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The Routledge Companion to Big History

Craig Benjamin, Esther Quaedackers, David Baker

Big History and astronomy – space is big

Publication details https://www.routledgehandbooks.com/doi/10.4324/9780429299322-4 Jonathan Markley Published online on: 21 Aug 2019

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The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The publisher shall not be liable for an loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 in thefinalday ofthecentury. on the sixtyfirstfinished withthefirst inthe years two weeks, three more decades in everything in its proper context. on the a course Imagine Twentieth Century new bookAMostImprobable Journey. ofOurPlanetandOurselves.A BigHistory of ­thousands or even mere centuries. To a purest, this is a violation of the very essence then latermillions, thentensofthousands, andby theendfocusnarrows to man beings. billionsofyears ofthecourse are covered Intheearlypart perclass, amongst thoselife-forms. Inshort, with everything, itstarts but endswithhu- and itultimatelyculminateswiththeimpactpossible future ofasinglespecies look at the creation and spread of the living organisms that inhabit that planet, ofasingleplanet,then lookingattheformation thennarrowing to stillfurther of galaxies and stars,­formation narrowing gradually to a single starsystem, and A typicalb Walter Alvarez provides astandard justificationforthisbig b the later parts of1999,the laterparts eventually narrowing andeven tosinglehours minutes ASTRONOMY –SPACE IS BIG next two weeks, andby was thesecondhalfofcourse entirely focused to aworld withnohumansatall. results –toahumansituationcompletelydifferent from what we know today or At innumerable points initshistory, events couldhave ledtototallydifferent zation thatcomesfrom isjusthow thestudyofBigHistory unlikely ourworld strongly influenced by events deeperinthepast… For metheastonishing reali- space, andalmosteverything thathastakenbeen placeinhumanhistory stretches thathasunfoldedacross of time and is theresult ofahistory enormous in humanhistory, but itisnot. The humansituationinwhichwe findourselves ofeverythingThe broader history mightseemirrelevant tosomeoneinterested ig h istory, ofeverything, thehistory whichseekstounderstand andtoput The paradox:Fermi its relevance to ig b h istory course starts at theBigBangandproceeds starts through course the istory ig h ig BIG HISTORY AND istory and the human race human istory the and Jonathan Markley 2 3 57 istory approachhistory inhis 1 that is. Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 formulated theDrakeformulated Equationin1961. scopes mightbeable todetectthepresence ofintelligentlifeelsewhere, FrankDrake our singleplanet. been able todetectthepresence ofintelligentlifeanywhere intheUniverse beyond conversation, thequestionhasgrown more broadly towonder why we have never impossible, ornotworth theeffort, oritmighttake toolong, etc.) Sincethisinitial seem tohave andspeculatedaboutanumber ofreasons occurred why. (Itmightbe to by andled wonder why­possibility ofvisitstoEarth flyingsaucers Fermi thisdidn’t 1950, “where iseverybody?” tem, the helpusunderstand doesinfact andthewiderstory “trek” thatledtoushere. like this. There ismore atstake forces thatshapedasinglestarsys- thantheparticular Walter Alvarez’s point: theimprobability ofthepresence ofhumanbeingsonaplanet other planets, ofinvestigating andthatthisisactuallyanessentialpart of thefinalpart In thischapter, must indeedconsiderothergalaxiesand Iarguethatbighistorians andFredquoted David Spier). Christian was given Chaisson(inwhichhe description A similarbut by more Eric critical

= the speed at which suitable stars form that can support intelligentlife. thatcansupport form R* =thespeedatwhichsuitable stars civilizations there are, isneededin but rather isatooltoconsider what information The Drake Equation was notmeantasatooltoactuallycalculate how many alien N = n L f f f f c p e i l Building from thisabstractquestionandtheincreasing possibilitythatradiotele- The Fermi paradoxThe Fermi was expressed first Fermi,by Enrico probably around May

= the proportion of those stars thathave =theproportion ofthosestars planets. = =theproportion ofthoseplanetonwhichyou actuallygetlife. =theproportion ofthoseplanetsonwhichyou getintelligentlife. = theamountoftimethosesignal emittingintelligentspecieshave beendoingso. = theproportion ofthoseintelligencespeciesthatdevelop technology sothat cosmic perspective. vast Universe, istoplacehumanityitself into alarger forthegoalofBigHistory given, toothergalaxies, stars, orplanetsthroughout thealmostunimaginably Earth, theSun, andtheMilky Way Galaxy. Scanttreatment isgiven, orneedbe concerns, inreverse order ofappearance, changesthatledtohumankind, the cosmictrek thatledspecificallytousonEarth.meandering Assuch, itmainly initswidercontext’human history mostlytothe (Spier2010…)–pertains initswidercontext’history or (Christian…) ‘an approach thatplaces tohistory Even bighistorians’ work islimited. BigHistory, asmostoftendefined– ‘human detect. the number of advanced aliensthat emit electro-magnetic signals that we can they emitsignalswe candetect. tain life. the number ofplanets, perstarsystem, thathave an environment thatcansus- 3 N =R*•f 4 A smallgroup ofscientistshadbeendiscussingthe Jonathan Markley Jonathan p 5 •n 58 e •f l •f i •f c •L Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 to reasonably estimatethevalue ofn quality ofthedatathatwillbeproduced by TESS andJWSTwillalsomake itpossible say thatplanetsare very common, andthevalue islikely toberelatively high. The simple tomake acloseestimateofthevalue off intothehundreds­reliably ofthousands. rise Bythatpointitshouldbecomerelatively scope ( the count islikely to increase rapidly. Assuming that the James Webb Space Tele- to reach itstargetorbitby mid-June 2018. Onceresults from comingin,TESS start ­Falcon 9on 18,April 2018, thischapter)was ontrack and(atthetime of writing and the use of radio did not become widespread until the twentieth century. was mantotransmitand Hertz thefirst receive controlled radio waves inthe1880s, have themselves hadthetechnology todetectsignalsfrom otherplanets. Heinrich suitable forlife. evidence oflife, any attempttoassignavalue tof some ofthesevariables. For example, untilwe findingplanetswith actuallystart order toanswer thatquestion. At thispointwe are completelyunable toestimate first isthat therefirst simplyare noalienstobe discovered. Thesecondisthatthey exist, this problem bothourpastandfuture. is incredibly forunderstanding important ofhowstory humanscametobehere andnow? As discussedbelow, theanswer to Why dothesequestions matterforbighistorians, istotellthe iftheultimatepurpose in theUniverse orwe are not. Bothare equallyterrifying.” CClarkeArthur isreputed tohave said, “two possibilitiesexist: Eitherwe are alone we have missedsomething crucial. We come back to the question, “where are they?” the finalthree must bezerovariables (orso closetozero asmakes nodifference), or sonable size, itmakes Fermi’s questionincreasingly puzzling. Either oneor more of longer aswe continue tosearch. signals wouldn’t have here yet. arrived Butyear by year, theviable window grows be within100lightyears forustobeable todetectitsemissions, as otherwisethose civilizationtechnological arose ataboutthesametimeasours, thenitwould have to so thatitssignalsdidn’t reachwindow, usinthecorrect we would never know. Ifa we could have detected intelligent life. If a civilization rose and fell before that time since the1960s. That meansthatin2018, there isonlya60-year window inwhich attempts atSETI(Search forExtra-Terrestrial Intelligence) have onlybeenmade life appears) ispurelife appears) conjecture. However, in1961f ants, etc.) confirmation. 929 ofthoseplanetsare defined as “terrestrial” gi- (asopposedtogas exoplanets,confirmed in2,783starsystems, withanother4,496candidates awaiting of theKepler spacemissionin2009. As oftheendMay 2018, NASAlisted3,730 sus other thanourown) until1995(theplanet waswas named51 notconfirmed Pega - systems) was also a complete unknown. exoplanet (aplanet circlingThe first a star TESS (Transiting Exoplanet Survey Satellite) was launched aboard a SpaceX The last factor (L)changesoverThe lastfactor time, becauseitreally relates tohow longhumans Possible paradox into two explanationsfortheFermi fall broad categories. The questions,Why are they terrifying andnotmerely anabstractintellectualexercise? intheDrake four numbers Since thefirst Equationare now known tobe of rea- b), but sincethat time the number has skyrocketed, since the launch particularly JWST) islaunchedsuccessfullyin2020, planetswill thenumber ofconfirmed 6 Big History and astronomy Big History e , thenumber ofplanetswithanenvironment 59 p but even withoutthat, we cannow l (thefractionofplanetsonwhich p (fraction of stars with planetary withplanetary (fractionofstars 7 Serious Serious Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 the Fermi paradox,the Fermi but italsoaddresses thesurvival prospects ofourown species. are than merely more beinga important “back-story” ofthehumanrace. totherise dard view hassucceededingainingmuch traction. Eachofthesestepsisincludedinastan- is stilllargelyinexplicable, theories, anddespitemany attemptstoformulate nosingle where “not life” becomes “life” time, forthefirst isastrong candidate. Itisastepwhich It now thatstep1isprobably appears relatively easytosatisfy. Step 2, biogenesis thefirst (9) (8) (7) (6) (5) (4) (3) (2) (1) ­impossible) topassthrough. Hansonsuggestedninepossible candidates: the ideathatthere bottlenecksthatare must incredibly becertain hard (oreven paradoxto explain the Fermi (sometimes also called “The Great Silence”) posits in 1998hisonlineessay “The Great Filter– Are We Almost Past It?” exist) istheconceptofGreat Filter. was introducedThis term by Robin­ extends the discussion of the Fermi paradoxextends thediscussionofFermi intotheideaofGreat Filter. has published numerous non-fiction works. onthe His1983article “Great Silence” isby Davidgood summary Brin. isbetterknown asasciencefictionauthor Brin but staying hiddensoasnottointerfere withourdevelopment. been suggestedthatthey are there, they are watching us, but they are deliberately Terrestrial intelligencetospotus.)Insomething called the “Zoo hypothesis” ithas civilization hasbecomeless “noisy” andtherefore itismore difficultforanExtra-­ broadcast electro-magnetic signals. (With fiber-optic cables etc., our own planetary we are simplylookingforthewrong things, andadvanced civilizations simplydonot ceeding, andthey hideinwait ready todestroy any species. newly emerging Perhaps there mightbeanadvanced civilization intentonpreventing any rivals from suc- have any interest in expanding beyond their own star system. More frighteningly, awayfar forustofindthem. Perhaps civilizations gettoapointwhere they nolonger we have notbeenlookingforalongenoughtime, orperhapsthey existbut are too as this possibilitysuggeststhere may atthesametime beothercivilizations emerging tothisdidnotallow species(and fortheemergenceofatechnological ditions prior we coulddetectthem. Alternately, we may simplybethefirst, perhapsbecausecon- prevents lifefrom comingintoexistenceorprevents lifedeveloping toapointwhere but we can’t findthemfor reasons.various They mightnotexistbecausesomething us). We mightnotbeable tofindthembecausethey comeandgotoorapidly, and The likelihood (or extreme improbability) ofeachtheabove stepsaddresses One ofthekey aliensdonot possibility(thattechnological aspects ofthefirst Numerous haveparadox, articles onthetopicofFermi beenwritten anda Colonization explosion Where we are now Tool-using animals withbigbrains Multi-cell life Sexual reproduction Complex (archaeatic &eukaryotic) single-celllife Simple (prokaryotic) single-celllife Reproductive something(e.g. RNA) star system(includingorganics) The right b ig h istory approach,istory andhopefullyitnow becomesapparent why thesetopics Jonathan Markley Jonathan 60 9 This attempt This Hanson 8 Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 fate ofhumanity.”fate galaxy. This makes paradox theFermi more puzzlingandmore relevant tothefuture absence ofaliensismore puzzling thanitwould beifwe simplyconsidered our own a stretch toextendtheirreach even intoothergalaxies. “This result impliesthatthe civilization capable of colonizing other star systems would not find it too much of Solar System, andeventually inthesky, otherstars nomatterthedangerandcost. that once it becomes possible, humans will attempt to colonize other planets in our Given theweight ofevidence over hundreds ofthousandsyears, we cansurely say voyaging tothe ontheMayflower canhaveAmericas toEngland. expectedtoreturn Native ofmodern cestors wereAmericans) alsoonaone-way mission. Few colonists (who would becomethean- Straitland-bridge humanstocrossThe first theBering on the one-way aspect of the mission as if thisissomethingunusual in human history. and dieofsimple ennui. Consider thatourown specieshomosapiens , even with it canbreak outofitsstarsystem, energy outof spiritual orperhapsinstead they run instead ofannihilatingthemselves, outofresources intelligentlifesimplyruns before which makes itpossible thatcanwipeoutalllife. tocreate super-viruses Perhaps themselves inglobalnuclear war. Perhaps scientific itisthebiological revolution Perhaps tosplittheatom and allsufficientlyadvanced species learn eventually destroy of us, then the “Great Silence” threat. suddenly becomes an ominous and terrifying step there must bebillionsofsuitable starsystems. Ifthatistrue, thatsuggestsstep8or one inabillion, thenthatwould that make simple lifevery commonconsidering of lifesuccessfullyovercoming stepsisaslow thefirst asoneinathousand, or even life hasemergedonany oftheexoplanetswe have discovered. Even ifthepossibility common? We donotyet possessthetechnology tobeable todetectifmulti-cellular colonize Mars in2023.colonize Mars They received 200,000 volunteers. championed by thelikes ofElonMusk. accomplishment was thantoday’s nolesschallenging proposed coloniesonMars acrossmigrate thePacific Ocean. Given thetechnology available tothem, this Americas, etc. Inalaterepoch, Polynesians overcame astonishingdistancesto No matterhow difficult, humans have found a way topopulate Australia, the from toalmostevery withtheexceptionof landmassonEarth Africa Antarctica. ent inouroldergeneticrelatives. We have knownhumansspread thatmodern hugedistancespre-dates ourowntendency tomigrate speciesandwas alsopres- and homoflorensis inIndonesia, we have cometoappreciate thattheinstinctand very nature ofourspecies. Inthelastfew years withthediscoveries ofDenisovans ponents of Perhaps we willbe the first, and perhaps we willbe the only one. Arguably pro- and we specieswe willbecometheinterstellar have beenhuntingforallalong. the future isassured. Oneday our SolarSystem, humancolony shipswilldepart good future prospects. steps, Lifehasalready accomplishedthemostcrucial and If itisnearlyimpossible topassthrough steps1to7, thenthehumanracehas paradox tosomethinguncomfortable.” gives rise In 2013, Stuart and Armstrong Sandbergwent astoarguethatanyAnders sofar A disturbingpossibilitypresents itself. What ifHanson’s steps1–7are relatively In 2013 the Mars OneFoundationIn 2013theMars calledforvolunteers foraone-way missionto 9 is the critical timeatwhichintelligentlifefails.9 isthecritical IftheGreat Filterisstillahead b ig h istory are bestpositioned of alltoappreciateistory that this is in the 11 Elsewhere stated,Armstrong “almost any answer totheFermi Big History and astronomy Big History 61 12 10 Mediatendedtofocus Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 questions, heasks Intelligence).search forevidence (SETI=Search forExtraterrestrial Amongst other Intelligence)asopposedtothepassive space (METI=MessagetoExtraterrestrial fiction, hastaken aleading andBrin role inopposingprojects tobroadcast signalsinto enoughtostaysmart quietifthey want tosurvive. These ideasare notmere science of loneliness, but adarkandforbiddingsilence inwhichevery intelligentspeciesis for many millennia. Healsoexplores theideathatGreat Silenceisn’t thesilence tion of resources, andthe sheer impossibility of maintaining an advanced civilization combined impossibilityofovercoming hostilecompetitors, culturaldecline, exhaus- by theGreat Filter. Noadvanced speciesever survives inthelongterm, duetothe including inhis2012novel Existence inhisguiseasascience-fictionauthorhasexploredDavid theseideasextensively, Brin for about300,000years, recent discoveries pushing the dateback, isonlythoughttohave beeninexistence dreaming.” and “speak softly, lestthey disturbtheinfant’s extravagant andcolourfultime of hope thatperhapsolderalien civilizations mightdeliberately concealthemselves dire. Brin, perhapsoptimistically, (citedabove) concludedhis1983 article withthe assuming they are notactively hostile, theconsequencesforhumanitycouldbe better weapons, etc. Even ifthere are more advanced creatures outthere, andeven vanced cultures tendtosufferdevastatinggroups with effectswhenencountering ofallfieldswill relate toBrin’sHistorians lessad- thattechnologically warning dence forlifeonMars, andtheSETIproject ingeneral: Future ofHumanityInstituteatOxford ofthesearch University forevi- towrite our ownjudging chancesofsurvival. oflifeelsewhere thecourse forunderstanding intheUniverse,important but alsofor future aheadforthehumanrace. paradoxAnswering theFermi istherefore notjust be millionsofyears old. thepossibilitythatthere must may face beno Bighistorians The ideathattheGreat FiltermightbeaheadofushasledNickBostrom ofthe for further discussion? for further If broadcasting issuchagoodidea, why aren’t othercivilizations doingit? great futuregreat forhumanity. life,the search forextraterrestrial nonews isgood news. Itpromises apotentially human race…. Iconcludethatthesilenceofnightskyisgolden, andwhy, in news… Scientificallyinteresting, certainly, but abadomenforthefuture ofthe news. Ifwe foundfossilsofsomethingmore advanced… itwould bevery Ifwemy discovered spirit… itwould bebad tracesofsomesimplelifeform… we tobecompletelysterile. findMars Dead rocks andlifelesssands would lift probesI hopethatourMars willdiscover nothing. Itwould begoodnews if If broadcasting is potentially a bad idea, how can it be delayed long enough If we attract hostileattention, whatcould “they” dotous, worst-case? 17 16 : 13 yet any civilization interstellar would probably have to 14 Jonathan Markley Jonathan 15 in which he describes aUniverse dominated inwhichhedescribes 62 bad Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 reduced by many ordersofmagnitudecompared to previous arguments.” small. They recognized this, statingthat “the likelihood ofintelligentlifemust be means thatthelikelihood lifeshouldbeastonishingly ofintelligenttechnological andSandberg’s­Armstrong argumentthatintergalacticspread isalsopossible, this ­Universe, anumber assmalloneinabillionwould toohigh. stillbefar Given intheMilky 100 to200billionstars Way, andpossibly galaxiesinthe many trillion requires anincredibly highthreshold before itoccurs. With somewhere between across thesky.) thananinfinitesimallysmall thing greater number, thenthere would belifeteeming mean thatlifeisnotpossible anywhere intheUniverse, includinghere. Ifitwas any- the existenceoflifeonEarth.that permits (Ifthenumber was actuallyzero itwould so tiny that it is very close to zero, but which also allows foratiny chance of success thattheDrakeappears Equation, however constituted, must leadtoanumber thatis and noevidence ofthepresence oflife(intelligentorotherwise)onany ofthem. It been discovered. We alsohave one negative datapoint: billionsandofplanets, advancedtechnologically species. At thispoint, we ourselves are theonlyonetohave on planetsfrom space, spreading from planettoandstarsystemsystem. ­Gordon. chanceorevenoccurring, perhapsa one inatrillion less. that itcanalmostnever happen, but whichstillhassomeextremely smallchanceof ligent life, and its extreme rarity? We need to find a process that is so utterly unlikely Explosion, letalonetheemergenceofhumanity. have completedthisprocess before theemergenceofcomplexlifeinCambrian years. (in relativeAn alien species with only a tiny head-start would already terms) 4.5 a few hundred thousandyears old thisseemslike alongtime, but ourplanetisabout less thanfourmillionyears tocolonize theentire Milky Way. For aspeciesthatisonly first proposedfirst by Svante in1908. Arrhenius conditions didnotallow forthistohappen. Italsobuilds ontheideaofPanspermia prior intelligentspeciestoemergeintheUniverseare (ornearfirst) thefirst because tially new. Itcontainselementsofexistingtheories, includingtheideathatperhapswe I would like to present paradox a possible solution to the Fermi that I believe is par- The term hasnow enteredThe term theEnglishlanguagesuchthatMeriam Webster rate atwhichcomputingpower was increasing, speedswere and various suggested. Gordon Moore, executive, anearlycomputingindustry madeobservations about the Their argumentwas inspired by Moore’s Law, aconceptfrom computer ­ amajorproblem,course by sincethispredates theageofEarth 5billionyears. have would onEarth have comeintoexistence about 9.5billionyears ago. This isof What isneededanexplanationthatallows forintelligentlifetoexistbut which We have onepositive mystery; datapointinthisgreat oneplanetwithlife; one A possible answer was suggested by thework of Alexei Sharov andRichard What possible explanationcouldexplainalongdelay intheemergenceofintel- colonization begins,One commonestimateisthatonceinterstellar itwould take billion years old, andtheUniverse itselfhasbeeninexistencecloseto13.8billion 20 Sharov andGordon arguedthat basedonastatisticalanalysis, thelifewe A possible solution paradox Fermi to the Big History and astronomy Big History 63 18 The ideaisthatlifecouldbe “seeded” technology. 19 Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 same timeprobably did. did nothave sufficient oxygen criticalperiod,available inthe atthe butearlyMars idized molybdenum was probably vitaltotheemergence oflife, but theearlyEarth the Earth, withonlyrare exceptions. In2013Steven Bennerargued thathighlyox- must have emerged in the conditions that were present billion in the first of years become biology? Most hypothesesdid chemistry work on the assumption that life gence oflifehave beensuggested, but none hasgainedwidespread acceptance. How mystery: abiogenesis. emer- forthefirst Many How scenarios begin? didlifefirst own planet where itcouldcontinue thesecondhalfofitsexistence. 4.5billionyears ago,formation andthatthissimplelifesomehow beseededontoour of its then somehow atthe beginning to our own betransferred SolarSystem right ten billionyears agoandlastedforaround five billion years. Thatsimplelife must around astarroughly equivalent toourown sun, andthatthisprocessabout begin sample ofone(lifeonEarth). what are forlife. thevitalingredients Itisvery hard todraw conclusionsbasedona succeed infindinglifeelsewhere, drawingwe willbeable tostart conclusionsabout at ultra-low temperatures? Isastrong magneticfieldessential?etc. Once(orif) we it enoughtojusthave liquidwater? Would someotherliquiddo, suchasmethane like ourown? What are ofanacceptable GoldilocksZone?Is theexactparameters have a large moon? Must it be tilted on its axis? Can life only emerge around stars tohaveIs itnecessary Mustit aplanetthesamesizeandcompositionasEarth? forlifeisthatweassumptions aboutwhatisnecessary lackany basisofcomparison. their exposure tohard X-rays. the habitable GoldilocksZone, andthismay well make theminhospitable becauseof would require any planetstoorbitmuch closertotheirstarinorder tobewithin plete their life cycle faster, and though red dwarf live stars considerably longer, this year mark, possible asearlyonly1or2billionyears from now. com- Largerstars increase, willbecomeinhospitable longbefore andconditionsonEarth the10 ­ like only last for about 10 billion years.stars ours As our sun ages, its temperature will own forlife, are necessary aten-billion-year timeframeisdifficulttoachieve, since and elements to appear in sufficient quantities. similar to our Assuming also that stars appear intheUniverse. Itwould typesofstars, take sometimefortheright planets, would helpsolve certainly theproblem ofwhy intelligentlifehastaken solong to Earth). therefore oflifeon aPanspermia solutiontotheproblem requiring oftheorigins today oftheSolarSystem(and on Earth must pre-dating have theformation origins life, inexistence andthiswas thebasisfor theirconclusionthatthespecificlifeforms They reasoned thatthe same methodology couldbe applied tothe complexity of using Moore’s Law toestimatethatthemicrochip hadbeeninvented inthe1960s. size.” Sharov andGordon reasoned thatyou (correctly) couldextrapolatebackwards that processing power doubles aboutevery 18monthsespeciallyrelative tocostor definesitasDictionary “anaxiomofmicroprocessor development usuallyholding The possibilitythatlifemight have elsewhere started issuggested by anothergreat onaplanet stepisthatsimple lifebegin roughlyequivalentThe first toEarth, It isworth pointingoutasanaside that the reason we have to make so many Assuming thatvery simplelifemightrequire around 10billionyears toemerge 21 23 According toBenner’s theory, lifemay on have originated 22 Jonathan Markley Jonathan 64 billion Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 4.5 billionyears, inwhichoursystemwas formed. first theperiod to Jupiter, astronomers considerthatithasbeenpresent inourSolarSystemforabout known as a retrograde orbit. Even more important, based on the way its orbit is linked visitor.permanent Itorbitsaround thesuninoppositedirection toalltheplanets, outside ofourSolarSystem.that originated Unlike ‘Oumuamua, 2015BZ509isa tobeanotherobject 2015 BZ509(whichwas detectedin2015) first was determined millions ofyears, tothatvoid. anditwillsoonreturn It isestimatedthat ‘Oumuamua must have spaceforhundreds beenininterstellar of means thatliquidwater isatleastphysically possible onProxima b. much closertoitsstarthantheEarth, but therelative coolnessofProxima Centauri wasthe sizeofEarth discovered orbitingProxima in2016. Centauri Itsorbitis years away, orover kilometers. 40trillion Proxima b, arocky planetabout1.3times iftheprocesscould besuccessfullytransferred required hundreds ofmillionsyears. to another system. On the otherhand, it seemslesslikely material that biological prove, however, from isthatitpossible onestarsystemtobetransferred formaterial have pointsofeitherobjects. any cluesabouttheorigin What theirpresence does sufficient sensitive toallow the ustobegin processofidentifyingthem. Wedonot likely thatthere are many more, anditis only now have thatourinstruments become now outbound, from and is already further the sun than Jupiter (as of June 2018). Solar System, visitor. but itisonlyabrief After slingshotting around oursunitis first”). It was thoughttohave object interstellar beenthefirst ever detectedinour spotted asteroid 1l/2017, now called ‘Oumuamua (“messengerfrom arriving afar not actuallyimpossible. InOctober 2017, thePan-STARRS1 telescopeinHawaii system intoourown. Itmust bevery unlikely (tosatisfytheDrake Equation)but ­exoplanet, from tobetransferred thatalienstar material andthenforbiological emergedonour to beassumediflifefirst own planet. available ontheearlyEarth, andthatitrequires thanhas amuch longertimeperiod Solar Systemwould satisfy both problems: thatelementsbepresent other thanwere satisfy theDrake EquationandtheGreat Silence. pointforlifeoutsideour A starting similar planetclosertowards thesun), but itdoesnotseemsufficientlyimprobable to outintheGoldilocksZone,one planetfurther toafairly andthembeingtransferred our own planet. makesThis possibilitycertainly complexlifelesslikely on (starting Mars, andthenwas seededviaanasteroid collisionthatwould have brought itto range will shrink by about1lightyear,range willshrink before itdraws away again. About 10,000years is actuallydrawing closertous, andover ofthenext30,000years thecourse the in and out in relation to us as they follow their galactic orbits. Proxima Centauri nearer or further awaynearer orfurther from asthey orbitthesun, theEarth as do many millions ofothersystems. Just asplanetswithin theSolarSystemmove than Proxima Centauri. Our own system orbitsthecenterofMilky Way Galaxy, couldbeaccomplished. material a transferofbiological away,seems too far and even if it is not, the closer the star, the chance that the greater In May 2018, itwas announcedthat ‘Oumuamua was afterall. notthefirst The nearest starsystemtoourown isProxima Centauri, whichisabout4.25light While onlytwo suchobjectshave beenidentifiedtodate, astronomers considerit For this scenario tobeplausible,For thisscenario itmust bepossible forlifetoemergeonan What isoftennotappreciated regularly isthatstars comeclosertotheSolarSystem Big History and astronomy Big History 65 27 otherstarsystemsmove 25 26 Four lightyears ­Asteroid 24

Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 ­comets.” clude that itwould have “likely impacton the flux of long-period causednegligible Cloud,close enoughtointeractwiththeOort ofthestudycon- thoughtheauthors 20 lightyears away, but 70,000years ago itapproached towithin0.8lightyears, between thetwo systemsasthey passby eachother. planets around oursun, itisnotonlypossible butwillbeshared likely thatmaterial three tofourmillionyears. While not closeenoughtointerfere withtheorbitsof mate thatthiswillmeanapproximately 10cometsevery year continuing foraround there Cloud. are ofcometsintheOort hugenumbers Inreal terms, esti- theauthors pushed intopotentiallyobservable orbits.” CloudcometsmightberemovedOort from thecloud, andupto0.01%mightbe thanSirius.three timesbrighter “After thepassageofGliese710, upto0.1%ofall point ofitsclosestapproach, itwillbeonly0.21lightyears distant. Itwillbeabout the GaiaSpace Telescope launched in December2013, it is now estimated that at the about 0.8lightyears atclosestapproach, but thankstomuch more accuratedatafrom years itwillcomestunninglyclosetoourSolarSystem. Initialestimatesputitat None ofthemwillapproach closerthanaround 3lightyears, whichstillseemstoofar. star systemsallcloserthan4.25lightyears nearest (ourcurrent galacticneighbor). About 45,000years from now Gliese445willalsoapproach, usthree giving separate after Proxima Centauri’s closest approach, Ross 248 will approach slightly closer still. life forms couldhavelife forms been propelled intothe outeredgesofthatstarsystem. That after amajorimpactontheir homeplanet, andtherocks containing thedormant habited theearlyEarth. Those organismscouldthenhave beenflungintospace ­taking billionsofyears toreach the level ofcomplexity astheorganismsthatin- afoothold tolifeonanotherworld.”giving body (Mars,and re-impact onto a planetary the Moon, or Europa, for example), thus an environment makingitsuitable tolifeaswe know it, couldsurvive theejection concluded,thors that can serve as the base of a food chain and transform “life forms samples ofasingle-celledalgaeintowater using atwo-stage lightgasgun. The au- placed outside the International SpaceStationfor548days. placed outsidetheInternational werebacteria exposedtospacefortendays. Inthesecond, additionalsamples were placed inspace. Inthefirst, they were launched by aRussianSoyez rocket andthe from were theearlyEarth) collectedfrom alimestonecliffinDevon, England, and (whichare inwhichcyanobacteria therefore experiments similartobacteria describe habited theEarth, couldsurvive inspacetoreach ajourney ourplanet. Two studies come closeenoughtotheSolarSysteminteractandshare material. in mindattemptedtoanswer thisquestion. intotheEarth’sre-entry earlyatmosphere. withjustsuchascenario An experiment (suchasalargeasteroidit intospacefrom surface collision) andtosurvive aplanetary time, itdoesnotprove thatitwould beable tosurvive theforces required topropel werethe bacteria able tosurvive. Gliese 710ishardly unique. Scholz’s Staranditscompanionbrown dwarf isnow The star system Gliese 710 is currently 63 lightyearsThe starsystemGliese710iscurrently away, but in1.35million Thus, itispossible thatsimplelifecouldemerge around anotherstarsystem, The nextquestioniswhethersimpleliving organisms, in- suchasthosethatfirst Even assuming thatlifecouldsurvive of onarock inspaceforanextendedperiod 29 These examplesare enoughtodemonstratethatstar systemscananddo Jonathan Markley Jonathan 66 28 31 This may seemlike atiny number, but involvedThe experiment frozen firing 30 Remarkably, someof Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 3 2 1 most dire threats ofextinction. eventually species, becominganinterstellar thenwe willhave eliminatedallbut the as thedinosaurs. Ifwe canlookforward toafuture ofreachingandto forthestars remain confinedtoasingleplanet, we continue fate tobethreatened withthesame close to the truth, because it would meanthat the Great Filter is behindus. While we be inescapable fact: we have notfoundany evidence oflifeelsewhere, andthere must must beacknowledged thatitismere speculation, but itisspeculationbasedonone paradoxexplanation fortheFermi hasbeenoffered. Like allotherexplanationsit is critical,which factor is just random happenstance. and which factor Finally, a new until we have somebasisofcomparison. Otherwiseitisnearlyimpossible toknow to answer many ofthefundamentalquestionsaboutwhy lifeexistsonourplanet the Great Filteraheadofus, orbehindus? We shouldrealize thatwe cannever hope own placeintheUniverse, andforestimatingour chancesofsurvival inthefuture. Is intelligent lifeinthosestarsystems, our tounderstanding importance are ofcritical We shouldalsorealize thatotherstarsystems, andthepotentialforbothsimple the heavens withmore thanjustthegoaloffindingoutwhere humanitycamefrom. should lookto This chapterhassoughttopresent theargumentthatbighistorians able todetectthemyet. likely bevery away, rare andfar andhenceitwould benaturalthatwe hadnotbeen possibility that there could be other species yet to be discovered, but they would more thanone, inthesky. ofstars outofallthe trillions Itdoesnotexcludethe chance?) couldallow fortheemergenceofoneintelligentspecies, andperhapsno toooften.happen far thatisvery rare (perhapsoneinatrillion Onlyascenario the Great Silence. would thathasarealistic chanceofoccurring Any scenario but notquiteimpossible. This isexactly thelevel ofprobability thatwould explain improbable, but justslightlypossible. When multiplied together, itmakes italmost could emergeafterbillionsmore years ofdevelopment. Eachoneofthesestepsis seeding ourplanetwiththelife, from whichcomplexorganismssuchasourselves could have beenflungintotheinnersystemwhere itimpactedontheearlyEarth, billion first years, andourSolarSystemcould have captured thatasteroid, which star systemcouldthenhave madeaclosefly-by ofour own SolarSysteminits ­Evolution. Name.” Another by History Big Than –More Evolution “Cosmic J. Chaison, Eric W.W. York, New 2017, Norton, p. 4. Ourselves, and Planet Our of History ABig Journey. Improbable AMost Alvarez, Walter space.” to peanuts just that’s but chemist’s, the to road the down it’s way along think you may Imean, itis. big the Galaxy to Guide Hitchhikers’ Adams’ Douglas from quote alarger to areference is Big” is “Space Barry H. Rodrigue, Uchitel Publishing House, Volgograd, 2011, p. 38. Volgograd, House, Publishing Uchitel Rodrigue, H. Barry something thatmakes itvery improbable indeed. Ihopemy explanationmay be

: “Space is big. You just won’t believe how vastly, hugely, mind-bogglingly mind-bogglingly You hugely, big. is won’t how vastly, just : “Space believe A Big History Perspective History A Big Concluding thoughts Big History and astronomy Big History , edited Leonid E. Grinin, Andrey V. Korotayev, Andrey Grinin, E. Leonid , edited Notes 67 Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 16

18 19 20 11 10 9 12 14 15 8 13 7 6 5 4 17

http://www.davidbrin.com/nonfiction/setisearch.html. Brin “The Great Silence” p. 307. Silence” Great “The Brin the concept of Panspermia of concept the life, for conditions chemical including chapter, this to relevant concepts with dealing ­Gordon book the of in a chapter appears Earth” before “Life article the of version Amodified review. under articles the within flaws the despite hypothesis aviable itis that state pressly York,New 1908. Universe the of Evolution The Making: the Worlds in Arrhenius, Svante citeas. Interestingly, none of the critics reject the idea of Panspermia of idea the reject critics the of none Interestingly, citeas. Direct ­ life”, before “Earth Yurtsever, Ulvi and Viswanathan Raju Marzban, Caren by rebuttal the one, second the for and article, earlier the for comments reviewers’ the ample ex for See criticism. heavy to subject been have ideas Their papers/1304/1304.3381.pdf. ­ 2013 https://arxiv.org/ftp/arxiv/ in article” a“pre-publication as issued was which Direct ­ life” of evolution and origin the for aclock as increase “Genome Sharov, A. A. hours”. six in “Eternity Sandberg, and Armstrong https://www.space.com/22758-mars-colony-volunteers-mars-one.html. https://mason.gmu.edu/ pp. 1–13. pp. Astronautica Acta paradox.” Fermi the sharpening and life of intelligent spreading Intergalactic hours: six in “Eternity Sandberg, &Anders Armstrong Stuart review.com/s/409936/where-are-they/. nothing.” finds life extraterrestrial for search the Ihope Why they? are “Where Bostrom, Nick David Brin, Existence Brin, David Journal of the Royal Astronomical Society Astronomical Royal the of Journal Life” Intelligent Extraterrestrial Concerning Controversy Silence’: The ‘Great “The Brin, David Glen https://phys.org/news/2013-08-silence-skybut.html. and the pan-African origin of Homo sapiens” Nature sapiens” Homo of origin pan-African the and Morocco Irhoud, Jebel from fossils “New Gunz, &Philipp Harvati Katerina Benazzi, Stefano Cabec, Le Adeline Bergmann, Inga Skinner, M. Matthew Neubauer, Simon Freidline, E. Sarah Bailey, E. Shara Ben-Ncer, Abdelouahed Hublin, Jean-Jacques Evening Post Evening you don’t when aradio?” own missing you are pleasure what you realised Have Evening! “Good customers, potential asked advertisements newspaper 1933, Feb his In of one ­Zealand. New of capital the Wellington, in years many for shop aradio owned My grandfather https://exoplanets.nasa.gov/. https://www.seti.org/drakeequation. date. exact the of certain were them of none and conversation, the at present were who men several of testimony oral on entirely based is 1985, pp. 1–12. story The Laboratory, ­National Alamos Los Question.” Fermi’s of Account An everybody?’ is “‘Where Jones, M. Eric Big History course. https://waitbutwhy.com/2014/05/fermi-paradox.html https://waitbutwhy.com/2014/05/fermi-paradox.html course. History Big my in readings course itas assigned fact in Ihave and concepts main the to introduction accessible an itgives but paradox) the to answers possible frightening more the of some describe to ‘we’re f**cked’ phrase the of uses two (including tone acasual in written is See also Tim Urban’s blog Waitbutwhy. His essay length post about the Fermi paradox paradox Fermi the about post length essay His Waitbutwhy. Urban’s blog Tim also See 9, no.1, 2014, Dec https://link.springer.com/article/10.1186/1745-6150-9-1# , 1, June 2006, pp. 17–26; A. A. Sharov & R. Gordon, “Life before Earth” Earth” before “Life Gordon, &R. pp. 17–26; Sharov A. A. 2006, , 1, June Habitability of the Universe Before Earth: Exploring Life on Earth and Beyond and Earth on Life Exploring Earth: Before Universe the of ­Habitability

& A. Sharov, Amsterdam, Elsevier, 2018. This book contains many chapters chapters many contains book 2018. This Elsevier, Amsterdam, Sharov, & A. pp. 72–77. https://www.technology 2008, May/June Review Technology MIT column 1, p. 9, 4 Feb 1933. Even then many households did not yet own aradio. own yet not did 1, households p. 9, 1933. 4Feb many column Even then , Tor, York, New 2012. ~ , etc. , etc. rhanson/greatfilter.html. Jonathan Markley Jonathan 68 546, June 2017, June 546, pp. 289–292. , 24, 1983,, 24, pp. 283–309. 89, Aug–Sep 2013, 2013, 89, Aug–Sep , Harper &Row, , Harper and some ex some and , ed. R. R. , ed. Biology Biology Biology - - Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 30 29 28 27 26 25 24 21 23 22 Berski, Filip, & Dybczynski, Piotr A. “Gliese 710 will Pass the Sun Even Closer Close Close Even Closer Sun the Pass 710 will “Gliese A. Piotr &Dybczynski, Filip, Berski, & York, New Harper Universe. the of Evolution The Making: the Worlds in Svante Arrhenius, Spreading Intergalactic Hours: Six in “Eternity Anders &Sandberg, Stuart, Armstrong, Ourselves. and Planet Our of History ABig Journey. Improbable AMost Walter Alvarez, 31

Astrophysics & Astronomy Release.” Data Gaia First the on based Recalculated Parameters Approach Row, 1908. 2013, pp. 1–13. Astronautica Acta Paradox.” Fermi the Sharpening and Life Intelligent of New Using Exposure to Low Earth Orbit.” Applied Orbit.” and Environmental Earth Microbiology Low to Exposure ­Using by Community Microbial aRock-Dwelling from Cyanobacteria ­Extreme-Tolerant Novel of “Isolation Cockell, S. Torre, Charles la de Rosa Olsson-Francis, Karen no.1, 2015. 12, 800, Feb Letters Journal Astrophysical The System.” Solar the to Star of a Flyby Known Closest “The J. Boffin, M. Henri Beletsky, Yuri Väisänen, Petri Y. D. Ivanov, Alexei Valentin Kniazev, Barenfeld, A. Scott Mamajek, E. Eric ­Letters Astronomy system.” Solar the encountering closely list Hipparcos the outside “Stars 595, Nov. 2016. https://doi.org/10.1051/0004-6361/201629835. V. also, Bobylev, See , &Astrophysics Astronomy release.” data Gaia first the on based recalculated parameters approach Close closer even Sun the pass 710 will “Gliese &P. Dybczynski, F. A. Berski sun. the orbit they as are Mars and Earth the where on ­depending km million 401 to km million 54.6 from varies Mars to distance the example, For https://www.space.com/33838-planet-proxima-b-full-coverage.html. 2018, pp. L117–L121,June https://doi.org/10.1093/mnrasl/sly057. 477, no.1, Letters 11 Society: Astronomical Royal the of Notices Monthly asteroid.” orbital ­ co- Jupiter’s retrograde for origin “An interstellar Morais, M. H. &M. F. Namouni https://solarsystem.nasa.gov/small-bodies/asteroids/oumuamua/in-depth/. of Astrobiology Frontiers in chapters) other as well (as contribution his also 2013. See 29th, August Italy, ­ Conference, Geochemistry Goldschmidt the at presented paper Benner, Steven habitable-zones. https://www.ewass.ras.ac.uk/10-x-rays-could-sterilise-alien-planets-in-otherwise- paradox. Fermi the for solution apossible about thinking me started that inspiration the was argument their Rather, unproven. are claims their that conclusion the to me leads work their of Criticism Sharov. and Gordon of conclusions the accept necessarily not Ido that stress to I wish copernicus.org/EPSC2013/EPSC2013-396.pdf. Abstracts S.” KM 6.07 of Velocities to up Events Impact Hypervelocity in Phytoplankton Nannochloropsis of “Survival MJ. Cole, Burchell, M.J. Price, M.C. Pasini, D.L.S. “Charles scientist lead the called PhysOrg.com website news science the at story the slip, Freudian 2011, 1–12. a Journal In ISME The earth.” early on and space outer in pressures selection microbial orbit: low Earth in days 548 to phototrophs of “Exposure Olsson-Francis, Karen Rabbow, Elke Rettberg, Petra 2010, Cockell, Apr. pp. S. 2115–2121; Charles York, W.W. 2017. Norton, , 36, no.11,, 36, Nov 2010, pp. 816–822. Cockwell 2013. https://meetingorganizer. Congress Science Planetary European 8, 595, Nov. 2016. doi:10.1051/0004-6361/201629835 , Cambridge, Cambridge University Press, 2012. Press, University Cambridge , Cambridge, .” https://phys.org/news/2010-08-microbes-survive-year-space.html .” https://phys.org/news/2010-08-microbes-survive-year-space.html Big History and astronomy Big History Bibliography 69 89, Aug–Sep 89, Aug–Sep , 76, ­ Florence Florence EPSC EPSC no.

7, 7, Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 Frontiers of Frontiers Astrobiology eds, José, &Funes, Jonathan, Lunine, Chris, Impey, Sharov, Alexei A., & Gordon, Richard “Life before Earth”: A “Pre-Publication Article.” Article.” A “Pre-Publication Earth”: before “Life Richard & Gordon, A., Alexei Sharov, Sharov, Alexei A. “Genome Increase as a Clock for the Origin and Evolution of Life.” of Evolution and Origin the for aClock as Increase “Genome A. Alexei Sharov, M. Burchell, M.C., Price, D.L.S, Pasini, Novel of “Isolation S. Charles & Cockell, Torre, Rosa, la de Karen, Olsson-Francis, Direct Biology life”, before “Earth Ulvi &Yurtsever, Raju, Viswanathan, Caren, Marzban, Namouni, Fathi, & Morais, Maria Helena Moreira “An Interstellar Origin for Jupiter’s for Origin “An Interstellar Moreira Helena Maria & Morais, Fathi, Namouni, Y., Alexei Väisänen, D., Ivanov, Kniazev, A., Valentin Scott Barenfeld, E., Eric Mamajek, ­ Los Alamos, Los Question, Fermi’s of Account An Everybody?’ Is ‘Where M. Eric Jones, Hublin, Jean-Jacques, Ben-Ncer, Abdelouahed, Bailey, Shara E., Friedline, Sarah E., E., Sarah Friedline, E., Shara Bailey, Abdelouahed, Ben-Ncer, Jean-Jacques, Hublin, Exploring Earth: Before Universe the of Habitability eds., Alexei, &Sharov, Richard, Gordon, of “Exposure Karen Olsson-Francis, Elke, Rabbow, Petra, Rettberg, S., Charles Cockell, Chaison, Eric J. “Cosmic Evolution – More Than Big History by Another Name.” In Name.” In Another by History Big Than –More Evolution J. “Cosmic Eric Chaison, Brin, David Existence David Brin, Intelligent Extraterrestrial Concerning Controversy Silence’: The ‘Great “The David Brin, Bostrom, Nick “Where Are They? Why I Hope the Search for Extraterrestrial Life Finds Finds Life Extraterrestrial for Search the IHope Why They? Are “Where Nick Bostrom, Bobylev, B. “Stars Outside the Hipparcos List Closely Encountering the Solar System.” System.” Solar the Encountering Closely List Hipparcos the Outside Bobylev, “Stars B. https://mason.gmu.edu/ https://exoplanets.nasa.gov/ www.davidbrin.com/nonfiction/setisearch.html 2013. https://arxiv.org/ftp/arxiv/papers/1304/1304.3381.pdf Biology Direct Biology pernicus.org/EPSC2013/EPSC2013-396.pdf Abstracts S.” EPSC KM 6.07 of Velocities to up Events Impact Hypervelocity in ­Phytoplankton 2115–2121. pp. 2010, Apr. Applied Orbit.” and Environmental Earth Microbiology Low to Exposure Using by Community Microbial aRock-Dwelling from Cyanobacteria ­Extreme-Tolerant ­Letters Society: Astronomical Royal the of Notices Monthly Asteroid.” Co-Orbital Retrograde 9, no. 1, 2014, Dec https://link.springer.com/article/10.1186/1745-6150-9-1#citeas no.1, 2015 12, 800, 4 Feb Letters Journal Astrophysical The System.” Solar the to Star ofa Flyby Known Closest “The M.J. Henry &Boffin, Yuri, Beletsky, Petri, 1985, pp. 1–12. Laboratory, National 2012. Press, University Cambridge and the pan-African Origin of Homo Sapiens” Nature Sapiens” Homo of Origin pan-African the and Morocco Irhoud, Jebel from Fossils “New Philipp & Gunz, Katerina, Harvati, Stefano, Benazzi, Adeline, Cabec, Le Inga, Bergmann, M., Matthew Skinner, Simon, ­Neubauer, Beyond and Earth on Life 1671–1682. 2011, 5, Journal ISME The Earth.” Early on and Space Outer in Pressures Selection Microbial Orbit: Earth Low in Days 548 to Phototrophs 2011, House, pp. 37–48. Publishing Uchitel Volgograd, Rodrigue, H. Barry ­Evolution. Journal of the Royal Astronomical Society Astronomical Royal the of Journal Life” com/s/409936/where-are-they/ Nothing.” Nothing.” Astronomy Letters 477, no. 1, 11 2018, pp. L117–L121, June doi:10.1093/mnrasl/sly057 8, European Planetary Science Congress 2013. https://meetingorganizer.co Congress Science Planetary European 8,

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Downloaded By: 10.3.98.104 At: 11:07 01 Oct 2021; For: 9780429299322, chapter3, 10.4324/9780429299322-4 www.space.com/33838-planet-proxima-b-full-coverage.html www.space.com/22758-mars-colony-volunteers-mars-one.html www.seti.org/drakeequation www.ewass.ras.ac.uk/10-x-rays-could-sterilise-alien-planets-in-otherwise-habitable- https://waitbutwhy.com/2014/05/fermi-paradox.html https://solarsystem.nasa.gov/small-bodies/asteroids/oumuamua/in-depth/ https://phys.org/news/2013-08-silence-skybut.html https://phys.org/news/2010-08-microbes-survive-year-space.html zones Big History and astronomy Big History 71