DOCSLIB.ORG

No, We Haven't Solved the Drake Equation, the Fermi Paradox, Or

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
No, We Haven't Solved the Drake Equation, the Fermi Paradox, Or 7/19/2018 No, We Haven’t Solved The Drake Equation, The Fermi Paradox, Or Whether Humans Are Alone Ethan Siegel Follow The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist. Jul 3 · 7 min read Intelligent aliens, if they exist in the galaxy or the Universe, might be detectable from a variety of signals: electromagnetic, from planet modication, or because they’re spacefaring. But we haven’t found any evidence for an inhabited alien planet so far. We may truly be alone in the Universe, but the honest answer is we don’t know enough about the relevant probability to say so. (Ryan Somma / ickr) No, We Haven’t Solved The Drake Equation, The Fermi Paradox, Or Whether Humans Are Alone The absence of evidence is not evidence of absence, but substituting wild speculation for evidence isn’t even science. In 1950, Enrico Fermi famously asked the question, “Where is everybody?” It wasn’t because his retinas detached; it was because he was curious about the lack of visits by extraterrestrials. If life in the Universe is ubiquitous, the argument goes, then surely the signs of it should be everywhere? Over the past 60+ years, we’ve developed a number of possible explanations for this puzzle, known today as the Fermi Paradox. https://medium.com/starts-with-a-bang/no-we-havent-solved-the-drake-equation-the-fermi-paradox-or-whether-humans-are-alone-8f31a559f741 1/13 7/19/2018 No, We Haven’t Solved The Drake Equation, The Fermi Paradox, Or Whether Humans Are Alone On the surface, this seems like a reasonable question to ask. There are billions of stars in the galaxy, many of which have Earth-like planets, and if Earth is fairly typical, some of these may have developed intelligent life. Many of us on Earth are working to develop interstellar travel, and even though the galaxy is 100,000 light years across, we’ve been around for many billions of years. If life is common, then where is everyone? A new paper claims to have the answer, but their conclusions are highly suspect. An artist’s rendition of a potentially habitable exoplanet orbiting a sun-like star. When it comes to life beyond Earth, we have yet to discover our rst inhabited world. (NASA Ames / JPL-Caltech) Clearly, if they’re out there, they haven’t shown up around these parts or left surere signs of their existence. Our searches for alien civilizations — such as with giant radio dishes and projects like SETI — have all come up empty, with no signatures of an alien intelligence out there. UFOs are likely to have earthly explanations, not extraterrestrial ones. Exoplanetary searches, exemplied by NASA’s Kepler mission, have turned up thousands of planets beyond Earth, many of which are Earth-like in size, teaching us that there are literally billions of chances for Earth-like life in our galaxy alone. Yet no life beyond Earth has ever been found; not on those worlds, nor on any of the other worlds in our Solar System. https://medium.com/starts-with-a-bang/no-we-havent-solved-the-drake-equation-the-fermi-paradox-or-whether-humans-are-alone-8f31a559f741 2/13 7/19/2018 No, We Haven’t Solved The Drake Equation, The Fermi Paradox, Or Whether Humans Are Alone The hematite spheres (or ‘Martian blueberries’) as imaged by the Mars Exploration Rover. These are almost certainly evidence of past liquid water on Mars, and possibly of past life. NASA scientists must be certain that this site — and this planet — are not contaminated by the very act of our observing. As of yet, there is no surere evidence for either past or present Martian life. (NASA/JPL- Caltech/Cornell/ASU) Water, light, heat, organic molecules, and the ingredients for life are indeed everywhere. But aliens of any type have yet to show themselves. For all we have hard evidence for, Earth may be it for life in the entire Universe. If that sounds pessimistic to you, or, as Carl Sagan put it, “an awful waste of space,” you’re not alone. Back in the early 1960s, Frank Drake put forth an equation that allowed us to make an estimate of the number of spacefaring, intelligent alien civilizations out there — in either our galaxy or the entire observable Universe — at any point in time. Although we knew very little about the various parameters in it, the Drake Equation is still used by many today to estimate the number of potential civilizations we can communicate with in space. https://medium.com/starts-with-a-bang/no-we-havent-solved-the-drake-equation-the-fermi-paradox-or-whether-humans-are-alone-8f31a559f741 3/13 7/19/2018 No, We Haven’t Solved The Drake Equation, The Fermi Paradox, Or Whether Humans Are Alone The Drake equation is one way to arrive at an estimate of the number of spacefaring, technologically advanced civilizations in the galaxy or Universe today. But until we know how to estimate these parameters, we’re just guessing at the possible answers. (University of Rochester) While we can make better estimates, today, of quantities like: • the number of stars in each galaxy, • the number of galaxies in the Universe, • the fraction of stars that are like our Sun, • and the fraction of Sun-like stars with potentially habitable, Earth- sized planets, there are still a few enormous unknowns that are out there. The possibilities of having another inhabited world in our Milky Way are incredible and tantalizing, but if we want to know whether it’s real or not, we absolutely have to get the science right. (Wikimedia Commons user Lucianomendez) https://medium.com/starts-with-a-bang/no-we-havent-solved-the-drake-equation-the-fermi-paradox-or-whether-humans-are-alone-8f31a559f741 4/13 7/19/2018 No, We Haven’t Solved The Drake Equation, The Fermi Paradox, Or Whether Humans Are Alone In particular, there are a few steps that we simply don’t know how frequently they occur. They clearly occurred here on Earth, but we haven’t, as of yet, discovered anyplace else in the Universe where even one has occurred. These are the steps that lead us from non-living molecules to the complex, dierentiated, intelligent species that we fancy ourselves to be. This equates to two (in the Drake equation) unknowns that are absolutely necessary to reach the ultimate goal of intelligent aliens: 1. the likelihood of creating life from non-life on an Earth-like world, 2. and the likelihood of that life evolving into an intelligent, communicative, and possibly interstellar species. In terms of raw probability, we have no idea how likely or unlikely these events are. Structures on ALH84001 meteorite, which has a Martian origin. Some argue that the structures shown here may be ancient Martian life, but others contend that this is Earth-originating life that has made its way into a Martian rock. No such fossils have been found in situ in the rocks examined on Mars. (NASA, 1996) Sure, there are plenty of sensible things we can say about them. We can talk about the experiments we’ve done to create organic molecules from raw, inorganic ingredients. We can discuss the complex organic molecules we nd in interstellar space or in meteorites. We can mention the tantalizing hints that worlds in our Solar System house https://medium.com/starts-with-a-bang/no-we-havent-solved-the-drake-equation-the-fermi-paradox-or-whether-humans-are-alone-8f31a559f741 5/13 7/19/2018 No, We Haven’t Solved The Drake Equation, The Fermi Paradox, Or Whether Humans Are Alone about watery pasts, sub-surface liquid oceans, and potentially fossilized microbes. And we can look at the fact that, if we extrapolate the genetic information encoded in extant organisms back to the formation of the Earth, they indicate that what we consider “life” to be may have had its origin billions of years before our planet came into existence. On this semilog plot, the complexity of organisms, as measured by the length of functional non- redundant DNA per genome counted by nucleotide base pairs (bp), increases linearly with time. Time is counted backwards in billions of years before the present (time 0). Note that, if we do this extrapolation, we might conclude that life on Earth began billions of years prior to Earth’s formation. (Shirov & Gordon (2013), via https://arxiv.org/abs/1304.3381) But none of that is reasonable for calculating a probability for the likelihood of life arising from non-life, given an Earth-like world. The odds may be extremely high, like a few percent, as some have estimated. But the odds could be catastrophically low: one-in-a-million, or even worse. Life could be incredibly rare. The fact that life exists on Earth does not mean we didn’t win the cosmic lottery. We cannot draw a reasonable conclusion from a sample size of one. And things get even worse if you try and extrapolate that second conditional probability: given life, what are the odds that it becomes intelligent, sentient, spacefaring and communicative across interstellar distances? https://medium.com/starts-with-a-bang/no-we-havent-solved-the-drake-equation-the-fermi-paradox-or-whether-humans-are-alone-8f31a559f741 6/13 7/19/2018 No, We Haven’t Solved The Drake Equation, The Fermi Paradox, Or Whether Humans Are Alone The Atacama Large Millimeter submillimeter Array (ALMA) are some of the most powerful radio telescopes on Earth. These telescopes can measure long-wavelength signatures of atoms, molecules, and ions that are inaccessible to shorter-wavelength telescopes like Hubble, but can also measure details of protoplanetary systems and, potentially, alien signals, that even infrared telescopes can’t see.(ESO/C.
Load more

Recommended publications
  • Monday, November 13, 2017 WHAT DOES IT MEAN to BE HABITABLE? 8:15 A.M. MHRGC Salons ABCD 8:15 A.M. Jang-Condell H. * Welcome C
    Monday, November 13, 2017 WHAT DOES IT MEAN TO BE HABITABLE? 8:15 a.m. MHRGC Salons ABCD 8:15 a.m. Jang-Condell H. * Welcome Chair: Stephen Kane 8:30 a.m. Forget F. * Turbet M. Selsis F. Leconte J. Definition and Characterization of the Habitable Zone [#4057] We review the concept of habitable zone (HZ), why it is useful, and how to characterize it. The HZ could be nicknamed the “Hunting Zone” because its primary objective is now to help astronomers plan observations. This has interesting consequences. 9:00 a.m. Rushby A. J. Johnson M. Mills B. J. W. Watson A. J. Claire M. W. Long Term Planetary Habitability and the Carbonate-Silicate Cycle [#4026] We develop a coupled carbonate-silicate and stellar evolution model to investigate the effect of planet size on the operation of the long-term carbon cycle, and determine that larger planets are generally warmer for a given incident flux. 9:20 a.m. Dong C. F. * Huang Z. G. Jin M. Lingam M. Ma Y. J. Toth G. van der Holst B. Airapetian V. Cohen O. Gombosi T. Are “Habitable” Exoplanets Really Habitable? A Perspective from Atmospheric Loss [#4021] We will discuss the impact of exoplanetary space weather on the climate and habitability, which offers fresh insights concerning the habitability of exoplanets, especially those orbiting M-dwarfs, such as Proxima b and the TRAPPIST-1 system. 9:40 a.m. Fisher T. M. * Walker S. I. Desch S. J. Hartnett H. E. Glaser S. Limitations of Primary Productivity on “Aqua Planets:” Implications for Detectability [#4109] While ocean-covered planets have been considered a strong candidate for the search for life, the lack of surface weathering may lead to phosphorus scarcity and low primary productivity, making aqua planet biospheres difficult to detect.
    [Show full text]
  • Fermi's Paradox Is a Daunting Problem – Under Whatever Label
    Fermi's Paradox Is a Daunting Problem – Under Whatever Label Milan M. Dirkovid1 Astronomical Observatory of Belgrade, Volgina 7, 11000 Belgrade, Serbia 1. Introduction Gray (2015) argued that Fermi's paradox (FP) is a misnomer, and it is not a valid paradox. Gray also speculated that the argument was misattributed to Fermi, whose lunchtime remarks did not pertain to the existence of extraterrestrial intelligence, but to the feasibility of interstellar travel. Instead, the paradox is ascribed to Hart and Tipler, and it is further suggested that the paradox is not a “real” problem or research subject and should not be used in debates about SETI projects. The arguments given are unpersuasive, ahistorical, and, in at least one instance, clearly hinge on literalistic and uncharitable reading of evidence. Instead, I argue the following three points: (i) Contrary to Gray’s assertion, the historical issue of naming of ideas or concepts is completely divorced from their epistemic status. (ii) FP is easily and smoothly generalized into the “Great Silence” paradox, so it makes no sense either theoretically or empirically to separate the two. (iii) In sharp contrast to the main implication of Gray’s paper, FP has become more aggravated lately due to advances in astrobiology. Research that deals with FP has greatly expanded in recent years on both a theoretical and observational stage (Davies 2010, 2012; Vukotid and Dirkovid 2012; Barlow 2013; Hair and Hedman 2013; Davies and Wagner 2013; Armstrong and Sandberg 2013; Lampton 2013; Cartin 2014; Nunn, Guy, and Bell 2014; Wright et al. 2014; Spivey 2015; Griffith et al.
    [Show full text]
  • Arxiv:1910.06396V4 [Physics.Pop-Ph] 12 Jun 2021 ∗ Rmtv Ieeitdi H R-Oa Eua(Vni H C System)
    Nebula-Relay Hypothesis: Primitive Life in Nebula and Origin of Life on Earth Lei Feng1,2, ∗ 1Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023 2Joint Center for Particle, Nuclear Physics and Cosmology, Nanjing University – Purple Mountain Observatory, Nanjing 210093, China Abstract A modified version of panspermia theory, named Nebula-Relay hypothesis or local panspermia, is introduced to explain the origin of life on Earth. Primitive life, acting as the seeds of life on Earth, originated at pre-solar epoch through physicochemical processes and then filled in the pre- solar nebula after the death of pre-solar star. Then the history of life on the Earth can be divided into three epochs: the formation of primitive life in the pre-solar epoch; pre-solar nebula epoch; the formation of solar system and the Earth age of life. The main prediction of our model is that primitive life existed in the pre-solar nebula (even in the current nebulas) and the celestial body formed therein (i.e. solar system). arXiv:1910.06396v4 [physics.pop-ph] 12 Jun 2021 ∗Electronic address: [email protected] 1 I. INTRODUCTION Generally speaking, there are several types of models to interpret the origin of life on Earth. The two most persuasive and popular models are the abiogenesis [1, 2] and pansper- mia theory [3]. The modern version of abiogenesis is also known as chemical origin theory introduced by Oparin in the 1920s [1], and Haldane proposed a similar theory independently [2] at almost the same time. In this theory, the organic compounds are naturally produced from inorganic matters through physicochemical processes and then reassembled into much more complex living creatures.
    [Show full text]
  • Fermi Paradox: a Simulation Solution YU HAIHAN, MARK
    Fermi Paradox: a simulation solution YU HAIHAN, MARK Introduction The paradox was proposed by Fermi in 1950 during a lunch with Edward Teller, Hilbert York and Emil Konopinski. When they were talking about mundane topics, Fermi asked a question:”Where is everybody?”(Webb, 2002) His partners immediately understood what he was talking about: If the extraterrestrial civilization exists, why we have not met them till now? If we believe that there is nothing special about earth and solar system, there should be other civilizations in the universe as its enormous size containing countless probabilities. Under such assumptions, the paradox occurred. To provide a forceful explanation, many efforts have been paid on the analysis on Drake equation. Drake equation: The number of civilization in the universe is represented by N. To estimate it, we need to know the yearly rate R at which stars forms the galaxy; the probability fp of stars that possess planets; the number ne of planets with suitable environment for life; the probability fl of suitable planets on which life actually develops; the probability fi of these planets on which develops intelligence; the probability fc of these intelligence that could communicate with other civilizations and the time L that such a culture would devote to communication (Webb, 2002). Though the equation is complicated as above, it can be just divided into 3 main factors. Consider the following equation: n=Npq This equation is provided by Professor David Aldous, which can be viewed as a simple version of Drake equation. In this equation, N is the number of suitable planets for life; p is the chance that an intelligence species would develop a capability to communicate with others and q the chance that such a species would survive in such a way as to be observable (Aldous, 2010).
    [Show full text]
  • 1 the SUSTAINABILITY SOLUTION to the FERMI PARADOX Jacob D
    THE SUSTAINABILITY SOLUTION TO THE FERMI PARADOX Jacob D. Haqq-Misra∗ Department of Meteorology & Astrobiology Research Center The Pennsylvania State University Seth D. Baum Department of Geography & Rock Ethics Institute The Pennsylvania State University No present observations suggest a technologically advanced extraterrestrial intelligence (ETI) has spread through the galaxy. However, under commonplace assumptions about galactic civilization formation and expansion, this absence of observation is highly unlikely. This improbability is the heart of the Fermi Paradox. The Fermi Paradox leads some to conclude that humans have the only advanced civilization in this galaxy, either because civilization formation is very rare or because intelligent civilizations inevitably destroy themselves. In this paper, we argue that this conclusion is premature by introducing the “Sustainability Solution” to the Fermi Paradox, which questions the Paradox’s assumption of faster (e.g. exponential) civilization growth. Drawing on insights from the sustainability of human civilization on Earth, we propose that faster-growth may not be sustainable on the galactic scale. If this is the case, then there may exist ETI that have not expanded throughout the galaxy or have done so but collapsed. These possibilities have implications for both searches for ETI and for human civilization management. ∗ Email address: [email protected] 1 1. INTRODUCTION The classic Fermi Paradox can lead to the conclusion that humans have formed the first advanced civilization in the galaxy because extraterrestrial intelligence (ETI) has not yet been observed [1]. Numerous resolutions to this paradox have been proposed [2], spanning the range of cosmological limits to sociological assumptions. A popular class of solutions assumes that the evolution of life is rare in the Universe: Earth may not be wholly unique, but other inhabited planets in the Universe could be too far away for any interaction or detection [3].
    [Show full text]
  • Dissolving the Fermi Paradox), and Quite Likely Once We Account for the Fermi Observation
    Dissolving the Fermi Paradox Anders Sandberg, Eric Drexler and Toby Ord Future of Humanity Institute, Oxford University June 8, 2018 Abstract The Fermi paradox is the conflict between an expectation of a high ex ante probability of intelligent life elsewhere in the universe and the apparently lifeless universe we in fact observe. The expectation that the universe should be teeming with intelligent life is linked to models like the Drake equation, which suggest that even if the probability of intelligent life developing at a given site is small, the sheer multitude of possible sites should nonetheless yield a large number of potentially observable civilizations. We show that this conflict arises from the use of Drake-like equations, which implicitly assume certainty regarding highly uncertain parameters. We examine these parameters, incorporating models of chem- ical and genetic transitions on paths to the origin of life, and show that extant scientific knowledge corresponds to uncertainties that span multi- ple orders of magnitude. This makes a stark difference. When the model is recast to represent realistic distributions of uncertainty, we find a sub- stantial ex ante probability of there being no other intelligent life in our observable universe, and thus that there should be little surprise when we fail to detect any signs of it. This result dissolves the Fermi paradox, and in doing so removes any need to invoke speculative mechanisms by which civilizations would inevitably fail to have observable effects upon the universe. 1 Introduction While working at the Los Alamos National Laboratory in 1950, Enrico Fermi famously asked his colleagues: ”Where are they?” [1].
    [Show full text]
  • Life Before Fermi – Back to the Solar System Dr David L Clements
    Life Before Fermi – Back to the Solar System Dr David L Clements Astrophysics Group, Blackett Lab, Physics Department, Imperial College, Prince Consort Road, London SW7 2AZ, UK Abstract 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. 1. Introduction The central realisation of the Fermi Paradox (see eg. Brin, 1983; Hart, 1975) is that a space- faring civilisation, spreading from habitable planet to habitable planet even at speeds substantially below that of light, can visit every star in the Galaxy on a timescale of 50- 100Myrs. This is a very small timescale compared to the age of the Galaxy (~10 Gyrs) or the age of the Sun (4.5 Gyrs).
    [Show full text]
  • An Answer to Fermi's Paradox in the Prevalence of Ocean Worlds?
    Habitable Worlds 2017 (LPI Contrib. No. 2042) 4006.pdf An Answer to Fermi’s Paradox In the Prevalence of Ocean Worlds? S. A. Stern1, 1Southwest Research Institute, Space Science and Engineering Divisdion, 1050 Walnut Street, Suite 300, Boulder, CO 80503, [email protected] Introduction: The Fermi Paradox asks the question about main sequence to stellar remnants). And (2) Environmental extraterrestrial civilizations, “Where are they?” Given specu- Stability. Again owing to the depth of typical Type II oceans lations based on numerical evaluations of the Drake Equation and the overlaying thermal insulation provided by the plane- that would seem to indicate that the likelihood of precisely tary lid atop these oceans, these environments are protected N=1 communicating extraterrestrial civilizations in the Uni- from numerous kinds of external risks to life, such as im- verse is small (i.e., that we are unique), the Fermi Paradox pacts, radiation, surface climate and obliquity cycles, poison- has not been resolved. Many explanations have been prof- ous atmospheres, and nearby deleterious astrophysical events fered [1]. We suggest another, that the great majority of such as novae and supernovae, hazards stellar flares, and worlds with biology and civilizations are interior ocean even phenomena like the Faint Early Sun. As a result of these worlds, cut off from communication because they are inside factors, WOWs of Type II require much less of their parent of their host world, therefore not easily revealing themselves. planet and star to remain oceans viable for life than do ocean The Fermi Paradox: The Fermi Paradox (hereafter, FP) worlds of Type I.
    [Show full text]
  • Could Affect Tech Advances in Space 14 May 2014, by Elizabeth Howell
    How the 'Great Filter' could affect tech advances in space 14 May 2014, by Elizabeth Howell That's an important part of the Great Filter, but more details about it are below. Here are a few possibilities for why the filter exists, both from Snyder-Beattie and from the person who first named the Great Filter, Robin Hanson, in 1996. 'Rare Earth' hypothesis Maybe Earth is alone in the universe. While some might assume life must be relatively common since it arose here, Snyder-Beattie points to observation selection effects as complicating this analysis. With Kepler-62f, an exoplanet that is about 40% larger than a sample size of one (only ourselves as the Earth. It’s located about 1,200 light-years from our solar observers), it is hard to determine the probability of system in the constellation Lyra. Credit: life arising – we could very well be alone. By one NASA/Ames/JPL-Caltech token, that's a "comforting" thought, he added, because it could mean there is no single catastrophic event that befalls all civilizations. "One of the main things we're focused on is the Advanced civilizations are hard to get notion of existential risk, getting a sense of what the probability of human extinction is," said Andrew Hanson doesn't believe that one. One step would Snyder-Beattie, who recently wrote a piece on the be going from modestly intelligent mammals to "Great Filter" for Ars Technica. human-like abilities, and another would be the step from human-like abilities to advanced civilizations. As Snyder-Beattie explained in the article, the It only took a few million years to go from modestly "Great Filter" is a response to the question of why intelligent animals to humans.
    [Show full text]
  • Jill Tarter PUBLIC LECTURE TRANSCRIPT
    Jill Tarter PUBLIC LECTURE TRANSCRIPT March 3, 2015 KANE HALL 130 | 7:30 P.M. TABLE OF CONTENTS INTRODUCTION, page 1 Marie Clement, Graduate Student, Chemistry FEATURED SPEAKER, page 1 Jill Tarter, Bernard M. Oliver chair for SETI Q&A SESSION, page 8 OFFICE OF PUBLIC LECTURES So our speaker tonight is Dr. Jill Cornell Tarter. Jill Tarter holds INTRODUCTION the Bernard M. Oliver chair for SETI, the Search for Extraterrestrial Intelligence at the SETI Institute in Mountain View, California. Tarter received her Bachelor of Engineering Physics degree with distinction from Cornell University and her Marie Clement master's degree and Ph.D. in astronomy from the University of California Berkeley. She served as project scientist for NASA Graduate Student SETI program, the High Resolution Microwave Survey, and has conducted numerous observational programs at radio Good evening, and welcome to tonight's Jessie and John Danz observatories worldwide. Since the termination of funding for endowed public lecture with Jill Cornell Tarter. I am Marie NASA SETI program in 1993, she has served in a leadership role Clement, a graduate student in the chemistry department and a to secure private funding to continue this exploratory science. member of the student organization, Women in Chemical Tarter’s work has brought her wide recognition in the scientific Sciences. Before we introduce tonight's speaker, I want to community, including the Lifetime Achievement Award from share some background about the generous gift to the Women in Aerospace, two Public Service Medals from NASA, University of Washington that allows the Graduate School to Chabot Observatory’s Person of the Year award, Women of host the series: the Jessie and John Danz Endowment.
    [Show full text]
  • Galactic Gradients, Postbiological Evolution and the Apparent Failure of SETI Milan M
    Galactic Gradients, Postbiological Evolution and the Apparent Failure of SETI Milan M. Cirkovi´´ c Astronomical Observatory Belgrade, Volgina 7, 11160 Belgrade-74, Serbia and Montenegro E-mail: [email protected] Robert J. Bradbury Aeiveos Corporation PO Box 31877 Seattle, WA 98103, USA E-mail: [email protected] Abstract Motivated by recent developments impacting our view of Fermi’s para- dox (the absence of extraterrestrials and their manifestations from our past light cone), we suggest a reassessment of the problem itself, as well as of strategies employed by SETI projects so far. The need for such reassessment is fueled not only by the failure of SETI thus far, but also by great advances recently made in astrophysics, astro- biology, computer science and future studies. Therefore, we consider the effects of the observed metallicity and temperature gradients in the Milky Way on the spatial distribution of hypothetical advanced extraterrestrial intelligent communities. While properties of such com- munities and their sociological and technological preferences are, ob- viously, entirely unknown, we assume that (1) they operate in agree- ment with the known laws of physics, and (2) that at some point they typically become motivated by a meta-principle embodying the central role of information-processing; a prototype of the latter is the recently suggested Intelligence Principle of Steven J. Dick. There are specific conclusions of practical interest to astrobiological and SETI endeavors to be drawn from coupling of these reasonable assumptions with the astrophysical and astrochemical structure of the spiral disk of our Galaxy. In particular, we suggest that the outer regions of the Galactic disk are most likely locations for advanced SETI targets, and that sophisticated intelligent communities will tend to migrate out- ward through the Galaxy as their capacities of information-processing increase, for both thermodynamical and astrochemical reasons.
    [Show full text]
  • Extraterrestrial Life
    ASTR / GEOL 3300 How did life originate? Extraterrestrial Life Until surprisingly recently - common theory was that of Instructor: Phil Armitage spontaneous generation… life arises from non-living TA: Emily Knowles matter whenever conditions are favorable. • How did life originate? Disproved by experiments by Pasteur (1864): life does not arise spontaneously in closed, sterilized containers. • Is there life elsewhere in the Universe? Scientific study of the (many) issues related to these Life arises from pre-existing life - question of grand questions: astrobiology its ultimate origin is meaningful. Extraterrestrial Life: Spring 2008 Extraterrestrial Life: Spring 2008 Is there life elsewhere in the Universe? Habitability of Mars was discussed in late 19th century: Opportunity rover image First in situ Mars landers: 1976 (Viking) First extrasolar planet around a Solar-like star found: 1995 Today 221 planets (mostly massive) known outside the Solar System Martian canals - proven not to exist in 1965 with first flybys of Mars Extraterrestrial Life: Spring 2008 Extraterrestrial Life: Spring 2008 Overview What is extraterrestrial life? How can we define “life”? Life (extant or fossil) beyond the Earth “The quality which people, animals and plants have In the case of Mars / Earth, extraterrestrial life could when they are not dead…” (Collins English dictionary) (in principle) have single point of origin “Dead: A person, animal or plant that is dead is no longer living…” Discovering life that had an independent origin would be most exciting NASA
    [Show full text]