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LectureattheSocietàDanteAlighieri,Rome,16Nov2017Ladiesandgentlemen,it isagreathonourandpleasureformetoaddressyouatthiswonderfulandhistoric place. Iwould like to thank SecretaryGeneral AlessandroMasi andAnnaRuedeberg of theBerneCommitteefortheirinvitation.Letmestartwithasmallincidentalremark.ItwasalsoNovember–inNovember1301–whenDantewaslasthereinRome.HewasonadiplomaticmissiontotheVaticantoavertthethreatoftheBlackGuelphs taking over Florence. It iswell known that this did not succeed, andDante had to flee hishometown after returning the following year. But why am I telling you this? In the weeks beforeDante'striptoRome,alargecometappearedinthesky.Thiscouldonlybeunderstoodasabadomen.Dante mentions it briefly in the Convivio, but strangely enough not at all in the Divine Comedy,althoughDantealwayspaidcloseattention tosignsofheaven.Todayweknowthat itwas themostfamous of all comets: the cometHalley. Its appearance in 1301 at least left itsmark on a friend ofDante's, Giotto di Bondone, who a few years later painted the star of Bethlehem as a comet in hisfamousfrescooftheAdorationoftheThreeMagiintheScovegnichapelatPadova.ItisundoubtedlythecometHalleyin1301.Butletusnowturntooursubject:therelationshipbetweentheworldofDanteandtoday'scosmology.Iwould like tosay inadvancethat thecomparisonsbetweenDante's journeyandourcurrentspaceexploration,whichIexplaininthefollowing,mustnotbeunderstoodinascientificsense.TheDivineComedy is stillpartofour culture today.Butona scientific level,Dante certainlyhasnothing todowithmodernastrophysics.Hismedievalworldiscompletelydifferentfromthemodernworldineveryrespect.Nevertheless, it is possible to compare the twoworlds in a validway, namely bymeans ofanalogies.Aspresentedindetailbelow,thereareastonishingsimilaritiesbetweenthecosmosofDanteandthemodernuniverse.–Butwhatexactlyisananalogy?Firstly,analogydoesnotmeanequality.Ananalogyisasimilarity–inform,proportion,structureorevenfunction–betweendifferentthingsthathavenothingtodowitheachothercausally.Analogousthingsareonparallelplanes,sotospeak,itisanon-causal relationship. Well, what are these analogies for? Are they just a nice game? There are

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peoplewho think so.Of course, I don'thave the sameopinion. I believe that theanalogiesbetweenDante'smedievalworldandthemodernoneshouldbeunderstoodassignsofacommonsymbolism,apsychological symbolism that seem to be inherent in both. This symbolism refers to the spiritualmeaningoftheDivineComedy,theDantistsspeakoftheanagogicalmeaning,thefourthsenseoftheDivineComedy,whichgoesbeyondtheliteral,allegoricalandmoralsense.LookingatthehierarchicalstructureofDante's cosmos, theethicaldimensionof theworld, fromevilat theverybottomto thegoodandholyattheverytop–andDante'sjourneytakesplacealongthispath,fromthebottomtothetop,likeanascent–thespiritualorpsychologicalsense,thesymbolismoftheDivineComedy,revealsitselfwithoutfurtherado:asapilgrimagetothedeepself,asareturntothedivinecoreandoriginofthehumansoul.The spiritual sense of contemporary cosmology, on the other hand, if we do not want to deny theexistenceofsuchasense,islessclearandappearsmorehidden.Onthecontrary:itisnothiddenatall,because there isnosense for itself, independentofus.Themeaningofa thing isnever found in theoutsideworld, it isalwayswhatweourselvesput into it.And it isprecisely throughtheseanalogiesshownherethatwehavetheopportunitytotransferthesymbolism,theobviousspiritualmeaningofDivineComedy,atleastinpart,tomoderncosmologicalresearch,totoday'sastrophysics–whateverthe truemeaning of analogies. In short, inmy opinion,we researchers of astrophysics and particlephysicsalsounconsciouslymakeasymbolicjourneytotheself,tothetranscendentorigin,andthiscan(butdoesnothaveto)giveourtaskaspiritualmeaning.Formethisisasatisfyingvision,forothersless.Ijustwanttomakeasuggestion,anofferofhowwecanseeandunderstandourworkinaverydifferent way. Conversely, these analogies may offer a new way of understanding, reading andespeciallyappreciatingtheDivineComedy.

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1Fortunately, it is not necessary to explain the Divine Comedy to an Italian audience. But a shortsummary of Dante's world with this standard scheme can be useful (Figure 1). His system isgeocentric, in accordancewith the knowledge of his time, ormore precisely, theworld of Dante isdiavolocentric because Lucifer occupies the center. Around the terrestrial globe, ormore preciselyaroundthesublunarspaceinwhichthefourelementsofAristotlearelocated(earth,water,air,fire),the spheres or heavens of the celestial bodies extend concentrically. The whole system is a littlereminiscent of the structure of an onion.The spherical shells consist of an indestructible substance(the fifth element, the quintessence) and rotate uniformly andwithout interruption. First come theplanets (Moon,Mercury, Venus, Sun,Mars, Jupiter and Saturn), then the fixed stars and finally thePrimumMobile,thefirstmovedobject,apurecrystalheaventhatsetsallotherspheresinmotion.Atthispointwereachtheboundaryofthephysicalworld,theboundaryofspaceandtime.Dantedesignsthreerealmsofthedead–thesearezonesthatcannotormustnotbereachedbeforedeath(exceptforDanteinhisvision!).Thethreerealmscorrespondtothethreeparts(cantiche)oftheDivineComedy:firstly, we have Hell (inferno) under the ground, where the lost and damned souls are; secondly,Purgatory(purgatorio),amountainontheothersideoftheearthunknownatthattime,withthesavedsoulsstilltobecleansed;andthirdly,Paradise(paradiso),wherethecleansedsoulsare.Thereare,infact, threedistinct categoriesofparadise: the terrestrialparadise (GardenofEden)on topofmountpurgatory,theheavenlyparadisethatencompassesallspheres,fromthemoontoPrimumMobile,andtheEmpyrean,theabsolutebeyondspaceandtime,seatofGod,theBlessedandtheangels.Theentiresystemisclearlybipolar.Everything,thewholeworld–likethehumansoul–issuspendedbetweenthe twopoles:God in thehighestplace,Lucifer in the lowest.Asalreadymentioned, thisdefinesanaxis, a scaleofmoralityandethics.TheDivineComedy tellsof thepoet's journey through the threerealmsof thedead.Dante is first guidedbyVirgil through theHell culminating in themeetingwithLucifer;fromtherehemovesupalongthisaxis(orscale),comesoutofHellandthencontinuesoverthe terraces of mount purgatory to the terrestrial paradise on its summit, where Beatrice takescommandofDante,ascendingwithhimthroughtheheavens,toGod.

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In the following I present some analogies between the cosmos of Dante and themodern one. Theeasiest analogy to discover relates to the structure of Hell. Here is the classic representation ofBotticelli (Fig. 2). Hell has the shape of a funnel, a huge cone placed on top of the apex, whichcorresponds to the center of the earth, the center of the entire cosmos – the seat of Lucifer, thearchbetrayerwhoistrappedintheice.TheupperpartofHellresemblesanamphitheatre,theloweroneawell.OneentersHellthroughagate,andabovethegatethereisaninscription:Danteisreadingit:Throughmethewayintothesufferingcity,...,Abandoneveryhope,whienterhere.ThisisthecertainlymostfamousverseoftheDivineComedy(–unfortunately,Iwouldsay.Itisknownthat most readers of Dante do not get beyond reading Hell. Hell is the world of evil, which iswidespreadinnewspapers,ontelevisionandtheInternet,soitisunderstoodverywell.Hellisfunny.Purgatoryalreadylessso,andParadiseseemssoabstract,incomprehensibleandboringthatitisnotread.Toobad!)

23ButbacktotheverseAbandoneveryhope ...:itpointstotheessentialcharacteristicofHell:onceyouhaveenteredit,youcannolongerescape;Hellisaneternalcaptivity.Nowinastrophysicsthereisanobjectof thisprisoncharacter, a trap, avery famousandpopularobject: (Fig. 3) theBlackHole, anobjectofEinstein'stheoryofrelativity.Ifamassiscompressedbeyondacertainlimit,thisleadstoatotal gravitational collapse. There is no longer anymatter, but only curved space around a centralsingularity. Intheusualdescriptionof thissituation, thefieldof thegravitationaleffect–reducedtotwo dimensions (necessarily) – is represented by a curved surface whose steepness indicates thegravitationalforce.Here'sthepictureofawell!Inaddition,theBlackHolealsohasagate:thereisacriticaldistancethatshouldnotbecrossed,otherwiseaneternalcaptivityfollowshereaswell:itisthe

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so-calledSchwarzschildradiusortheeventhorizon;nonevenlightcanescapefromtheinsideofthisboundary(thereforethenameBlackHole).The symbolism of gravity is very clear. Gravity symbolizes evil or the inclination for evil deeds. Incolloquial language, for example, it is said: evil pulls someone down, or an immoral act causessomeone to falldown,andsoon.Thecentral singularity inDante'sHell isoccupiedbyLucifer,whorepresents, embodies and symbolizes evil in itself. The singularity concerns not only the centralposition,butalsotheeffectofgravity.Let's takea lookatwhathappensat themomentwhenDanteandVirgilareabouttopassLucifer,andlistentothefollowingverses(Fig.4):

4...heavystrainandruggedwork –Thismeans that the closeryouare to the center, the stronger thegravityisthere.AccordingtoNewton'sgravitationallaw,theoppositeistrue:Thegravitationalforcedecreases to zerowhen approaching the center of the earth. The situationdescribedbyDante thusresemblesEinstein'sgravityratherthanthatofNewton.Thesingularityisaturningpointatwhichtheimpression, the feelingof "goingdown" changes almost instantly (Fig. 5) to a feelingof "goingup",whichastonishes,confusesandirritatesDante.Hecontinueshisreport:

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5...thepointtowhich,fromeverypart,allweightsaredrawn–thatisthesingularity.Howdo thepilgrimandhisguideescape fromHell? (Fig. 6)Throughanarrow tunnel that leads tolightfromtheothersideoftheearth.HowtoescapeaBlackHole?Inthesameway:Youcan'tcomereturn,thereisonlytheescapeforward,throughthesingularity.(Fig.7)AnevenmoreexoticobjectofEinstein'stheorythantheBlackHoleiscalledaWormhole.TheconnectionoftwoBlackHolescreatesa wormhole – and this connection at least theoretically makes such a transit possible through thegravitationalsingularity.

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8(Fig.8)...weemerged,tosee–oncemore–thestars.ThisishowthelastverseofthefirstpartoftheDivineComedysounds.ThestarsweremissinginHell,andthisabsenceisperhapstheworstthinginHell.Then comes the secondpart, Purgatory.We'll skip it.Here is its last verse: ...pureandpreparedtoclimbuntothestars.(Fig.9)Again,thelastwordisstars–andsoitwillbeattheendoftheParadise,attheveryendoftthewholepoem,asyouknow.(NowonderanastronomerisinterestedinDante!–)

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10Butwhat happened here? After climbing themountain, Dante andVirgil reach the Garden of Eden,where Beatrice finally appears and Virgil disappears. It follows Dante's confession and penance toBeatrice,andafterbathingintheriversofearthlyparadise,Danteispureandpreparedtoclimbuntothestars.NowDantecannotonlyseethestars,buthecanclimbuptothestars.Gravityreturnsagainasasymbolofevil,ormorepreciselytheotherwayaround,antigravityasasymbolofgoodness.Assoonasevilisovercome(bycatharsis),thesoulriseslikeahot-airballoonaftertheballasthasbeenthrowndown.ThusbeginstheascentofDanteandBeatrice(Fig.10).Theascentleadsthemthroughalltheheavens,i.e.allthesphereswheretheymeetthesoulsofthesaints,uptothePrimumMobile,thehighestsphere,and–metaphorically(inhisvision)–furtherintotheEmpyrean,therealmbeyondspace and time. On the spiritual level, the ascension signifies the return of souls to the Creator, asshownhereontheleftinthisbeautifulcontemporaryillustration.Thewholeprocessisabitliketheone inwhichanunderwaterbubbleofair rises to thesurfaceandreturns to itsplaceoforigin.Theimageofascension(andofspiritualhierarchy ingeneral) isbasedonaneoplatonicconception.TheunspeakableOne of theneoplatonists leads to the intellect (logos)which in turn leads to theanimamundiandtheindividualsouls,andfinallytothephysicalthings. It isasequenceofemanationsandresultsinahierarchy,anethicalscalethatleadsfromtoptobottom.Andafterdeath,assumingthatithasnotmadeonlyaone-wayticket,thesoulgoesbackfrombottomtotop,totheOne(thatis,toGodintheChristiansense).Butthisreturntothesourcecanalreadyhappeninlife–atleastonthementallevel–throughmeditation,art,poetry;andsuchdidDanteinhisvision!Butwhatdoesmodernastrophysicshavetodowiththis?Forcenturieswehaveknownthatincosmicspace, in the universe, there are no longer "above" and "below". There are no spheres, there is nohierarchy,there isnopreferreddirectioninspace. Infact,ourworldviewandour ideaoftheworldseemstobeinfinitelydifferentfromthatoftheMiddleAges.Let'shavealookwhereweare.(Fig.11)Earthisaglobe,thatistrue,butitmovesaroundtheSun,liketheotherplanets.AndtheSunisjustonestaramongthousandsandmillionsofotherstars–hugeballsofhotgas,indistancesandseparationsbetween them,whicharealreadyso large that it isbetter to convert theunitofmeasurement from

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kilometersintolightyears.Further,thesunandallthestarsweseeatnightarepartofahugesystemof abouthundredbillion stars, called theMilkyWay, our galaxy;we are locatedon the edgeof thissystemandridearoundthecenterofthegalaxyoncein230millionyears.Finally,ourgalaxyisonlyoneofbillionsofbillionsofothergalaxiesthatmakeupthewholeuniverse.Sohowcanwecomparethisvast,almostinfiniteuniversewiththetinycosmosofDantethathetravelsinafewdays?Itseemsridiculous!

11Thisiswhereoneofthemostfundamentalobservationsofmodernsciencemustbebroughtintoplay:the finitenessof thespeedof light!AccordingtoEinstein's theoryofrelativity,nothingcanbe fasterthanlightwhichtravelsadistanceofalmost300,000kmpersecond.Theconsequencesofthisfactarenotobviousineverydaylife,butonthescaleofastronomyandcosmologytheyareverydrastic.Whenwe lookat theskyaboveus,wesee thecelestialbodiesnotas theyareat thatmoment,butas theywerewhen they radiated the light we see now. Every look into the depths of the sky is actually aglimpseintothepast,ormoreprecisely:Thefurtherwelookintothespace,thefurtherwepenetrateintothepast,thatis,theclosertotheoriginoftime.

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12(Fig.12)Sowedonotseethemoonasitisatthismoment,butasitwasasecondago,inaccordwiththetimeittakesforthelighttoreachtheearth.Okay,thisisnotaseriousdelay.Buttheimageofthesuncomesalready8minutestoolate,becausethesunis8lightminutesawayfromus.Thestarsthatarevisibleatnight,atdistancesfromafewlightyearstothousandsoflightyears,weseeastheyweresomanyyearsorthousandsofyearsago.Whoknows,oneortheotherstarisnolongerthere(perhapsexploded or extinguished), but the signal has not reached us yet.We have no access to the distantspaceasitisatthemoment,thisiscompletelyimpossible;spaceandtimearealwaysinterconnected.Arelativelyclosegalaxy,say10million(!)lightyearsaway,isseenasitwas10millionyearsago.Andso

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on–penetratingeverdeeperintothedepthsofspace.Ondeepimagesofverylongexposuretimesasreceivedby theHubble SpaceTelescope,we look at galaxies billions of light years away, sowe seethemastheywerebillionsofyearsago.Infact,verysmallgalaxiesonimagesofthiskindmustbeatextremedistancesandbeenrecordedinstatunascendi.Eventually,goingdeeperstill,wereachanepochofthepastinwhichneithergalaxiesnorstarsexistedbecause theyhadnotyetbeen created.For this reason,nothing canbe seen, at leastnothing in thevisiblewavelengths.Wepenetratethedarkness...uptotheearliesttimes,whentheuniversewasstilladenseandhotparticlesoup,about14billionyearsago.Fromthisepochwereceivearadiation,whichwasdiscovered50yearsagowith this radio telescope (smallb/w insert,bottomright). It is the so-calledCosmicMicrowaveBackground, a fossil radiation, a kind ofweak echo of theBigBang;weak,because the universe has expanded a thousand times since then and therefore cooled down by thesamefactor.Inthisway,thewavelengthoftheradiationwasalsostretched,suchthattodaywereceivemicrowaves. The image of background radiation,with these tiny irregularities – they constitute theseedsofcosmicstructure– isasnapshotof thebeginningofourworld.Whatwesee in thispicturecorresponds to a direct view of themost distant regions of the cosmos and at the same time of itstemporalbeginning.(Note,however:ItisnotthecasethatweseetheBigBangitselfhere;thefirstfourhundredthousandyearstheuniversewasintransparenttoradiation;thereforetheBigBang,theactofcreationitself,remainshidden,anobjectoftheoreticalinvestigation.)

13Ifwenowputtogetheralltheimagesofobjectsthatwehaveseeninthepastinasequenceofspaceand time,weobtain the followingcosmic schema(Fig. 13).Allobjects thatweobserve in the same(arbitrary)pastareatthesamedistance,i.e.thedistancecorrespondingtothepastmomentinwhichthe light thatwe now receive has been emitted; so these objects are on the surface of a sphere; aparticularcosmiceradefinesaparticularsphere.TheresultisasequenceofconcentricsphereswithusviewersinthemiddleandwiththeBigBang,thebeginningoftime,projectedontothelast(largest)sphere.Onecouldspeakof'„temporalspheres“.Butthesespheresarenotindividuallyvisible:timeisacontinuousquantity, so the sequenceof spheres is also continuous.But it is immediatelynoticeablethat the imageof theonion returnsasamodelor figureof the cosmos!Due to the finitenessof thespeedoflight,theobserveduniverse–moreprecisely:theobservableuniverse–necessarilytakesthe

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formofasphere.Theschemaheredoesnotrepresentthespatialstructureoftheuniverse,whichhasneitheracenternoraboundary; itrepresentsthetemporalstructureofthecosmos,sincetimedoeshavea"boundary",abeginning.Theentireevolutionoftheuniverse,fromtheBigBangtothepresentday,istransformedintoasphericalspatio-temporalmap.Thepresentepochishere,atthecenter,andtheBigBangdefinestheboundaryofthesphereoftheobservablecosmos.

14Inowcometothecentralpointofmypresentation(Fig.14).Let'smakeacomparisonwiththesystemof the medieval world on which the Divine Comedy is based (left). The analogy between the twoworldsshouldcatcheveryone'seye!TheuppermostsphereofDante’scosmosisthePrimumMobile,thetransmissionbeltofthewholeworld;inthemoderncosmositistheBigBang–andithasthesamefunction:everythingderivesfromtheBigBang,itisaPrimumMobileaswell!Surelyonecouldarguethatthiscomparisondoesn'twork,becausethemoderncosmiconionisalmostinfinitelymuchlargerthantheoldone;–that'strue,butthat’saquantitativeargument.Thequalityofathing–likeformandfunction–seemstometobemoreimportantthanquantity–likesize.Ananalogyisalwaysbasedonqualitativeratherthanquantitativeproperties.Moreover,thecosmosofDantewasasinaccessibletoamedievalmanastheBigBangcosmosistous.Inaddition,theanalogyisnotlimitedtotheshapeofthesphereandtheprimummobilelimit.Theentiremoderncosmostakesoverthehierarchicalstructurethat we know from the old cosmos. In the latter, the direction of action was from top to bottom,primarilyasacausalchain(afterAristotle),butalsoasemanation(aftertheneoplatonists).Bothways– the causal chain and the radiation topdown– are reflected in themodern spherical cosmos quitenaturally,becausealongthisdirectionthetemporalflowtakesplace.Theanalogyalsoappliestothereversedirection,frombottomtotop.Asfarastheancientcosmosisconcerned,wehaveseenthattheascentofDantethroughthespherestothePrimumMobileandbeyond,inneoplatonicthinking,meansareturntothesource,totheCreator.Thisnaturallyalsodescribesthedirectionofourresearch,ifitispresentedinthisway(Fig.15).

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15With our telescopes we penetrate the depths of the universe to a distance (spatial and temporal)wheretherearenomoreobjectstoobserve.Thisiswherethephysicistsofelementaryparticles,whocarryoutexperimentsanddevelop theories inorder tounderstand thepropertiesofmatteratveryhighenergies,comeintocontactwiththeBigBanginametaphoricalsense.ExplainingthephysicsoftheBigBang,understandingtheoriginofthematerialworld,isperhapsthenoblestgoalofphysicsandastronomy.TheBigBangistheAlphaandOmega,itisourmaterialorigin–andourmentalgoal,theultimate goal of our research. We researchers, too, make a kind of virtual journey to the source;representedgeometrically,itresemblesanascension.LetusnowseewhathappenstoDante,thepilgrim,onhisjourney,alreadyclosetoitsend(Fig.16).Entered into the sphere of thePrimumMobile, as always looking inBeatrice's eyes,Dantemakes avisualexperiencedescribedintheversesofcanto28ofParadise:...justasonewhoseesamirroredflame...,inwhichLovemadethenoosethatholdsmetight.

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16In otherwords, Dante perceives a certain sparkle in Beatrice's eyes thatmust originate behind hisshouldersandisreflectedinBeatrice'seyes.Heautomaticallyturnsaroundtoseewhatshines.Here'shisreport:AndwhenIturnedandmyowneyesweremet...,...onelooksintentlyatistrevolution,–(Fig. 17) Isawapointthatsentforthsoacute ... , „OnthatPointdependtheheavenandthewholeofnature.“

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ThispointofextremebrightnessisarepresentationofGod,andaveryappropriateone:thedotshape(i.e.asingularity)andtheluminosity,thebrightness–infact, lightingeneral–haveadeepspiritualmeaning.NineluminousconcentriccirclesturnaroundGod,correspondingtothenineangelicchoirs.TheSeraphsclosest,thentheCherubsandsoontothearchangelsandangelsatthegreatestpossibledistance.Andthisspatialorderisaccompaniedbyakineticorder:TheclosertheyapproachGod,thefasterthecelestialbeingsmove,sothattheSeraphsrotateatmaximumspeed,theangelsatminimumspeed.Inthegeocentricworldofthespheres,however,thekineticorderisexactlytheopposite:Thespheres move faster the more distant from the center (earth) and the closer to God they are, thePrimumMobilerotatesatmaximumspeedand theMoonat the lowestspeed. (Note that thespatialand kinetic order of the angels of Dante corresponds exactly to the order of the planets in theheliocentricsolarsystemafterCopernicus;–itisabitasifDante,thepoet,hadanticipatedthisordertwocenturies(!)beforeCopernicus,butonlyinthespiritualrealm,notinthephysicalworld.)Inanycase,Dante,thepilgrim,feelsconfusedbythereversaloforderbetweenthespheresandangels.Whythisreversal?(Fig.18)AsalwaysBeatriceteacheshimandexplainsthereversalasfollows:

18Thisisnotexactlyabrilliantexplanation,butitsimplymeansthatitismorenobletobelargeonthelevel of space, butmore noble to be fast on the level ofmovement. Andbecause that thing (be it asphereoranangelicchoir)thatisclosertoGodismoremoved,thereversalbetweenthespheresandchoirsoftheangelsfollowsstrictlylogically.Thedrawinghereontherightservesasanimaginationofhow themovement of angels in the spiritual realm outside of space and time is transferred to thespheres inthephysicalworld; it isan invisibleprocess.This isalsohowthenatural lawsofmodernsciencework.The reverse situation reminds me of another matter of physics. Let us return to the image of themodern spherical cosmos (Fig. 15). As alreadymentioned: Approaching the Big Bang, at a certainpointoneenters intotheprimordialparticlesoupandthusalso intothe fieldofelementaryparticle

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physics. As we virtually march towards the Big Bang (which defines the boundary of this spatio-temporalglobe),thetemperatureofthesoupalsoincreases,becausewecontinuetopenetratefurtherinto the past (remember that the universe has cooled continuously due to its expansion).Theoretically, the temperature at the Big Bang singularity was infinitely high. Now, inthermodynamics,thetemperatureofasubstratecorrespondstotheenergyorvelocityoftheparticlesin it.With increasing temperature, i.e.with increasing energyor speed,more fundamental particlescome intoplay – smallerparticles, in ametaphorical sense.And the speedapproaches the speedoflightmoreandmore,tothepointwheretheparticlesbecome"relativistic"(asthephysicistssay)andthus(inacertainway)assumethecharacterofradiation(insteadofmatter).Theearlyuniversewasdominatedbyradiation,wecallthisepochthe„radiationera“.(andsinceradiationisessentiallylight,thisremindsusofthefiatluxofthebiblicalstoryofcreation).

19(Fig. 19) At this point Iwould like tomention a (forme) very nice analogy between photons andangels,astheyappearinDante’spoem.Bothare,inmodernterms,lightquanta,messengerparticles,forcecarriers,bothhavenomass,butarepureenergy,withoutnumber,effectiveintheworld,while„living“ outside the world, in the realm of eternity. In addition, the hierarchy of angels endlesslydiscussed by medieval scholars seems to return in the form of a particle hierarchy, including thephoton. There is no time to go into detail; suffice it to express the idea that there is actually apossibility to accomodate the concept of angels also in themodernworld – through analogies, andwithoutconflictingwithscienceortwistingscientificfacts!(Fig.20)Inanycase,itisobviousthattheinversionbetweentheorderofthespheresandtheorderofthe angels can be analogizedwith the inversion betweenmicrocosm andmacrocosm. Near the BigBang,at the largestdistances,weentertherealmof themicrocosm. IntheBigBang, the largestandsmallest things, themacrocosm and themicrocosm, come together, or as it is called in French:Lesextrèmes se touchent. Shown is a picture of the situation after Sheldon Glashow, Nobel laureate ofphysics,fromtheeighties,usingaveryoldhermeticsymbol:theUroboros,thesnakethatbitesitsowntail.

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20Iwould like to present one last example of an analogy. (Fig. 21) It concerns the four fundamentalforces, or interactionsofnature: gravity, electromagnetism, and,withanextremely small range, the„weak“nuclearforceandthe„strong“nuclearforce.Understandingthisdiversity,orrathertheunityoftheseforcesisperhapsthemostfundamentalproblemofphysics,liketheproblemofunderstandingthe Big Bangmentioned above (but perhaps it is the same problem). The theoretical unification offorces iswell advanced: there is a standard theory for the unification of electromagnetism and theweakforce.Ontheotherhand,itisnotclearhowthestrongforcecanbeadded;thereareideas,butnotmore.Andgravityhassofarresistedunificationaltogether;aquantumtheoryofgravityismissingtoachieveit.

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(Fig. 22) However, thenotionor idea inphysics is that the forcesatveryhighenergies, i.e.atveryhigh temperatures, are indistinguishable andunified in this sense.And in thisway the fundamentalforcesmustalsohavebeenunitedintheveryearlyuniverse, inthealmost infinitelyhotsoupattheBig Bang; therewas only one force, so to speak. But already after a very short time, less than onebillionth of a second, the forceswere differentiated and separated from the original unit, as can beseen in this graphic representation of the process. The first force that theoretically separated fromunitywasgravity,10tominus43secondsaftertheBigBang–anunimaginablyshorttimespan!

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23AtthispointIseeananalogywithacosmiccatastropheofmythology,especiallyasitisdescribedintheDivineComedy,namelythefallofLucifer(Fig.23).Itshouldberememberedthatevil,personifiedbyLucifer,issymbolizedbygravity.ThefallofLuciferandhiscompanionsismentionedintheComedyinthefollowingverses:

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Then, sooner than it takes to count to twenty,aportionoftheangels violentlydisturbed the lowestofyourelements.So this is also a veryquickprocess: as soonas theworldwas created, in less than twenty seconds,Lucifer, initially the Prince of Angels,was expelled from heaven for his pride. The consideration ofsuchashortperiodoftimeintheMiddleAgesseemsremarkabletome.Luciferfellanddisturbedthelowestofyourelements,asitissaidinthetext.ThismeansthatLuciferstructuredtheworldthroughhisfall(especiallyHellandPurgatory,asshowninthediagramontheleft).Andthiscanalsobefoundinastrophysics: it is thegravitational force that formsthestructureof theuniverseona largescale,leadingtotheformationofgalaxies,stars,andplanets.The other three forces that physicists are trying to unify remain – a goal that has not yet beenachieved. The theoretical unification of the fundamental forces of nature is a tremendous task, itrequiresanenormousintellectualeffort.Perhapsunificationisnotpossiblewithouttheintegrationofgravity.Perhapsitremainsanunsolvableproblemifhumanconsciousnessisnottakenintoaccountinsomeway.(Fig. 24) Back to the last lines of the Divine Comedy. Dante, the pilgrim, approaches the divinesingularity(God)intheEmpyrean,wherehelooksattheHolyTrinityandwantstounderstandit:

24Asthegeometerintentlyseekstosquarethecircle,buthecannotreach,throughthoughtonthought,theprincipleheneeds,...„Squaringthecircle“isanold,mythicalimageforaninsovableproblem.Maybetheunificationoftheforces belongs to this category. Inmy book I boldly declared this passage of the Divine Comedy acompulsory reading for theoretical physicists! However, Dante solves the problem in a different,holisticandcontemplativeway:

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... so I searched that strange sight ... by the Love thatmoves the sun and the other stars (l’amor chemoveilsoleel’altrestelle).HereistheendofDante’spoem,andalsotheendofmypresentation,thankyouforyourattention!★ AllDantequotesfrom:DanteAlighieri:TheDivineComedy,versetranslationbyAllanMandelbaum,3vols.,BantamClassics,NewYork1983Fig.13(und14,15)reproducedwithpermissionfrom:NancyAbramsundJoelPrimack:Thenewuniverseandthehumanfuture(Terrylectures),YaleUniversityPres,NewHaven2011Literature:BrunoBinggeli:PrimumMobile–DantesJenseitsreiseunddiemoderneKosmologie,Ammann,Zürich2006(onlygerman)Horia-RomanPatapievici:GliocchidiBeatrice–Com’eradavveroilmondodiDante?BrunoMondadori,Milano2006(onlyitalian)RobertOsserman:PoetryoftheUniverse.BantamDoubleday,NewYork1995