemistry would caused by cooling down, remain hot and vulcanic for a consid- be so similar that it would be difficult to imagine extreme -en erable amount of time. The age of the Earth is about 4.5 billion vironments where one version would be able to adapt to where years [23], and the earliest detectable traces of life date from at the other one could not [16]. around 3.5 billion years ago [24]. This strongly suggests that life – unless seeded from extraterrestrial sources – arose surpris- More radical deviations in the chemistry of life would be ingly quickly (within 1 billion years) under hyperthermophil- the large-scale inclusion of silicon and germanium which share ic conditions [25]. The high temperatures may have favoured certain chemical similarities to the key building block, carbon, chemical reactions to favour the abiotic synthesis of metabolites of terrestrial life [17]. Silicon fulfils at least some of the chemi- and precursors, helped with concentrating the compounds and cal requirements for building complex structures suitable as bi- provided complex silicate weathering products to act as chemi- ological information carriers, but is chemically more restricted cal catalysts. It is therefore likely that studies of currently living in forming bonds with other chemical elements, thus reducing extremophiles reveal, at least partially, some of the biochemical the rich diversity found in earthly biological metabolism [18]. mechanisms acting during the earliest stages of life and that are Potentially more interesting are speculations about replacing universally applicable to many other planets. Careful studies of water as the universal solvent [19, 20]. Suggestions range from extremophilic life forms may therefore provide us with a sig- ammonia, sulfuric acid, formamide and various hydrocarbons nificantly improved understanding under which conditions at to liquid gases, such as nitrogen or hydrogen. Ammonia is least primitive life could emerge elsewhere in the universe (one comparable in several aspects to water as a polar and cosmi- must be careful with such assumptions because some of the ad- cally abundant molecule [21]. Non-polar liquid hydrocarbons aptations found in extant extremophiles may have evolved sig- lakes, consisting of methane and ethane, have been detected on nificantly later). surface of Saturn’s largest moon, Titan [22]. None of these proposed solvents are compatible with terrestrial life, but this fact Another puzzle of contemporary extremophilic biology is makes them particularly interesting for supporting radically the question why higher, multicellular life forms, seem to de- different biochemistries in truly extreme environments that pend on a mesophilic environment and are essentially absent in could not be colonized by earthbound organisms. Unfortunate- the extremophilic environments densely populated by bacteria, ly, it is currently only possible to speculate about the feasibility archaea and – occasionally – some fungi and algae. Which bio- of such different life chemistries because our chemical and biochemical mechanisms required for multicellularity, and by im- logical knowledge is not sufficient to estimate the likelihood of plication, the emergence of intelligent forms of life, are impeded simple, let alone intelligent life forms to exist under such con- in such environments? Is Life common in the universe, but only ditions. Such speculations are not making a useful contribution manifested predominantly as microbes that may even be trans- towards estimating parameters of the Drake’s equation. ported extraterrestrially through space by meteorites and other mechanisms, but rarely evolves into multicellular organisms of 4 CONCLUSIONS a complexity required for intelligence and civilizations?

There are several deep questions that arise from our current Further research will, without doubt, fill in some of the understanding of terrestrial life in mesophilic and extremo- missing details over the next decades, but to answer some of philic environments. The question that is most difficult to an- these really fundamental questions we would need to find oth- swer is whether life originally evolved in an extremophile en- er examples of independently emerged and evolved life forms vironment and adapted subsequently to the more mesophilic to understand the truly universal principles of biology.

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12. Kashiwagi S, Kuraoka I, Fujiwara Y, Hitomi K, Cheng QJ, Fuss JO, chemical model for life in the universe?". Current Opinion in Chemical Shin DS, Masutani C, Tainer JA, Hanaoka F, Iwai S: Characterization Biology 8, 676–680. of a Y-Family DNA Polymerase eta from the Eukaryotic Thermophile 20. Committee on the Limits of Organic Life in Planetary Systems, Alvinella pompejana. J Nucleic Acids. 2010, pii: 701472. Committee on the Origins and Evolution of Life, National Research 13. Sloan, D., Alves Batista, R.; Loeb, A. (2017). "The Resilience of Life to Council. The Limits of Organic Life in Planetary Systems; The National Astrophysical Events". Scientific Reports. 7 (1): 5419. Academies Press, 2007. 14. Pérez-Fillol, M.; Rodríguez-Valera, F. (1986). "Potassium ion 21. Haldane, J.B.S. (1954). The Origins of Life.New Biology 16, 12–27. accumulation in cells of different halobacteria". Microbiología. 2 (2): 22. Stofan, E. R., Elachi, C., et al. (2007). The lakes of Titan.Nature . 445, 73–80. 61–64. 15. Soppa, J. (2011). "Ploidy and gene conversion in Archaea". Biochem. Soc. 23. Manhesa, G., Allègre, C.J., Dupréa, B., Hamelin, B. (1980). Lead isotope Trans. 39 (1): 150–154. study of basic-ultrabasic layered complexes: Speculations about the age 16. Davies, P.C.W., Lineweaver, C.H. (2005). Hypothesis Paper: Finding a of the earth and primitive mantle characteristics. Earth and Planetary Second Sample of Life on Earth. Astrobiology 5, 159. Science Letters 47. 370–382. 17. Sagan, C. (2000). Carl Sagan's Cosmic Connection: an Extraterrestrial 24. Schopf, J.W. (2006). Fossil evidence of Archaean life. Philosophical Perspective (2nd ed.). Cambridge University Press. Transactions of the Royal Society B 361, 869–885. 18. Pace, N.R. (2001). "The universal nature of biochemistry". PNAS USA 25. Shaw, G.H. (2016). Earth’s early atmosphere and oceans, and the origin of 98,805–808. life. Springer International Publishing. 19. Benner, S.A., Ricardo, A., Carrigan, M. A. (2004). Is there a common

Received 11 September 2018 Approved 13 September 2018

JBIS Vol 71 No.6 June 2018 221 JBIS VOLUME 71 2018 PAGES 222–224

LIFE BEFORE FERMI – Back to the Solar System

DAVID L. CLEMENTS Astrophysics Group, Blackett Lab, Physics Department, Imperial College, Prince Consort Road, London SW7 2AZ, UK email [email protected]

The existence of intelligent, interstellar traveling and colonising life is a key assumption behind the Fermi Paradox. Until recently, detecting signs of life elsewhere has been so technically challenging as to seem almost impossible. However, new observational insights and other developments mean that signs of life elsewhere might realistically be uncovered in the next decade or two. We here review what are believed to be the basic requirements for life, the history of life on Earth, and then apply this knowledge to potential sites for life in our own Solar System. We conclude that the necessities of life – liquid water and sources of energy – are in fact quite common in the Solar System, but most potential sites are beneath the icy surfaces of gas giant moons. If this is the case elsewhere in the Galaxy, life may be quite common but, even if intelligence develops, is essentially sealed in a finite environment, unable to communicate with the outside world.

Keywords: Fermi Paradox; Extraterrestrial life; Solar System

1 INTRODUCTION tem, on the basis of available resources, might be capable of hosting life. We discuss these results and draw our conclusions The central realisation of the Fermi Paradox [e.g.1, 2 is that in Section 5. a space-faring civilisation, spreading from habitable planet to habitable planet even at speeds substantially below that of 2 THE EARLY HISTORY OF LIFE ON EARTH light, can visit every star in the Galaxy on a timescale of 50- 100Myrs. This is a very small timescale compared to the age Determining the date at which life emerged on Earth is a cen- of the Galaxy (~10 Gyrs) or the age of the Sun (4.5 Gyrs). Our tral goal of paleobiology and a very active field. In recent years, hypothetical aliens should thus already be here, and yet they the date of the earliest known life on Earth has been pushed are not. This can be used as an argument against the existence to ever earlier epochs. Fossilised stromatolites – distinctive of intelligent extraterrestrials [e.g. 1; 4, 5], but our own ex- sedimentary rock formations produced by layers of photo- istence is proof that intelligent life can and does arise in the synthesising bacteria – and microfossils clearly show that life Galaxy. This is the central puzzle of the Fermi Paradox. was well established 3.5 Gyr ago [8]. More recent studies have pushed back the date of stromatolites to 3.7 Gyr ago [9], just Many solutions have been suggested to the Fermi paradox 800 Myr after the formation of the Earth. The earliest date (eg. Brin, 1983; Webb, 2002, Sandberg et al., 2017) but all this claimed for life on Earth so far is 4.28 Gyr ago, based on the discussion has taken place inside a vacuum of observational discovery of microfossils in sedimentary rocks believed to be evidence. This may change in the next decades with the advent associated with a seafloor hydrothermal vent [10]. This would of instruments like the Square Kilometre Array (SKA), which place the emergence of unicellular life on Earth at a time al- is sufficiently sensitive that it should be able to detect air traffic most simultaneous with the end of the Hadean epoch 4 Gyr control radars out to a distance of 10pc with relative ease [7]. ago, and the end of the late, heavy bombardment, a period of However, there are other steps on the road to the Fermi Par- intense asteroid and comet impact activity, signs of which are adox that we can examine with observational evidence from found throughout the inner Solar System [11]. An early date our own Solar System that is already available. We aim to do for the emergence of life is supported by the results of isotopic this in the current paper through looking first at the history of analysis of graphite inclusions in a 4.1 Gyr old zircon from life on Earth, then at the resources that seem to be essential for Western Australia [12]. the emergence of life, and then an examination of the sites in the Solar System where these resources may exist. The discovery of evidence for life on Earth over 4 Gyr ago is rather surprising since the young Earth was a truly hostile The rest of the paper is structured as follows. In Section 2 environment, with a largely molten surface. If our ideas about we look at the history of life on Earth, incorporating the latest the young Earth are correct, then it would appear that life de- information about the emergence of both life, habitability, and veloped on Earth almost as soon as it was possible for it to de- currently habitable environments. In Section 3 we look at the velop. Needless to say, this has significant implications for the resources that appear to be essential for the existence of life. search for extraterrestrial life and intelligence since it suggests Then in Section 4 we examine which bodies in the Solar Sys- that life can emerge very rapidly in compatible environments.

222 Vol 71 No.6 June 2018 JBIS LIFE BEFORE FERMI – Back to the Solar System

3 RESOURCES NECESSARY FOR LIFE TABLE 1 Summary of the available volumes of water in a number of Solar System bodies Life on Earth, as we commonly see it, is almost entirely depend- Object Radius (km) Water volume (km3) ent on photosynthesis, and thus light form the Sun. One might therefore think that access to sunlight on the surface of a plan- Earth 6370 140 x 107 et, be it on land or in an ocean, is a requirement. However, as Enceladus 252 4.4 x 107 we have seen above, one of the potential sites for the first life on 7 Earth is in fact a deep seafloor hydrothermal vent. Such vents Dione 561 46 x 10 still exist in the deep ocean today, and are well known as oases Europa 1565 280 x 107 of biological activity in the otherwise barren ocean depths [e.g. Pluto 1187 430 x 107 13]. The primary energy source for these rich biological com- Triton 1352 670 x 107 munities is chemosynthetic rather than photosynthetic, with 7 bacteria using the rich chemical mix emerging from the ocean Callisto 2410 2440 x 10 7 floor as their primary source of energy. There is even evidence Titan 2576 2830 x 10 that sub-oceanic basalts contain large communities of chemo- NASA/JPL-CALTECH FROM STEVE VANCE: USES DATA Ganymede 2631 5440 x 107 synthetic bacteria [14], raising the possibility that the largest Note that many of these bodies have available water volumes up to component of the Earth’s biosphere actually lies in the rocks several tens of times that of the water volume of the Earth. They could that extend kilometres deep beneath the oceans and cover 60% thus potentially have much larger biospheres given a source of energy to of the surface of the Earth [15]. feed it, and to ensure the water is liquid and not frozen.

From this we can conclude that the availability of energy is the common thread, rather than dependence on any specific minor planets in the Solar System. Even tiny Dione, a small form of energy, such as sunlight. moon of Saturn, has 1/3 of the water of the Earth, while Gany- mede has forty times as much. The other common factor that seems to apply to all of the biological communities we are aware of on Earth is water, 5 DISCUSSION AND CONCLUSIONS which provides the liquid substrate in which all biological reactions occur. While there have been suggestions that other Since we have deemed that water is the essential environment solvents might be capable of supporting biological processes, for life, the implication of these numbers is that the icy moons such as ammonia, hydrocarbons and other more exotic com- of the outer Solar System can potentially host much larger eco- pounds [e.g. 16, 17], there is to date no evidence supporting systems than the one that is present on the Earth. There are these suggestions. certainly other requirements, such as an adequate supply of energy, potentially from radiogenic or tidal heating, but we We thus conclude that our consideration of possible loca- know such power sources are present from observations of the tions for life in the Solar System must be restricted to bodies plumes on Europa and Enceladus. where liquid water and an available supply of energy can be found. While this is a conservative assumption, as we shall see Secondly, the history of life on Earth now seems to be show- many such locations are available. ing us that life, albeit very simple prokaryotic monocellular life, emerged very rapidly once the Earth had become compatible 4 HABITABLE BODIES OF THE SOLAR SYSTEM with its existence.

Given these assumptions about the requirements for life, What are the implications of these results for the Fermi we can make some assessments of the size of potential eco- Paradox? If we put the two sets of results together we find the systems in various Solar System objects by looking at the vol- following: ume of water available. A viable ecosystem in these locations would then arise if there is a source of energy to both melt – Th e rapid emergence of life on Earth suggests that life can some fraction of this available water, and power any emergent emerge wherever there is a compatible environment ecosystem. Table 1 shows a summary of the amount of water – There are large bio-compatible environments inside the available in a number of different Solar System bodies. While a icy moons of Solar System gas giants significant fraction of the water in many of these bodies will be – The size of the bio-compatible environments inside gas frozen into ice, there is abundant evidence that some of these giant moons is much larger, both in sum and, in the case objects (at least Enceladus, Europa, Titan and Ganymede) of the large moons like Ganymede and Titan, individual- contain large bodies of liquid water below their icy surfaces ly, than the biosphere of Earth [18, 19, 20, 21, 22]. The discovery of geysers on Enceladus and Europa, ejecting water and other material from a subsurface The conclusion of this analysis for our own Solar System is ocean [23, 24, 25] provides clear confirmation of the presence that the interior of the icy moons may be where the bulk of life of liquid water and a source of energy keeping it liquid in at in the Solar System is to be found. However, this life, intelligent least these two objects. Meanwhile, though it seems highly or otherwise, would be locked beneath many kilometres of sol- likely that water flowed on Mars in the distant past and likely id ice, only able to escape into the broader universe through survives there today, a full estimate for the amount of water catastrophic geyser eruptions such as those found on Encela- in this traditional target of searches for extraterrestrial life, is dus and Europa. still missing. There are already indications that moons exist around some The most surprising result from these numbers is that the exoplanets [26], and there is no reason to think that moons Earth, often referred to as the blue planet because of its abun- around gas giant exoplanets should be any different from those dant water, has far less water than many of the icy moons and seen in the Solar System. There may thus be a very large num-

JBIS Vol 71 No.6 June 2018 223 DAVID L. CLEMENTS ber of them. Given the discussion here, it could be that the sub- Further exploration of the content of the oceans beneath the surface oceans of gas giant exomoons are in fact the dominant icy moons in our own Solar System through new missions like home for life in the Galaxy, with life on Earthlike, terrestrial JUICE (JUpiter ICy moons Explorer), ground-based observa- planets, being the exception rather than the rule. We note that tions looking for the spectral signatures of organic molecules the prospects for identifying more exomoons and for their de- [24], or thorough analysis of existing data from past missions tailed study in the next few years are very good [27, 28] using like Cassini [29], will help determine the validity of the specu- data from Kepler or the James Webb Space Telescope. lations in this paper. We note that the latest results from Cassini suggest the presence of complex biochemical molecules in the In the context of the Fermi Paradox, we know that species ocean of Enceladus, though their origin remains unclear. that live in water can evolve to a high level of intelligence – dolphins and octopuses are good examples (though it should We are left with the rather chilling prospect that the gal- be noted that dolphins are evolutionary returnees to the wa- axy may be filled with life, but that any intelligence within it ter). However, a liquid environment may be a limiting factor is locked away beneath impenetrable ice barriers, unable to in the development of technology. The dominant concern in communicate with, or even comprehend the existence of, the this context, though, is the location of these vast watery envi- universe outside. ronments beneath tens or hundreds of kilometres of water ice. While there may be water geysers in some of these, the larg- Acknowledgements er environments of Titan, Callisto and Ganymede in our own Solar System show no signs of escaping water since they are It is a pleasure to thank Gerry Webb and the BIS for the invi- likely capped by an ice layer over 100 km thick. This probably tation to contribute to the Fermi Paradox discussion meeting presents an insurmountable obstacle to any intelligence dwell- and to this special edition. I would also like to thank my PhD ing there even knowing about the outside universe, let alone students Josh Greenslade and Tai-an Cheng for useful discus- attempting to communicate with it. sions.

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1. G.D. Brin, The great silence: the controversy concerning extraterrestrial 16. J.A. Baross, (2007), The Limits of Organic Life in Planetary Systems, intelligent life, Quarterly Journal of the Royal Astronomical Society, 24, National Research Council, The National Academies Press, Washington pp 283–309, 1983 DC, doi.org/10.17226/11919, 2007 2. M.H. Hart, An explanation for the absence of extraterrestrials on Earth. 17. C. McLendon, et al., Solubility of Polyethers in Hydrocarbons at Low Quarterly Journal of the Royal Astronomical Society, 16 pp 128–135, Temperatures. A Model for Potential Genetic Backbones on Warm 1975 Titans, Astrobiology, 15, pp 200-206, 2015 3. F.J. Tipler, Extraterrestrial intelligent beings do not exist. Quarterly 18. S.D. Vance, S.D., Geophysical Investigations of Habitability in Ice- Journal of the Royal Astronomical Society, 21 pp 267–281, 1980 Covered Ocean Worlds, Journal of Geophysical Research (Planets) 123, 4. A. Sandberg, E. Drexler, T. Ord, T. Dissolving the Fermi Paradox, ArXiv pp 180-205, 2018 e-prints arXiv:1806.02404, 2018 19. M. Beuthe, et al., Enceladus’s and Dione’s ﬂoating ice shells supported 5. S. Webb, If the Universe Is Teeming with Aliens, Where Is Everybody? by minimum stress isostasy, Geophys. Res. Lett., 43, pp 10,088–10,096. Fifty Solutions to Fermi’s Paradox and the Problem of Extraterrestrial Life, 2016 Springer, New York, 2002 20. T.A. Hurford, et al., Triton's Fractures as Evidence for a Subsurface 6. A. Sandberg, S. Armstrong, M.M.Cirkovic, That is not dead which can Ocean, Lunar and Planetary Science Conference 48, 2376, 2017 eternal lie: the aestivation hypothesis for resolving Fermi's paradox, 21. J.T. Keane, et al., Reorientation and faulting of Pluto due to volatile ArXiv e-prints arXiv:1705.03394, 2017 loading within Sputnik Planitia, Nature 540, pp 90-93. 2016 7. A. Siemion, et al. Searching for Extraterrestrial Intelligence with the 22. F. Nimmo, F., et al., Reorientation of Sputnik Planitia implies a Square Kilometre Array, Advancing Astrophysics with the Square subsurface ocean on Pluto, Nature 540, 94-96, 2016 Kilometre Array (AASKA14) 116, 2015 23. C.J. Hansen, et al., Enceladus' Water Vapor Plume, Science 311, pp 1422- 8. J.W. Schopf, Fossil evidence of Archaean life, Philos. Trans. R. Soc. Lond. 1425, 2006 B, 361(1470) pp 869–885, 2006 24. E. Drabek-Maunder, et al., Ground-based detection of a cloud of 9. A.P. Nutman, et al., Rapid emergence of life shown by discovery of methanol from Enceladus: When is a biomarker not a biomarker? 3,700-million-year-old microbial structures, Nature 537, pp 535–538, International Journal of Astrobiology, 1-8. https://doi.org/10.1017/ 2016 S1473550417000428. 2017 10. M.S. Dodd, Evidence for early life in Earth’s oldest hydrothermal vent 25. W.B. Sparks, et al., Probing for Evidence of Plumes on Europa with precipitates, Nature, 543 pp 60-64., 2017 HST/STIS, The Astrophysical Journal 829, pp 121-142. 2016 11. W.F. Bottke, & M.D. Norman, The Late Heavy Bombardment,Annual 26. M.A. Kenworthy, et al. Modeling giant extrasolar ring systems in eclipse Review of Earth and Planetary Sciences, 45, pp 619-647. 2017 and the case of J1407b: sculpting by exomoons?, The Astrophysical 12. E.A. Bell, et al., Potentially biogenic carbon preserved in a 4.1 billion- Journal 800, pp 126-136, 2015 year-old zircon, Proc. Natl. Acad. Sci., 112, pp 14518-14521. 2015 27. M.A. Peters, & E.L. Turner, On the Direct Imaging of Tidally Heated 13. R.A. Lutz, & M.J. Kennish, The Ecology of Deep Sea Hydrothermal Vent Exomoons, The Astrophysical Journal 769, pp 98-106, 2013 Communities: A Review, Reviews of Geophysics, 31, pp 211-242, 1993 28. D.M. Kipping, et al. On the detectability of habitable exomoons with 14. M.A. Lever, et al., Evidence for Microbial Carbon and Sulphur Cycling Kepler-class photometry, Monthly Notices of the Royal Astronomical in Deeply Buried Ridge Flank Basalt, Science 339, pp 1305-1308, 2013 Society, 400, pp 398–405, 2009 15. K.J. Edwards, et al., The Deep, Dark Energy Biosphere: Intraterrestrial 29. F. Postberg, et al., Macromolecular organic compounds from the depths Life on Earth, Annu. Rev. Earth Planet. Sci., 40, pp 551–68, 2012 of Enceladus, Nature, in press, 2018

Received 31 July 2018 Approved 19 October 2018

224 Vol 71 No.6 June 2018 JBIS JBIS VOLUME 71 2018 PAGES 225–232

ALIEN AIRCRAFT: Have they been observed on Earth? ALAN BOND, Mirror Quark Ltd, 34 Hunters Field, Stanford in the Vale, Oxfordshire, UK SN7 8LX

The subject of Flying Saucers or, more generally UFOs, immediately polarises the scientific community. It is therefore with some trepidation that the author embarks on this paper, feeling vulnerable to accusation from some eminent quarters that the subject is simply unworthy of consideration. It is a subject which has developed huge stigma in scientific circles, drawing scorn from some people to whom the very prospect of alien visitors is preposterous. In particular, they would cite with one sweep the incredulous nature of the UFO literature as representing a manifestation of intelligent contact by alien species with our planet. It must be admitted that the author has great sympathy with this intuitive point of view. Yet it is the author’s opinion that proper scientific method has not been adequately applied to the vast number of reports of unfamiliar vehicles in our skies. Indeed, this paper was presented at a conference predicated on the hypothesis that aliens should exist and, while discussing the apparent absence of them, dismissing that reports of strange machines in our skies could be valid evidence of their presence. The author therefore craves indulgence while undertaking examination of the evidence from the point of view of a propulsion engineer, with considerable background in aerospace and nuclear power engineering, especially nuclear fusion. In addition, the author has had long standing interest in the issues surrounding the Fermi Paradox and has extensively studied the problems of interstellar flight. In the following paper propulsion will be the central focus of consideration, together with such issues as the observation and visibility of vehicles in the sky. Consideration will be given to observer credibility and example hoaxes will be drawn upon.

Keywords: UFO, Fermi Paradox, Magneto-Hydrodynamic Vehicles

1 PREAMBLE particularly influential.

The Condon Report [1] will spring to many people’s mind as Although there is a vast literature on UFOs (some less ex- the defining serious attempt to bring scientific study to bear on treme works are cited in the bibliography) the references the subject of Unidentified Flying Objects (UFOs). However, employed in most of this analysis were restricted to just two most people quoting the Condon Report will not have read it books; The Hynek UFO Report (1977) [2], by J. A. Hynek and first-hand (it is a tedious read!) and they only recall the idea The Truth About Flying Saucers (1956) by Aimé Michel [3]. This that a deep scientific investigation took place and proved that was done because the author trusts their motives in publishing UFOs are all nonsense. That was not in fact the case. The Con- their work. This is not to say that other authors are not trust- don review, which was scientifically rigorous and well executed, worthy, but only that this author has some confidence in these found many UFO reports inexplicable in terms of atmospheric, particular authors. We will use Hynek’s classification of cases. astronomical or meteorological phenomena but still concluded that there was no evidence of aliens. The author has also investigated a number of UFO sightings personally. The author considers that the people he has in- It is the author’s considered view that it was impossible for terviewed, without exception, were absolutely sincere in what aliens to be acceptable as an explanation for the phenomena they said and absolutely believes that they were telling the truth investigated in the Condon review, by definition. The Condon as they saw it. Report, like many similar exercises, set out to explain UFO reports in terms of well understood terrestrial phenomena. They However, the UFO field is generally a murky one, full of did not admit the hypothesis that extraterrestrial vehicles could misidentification, hallucination and outright lies. Most of the have been involved and then attempt to determine if such vehi- literature is manifestly fabricated by the authors, or delusional, cles could be consistent with the reports. and it is this overriding impression of the ‘lunatic fringe’ which engenders the cynical dismissive response from the scientific The discussion of the subject here is limited to the period community. Before we can examine possible real observations before the Star Wars film (first released in 1977) and mod- it is therefore necessary to ‘clear the undergrowth’ by reviewing ern computer graphics reached the cinema. This is because some Close Encounter (Hynek's CE) cases. one can detect a large influence of the cinema on individuals who claim to have experienced contact with aliens. Spielberg’s 2 CONTACT: ENCOUNTERS OF THE THIRD KIND Close Encounters of the Third Kind (1977) and ET (1982), as well as the television series The X-Files have, it seems, been Everyone has difficulty with these cases. Hynek himself

JBIS Vol 71 No.6 June 2018 225 ALAN BOND states “Approaching the Edge of Reality”. Of all the reported UFO cases these are just a few percent, although they receive most of the public attention. They are dealt with first because the author has studied a number and can find none which are either credible or which are not explicable in terrestrial terms. This discussion is restricted to the favourites that are usually presented as evidence by the UFO community. In order not to take up space in this article most cases are simply quoted by name and not restated here. Interested readers can easily follow up the detail on Google. We will not touch on cases, mostly crashed vehicles with dead occupants, which are clearly fictitious invention of the authors. They are self evident to any rational mind. Fig.1 Unexplained Blue Book UFO cases by year 1947 – 1969 The not-credible CE cases are very reflective of what has Hynek2 (Appendix D). come out of cinema, often with caped and silver booted occupants. They have a dream-like quality to them and it is suspect- Papua (1959). In 1994 the author had a personal interview with ed that, of the sincere proponents, self hypnosis and delusion Col. Charles Halt, who had been Deputy Base Commander at plays a large role in their creation. The Betty and Barney Hill Woodbridge in England. In each of these cases it is concluded abduction case (1961) is probably the classic example, although here that UFO stories were used by governments to deliberate- there are several in this class. ly confuse embarrassing terrestrial incidents.

False memory is most probably an important factor in some When looking beyond the story for a terrestrial answer it close encounter cases and the author has had an opportunity should be remembered that Roswell was the home of the only to investigate such a case. The person involved only began to nuclear bomber squadron and that Woodbridge is close to the talk about their experience 15 years after the event. It involved Sizewell nuclear power station, which was politically sensitive the sighting of a large glowing dome shaped vehicle that passed at the time. At the time of the interview with Halt, he claimed from right to left over their car as they rounded a right hand to still have radioactive samples he collected that night in his turn early one evening in 1981. This was in Abingdon, Oxford- desk drawer. It is left to the reader to make their own inferences shire, at a busy location and the date, which the person had in these two instances. forgotten, could only be narrowed down to one of four possibilities. Clearly, no one else had reported it when they certainly The Boianai observations are explicable if one postulates would have done so had something extraordinary really been the involvement of a monitoring platform based on novel air- visible in the sky. Using the astronomy program, Red Shift, sky ship design entirely within the technology of the day. This was views were modelled on each of the potential dates. One was the height of the Cold War in a region having USAF, RAF and remarkable. It was a half moon almost horizontal, just rising RAAF interests. It was the early years of the Space Age when at the end of the road they were turning into. The author next a lot of devious schemes were in play. Although no references drove his car round a bend in a similar fashion while watching have been found to such a craft having been built, B. D. Gild- an astronomical object through the driver’s side window. It ap- enberg [7] has written extensively on the classified work that parently ‘flew’ over the car exactly as described. The reader can came within the Skyhook balloon programme. The author has try it, taking due precautions of course! carried out a design study of a propelled buoyant platform which would have the reported characteristics. What seems The author undertook several more interviews with the more likely, an alien craft having come light years to wave at the person without telling them about the modelling results. Their local mission, or a terrestrial allied operation associated with recollection became more and more embellished with details, Cold War intelligence gathering? such as portholes and small jets. It needs to be stressed that this person is unquestionably 100% sincere and was recalling The above synopsis has touched lightly on only a few of the genuine memories. It can only be assumed that something cases that the author has investigated in this category. There like a dream pulled this subliminal observation to the fore and are none where an extraterrestrial explanation was required. To fabricated it into a recollection of an event witnessed, 15 years the author, evidence of government(s) conspiracy does seem later. The author has memories he knows to be impossible and probable, not to hide aliens, but to use them to deflect atten- recognises them as such. Interestingly he has met other peo- tion from terrestrial political embarrassments! We now move ple with the same kind of childhood recollections. The field of on to examining more substantial reports which can be subject False Memory is one of active research. to some analysis.

Some high profile CE UFO cases are indisputably straight- 3 DAYLIGHT DISCS AND NOCTURNAL LIGHTS forward hoaxes, for example Adamski (1953) [4] and Alling- ham (1954) [5]. Other cases most probably involve sincere peo- Hynek [2] presents a useful set of statistics addressing the ‘un- ple duped by others, as with the The Scoriton Mystery (1967) explained’ reports derived from the Project Blue Book files. [6] and the Kelly-Hopkinsville (1965) case. These cases take These have been shown graphically in Fig.1. We retain Hy- some tortuous detective work to sort out the perpetrator, but it nek’s nomenclature of Nocturnal Lights, Daylight Discs, Radar helps that the author grew up with a father who was a ventrilo- Visual, Radar and Close Encounters. quist and stage illusionist! We now concentrate on the incidence of Daylight Discs The remaining cases in this class are more interesting. We (DD) and nocturnal lights (NL), having dismissed Close En- cite Roswell (1947), USAF Woodbridge (1980) and Boianai, counters (CE) from further consideration. Most of these DD

226 Vol 71 No.6 June 2018 JBIS ALIEN AIRCRAFT: Have they been observed on Earth?

Fig.2a Basic Magneto-Hydrodynamic Vehicle concept (from private notes). Fig.3 LASER sustained discharge. and NL sightings were reported by professional people in re- having a long standing interest in MHD, had not employed it spectable jobs. Many of these were armed forces and police other than in the Daedalus starship study. Working closely with personnel where reporting what they did could have seriously Tony Martin resulted in many stimulating and wide ranging damaged their careers. In the current author's opinion there is discussions on spaceflight, both Solar System and interstellar, little doubt that most, but not all, of these reports were made and the Fermi Paradox. in good faith. The reports are generally of a character that an observer reporting a passing automobile or aircraft would In 1978 we realised that if it were practical to make the at- make, i.e. of solid objects of substantial duration making the mosphere locally electrically conducting through ionisation, a usual impact of physical events on human senses. rather different type of aircraft to the conventional would be possible (Fig.2a) This was not in connection with explaining We will take a different approach to the problem to that UFOs, of which we were both highly sceptical. used by most researchers trying to dismiss the observations with concocted terrestrial explanations. We will ask the ques- In its simplest form, this vehicle would have a large diameter tion ‘do the reported configurations of these machines make high field magnetic coil with two electrodes placed diametri- any sense?’ If we conclude that they do, we will then examine cally opposite. In a conducting atmosphere, passing a current if we have any other basis for dismissing them as manifes- through the electrodes across the magnetic field would force tations of extraterrestrial presence. Michel [3] adopted this the air rearward and the reaction on the field coil would drive approach and tried to address the shape of a flying saucer us- it forward. By having an elliptical cross section the body could ing a propulsion theory proposed by Lieutenant Plantier [8]. derive lift from the airflow pulled over it by the electromagnetic However, this theory invoked unknown physics for which (Lorentz) force. there is no current justification in our understanding of the workings of the Universe. In 1978 a test model was constructed which performed a series of successful tests to prove the principle in a tank of salt 4 A MAGNETO-HYDRODYNAMIC (MHD) VEHICLE water (Fig.2b). The salt water tank was employed because of the difficulty of producing long-lived ionisation of the air at sea Following on from Project Daedalus [9] the author joined level. Although the atmosphere is not normally conducting it the Atomic Energy Authority working on nuclear fusion at can be, as lightning demonstrates. In 1980 the LASER research the Culham site, where Dr. Tony Martin, who also edited the group at Culham accidentally initiated an atmospheric dis- Daedalus Report, already worked. One of the author’s roles was charge (Fig.3) at the focus of a CO2 LASER. This proved to be magnetic field coil design for the JET experiment and while completely controllable and could be turned on and off at will.

Fig.2b Proof of principle MHD test item suspended in salt water.

JBIS Vol 71 No.6 June 2018 227 ALAN BOND

While this showed that stable atmospheric density plasmas are possible, the power demand would be extreme. However, another phenomenon is frequently observed: Ball Lightning.

There is little doubt that Ball Lightning is a real cold plasma phenomenon and there have been extensive investigations into what it is as reviewed by Singer [10] and testified by Los Alamos report from 1971 (Fig.4). The author has interviewed, in detail, two very reliable witnesses who experienced Ball Lightning very close up, less than 1 metre away. One was the pilot of a Vulcan Bomber at high altitude in the North Atlantic when a glowing ball suddenly appeared over his throttle sticks before detaching and passing down the aircraft. The second witness was a young man about to go to sleep when a small glowing orb winked into Fig.5 Experimental Fusor in Star Mode. existence and passed down his bedroom. sion called Inertial Electrostatic Confinement (IEC). This was With some modest assumptions regarding the ionisation first proposed in the 1950s by Russian and US physicists and a mechanism, a computer model was produced of this type of device was patented by Farnsworth, the inventor of cathode ray plasma and combined with an aerodynamic model of a MHD tube television, in 1966. There is still a long way to go to realise propelled disc. The scoping study employed a vehicle with a a practical device, but it has promise as shown in the review mass of 15 tonne and diameter of 6m. This model in turn was by Miley [11]. They are usually termed Fusors (Fig.5). An im- incorporated into a trajectory program and flown to 8km/s at portant aspect of these devices is that they hold the possibility 45.5km altitude, which placed it into a transfer orbit to 500km for direct conversion of the output power to electrical power altitude. The maximum power demand was about 1GW. At ap- without an intervening thermodynamic cycle and heat engine ogee the 1GW was diverted to a plasma rocket engine for space and, in principle at least, they could also operate with thermo- propulsion. The vehicle was circular in planform because of the nuclear reactions having poor reaction cross sections and low, very high stress levels in the main magnetic field coil, which or no, neutron output. had to sustain 0.5 Tesla while being of flight weight. Summarising the discussion above, there are very good rea- Of course a 1GW power supply with such a small mass is sons why an advanced aircraft would be circular in planform for not easy, to say the very least! Conventional nuclear power via structural reasons of the main magnet. Its recombining ionised fission or magnetically confined fusion could not deliver the region would emit a faint glow like Ball Lightning, have strong required power/weight ratio by a large factor. magnetic fields and be capable of vertical takeoff through a bal- ance of thrust against aerodynamic drag and lift. It would be However, there is a promising line of research in nuclear fu- very manoeuvrable since it is only necessary to switch power to different electrodes to change the thrust direction. The ionisation system could have physiological effects on nearby people.

A flat elliptical cross section disc is, however, not a good shape for containing internal pressure and anything pressurised would need to be a separate internal structure. If a large pressurised volume were required the shape would be that of an aircraft fuselage and the magnetic field coils would then have to compromise, with a mass penalty, to fit that shape. This vehicle would generate little aerodynamic lift which would therefore need to be entirely produced by MHD. The frontal area per unit volume is similar for both shapes and propelling them to high speed has a similar power demand for a given enclosed volume. Spindle shaped vehicles are the second most highly reported UFO shape, comprising roughly 10% of unexplained reports.

From a propulsion point of view we must conclude that the reported UFO sightings cannot be dismissed on the grounds of not representing a practical vehicle. On the contrary, there are very good reasons why the two main shapes and the reported associated phenomena, such as the tilt at take-off, the glow (only obvious in low light) and magnetic field, would be expected of an advanced aircraft powered by fusion and driven by magneto-hydrodynamic engines.

It is stressed that all of the above considerations are based on known physical principles and employ technology currently under active research. It is not necessary to wander into the realms of fantasy with inertia control, worm holes and other metric controlling devices to explain the described be- Fig.4 Los Alamos 1973 report on Ball Lightning. haviour of the majority of credible, unexplained, UFO reports

228 Vol 71 No.6 June 2018 JBIS ALIEN AIRCRAFT: Have they been observed on Earth? of the DD and NL type. as, leading to the most detailed coverage of such an event as we have. Why is there no similar coverage of a flying saucer? 5 CONSIDERATIONS OF OBSERVATION Some years ago, the author interviewed an ornithologist who An aircraft in the sky is visible over very large distances. A 10m reported seeing a number of small discs performing manoeu- diameter object would present an angular size of 1/10th of the vres near the UKAEA Culham site. This was under conditions moon at a distance of 10km. On approach to the Earth, in sun- of a low mid-day November sun while looking northward. The light, a disc of this size would be very bright. It would be a faint author actually reproduced his observations personally a few but potentially naked eye object at 10,000km and a very bright years later and found it was sunlight reflecting off pigeons at star like object at 2,500km. It would be resolvable as a body at the limit of resolution, when they do indeed look like manoeu- a distance of 60km. Many of us have watched very bright sat- vring shiny discs. Further observations of birds were deliber- ellites of much smaller dimensions than this pass overhead at ately made with bright low altitude sunlight coming from be- altitudes of 200 to 300km. A small telescope would be able to hind the observer and it is surprising how machine-like they detect such an object at 160,000km. The S4 stage of the Apollo can look, moving with a pulsating light. But it is also surprising missions was indeed followed optically on its way to the Moon. that an experienced ornithologist could make such a mistake. A self luminous object would also be very visible at night as can be observed with aircraft lights. In the data that Hynek presents of unexplained UFO sightings there is a very marked, and well verified, increase in Reported observations of large UFOs in crowded places UFO activity in 1952. Leaving 1952 out of the calculation, the when only one person has seen it are not credible unless it was data are well normally distributed, as one would expect for at very low altitude in an obstructive background. Even then, it mistaken observations at random. However the 1952 figures has to come and go. Bear in mind that the example used above are over 6 standard deviations larger and so something clear- (10m diameter) is at the small end of reported sightings 30m – ly happened in that year. Gildenberg [7] states that this was 60m being common. probably down to the vast increase in the number of hours of classified Skyhook balloon flights in that year (from 92 hours There are many photographs of UFOs on record. When a in 1951 to 694 hours in 1952). He also states that his team had laboratory pronounces a photograph as genuine they mean that close relationship with the Blue Book team which they used it has not been manipulated or used multiple exposures. The to monitor public feedback on these secret missions. The Sky- duration of exposure can usually be assessed and compared hook flights also started in 1947, the year that the first Flying with the claimed focal length and stop employed. Lighting an- Saucer story broke. gles can also be considered. What cannot be said, without other objects in the frame, is whether the object photographed was While there may be some truth in this explanation, the ac- genuine. When other objects are in the picture, relative distanc- tual nature of many of the reports, particularly from pilots of es can usually be obtained. The author has considered many of aircraft describing close up observations of disc shaped craft the popular ‘genuine’ photos and remains convinced that the under the influence of powerful propulsion, is hard to fit into objects portrayed are either lighting effects, common items that explanation. Many of these reports are supported by mul- tossed into the air and photographed, or purpose built models. tiple independent observers.

A number of people now spend time debunking UFO pic- Could other events have been responsible for overactive tures. It is indeed odd that, in these days of ubiquitous photogra- imagination in 1952? Table 1 shows technological events and phy, UFO pictures are not commonplace. In 2013 a very large major films during this period. The Mike hydrogen bomb test meteorite entered the atmosphere over Chelyabinsk in Russia. It was later than the peak of the UFO ‘flap’. The two main -in was captured on several dashcam recorders and security camer- fluential films, in red, preceded the ‘flap’ but by quite a time.

MILESTONES RELEVANT FILMS 1947 Early atomic bombs 1948 1949 1950 Rocketship Destination Moon 1951 Thing from Another World (The Thing) The Day the Earth Stood Still When Worlds Collide 1952 mike (November) 1953 It Came From Outer Space War of the Worlds 1954 bravo 1955 This Island Earth 1956 Earth vs Flying Saucers Forbidden Planet 1957 Sputnik 1958 1959 1960 1961 Ranger, Gagarin 1962 Mariner Venus 1963 1964 Mariner Mars Robinson Crusoe on Mars 1965 1966 1967 Apollo TABLE 1 Technological events and 1968 major films 1947-69. 1969 2001: a Space Odyssey Quatermass and the Pit (film)

JBIS Vol 71 No.6 June 2018 229 ALAN BOND

Nonetheless, it is felt here that those films, carrying powerful ‘home’ must be about 1 to 2 light years away at the most. This is messages, may have had some influence, especially in close much closer than any stellar system. encounters cases. In 1978 Maurice G. de San [12] published a monograph ‘Hy- Some observations have multiple witnesses who are consid- pothesis on the UFO Origin’. This followed from his hypothesis ered reliable and in responsible jobs. In December 1957, the Ra- that the finite time in which a world would remain habitable dio Officer of the British Naval ship SSRamsay , T Fogl, took a would eventually force all intelligent entities to follow a no- series of photographs of a flying saucer (Fig.6) as it passed over madic existence. He concluded that the majority of civilisations his vessel off the coast of California. The crew of 12 all signed in the Galaxy are in fact in world ships travelling between stars. affidavits testifying to the truth of the event. These were widely regarded as the best photographic evidence for flying saucers, It is the author’s personal view that all biological intelligent even by the author at the time he first saw them (about 1961). creatures would eventually replace themselves with machine intelligence well before being driven from their home world. However, it was a hoax which they admitted to after many If we add up these various hypotheses, we might propose that years. This case is cited to caution against the belief that there there is a nomadic machine intelligence heading our way, cur- is honesty in numbers. At least in this case there was ultimate- rently a light year or two away, scouting out our culture and ly honesty, but it presents a cautionary lesson. The question is its evolution. If this is correct and considering past BIS studies then, if one group of people can get together and lie convinc- [13], their main fleet should be travelling relatively slowly, at ingly, does that mean that this has happened in all such cases? 0.1% to 0.5% of the speed of light, and will have been on its way The answer probably depends on how cynical one is about peo- here for some thousands of years. They could arrive in about ple and their motives! Further discussion of hoaxing is relegat- 200 to 400 years time. We would have been no threat when they ed to the Annex since this paper is about assessing the credibil- set out in our direction, but in a couple of centuries from now ity of UFO propulsion. they may have to negotiate entry to our solar system. Will that be ‘Independence Day’!? [14] 6 A SCENARIO 7 SUMMARY If we accept that the propulsion could be possible, can we con- ceive a scenario in which it would be used as observers claim? In this short paper the author has tried to indicate that the more reasonable UFO reports cannot be dismissed as a man- Consider, as a thought experiment for the moment, the hy- ifestation of alien activity on technical grounds. This is not to pothesis that someone visited this planet in 1952 with advanced say that it is such an activity, but only that it should be consid- probes. If we accept the observations in that year as valid, then ered seriously along with other terrestrial explanations of such we would also have to accept the observations in other years sightings. Clearly, it would be foolish to jump to conclusions as well, since they describe the same sort of phenomena. This that all unexplained objects in the sky are alien spaceships. could imply that we are under continuous scrutiny and that for some reason 1952 was special. It would also imply that we are In trying to understand possible alien motives and, there- under study in a way that does not involve contact, i.e. ‘they’ fore, how their appearance here would manifest, it is necessary want to simply observe us and our planet. to think well outside human behaviour. If they have crossed vast reaches of space in a world ship fleet, they will be looking World War II resulted in a huge technological revolution, for resupply. The solar system has abundant material in other which we presume was reported ‘home’. Assuming 1952 was a places than Earth. To a very advanced culture, their knowledge response to that it would suggest that if communication home of physics, biology, the origins of life and its evolution will be was at the speed of light, and new probes were then hurriedly ‘old hat’. However, like any entomologist, they will undoubted- dispatched at, say, about 20% of the speed of light to investigate, ly be interested in studying and classifying any examples they

Fig.6 The Fogl images of a flying saucer taken in 1957.

230 Vol 71 No.6 June 2018 JBIS ALIEN AIRCRAFT: Have they been observed on Earth? come across. The Universe is vast and complex and it is beyond doubt that there are a very large number of variations on a theme. The satellites of the solar system are an example of that in a relatively simple case.

The author does not want to give the impression that he believes in alien flying saucers, or that they are about to invade us. However the technology is possible and the author is actively working on MHD propelled vehicle concepts which of- fer great potential for solar system and even interstellar flight. The evidence for the extraterrestrial origin of some UFOs is not compelling but it is argued here that the possibility of an extraterrestrial origin has been lightly dismissed from reasonable study, mainly through the conviction of the impossibility of the technology and the bias born of ludicrous contact stories.

8 CONCLUSIONS Fig.7 The Watchkeeper Drone at Farnborough 2010. On technical grounds, we cannot rule out ‘flying saucers’ as being possible alien drones surveying our planet. “At 10.13pm on Sunday 21 June 2009 I was returning to my On observational grounds, it is hard to understand why home when I encountered one of my neighbours also return- firmer evidence does not exist if there are, in fact, alien vehicles ing home from work. Suddenly we both heard an ear splitting in our skies. explosion with a very sharp shock front such as is generated by an electrical discharge. We could see no evidence of its source. The author has personally interviewed a dozen eyewitnesses The following morning another neighbour came to see me. The and has not found a single observer who he thinks saw an alien previous evening he had been watering his garden at the rear craft. In addition he has analysed in detail about 10 high profile of the houses when he saw an indistinct torpedo shaped object close encounter cases (one in person) and finds only evidence pass low and slow between the clouds which were extensively of terrestrial activity. obscuring the sky. Suddenly, it emitted a bright flash from a point on it, “like a flash bulb”, accompanied by the explosion. We must conclude that some reports, by professional people On hearing of this I immediately visited various homes in the with multiple observers, are explicable only by two options, ei- village and found no one who had seen it and only one person ther they were all lying or they saw alien craft. who recalled hearing a distant bang.”

The author would require strong evidence to dismiss either Although the author has found no one in Government or option. industry prepared to confirm it, this seems certain to have been a drone (Fig.7). They are reported to carry high voltage equip- 9 FINALLY ment on the outside. The neighbour only saw the object in poor light and for a few seconds. Rough calculations of its size from Although the author has interviewed several sincere UFO ob- the neighbour’s description suggest it was a few metres (3–5) servers, not one event appears to have been other than terres- long. It should not have been flying legally in that location. It trial in origin. The following recalls, in first person, an event has already been suggested here that UFOs are a good cover encountered personally by the author: story for embarrassing down to Earth events!

REFERENCES

1. Dr. Edward U. Condon, Ed., The Scientific Study of Unidentified Flying 10. Stanley Singer, The Nature of Ball Lightning, Plenum Press, 1971 Objects, University of Colorado, 1969 11. G.H. Miley & S.K. Murali, Inertial Electrostatic Confinement Fusion, 2. Dr. J.A. Hynek, The Hynek UFO Report, Sphere Books Ltd, 1978 Springer, 2014 3. Aimé Michel, The Truth About Flying Saucers, Pyramid Books Edition 12. Maurice G. de San, Hypothesis on the UFO Origin, UPIAR Monograph, 1967, S. G. Phillips 1956 1978 4. G. Adamski & D. Leslie, Flying Saucers Have Landed, London, 1953 13. Dr. A.R. Martin, Ed., JBIS vol 37.6 June 1984, Special Issue on 5. Cedric Allingham, Flying Saucers From Mars, Frederick Muller Ltd., Worldships 1954 14. Film: Independence Day, Prod. Dean Devlin, Dir. Roland Emmerich, 6. Eileen Buckle, The Scoriton Mystery, Neville Spearman Ltd, 1967 1996 7. B. D. Gildenberg, The Cold War Classified Skyhook Program: A Participants Revelations, The Skeptical Enquirer Vol. 28.3, May/June Bibliography – selected UFO references of general interest 2004 Timothy Good, Above Top Secret, Harper Collins Edition 1993, Sidgick 8. Lieutenant Plantier, Une Hypothèse sur le fuctionnement des “Soucoupes & Jackson 1987 Volantes”, FORCES AÉRIENNES FRANÇAISES, 1953 Frank Edwards, Flying Saucers Serious Business, Mayflower, 1967 9. Dr. A.R. Martin, Ed., Project Daedalus, JBIS Supplement, 1978 Donald H. Menzel, Flying Saucers, Putnam & Co., 1953

JBIS Vol 71 No.6 June 2018 231 ALAN BOND

ANNEX ASSESSING UFO REPORTS

This paper has focused on the credibility of propulsion and vehicle and flexible option is that of re-photographing enlarged photographs characteristics of reported UFOs for which no terrestrial explanation was of a scene which has had the object added after careful consideration of found. It was not intended to address the question of the credibility of the geometry and illumination of the scene. This technique was popular UFO reports in general. However, it is felt appropriate to include some in cinematography before the advent of CGI. It also works for Polaroid comments relating to the wider issue of UFO reports and what can be images, which do not have a negative. admitted as potential observation for analysis. In evaluating a lone reported sighting supported by photographs it is therefore essential to ask the question, could the image have been faked? A.1 The Hoaxer If it is to be admissible as scientific evidence the answer must be “no”. If An argument frequently cited in UFO circles is along the lines of “look it is concluded that the image could have been faked it must be rejected at how many cases have been reported, it must be true!” It is useful as evidence. This may seem a hard line to take, but in terms of the above to consider the question of how many hoaxes we might expect to be statistical expectation of hoaxes, it is the only scientific option unless we perpetrated relative to the size of human populations involved. want to move to the realms of ‘belief’. A hoax presumably begins with an individual wanting to satisfy some At 12:37pm Pacific Daylight Time on Tuesday 3 August 1965 Rex personal goal, mostly a psychological one since generally there is little Heflin, while out in the course of his work for the highways department, material gain to be made. In the event of this latter case we move from photographed a flying machine (4 separate Polaroid images) close to the hoax to con, a criminal activity which does occur. The psychological goal Santa Ana freeway (Route 405 connecting Los Angeles to San Diego) just must involve some sense of feeling superior in the knowledge that the outside Santa Ana, California. All of the analysis of the photos (which hoaxer knows something that the gullible people around them don’t. the author has also personally checked) is consistent with the time and location Heflin stated. These images are widely regarded as authentic in In order to find some statistics which may be relevant we can draw the UFO community. However, the traffic on the freeway is close by and upon data for the distribution of criminal activity in western society. clearly visible with windscreens facing the photographer. Located a few In looking at the incidence of criminality in western populations, miles away was the El Toro Marine Airbase, one of the busiest military burglary runs two orders of magnitude higher than crimes such as airfields in the USA at the time, with ‘state of the art’ radar coverage. In robbery or sexual offences where the perpetrator has to interact with addition, the civilian airport at Los Angeles was only a few miles in the the victim, while burglary is faceless. Reported burglary runs at about opposite direction, also with radar. 1-2% per head of the population per annum depending on levels of Heflin was the only observer reporting this machine despite the fact unemployment. We can consider burglary as a process encompassing that it would have subtended an angle five times that of the Moon to those who consider it, with a percentage of those having the compulsion the nearest vehicles on the freeway at an altitude of only 150 feet under to do it, with a percentage of this sample having the wherewithal (ladder, almost perfect lighting by the Sun, and been in the middle of radar crowbar, gloves, van, etc) to carry it out. controlled airspace. The images are capable of having been faked by We will assume that a similar process applies to a hoax, but the either of the methods stated above, although they would have required successful hoax is perhaps harder to achieve. The hoax is fundamentally considerable geometrical skill on behalf of Heflin. Heflin was a skilled a lie supported by additional fabricated evidence intended to make it model railway enthusiast, and produced enlargements of the Polaroid appear true, not too dissimilar to the stage magician. If we assume that images himself suggesting competence with photography. He also had a the number of people seeking personal gratification from a hoax and reputation for an odd sense of humour. who are prepared to act is similar in numbers to burglars we might It cannot be proved conclusively that Heflin’s images are faked, but assume that this is 0.01 per head of population. However, a hoax is it can be shown that they easily could have been. In the circumstances technically difficult and probably only 0.01 of potential hoaxers have the described, they have to be classified as inadmissible as scientific evidence. resources (skills, equipment, finance, opportunity, etc) to be successful. The onus has to be with the observer to prove the truth of their statement Thus we are possibly considering 10-4 puzzling events reported per head if the possibility exists that they are lying. This is not the same as an of population. Of course hoaxers will be operating in all kinds of fields accusation of lying. of human endeavour (paranormal, perpetual motion etc) and those choosing the UFO field may be only (say) 10% of the total. We may therefore expect in the order of 10-5 UFO hoaxes per annum per head of A.3 What is Acceptable Evidence? population. Ideally a report would come from multiple unrelated observers over a Considering the distribution of populations from which UFO reports wide area, with multiple clear independent photographic images and/ are collated and reported, we are possibly looking at a total of 109 people or video, and perhaps radar, of the same event, as occurred with the from a very wide geographical distribution. From the above sweeping Chelyabinsk meteorite argument we might expect to see 104 credible hoaxes reported per year worldwide. This is indeed close to the number reported. However, most of those are readily identified for what they are and only a small number There are such reports but, as the author has found, always with some remain controversial each year. detraction which render them unreliable. In particular, statements like: “the evidence was submitted to the air force in a 50 page report but they Clearly the above argument is open to criticism, in particular in have lost it and now deny ever having it”. In such cases we only have the regarding hoaxers as being opportunists. The point to be conveyed is that statement of one individual that such a document ever existed. Of course we would expect to see a large number of credible UFOs reported each the conspiracy theorists believe the witness. If we are to remain impartial, year just from this source alone, whatever the precise number may be. we can believe no individual or group of related individuals (recall the S.S. Ramsay). Again, this is not the same as stating that we disbelieve A.2 Reaching Scientific Conclusions them, we simply cannot use it as evidence. The lack of credibility of large alien vehicles being seen by single eyewitnesses in populated areas has been addressed in the main body of Despite investing considerable effort with (hopefully) an open mind, the paper. the author has not yet come across a single UFO report meeting these Photographic evidence from a single source also raises problems. simple requirements which was not subsequently shown to be a natural The suspension of models using filaments which are below resolution in event or an object of manmade origin. It is significant that observations photographs is entirely possible using translucent fibres of high strength meeting the above requirements do exist for these latter events (entry of (nylon, glass) as used by Fogl on the S.S. Ramsay. A much more credible large meteors or spacecraft, for example) but not for UFO events.

Received 31 July 2018 Approved 19 October 2018

232 Vol 71 No.6 June 2018 JBIS DIARY FORTHCOMING LECTURES & MEETINGS OF THE BIS

APOLLO 8 – MEN TO THE MOON 18 December 2018, 7.00pm VENUE: BIS, 27/29 South Lambeth Road, London, SW8 1SZ Jerry Stone takes us on the next step in his series of 50th anniversary talks covering every Apollo mission up to and including Apollo 17 by looking back at Apollo 8's historic journey into lunar orbit – a triumphant end to an otherwise turbulent and tragic year. APOLLO MISSIONS: THE MECHANICS OF RENDEZVOUS & DOCKING BY DAVID BAKER 20 February 2019, 7.00pm VENUE: BIS, 27/29 South Lambeth Road, London, SW8 1SZ Starting with Apollo 9 launched on 3 March 1969, a key feature of the Apollo missions was the ability to rendezvous and dock in orbit – a capability that NASA had evolved over the preceding four years. SpaceFlight Editor David Baker describes the process in detail and casts an expert eye over the different options considered by mission planners in the run-up to the lunar landing missions. APOLLO 9 – RENDEZVOUS IN EARTH ORBIT 6 March 2019, 7.00pm VENUE: BIS, 27/29 South Lambeth Road, London, SW8 1SZ Jerry Stone continues his series of talks to celebrate the 50th anniversary of the Apollo missions with a uniquely personal take on the story of Apollo 9 – the first test of the full lunar landing package and only the second outing of the Lunar Module. WEST MIDLANDS BRANCH: A NEW SPACE RACE? & PROJECT CHEVALINE 16 March 2019, 1.45pm VENUE: BIS, 27/29 South Lambeth Road, London SW8 1SZ Gurbir Singh posits the beginning of a new space race between India and China, while John Harlow and Paul Jackman look back to the days of Project Chevaline and the famed Twin Chamber Propulsion Unit. APOLLO 10 – RENDEZVOUS IN EARTH ORBIT 22 May 2019, 7.00pm VENUE: BIS, 27/29 South Lambeth Road, London SW8 1SZ Jerry Stone continues his coverage of Apollo with the first flight to carry both the Apollo spacecraft and the Lunar Module on a full dress rehearsal of a landing. Call for Papers RUSSIAN-SINO FORUM 1-2 June 2019, 9.30 am to 5pm (tbc) VENUE: BIS, 27/29 South Lambeth Road, London SW8 1SZ The BIS has now scheduled its 39th annual Russian-Sino Forum – one of the most popular and longest running events in the Society's history. Papers are invited. Watch this space for further details. APOLLO MISSIONS: LANDING ON THE MOON BY DAVID BAKER 12 June 2019, 7.00pm VENUE: BIS, 27/29 South Lambeth Road, London, SW8 1SZ SpaceFlight's editor looks at the systems evolved by NASA for calculating optimum lunar landing trajectories, and at the descent procedures needed to achieve the maximum chance of success while preserving emergency abort and safety considerations. Journal of the British Interplanetary Society

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ISSN 0007-084X PUBLICATION DATE: 6 DECEMBER 2018