Astronomija

Ali se v inflacijskem prostoru tvori materija?

Ali se v inflacijskem prostoru tvori materija?


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Po odgovorih in razmišljanju od tu Ali je po umiranju zvezde ostalo dovolj vodika, da bo imela druga zvezda dovolj, da se prižge?

Spraševal sem se, ali obstaja možnost vedeti, ali je tam, kjer se ustvarja nov prostor med galaksijami, ustvarjena tudi kakršna koli nova snov (tj. Vodik ali subatomski delci, ki bi sčasoma lahko tvorili atome, kar bo privedlo do nastanka novih zvezd in galaksije)?


Opomba: ne govorite o inflaciji za trenutno širitev. Inflacija je kratko obdobje takoj za BB, ko se je vesolje nenavadno razširilo.

Materija je nastala, ko je bilo vesolje tako kompaktno, da je bila njegova temperatura milijarde in celo bilijone Kelvina vroča. Energija vakuuma v kateri koli prostornini je bila tako velika, da so nastali pari snov-antimaterija, ki so se običajno hitro izničili. Včasih pa so se ti kratkotrajni delci trčili in sproščali velike količine energije. Na primer, če želite ustvariti elektron, potrebujete energijo 0,5 MeV. Spodnji graf prikazuje, da je pri temperaturi 10 ^ {16} $ K energija trka lahko tudi 1 TeV.

Zaradi svoje širitve se je vesolje toliko ohladilo, da je njegova temperatura manjša od 3 K, kar pa še zdaleč ni dovolj za ustvarjanje novih delcev.

Graf prikazuje, kako temperatura in energija padeta, ko se vesolje širi v prvih sekundah po BB. Upoštevajte, da je pri 1000 sekundah (približno 20 minut) energija prenizka, da bi ustvarili elektrone (0,5 MeV), kaj šele težje elemente.

Kaj je v ekspanziji pa je temna energija. Njegova gostota je konstantna, zato se bo, ko se vesolje razširi, da se bo podvojilo, podvojila tudi količina temne energije. (To je razlog, zakaj gre razširitev vedno hitreje in hitreje, ničesar pa ne more ustaviti.)


Tako kvantna fizika ustvarja največje kozmične strukture od vseh

Nastanek kozmične strukture tako na velikih kot na majhnih lestvicah je zelo odvisen od tega, kako. [+] Temna snov in normalna snov medsebojno vplivata, pa tudi začetna nihanja gostote, ki izvirajo iz kvantne fizike. Strukture, ki se pojavijo, vključno z jatami galaksij in nitami večjega obsega, so nesporne posledice temne snovi.

Illustrisovo sodelovanje / Illustrisova simulacija

Na makroskopski ravni se zdi, da je Vesolje povsem klasično. Gravitacijo lahko opišemo z ukrivljenostjo vesolja v skladu s pravili splošne relativnosti. Elektromagnetne učinke popolnoma opisujejo Maxwellove enačbe. Le na ultra drobnih lestvicah začnejo prihajati kvantni učinki, ki se kažejo v značilnostih, kot so atomski prehodi, absorpcijske in emisijske črte, polarizacija svetlobe in dvojno lomljenje.

Pa vendar, če ekstrapoliramo nazaj v najzgodnejše faze vesolja, je bila vsaka pomembna interakcija, ki se je zgodila, povsem kvantne narave. Posamezni kvantni delci in polja so medsebojno vplivali na kratke lestvice in z ogromno energijo, kar je danes privedlo do številnih opazovalcev, ki imajo vtisnjeno kvantno zapuščino. Zlasti največje galaktične in supergalaktične strukture dolgujejo svoj izvor tudi kvantni fiziki. Evo kako.

Galaksije, primerljive s današnjo Mlečno pot, so številne, vendar mlajše galaksije, ki so Mlečne. [+] Podobno podobni so že po naravi manjši, modrejši, bolj kaotični in na splošno bogatejši s plinom kot galaksije, ki jih vidimo danes. Za vse prve galaksije bi bilo treba to narediti do skrajnosti in ostati veljavno, kot smo še kdaj videli. Izjeme, ko jih srečamo, so tako zmedene kot redke.

Če se želimo ozreti nazaj v čas, moramo le pogledati v Vesolje, kakršno se je pojavljalo na vedno večjih razdaljah od nas. Ker svetloba potuje le s končno hitrostjo, svetloba, ki jo vidimo danes in prihaja po potovanju ene milijarde let, ustreza svetlobi, ki je bila oddana pred milijardo let: milijardo let bližje Velikemu poku.

Ko gledamo na ta način, ne vidimo le, da so se posamezne galaksije (zgoraj) razvile, postale večje, bolj masivne in v celoti bolj rdeče barve, ampak da je vesolje kot celota postalo bolj strmo, bolj strnjeno in z več izrazita spletna struktura. Čeprav se nam zdi, da je naše vesolje praktično izenačeno na največjih kozmičnih lestvicah, zlasti v zgodnjih časih, so morale biti sprva preobremenjene in podhlajene regije, da bi lahko to vesoljsko mrežo oblikovale in rasle.

Razvoj obsežne strukture v vesolju, od zgodnjega, enotnega stanja do. [+] gručasto vesolje, ki ga poznamo danes. Vrsta in številčnost temne snovi bi prinesla povsem drugačno vesolje, če bi spremenili to, kar ima naše vesolje. Upoštevajte, da v vseh primerih nastane majhna struktura, preden se pojavi struktura na največjih lestvicah, in da tudi najbolj neobdelana območja še vedno vsebujejo nič-nič snovi.

Angulo et al. 2008, prek univerze Durham

Ker nam v zgodnjem vesolju zmanjka vidnih struktur za sondiranje - ne samo v praksi, ampak tudi načeloma - moramo ekstrapolirati, kako je struktura rasla v prvih nekaj sto milijonih let: dokler ne opazimo prvih zvezd in galaksij. Čeprav so naše teorije v tem režimu zelo dobre, moramo to, kar vidimo, primerjati z opazovanji, ali pa je vse za nič.

Na srečo pa nam Vesolje priskrbi še eno sondo zgodnjih semen sodobne kozmične strukture: pomanjkljivosti v ostankih žarenja od Velikega poka: vesoljsko mikrovalovno ozadje. Kar zaznavamo kot temperaturna nihanja v zgodnjem vesolju, kot lokacije, ki so nekoliko hladnejše ali nekoliko bolj vroče od povprečja, so pravzaprav povezane z nihanji gostote, ki bodo prerasli v obsežno strukturo, ki jo opažamo danes.

Nihanja mraza (prikazana modro) v CMB po svoji naravi niso hladnejša, temveč predstavljajo. [+] območja, kjer je zaradi večje gostote snovi večji gravitacijski vlek, medtem ko so žarišča (v rdeči barvi) bolj vroča, ker sevanje v tem območju živi v plitvejšem gravitacijskem vodnjaku. Sčasoma bodo preveč goste regije veliko bolj verjetno prerasle v zvezde, galaksije in kopice, medtem ko bodo manj gosto regije to manj verjetno. Gravitacijska gostota regij, skozi katere svetloba prehaja med potovanjem, se lahko pokaže tudi v CMB in nas uči, kakšne so te regije v resnici.

E.M. HUFF, EKIPA SDSS-III IN EKIPA TELESKOPA NA JUŽNEM POLU GRAFIKA ZOSIJE ROSTOMIAN

Ostanki sijaja velikega poka - kozmično mikrovalovno ozadje (CMB) - segajo v čas, ko le

Od samega dogodka Velikega poka je minilo 380.000 let. V vseh smereh, ne glede na to, kam na nebo gledamo, vidimo, da proti nam prihaja sevanje pri skoraj enaki natančni temperaturi: 2,725 K.

Toda pomanjkljivosti pri tej temperaturi so zelo pomembne, čeprav so od povprečja oddaljene le nekaj deset ali sto mikrokelvinov. Območja, ki se zdijo nekoliko hladnejša, imajo enako sevanje kot katera koli druga regija, vendar imajo nekoliko več snovi, kar pomeni, da morajo fotoni, ki zapustijo te regije, zaradi gravitacijskega rdečega premika izgubiti več energije kot v povprečni regiji. Nasprotno pa so nekoliko bolj vroče od povprečja regije premajhne, ​​zato vroče-hladne točke, ki jih vidimo, ustrezajo regijam z večjo ali manjšo gostoto od povprečja.

Prekomerne, povprečne gostote in prenizke regije, ki so obstajale, ko je bilo vesolje pravično. [+] 380.000 let zdaj ustrezajo hladnim, povprečnim in vročim točkam v CMB, ki pa so nastale zaradi inflacije.

E. Siegel / Beyond the Galaxy

Izmerimo lahko tisto, kar dejansko opazimo v CMB, in izračunamo, kakšna so bila začetna nihanja: tista, s katerimi se je vesolje rodilo ob začetku Velikega poka, namesto v kaj so se razvila v stotisoče let kasneje.

Ko to storimo, ugotovimo, da se je vesolje moralo roditi s skoraj nespremenljivim spektrom teh nihanj, da bi dobili natančen vzorec vrhov in dolin, če gledamo na večje ali manjše kotne lestvice. Na večjih lestvicah obstajajo nekoliko večja nihanja, na manjših pa nekoliko manjša, vendar je na splošno le nekaj odstotkov razlike. Vzorec, ki ga vidimo v sodobni CMB, ne odraža le, kakšna so bila ta začetna nihanja, ampak tudi to, kako so se razvijali, ko se je vesolje v prvih nekaj sto tisoč letih širilo, ohlajalo in gravitiralo.

Začetni spekter nihanj gostote lahko zelo dobro modeliramo z ravno vodoravno črto. [+], kar ustreza obsegu nespremenljivega (n_s = 1) spektra moči. Rahlo rdeč nagib (do vrednosti manj kot ena) pomeni, da je več moči na velikih lestvicah, kar pojasnjuje razmeroma raven levi del (na velikih kotnih lestvicah) opazovane krivulje. Vesolje prikazuje kombinacijo scenarijev od zgoraj navzdol in od spodaj navzgor.

Od kod torej ta začetna nihanja gostote? Zakaj vesolje ni bilo rojeno popolnoma gladko?

Odgovor na ta vprašanja izhaja iz same teorije, ki je pred Velikim pokom nastala, jo postavila in povzročila: kozmična inflacija. Preden se je vesolje napolnilo z delci, antidelci in sevanjem - preden se je med širjenjem ohladilo in postajalo manj gosto - je bila faza napolnjena z nekakšno vakuumsko energijo ali energijo, značilno za samo tkivo vesolja.

V tej inflacijski fazi se je vesolje eksponentno širilo, kar pomeni, da se stopnja širjenja ne spreminja s časom. Razdalje podvojijo vsak majhen delček sekunde, ki odžene vse delce drug od drugega, daje našemu opazovanemu vesolju povsod enake lastnosti in razširi vesolje v stanje, ki se ne razlikuje od ravnega.

Na zgornji plošči ima naše moderno vesolje povsod enake lastnosti (vključno s temperaturo). [+], ker izvirajo iz regije z enakimi lastnostmi. Na srednji plošči je prostor, ki bi lahko imel poljubno ukrivljenost, napihnjen do te mere, da danes ne moremo opaziti nobene ukrivljenosti, kar reši problem ravnosti. Na spodnji plošči se napihnejo že obstoječe visokoenergijske relikvije, ki zagotavljajo rešitev problema z visokoenergijskimi relikvijami. Tako inflacija rešuje tri velike uganke, ki jih Veliki pok ne more razjasniti sam.

E. Siegel / Beyond the Galaxy

Skratka, inflacijska faza pred in vzpostavi Veliki pok. Ko se inflacija konča, se vsa energija, ki je bila vesolju neločljiva, odvrže v snov, antimaterijo in sevanje: celoten nabor delcev in polj, ki jih dovoljujejo standardni model in zakoni fizike.

Vendar je le približek, da bo gostota energije na vseh lokacijah popolnoma enaka. Veste, tako kot vsako polje v vesolju mora biti tudi neko polje, ki je končno odgovorno za inflacijo, samo po sebi kvantno polje. In vsako kvantno polje nima samo vrednosti, ki s časom ostane nespremenjena, temveč ima lastna nihanja in vzbujanja: teh kvantnih nihanj ni mogoče prezreti. Ker je inflacija časovno obdobje, ko je energija Vesolja vezana na kvantno polje, ki je lastno vesolju, bo tudi to polje imelo kvantna nihanja, ki ustrezajo regijam z malo večjo ali manjšo energijo od povprečja .

Vizualizacija QCD prikazuje, kako pari delcev / antidelcev izstopajo iz kvantnega vakuuma. [+] zelo majhna količina časa kot posledica Heisenbergove negotovosti. Kvantni vakuum je zanimiv, ker zahteva, da sam prazen prostor ni tako prazen, ampak je napolnjen z vsemi delci, antidelci in polji v različnih stanjih, ki jih zahteva kvantna teorija polja, ki opisuje naše vesolje. Vse skupaj združite in ugotovite, da ima prazen prostor energijo ničelne točke, ki je dejansko večja od nič.

Ta nihanja se začnejo v zelo majhnih razsežnostih: enaka kvantna nihanja, ki si jih pogosto predstavljamo kot pare delcev in delcev, ki se pojavijo zelo kratek čas, nato pa ob ponovnem izničenju izginejo.

Toda med inflacijo se vesoljsko tkivo prehitro širi in odvaja ta pozitivna in negativna nihanja tako ekstravagantno, da jih ni mogoče ponovno izničiti. Namesto tega se preprosto raztegnejo po vesolju, nato pa se nova namestijo na stara. Ko se inflacija konča, ima vesolje skoraj (a ne povsem) niz nihanj gostote, nespremenljive glede na lestvico, na vsaki lestvici, ki jih lahko opazimo.

Kvantna nihanja, ki se pojavijo med inflacijo, se resnično raztezajo po vesolju,. [+], povzročajo pa tudi nihanja skupne gostote energije. Ta nihanja polja povzročajo pomanjkljivosti gostote v zgodnjem vesolju, ki nato vodijo do temperaturnih nihanj, ki jih doživljamo v kozmičnem mikrovalovnem ozadju.

E. Siegel / Beyond the Galaxy

Zaradi teh kvantnih nihanj, ki nastanejo med inflacijo, bo vesolje ob nastopu Velikega poka imelo območja vesolja na vseh kotnih lestvicah, ki se od povprečne gostote odstopajo za približno 1 del v 30.000. Sčasoma bo gravitacija delovala tako, da bo prekomerna območja propadla in jim ukrala snov, medtem ko sevanje seče iz ali v območja, ki odstopajo od te povprečne gostote.

Kombinacija tega učinka z interakcijami med delci, sevanjem in drugimi delci ustvarja vzorce nihanja, ki jih danes vidimo v CMB, pa tudi prenapeta in neobsežna območja, ki prerastejo v kozmično mrežo obsežne strukture, ki jo vidimo danes. . Vse skupaj lahko izsledimo do njegovega inflacijskega izvora, ki ni le v skladu z vsem, kar vemo in opažamo o vesolju, ampak dokazuje nujnost inflacije, ki jo poganja kvantno polje.

Kvantna nihanja, ki se pojavijo med inflacijo, se raztezajo po vesolju in kdaj. [+] inflacija se konča, postanejo nihanja gostote. To sčasoma vodi do obsežne strukture v vesolju danes, pa tudi do temperaturnih nihanj, opaženih v CMB. Rast strukture teh nihanj semen in njihovi odtisi na spekter moči vesolja in temperaturne razlike CMB lahko uporabimo za določanje različnih lastnosti našega vesolja.

E. Siegel s slikami, pridobljenimi iz ESA / Planck in medresorske delovne skupine DoE / NASA / NSF za raziskave CMB

Če ne bi bilo kvantne fizike, bi bilo vesolje rojeno popolnoma gladko, saj bi vsaka vesoljska regija imela popolnoma enako temperaturo in gostoto kot vsa druga regija. S časom bi še vedno morali, da bi materija premagala antimaterijo, oblikovala lahke elemente z nukleosintezo in nato ustvarila nevtralne atome, ko se je Vesolje širilo in ohlajalo.

Toda zvezd in galaksij ne bi oblikovali tako, kot je to delalo naše vesolje. Mnoge milijarde let bi trajalo, da bi se oblikovale celo prve: mnogo stotine krat dlje, kot dejansko vidimo. Obstoj ogromnih kopic galaksij in obsežnega kozmičnega spleta bi bil prepovedan, saj semena strukture ne bi mogla zrasti. In temna energija bi bila končni žebelj v krsti, ki bi preprečila, da bi se največje strukture kdajkoli oblikovale.

Edini razlog, da jih sploh imamo, je zaradi kvantne narave našega vesolja. Le zaradi povezave med najmanjšo in največjo lestvico - kvantno in kozmično - lahko sploh razumemo svoje vesolje.


Študija: Življenje je lahko pogosto v inflacijskem vesolju

V prispevku, objavljenem v reviji Znanstvena poročila, Profesor Univerze v Tokiu Tomonori Totani, je preučil, kako lahko gradniki življenja spontano nastanejo v vesolju & # 8212 proces, znan kot abiogeneza.

Morda smo edino inteligentno življenje v opazovanem vesolju. Kreditna slika: NASA.

Kljub nedavnemu hitremu razvoju biologije, kemije, znanosti o Zemlji in astronomije je izvor življenja skozi abiogenezo v znanosti še vedno velika skrivnost.

Pomembna značilnost življenja so urejene informacije, shranjene v DNA in RNA, in kako pomembno je, kako so te informacije izhajale iz abiotskih procesov.

"Ker edino življenje, ki ga poznamo, temelji na Zemlji, so študije o izvoru življenja omejene na posebne pogoje, ki jih najdemo tukaj," je dejal profesor Totani.

"Zato večina raziskav na tem področju obravnava najosnovnejše sestavine, ki so skupne vsem znanim živim bitjem: RNA."

"To je veliko bolj preprosta in bistvena molekula kot bolj znana DNA, ki določa, kako smo sestavljeni."

"Toda RNA je še vedno veliko bolj zapletena od vrst kemikalij, ki se nagibajo k temu, da lebdijo v vesolju ali se držijo obraza brez življenja."

RNA je polimer, kar pomeni, da je narejena iz kemičnih verig, v tem primeru znanih kot nukleotidi. Ob zadostnem času se lahko nukleotidi spontano povežejo v RNA ob ustreznih kemijskih pogojih.

Raziskovalci ne vedo, kako se je polimer RNA dovolj dolgo, da je imel samorazmnoževalno aktivnost (RNA polimeraza ribozim), pojavil iz prebiotičnih razmer in nato sprožil evolucijo.

Molekule RNA, krajše od 25 nukleotidov, ne kažejo določene funkcije, vendar obstaja upanje, da bomo našli delujoč replikazni ribozim, daljši od 40-60 nukleotidov. Ribozimi RNA-polimeraze, proizvedeni do zdaj v laboratorijskih poskusih, so daljši od 100 nukleotidov.

"Trenutne ocene kažejo, da čarobno število od 40 do 100 nukleotidov ne bi smelo biti mogoče v prostoru, ki ga obravnavamo kot opazovano vesolje," je dejal profesor Totani.

»Vendar je vesolje več kot opazljivo. V sodobni kozmologiji se strinjamo, da je vesolje doživelo obdobje hitre inflacije, ki je povzročila veliko območje širjenja onkraj obzorja tistega, kar lahko neposredno opazimo. Če to večjo količino vključimo v modele abiogeneze, močno povečamo možnosti za življenje. "

Dejansko opazovano vesolje vsebuje približno 10 22 zvezd. Statistično gledano bi lahko snov v tolikšni količini proizvedla le RNA približno 20 nukleotidov.

Toda zahvaljujoč hitri inflaciji lahko vesolje vsebuje več kot 10 100 zvezd, in če je temu tako, so bolj zapletene in življenjsko pomembne strukture RNA več kot le verjetne, so praktično neizogibne.

"Tako kot mnoge na tem področju raziskovanja tudi mene vodijo radovednost in velika vprašanja," je dejal profesor Totani.

»Združevanje moje nedavne preiskave kemije RNA in moje dolge zgodovine kozmologije me vodi do spoznanja, da je vesolje verjetno prešlo iz abiotskega stanja v biotsko. To je vznemirljiva misel in upam, da bodo raziskave lahko nadaljevale na tem, da bodo odkrile izvor življenja. "

T. Totani. 2020. Pojav življenja v inflacijskem vesolju. Sci Rep 10, 1671 doi: 10.1038 / s41598-020-58060-0


Astronomi najdejo možen eksoplanet v nastajanju v svojem vrtincu

Pogled na mlado zvezdo HD 163296 z novoodkritim vrtincem ali & # 8220whirlpool & # 8221 prahom in kamenčki, ki krožijo okoli njega. Raziskovalci menijo, da se novi planet oblikuje v najsvetlejši regiji, kjer se kamenčki meljejo in tvorijo toplejši prah. Slika prek J. Varga in sod. / Astronomie.nl.

Planeti se rodijo v masivnih vrtinčastih diskih plina in prahu okoli novonastalih zvezd. Astronomi so opazili veliko teh protoplanetarnih diskov in pogosto lahko na njih vidijo koncentrične reže, kot so utori na stari plošči vinilnega fonografa. V tistih vrzelih, ki jih planeti tvorijo iz spajanja plinov in prahu, se nahaja. 21. januarja 2021 je mednarodna skupina znanstvenikov, ki jo vodijo raziskovalci na Nizozemskem, objavila, da & # 8217ve povečan še malo in našli, kar mislijo, da je planet v procesu nastajanja znotraj lastnega vrtinca ali vrtinca prahu in kamenčkov. To pomeni, da ne vidijo zgolj vrzeli na disku, ampak dejanski svet, ki se rodi v svojem lastnem vrtincu, ki tvori planete. Odkritje je bilo odkrito z novim instrumentom MATISSE, ki združuje in analizira svetlobo štirih ločenih teleskopov v observatoriju ESO & # 8217s Very Large Telescope (VLT) na Cerro Paranal na severu Čila.

Odkritje je napovedal Astronomija.nl 21. januarja 2021, članek je v teku, vendar še ni objavljen. Vendar je na spletnem mestu arXiv na voljo brezplačna različica pred tiskom.

Glavni protoplanetarni disk prahu, kamenčkov in plina obdaja mlado zvezdo HD 163296. Znano je, da znotraj vrzeli diska nastajajo tudi trije drugi orjaški planeti. Slika prek ALMA / ESO / NAOJ / NRAO / AUI / NSF / A. Isella / B. Saxton / Sci-News.

Mlada zvezda HD 163296 je oddaljena približno 330 svetlobnih let od Zemlje v ozvezdju Strelec. Star je le približno štiri milijone let in dvakrat večji od našega sonca.

Zvezdo so astronomi že veliko preučevali, toda raziskovalci, ki jih je vodil József Varga z nizozemske univerze Leiden, so si želeli podrobneje ogledati notranji del diska, ki obkroža zvezdo. To so storili marca in junija 2019 in videli nekaj zanimivega: manjši obroč toplega, drobnega prahu, ki kroži okoli zvezde, na približno enaki razdalji, kot je Merkur od našega sonca.

Bi se tu lahko oblikoval planet? Raziskovalci pravijo, da je verjetno točno to, saj so pri obroču opazili še nekaj: en del je bil veliko svetlejši in bolj vroč kot preostali del, na posnetih slikah pa je videti svetlo belkasto rumen.

Po mnenju raziskovalcev je to svetlo področje vrtinec, tj. vihra, kjer se pred našimi očmi postopoma oblikuje planet.

Umetnikov koncept mladih protoplanetov, ki se oblikujejo v protoplanetarnem disku okoli zvezde. Slika prek NRAO / AUI / NSF / S. Dagnello / Sci-News.

Zakaj je ta vrtinec videti tako svetel? Znanstveniki pravijo, da kamnite kamenčke meljejo v droben prah in proizvajajo več toplote. To se nekoliko razlikuje od drugih krajev na disku, kjer se kamenčki zgolj strgajo.

Planeti v našem lastnem sončnem sistemu, vključno z Zemljo, so začeli svoje življenje na približno enak način, ko so se prah, kamenčki in plini združili, sčasoma pa ustvarili dejansko skalnate, ledene in plinaste svetove.

Instrument MATISSE je močan s kombiniranjem svetlobe štirih teleskopov in ustvarja ekvivalent enega samega teleskopa z navideznim premerom 200 metrov (656 čevljev). Njegova glavna naloga je analizirati infrardeče sevanje zvezd. Ker prašni diski in planeti oddajajo tovrstno sevanje, jih MATISSE lahko zazna z analizo količine oddanega sevanja.

József Varga z nizozemske univerze Leiden, vodilni avtor nove študije. Slika prek univerze Leiden.

Za HD 163296 je že znano, da ima tri druge orjaške mlade planete v širokih orbitah. Kot najnovejše odkritje so tudi ti planeti dojenčki, ki še vedno niso popolnoma oblikovani. Njihovo odkritje, ki ga je opravil observatorij Atacama Large Millimeter / submillimeter Array (ALMA), je bilo napovedano leta 2018. Tako kot drugi protoplaneti, kot jih imenujejo, prebivajo v režah na glavnem protoplanetarnem disku, ki obdaja zvezdo. Te planete sta odkrili dve skupini astronomov, ki so merili pretok plina znotraj diska. Po Christopheju Pinteju, astronomu z avstralske univerze Monash:

Merjenje pretoka plina znotraj protoplanetarnega diska nam daje veliko večjo gotovost, da so planeti prisotni okoli mlade zvezde. Ta tehnika ponuja obetavno novo smer za razumevanje nastanka planetarnih sistemov.

Astronom z Univerze v Michiganu Richard Teague, vodja druge ekipe, je dodal:

Ogledali smo si lokalizirano majhno gibanje plina v protoplanetarnem disku zvezde. Ta povsem nov pristop bi lahko odkril nekatere najmlajše planete v naši galaksiji Rimske ceste, vse zahvaljujoč slikam ALMA z visoko ločljivostjo.

Instrument MATISSE na ESO & # 8217s Interferometer zelo velikem teleskopu (VLTI). Slika prek ESO / P. Horalek / Astronomie.nl.

Ta najnovejši in manjši planet bi bil, če bi bil potrjen, četrti v tem sistemu.

Zdaj želijo raziskovalci podobno opazovati druge zvezde s protoplanetarnimi diski, zlasti tiste, ki lahko vsebujejo razvijajoče se kamnite planete, kot je Zemlja. To bi nam dalo pomembne namige o tem, kako se je rodil in razvijal naš svet.

Spodnja črta: Mednarodni raziskovalci, ki jih je vodila ekipa na Nizozemskem, so odkrili morebitni novorojeni planet, ki se oblikuje v & # 8220whirlwind & # 8221 prahu in kamenčkov okoli mlade zvezde.


2. Splošni okvir

Inflacijska paradigma je običajno oblikovana v pogojih glede lokalne ravnosti na poljuben potencial, ki lahko načeloma vsebuje veliko število ekstremov in pobočij (Artymowski in Rubio, 2016). Ta sploščenost je običajno povezana z obstojem približne simetrije premika, ki jo je za namene Higgsove inflacije primerno preoblikovati kot nelinearno realizacijo približne nespremenljivosti merila.

2.1. Inducirana gravitacija

Začnimo z razmislekom o inducirana gravitacija scenarij

ki vključuje skalarno polje h, vektorsko polje B& # x003BC in fermionsko polje & # x003C8, z interakcijami, podobnimi tistim, ki se pojavljajo v SM fizike delcev, če so zapisane v enotnem merilniku H = (0, h / 2) T. Količina F & # x003BC & # x003BD F & # x003BC & # x003BD pomeni standard B& # x003BC kinetični izraz, ki ga zaradi poenostavitve razumemo kot abelovskega. V tem modelu igrač je efektivna Newtonova konstanta inducirana s pričakovano vrednostjo skalarnega polja,

Da bi GN, eff za dobro obnašanje je neminimalna sklopka & # x003BE omejena na pozitivne vrednosti. Ta pogoj je enakovreden zahtevanju polpozitivne določenosti kinetičnega izraza skalarnega polja, kar je mogoče zlahka videti z izvedbo redefinicije polja h 2 & # x02192 h 2 / & # x003BE.

Pomembna lastnost inducirana gravitacija delovanje (2.1) je njegova nespremenljivost pri transformacijah lestvice

Tu je & # x003B1 poljubna konstanta, & # x003C6 (x) kompaktno označuje različna polja v modelu in & # x00394& # x003C6& # x00027s so njihove ustrezne dimenzije skaliranja. Posledice te dilatacijske simetrije je lažje razumeti v minimalno sklopljenem okviru, ki prikazuje standardni Einstein-Hilbertov izraz. To Einsteinov okvir dosežemo z Weylovim redefiniranjem metrike 4

skupaj z Weylovim spreminjanjem skale vektorskih in fermionskih polj,

Po trivialni algebri dobimo Einsteinovo akcijo 5

, ki vsebuje nekanonski izraz za polje & # x00398. Koeficient tega kinetičnega izraza,

vključuje kvadratni pol pri & # x00398 = 0 in konstanto

spreminja med ničlo pri & # x003BE = 0 in & # x022121 / 6, ko & # x003BE & # x02192 & # x0221E. Kinetični izraz & # x00398-polje lahko postane kanoničen z izvedbo dodatne redefinicije polja,

preslikava bližine pola pri & # x00398 = 0 do & # x003D5 & # x02192 & # x0221E. Posledično dejanje

je invariantno pri transformacijah premikov & # x003D5 & # x02192 & # x003D5 & # 43C, s C stalnica. Eksponentno preslikava v enačbi (2.9) kaže, da takšna translacijska simetrija ni nič drugega kot nelinearna realizacija prvotne nespremenljivosti merila, ki smo jo začeli v enačbi (2.1) (Csaki et al., 2014). Prehod Einsteinovega okvira v enačbi (2.4) je res enakovreden spontanemu razbijanju dilatacij, saj smo implicitno zahtevali polje h pridobiti vrednost, ki ni enaka nič, pričakovanja. Kanonsko normalizirano skalarno polje & # x003D5 je pridruženi Goldstoneov bozon in je kot tak popolnoma ločen od snovnih polj B& # x003BC in & # x003C8. Nenimalna sklopka z gravitacijo učinkovito nadomešča h avtor F& # x0221E v vseh interakcijah dimenzije 4, ki vključujejo konformne stopnje svobode. Upoštevajte pa, da ta izjava o ločitvi ne velja za razširitve, invariantne glede na skalo, vključno z dodatnimi skalarnimi polji (Kaiser, 2010 Garcia-Bellido et al., 2011 Bezrukov et al., 2013 Kaiser et al., 2013 Kaiser in Sfakianakis, 2014 Karananas in Rubio, 2016) ali druge nekonformalne interakcije, kot so R 2 izraza (Starobinsky, 1980 Gorbunov in Panin, 2011, 2012 Gorbunov in Tokareva, 2013).

2.2. Higgsova inflacija iz približne nespremenljivosti lestvice

Čeprav zgoraj predstavljeni model igrač vsebuje številne ključne sestavine Higgsove inflacije, fenomenološko ni izvedljiv. Zlasti potencial Einsteinovega okvira je popolnoma simetričen in ne omogoča konca inflacije. Poleg te omejitve je skalarno polje & # x003D5 popolnoma ločeno od vseh konformnih polj, kar izključuje možnost nastajanja entropije in morebiten začetek dobe, v kateri prevladuje sevanje. Vse te fenomenološke omejitve so neločljivo povezane z natančno realizacijo nespremenljivosti lestvice in kot taki naj bi pričakovali, da bodo izginili, ko bo v dejanje vključen (velik) dimenzijski parameter. Prav to se zgodi pri Higgsovi inflaciji. Skupaj Higgsova inflacija akcija (Bezrukov in Shaposhnikov, 2008)

vsebuje dva dimenzijska parametra: pomanjšani Planck M P & # x02261 1/8 & # x003C0 G N = 2. 435 & # x000D7 1 0 18 GeV in pričakovana vrednost Higgsovega vakuuma vEW & # x02243 250 GeV, odgovorno za mase znotraj SM lagrangijeve gostote L SM. Med tema dvema lestvicama je Planckova masa najpomembnejša pri velikih poljskih vrednostih, pomembnih za inflacijo. Za ponazoritev, kako vključitev MP spreminja rezultate prejšnjega oddelka, upoštevajmo graviskalni del enačbe (2.11) v enotnem merilniku H = (0, h / 2) T, in sicer

običajni potencial SM za prekinitev simetrije. Tako kot v scenariju inducirane gravitacije tudi vključitev neminimalne sklopke na gravitacijo spremeni moč gravitacijske interakcije in postane odvisna od Higgsovega polja,

Da bi bil propagator gravitona sploh dobro opredeljen h vrednosti, mora biti nominalna sklopka & # x003BE pozitivna 6. Če & # x003BE & # x022600, se ta zahteva pretvori v oslabitev efektivne Newtonove konstante pri naraščanju Higgsovih vrednosti. Za neminimalne sklopke v območju 1 & # x0226A & # x003BE & # x0226A M P 2 / v EW 2 je ta učinek pomemben v režimu velikega polja h & # x0226B M P / & # x003BE, sicer pa je zanemarljiv.

Kot smo storili v oddelku 2.1, je primerno preoblikovati enačbo (2.12) v Einsteinovem okviru z izvedbo Weylove transformacije g& # x003BC & # x003BD & # x02192 & # x00398g& # x003BC & # x003BD s

V novem okviru so vse nelinearnosti, povezane z neminimalno interakcijo Higgs-gravitacije, premaknjene v skalarni sektor teorije,

ki zdaj vsebuje a ne ravno ravno potencial

in nekanonični kinetični sektor, ki je posledica spreminjanja merila metrične determinante in nehomogenega dela Riccijeve skalarne transformacije. The kinetic function

shares some similarities with that in Equation (2.7). In particular, it contains two poles located respectively at Θ = 0 and Θ = 1. The first pole is an inflationary pole, like the one appearing in the induced gravity scenario. This pole leads to an enhanced friction for the Θ field around Θ = 0 and allows for inflation to happen even if the potential V(Θ) is not sufficiently flat. The second pole is a Minkowski pole around which the Weyl transformation equals one and the usual SM action is approximately recovered. To see this explicitly, we carry out an additional field redefinition 7 ,

to recast Equation (2.16) in terms of a canonically normalized scalar field ϕ. This differential equation admits an exact solution (Garcia-Bellido et al., 2009)

In terms of the original field h, we can distinguish two asymptotic regimes

separated by a critical value

The comparison between these approximate expressions and the exact field redefinition in Equation (2.20) is shown in Figure 3.

Figure 3. Comparison between the approximate expressions in Equation (2.21) (dashed black and blue lines) and the exact solution (2.20) (solid red). Below the critical scale ϕc, Higgs inflation coincides, up to highly suppressed corrections, with the SM minimally coupled to gravity. Above that scale, the Higgs field starts to decouple from the SM particles. The decoupling becomes efficient at a scale F, beyond which the model can be well approximated by a chiral SM with no radial Higgs component.

The large hierarchy between the transition scale ϕC and the electroweak scale allows us to identify in practice the vacuum expectation value vEW with ϕ = 0. In this limit, the Einstein-frame potential (2.17) can be rewriten as

At ϕ < ϕC we recover the usual Higgs potential (up to highly suppressed corrections, cf. section 3.1). At ϕ > ϕC the Einstein-frame potential becomes exponentially stretched and approaches the asymptotic value F at ϕ > M P / ( 2 | a | ) . The presence of MP in Equation (2.11) modifies also the decoupling properties of the Higgs field as compared to those in the induced gravity scenario. In particular, the masses of the intermediate gauge bosons and fermions in the Einstein-frame 8 ,

coincide with the SM masses in the small field regime (ϕ < ϕC) and evolve toward constant values proportional to F in the large-field regime ( ϕ > M P / ( 2 | a | ) ). The transition to the Einstein-frame effectively replaces h avtor F(ϕ) in all (non-derivative) SM interactions. This behavior allows us to describe the Einstein-frame matter sector in terms of a chiral SM with vacuum expectation value F(ϕ) (Dutta et al., 2008 Bezrukov and Shaposhnikov, 2009).

2.3. Tree-Level Inflationary Predictions

The flattening of the Einstein-frame potential (2.23) due to the Θ = 0 pole allows for inflation with the usual slow-roll conditions even if the potential V(Θ) is not sufficiently flat. Let us compute the inflationary observables in the corresponding region ϕ > ϕC, where

The statistical information of the primordial curvature fluctuations generated by a single-field model like the one under consideration is mainly encoded in the two-point correlation functions of scalar and tensor perturbations, or equivalently in their Fourier transform, the power spectra. Following the standard approach (Mukhanov et al., 1992), we parameterize these spectra in an almost scale-invariant form,

and compute the inflationary observables

the first and second slow-roll parameters and the primes denoting derivatives with respect to ϕ. The quantities in (2.28) should be understood as evaluated at a field value ϕ* ≡ ϕ(N*), with

the e-fold number at which the reference scale k* in Equation (2.27) exits the horizon, i.e. k* = a*H*. Here,

stands for the field value at the end of inflation, which is defined, as usual, by the condition ϵ(ϕE)𢘑. Equation (2.30) admits an exact inversion,

with W 𢄡 the lower branch of the Lambert function and

a rescaled number of e-folds. Inserting Equation (2.32) into (2.28) we get the following analytical expressions for the primordial scalar amplitude,

and the tensor-to-scalar ratio

At large |a|N*, these predictions display an interesting attractor behavior, very similar to that appearing in α-attractor scenarios (Ferrara et al., 2013 Kallosh et al., 2013 Galante et al., 2015) (see also Artymowski and Rubio, 2016). Indeed, by taking into account the lower bound on the Lambert function (Chatzigeorgiou, 2016),

we can obtain the approximate expressions 9

at 8 | a | N ̄ * ≫ 1 . The free parameter |a| (or equivalently the non-minimal coupling ξ) can be fixed by combining Equation (2.34) with the normalization of the primordial spectrum at large scales (Akrami et al., 2018),

Doing this, we get a relation

among the non-minimal coupling ξ, the number of e-folds N ̄ * and the Higgs self-coupling λ.

The precise value of the number of e-folds in Equations (2.38), (2.40) depends on the whole post-inflationary expansion and, in particular, on the duration of the heating stage. As the strength of the interactions among the Higgs field and the SM particles is experimentally known, the entropy production following the end of inflation can be computed in detail (Bezrukov et al., 2009a Garcia-Bellido et al., 2009 Repond and Rubio, 2016) 10 . The depletion of the Higgs-condensate is dominated by the non-perturbative production of massive intermediate gauge bosons, which, contrary to the SM fermions, can experience bosonic amplification. Once created, the W ± and Z bosons can decay into lighter SM fermions with a decay probability proportional to the instantaneous expectation value of the Higgs field ϕ(t). The onset of the radiation-domination era is determined either by i) the time at which the Higgs amplitude approaches the critical value ϕC where the effective potential becomes quartic or by ii) the moment at which the energy density into relativistic fermions approaches that of the Higgs condensate whatever happens first. The estimates in Garcia-Bellido et al. (2009), Bezrukov et al. (2009a), and Repond and Rubio (2016) provide a range

with the lower and upper bounds associated respectively with the cases i) and ii) above. For the upper limit of this narrow window, we have N ̄ * ≃ N * ≃ 59 and we can rewrite Equation (2.40) as a relation between ξ and λ,

Note that a variation of the Higgs self-coupling in this equation can be compensated by a change of the a priori unknown non-minimal coupling to gravity. For the tree-level value λ~ O (1), the non-minimal coupling must be significantly larger than one, but still much smaller than the value ξ ~ M P 2 / v EW 2 ~ 1 0 32 leading to sizable modifications of the effective Newton constant at low energies. In this regime, the parameter |a| is very close to its maximum value 1/6. This effective limit simplifies considerably the expression for the critical scale ϕC separating the low- and high-energy regimes,

and collapses the inflationary predictions to the attractor values (Bezrukov and Shaposhnikov, 2008)

in very good agreement with the latest results of the Planck collaboration (Akrami et al., 2018). Note that, although computed in the Einstein frame, these predictions could have been alternatively obtained in the non-minimally coupled frame (2.12), provided a suitable redefinition of the slow-roll parameters in order to account for the Weyl factor relating the two frames (Makino and Sasaki, 1991 Fakir et al., 1992 Komatsu and Futamase, 1999 Flanagan, 2004 Tsujikawa and Gumjudpai, 2004 Koh, 2006 Chiba and Yamaguchi, 2008, 2013 Weenink and Prokopec, 2010 Postma and Volponi, 2014 Ren et al., 2014 Jarv et al., 2015a,b, 2017 Burns et al., 2016 Kuusk et al., 2016 Karam et al., 2017 Karamitsos and Pilaftsis, 2018a,b).


1st matter in the universe may have been a perfect liquid

Scientists have recreated the first matter that appeared after the Big Bang in the Large Hadron Collider.

Smashing together lead particles at 99.9999991% the speed of the light, scientists have recreated the first matter that appeared after the Big Bang.

Out of the wreck came a primordial type of matter known as quark-gluon plasma, or QGP. It only lasted a fraction of a second, but for the first time, scientists were able to probe the plasma's liquid-like characteristics — finding it to have less resistance to flow than any other known substance — and determine how it evolved in the first moments in the early universe.

"This [study] shows us the evolution of the QGP and eventually [could] suggest how the early universe evolved in the first microsecond after the Big Bang," said co-author You Zhou, an associate professor at the Niels Bohr Institute, University of Copenhagen in Denmark.

After the Big Bang, the universe was thought to be a soup of energy before it rapidly expanded during a period known as inflation, which allowed the universe to cool enough for matter to form. The first entities thought to emerge were quarks, a fundamental particle, and gluons, which carry the strong force that glues quarks together. As the universe cooled further, these particles formed subatomic particles called hadrons, some of which we know as protons and neutrons.

Scientists created this soupy stew at the world's largest atom smasher, the Large Hadron Collider (LHC) on the border of Geneva, in Switzerland. By smashing heavy atomic nuclei together, the scientists could create a tiny fireball that effectively melts particles into their primordial forms for a fraction of a second. The scientists think they first created a QGP in 2000, but the latest batch, reported online on May 11, 2021 in the journal Physics Letters B, was the first time they could probe the characteristics of its liquid nature in detail. Since the plasma only lasted 10 to the minus 23 seconds, the scientists used new computer simulations along with the data they gathered from an instrument called ALICE — short for A Large Ion Collider Experiment — in the accelerator to figure out the properties of the matter and how it might have changed between the instant it formed and when it condensed into hadrons. They found the QGP was a perfect liquid — which means that it had almost no viscosity or resistance to flow — and it also changed shape over time in a manner unlike other forms of matter.

This information helps scientists understand what the universe was like in its first infant moments after the Big Bang. The scientists hope to uncover more details as the accelerator is upgraded and a new billion-dollar accelerator in the United States comes online. More studies could help scientists understand how the quarks and gluons are arranged into protons and neutrons and "potentially link to the earlier stage [called] quantum inflation in the Big Bang model," Zhou said.


Explore the OLL Collection: Images of Liberty and Power Encyclopedic Liberty and Industry

This illustrated essay explores some images of "liberty" and "industry" from Diderot’s Encyclopédie, ou Dictionnaire raisonné des sciences, des arts et des métiers (Encyclopaedia, or a Systematic Dictionary of the Sciences, Arts, and Crafts) (1751-1772). They have been taken from Liberty Fund’s anthology of articles, Encyclopedic Liberty: Political Articles in the Dictionary of Diderot an.


De Sitter Space and Cosmology

A standard topic in an introductory General Relativity (GR) course is the study of maximally symmetric solutions. These are flat (Minkowski) spacetime, de Sitter spacetime (obtained when the cosmological constant is positive) and Anti-de Sitter spacetime (when the cosmological constant is negative). While this last space has been of great interest in physics during the last fifteen years due to its central role in the correspondence between gauge theories and gravity, it is de Sitter space with which I'll be concerned here.

The idea of cosmological inflation is our best developed idea of how the physics of the early universe might lead to the observed universe today. This idea has been widely discussed in popular books and beyond, and in this context, many students have heard the loose description that inflation occurs when the universe is in an almost de Sitter state, and undergoes exponentially rapid expansion. There is nothing wrong with this explanation, but one consequence of accepting it before having a thorough grounding in GR is that it seems to imply that de Sitter space is a solution to GR that undergoes a rapid change over time. This leads to a few confused looks when I get to maximally symmetric spaces in my course.

You see, maximal symmetry means that you should be able to look at the space at different places and at different times and the metric should be just the same. So how are we to square that with the idea of an exponentially growing universe? Well, it all comes down to coordinate choices and the crucial existence of other matter in the universe.

Pure de Sitter space - the solution to the Einstein equations with a positive cosmological constant and no other matter sources - is, indeed, a maximally symmetric space. There exist a number of particularly useful coordinate choices for this space. In some cases, these consist of picking a useful time choice, and thus defining a family of spacelike surfaces (the spatial part of the spacetime at a constant value of this time choice). This is referred to as a slicing of the space, and it is, actually, possible to slice the space in three different ways that correspond to cosmologically expanding spaces with flat, positively-curved and negatively curved spatial parts, respectively. These are the ways of describing de Sitter space that are useful when considering inflation. However, there also exists a choice of coordinates in which the metric does not depend on time at all, and the mere existence of such a choice is enough to tell us that there is no fundamental sense in which this is an expanding cosmological spacetime. In fact, from what I just wrote, you might have a related question: even in the cosmological coordinates, what decides if the universe is flat, positively, or negatively curved?

In the case of pure de Sitter space there is no answer to these questions. All the coordinate choices are equally allowed of course, and so we might as well look at the static coordinates, and there is no cosmology here. However, importantly, in cosmology we are never interested in pure de Sitter space. We know that there is other matter in the universe. This may be either in the form of particles like us, or, in the case of inflation, the background field that causes inflation in the first place - the inflaton . These types of matter mean that the behavior of the metric is at best almost de Sitter - the difference from pure de Sitter being that, crucially, there are only certain coordinate systems in which the regular matter is homogeneous and isotropic, whereas for a cosmological constant this is true in all coordinate systems. Thus an almost de Sitter space has less symmetry than pure de Sitter. One is free to transform coordinates as much as one likes, but there will no longer be any choices in which the metric is static!

Of course, we find it most convenient to discuss cosmology in the (Friedmann, Robertson-Walker) coordinates that exploit the natural homogeneity and isotropy of the relevant matter sources. This picks out a slicing of the spacetime, and in this slicing, when the universe is almost de Sitter, the universe does expand almost exponentially rapidly - inflation! This also decides among the flat, positively and negatively curved options for the spatial part of the metric.

So it matters that inflation is "quasi-de Sitter". It is this that gives sense to statements about inflation beginning, ending, and even operating in the way we usually describe. de Sitter space is beautiful symmetric and rich, but out real universe is somewhat messier, even at its earliest times.


Musings From a Coffee Shop

Derrick Rossi was born in 1966 in Toronto. He is the youngest child of Maltese immigrants who did not have a college education but worked hard to raise…

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Derrick Rossi was born in 1966 in Toronto. He is the youngest child of Maltese immigrants who did not have a college education but worked hard to raise their five children. Rossi’s father worked in an auto body shop for fifty years and his mother was part owner in a Maltese bakery. Their son went on to develop an interest in molecular biology and made early discoveries in the field of messenger RNA. He founded ModeRNA Therapeutics in 2010 to commercialize his research.

Rossi never envisioned that his work would lead to vaccine development and he is no longer involved in the company. However, there’s no doubt that his early discoveries played a key role in making Moderna’s COVID-19 vaccine possible. Clinical trials indicate that the Moderna vaccine is 94.1% effective at preventing COVID-19 illness in people who received two doses and had no evidence of being previously infected. The FDA issued an emergency use authorization for the Moderna vaccine on December 18, 2020. The Pfizer-BioNTech vaccine, also utilizing mRNA technology, received an emergency use authorization on December 11, 2020.

Vaccine development was always a process measured in years, not months or weeks, and the most optimistic estimates early in the pandemic was that a vaccine may require a year to eighteen months to develop. But in a matter of weeks, Moderna had developed a vaccine and it rapidly entered clinical trials. The timeline is simply remarkable.

The federal government anticipates that all adults in the United States will be able to make appointments for vaccination by April 19, 2021, just two weeks from now. Both the Moderna and Pfizer vaccines require two doses and not everyone will be able to get immediate appointments. However, it is likely that everyone who wants a vaccine should have an opportunity to be fully vaccinated by the end of June.

One week after receiving the second Moderna vaccine shot, I am able to sit inside a coffee shop and write this article. That might not seem like a big deal, but it has been over a year since I last did something this mundane. And the mundane now seems like a milestone.

Slowly, but surely, the economy is reawakening from a long slumber. Over the weekend, outdoor dining was packed and more restaurants are opening up inside seating as well. Bolstered by stimulus payments, pent-up demand, and beautiful spring weather, people want to get back to their lives, and that’s a great thing to see.

Exactly a year ago, I observed that the world has no pause button, and it’s a useful personal exercise to reflect on how I thought the pandemic would evolve compared to what actually happened:

The speed and shape of the recovery is on everyone’s minds at this point, and much will depend on Keynes’s animal spirits. Will the boarded up businesses scattered through countless American cities open up again when governments give the all-clear to do so? Will the customers of these businesses be willing to again go out and spend money in person after weeks or months of self-isolation?

Much will depend on whether the coronavirus pandemic is viewed as a one-time event or as a potentially recurring feature of our lives going forward. If the pandemic is viewed as a horrible, but temporary, interlude in an era of prosperity, then the government’s efforts to induce a “medical coma” of the hardest hit sectors of the economy could well succeed. Sound businesses will emerge with muscle atrophy. Those that were weak even before the crisis may never reopen at all. But the overall system will rebound and regroup.

In early April 2020, few people believed that the lockdowns and related restrictions would last a year rather than weeks or months. I recall watching small businesses close, following the talk on Facebook and elsewhere, and the sentiment seemed to be that things would be back to normal by the summer, at the latest. The first stimulus bill had passed and the hope was that this temporary palliative would be able to staunch the bleeding for the time required to “stop the spread”. But the situation did not abate and the country endured month after month of constrained economic activity. The federal government responded with two additional stimulus bills funded by issuing trillions of dollars of new debt.

At the start of the pandemic, financial markets clearly did not anticipate that the federal government would step in as vigorously. Yet here we are in early April 2021 with stock markets at record highs. Who would have believed that in March 2020 when I was writing about how to cope with the massive market meltdown that was underway?

I was wrong about many aspects of the pandemic, but I was correct to not panic when stocks crashed. I don’t know how other investors handled that crash mentally, but I anchored on the actual businesses that are represented by the ticker symbols I own. For example, I took the time to examine Berkshire Hathaway as a business and tried to understand how the shutdowns would affect the company’s subsidiaries. I did the same for other companies that I own.

Make no mistake about it, I understood that, with few exceptions, all owners of American businesses were poorer due to the pandemic. It would be delusional to think that my portfolio had not declined in intrinsic value terms. The question was whether the market was appraising the situation accurately or acting with emotion. As usual, stock market participants reacted more emotionally than an owner of a privately held business that has no market quote. In panics, quotes are an emotional burden for those who do not understand the intrinsic value of what they own.

Conviction has to be built up during ordinary times if you want to fortify yourself mentally for the tough times. A market crash is not the time to begin to study the intrinsic value of your holdings. I made one major portfolio change during the pandemic, not because the price of the stock in question had declined but because my conviction in the business declined. Of course, I had studied the company in depth prior to owning it. But in retrospect, I did not have enough conviction to own that business at all. This lack of conviction did not manifest until tested by a crisis.

So where do we go from here? If we assume that all adults in the United States who want a vaccine can be fully vaccinated by the summer, will things go back to normal at that time?

I suspect that we will have several more months of restrictions before we are truly back to normal, but the reality is that no one can really predict the trajectory of the rest of the year. I’m not going to post any polls on vaccine acceptance because they seem to be changing all the time, but it is quite clear that a significant percentage of Americans view the vaccines with suspicion and may not be willing to get the shots. In May 2020, I wrote about the politicization of masks and the discourse regarding vaccines seems to be developing in the same way. Talk of “vaccine passports” and coercive measures to obtain compliance are likely to backfire.

Society has an interest in maximizing the percentage of the population accepting the vaccines because we want to reach “herd immunity” — the point at which the COVID virus will not find enough susceptible people to remain a threat to the population at large. Convincing as many people as possible to accept vaccinations will reduce the time required to reach herd immunity. However, in a free society, government should not compel people to accept vaccination through coercive methods.

A key question remains whether unvaccinated people represent a direct threat to vaccinated people. The CDC’s latest recommendations indicate that vaccinated people should continue taking precautions but can gather in small groups with other vaccinated people as well as with unvaccinated people who are not at risk of severe illness from COVID:

You can gather indoors with fully vaccinated people without wearing a mask or staying 6 feet apart. You can gather indoors with unvaccinated people of any age from one other household (for example, visiting with relatives who all live together) without masks or staying 6 feet apart, unless any of those people or anyone they live with has an increased risk for severe illness from COVID-19.

When you’ve been fully vaccinated – retrieved on April 6, 2021

Will unvaccinated people pose any risk to vaccinated people? If not, should vaccine passports be required? Should masks be required after everyone who wants to be vaccinated has been able to get the vaccine?

These are the key questions that should guide policy in the months ahead. If the vaccine is available to everyone who wants it, we should be in a position to return to normal. It is reasonable for people to expect society to take precautions to protect them if there is no vaccine available, but not reasonable to expect continued restrictions if a vaccine is an option.

As I look back over the past year, I am amazed by the advances in science that led to vaccine development in record time. But I am dismayed by the politicization of the pandemic and the great divide between Americans. When political party affiliation is so tightly correlated with issues such as masks and vaccines, something has gone terribly wrong in our national discourse.

Politicians need to focus on getting society back to normal as soon as possible and resist the temptation to not let a crisis “go to waste”. The pandemic has cast a spotlight on many longstanding problems in America, but longstanding problems deserve reasoned debate and deliberation outside the context of an emergency.

It’s hard to be optimistic about politics, but right now it is hard to be a total pessimist on a nice spring day as I sit inside a coffee shop for the first time in thirteen months.


Official AskScience inflation announcement discussion thread

Today it was announced that the BICEP2 cosmic microwave background telescope at the south pole has detected the first evidence of gravitational waves caused by [cosmic inflation.](https://en.wikipedia.org/wiki/Inflation_(cosmology))

This is one of the biggest discoveries in physics and cosmology in decades, providing direct information on the state of the universe when it was only 10 -34 seconds old, energy scales near the Planck energy, as well confirmation of the existence of gravitational waves.

As this is such a big event we will be collecting all your questions here, and r/AskScience's resident cosmologists will be checking in throughout the day.

What are your questions for us?

Handheld video (until we get an official video) of technical presentation for scientists (mostly an overview of their data collection and analysis procedures and results. Not recommended for non-astronomers): part 1 and part 2.

Okay I'll do it.. someone please ELI5

Quick run down for those not in the field: The BICEP telescope measures the polarization of the Cosmic Microwave Background (CMB).

The CMB is light that was released

380,000 years after the Big Bang. The Universe was a hot dense plasma right after the Big Bang. As it expanded and cooled, particles begin to form and be stable. Stable protons and electrons appear, but because the Universe was so hot and so densely packed, they couldn't bind together to form stable neutral hydrogen, before a high-energy photon came zipping along and smashed them apart. As the Universe continued to expand and cool, it eventually reached a temperature cool enough to allow the protons and the electrons to bind. This binding causes the photons in the Universe that were colliding with the formerly charged particles to stream freely throughout the Universe. The light was T

= 3000 Kelvin then. Today, due to the expansion of the Universe, we measure it's energy to be 2.7 K.

Classical Big Bang cosmology has a few open problems, one of which is the Horizon problem. The Horizon problem states that given the calculated age of the Universe, we don't expect to see the level of uniformity of the CMB that we measure. Everywhere you look, in the microwave regime, through out the entire sky, the light has all the same average temperature/energy, 2.725 K. The light all having the same energy suggests that it it was all at once in causal contact. We calculate the age of the Universe to be about 13.8 Billion years. If we wind back classical expansion of the Universe we see today, we get a Universe that is causally connected only on

degree sized circles on the sky, not EVERYWHERE on the sky. This suggests either we've measured the age of the Universe incorrectly, or that the expansion wasn't always linear and relatively slow like we see today.

One of the other problem is the Flatness Problem. The Flatness problem says that today, we measure the Universe to be geometrically very close to flatness, like 1/100th close to flat. Early on, when the Universe was much, much smaller, it must've been even CLOSER to flatness, like 1/10000000000th. We don't like numbers in nature that have to be fine-tuned to a 0.00000000001 accuracy. This screams "Missing physics" to us.

Another open problem in Big Bang cosmology is the magnetic monopole/exotica problem. Theories of Super Symmetry suggest that exotic particles like magnetic monopoles would be produced in the Early Universe at a rate of like 1 per Hubble Volume. But a Hubble Volume back in the early universe was REALLY SMALL, so today we would measure LOTS of them, but we see none.

One neat and tidy way to solve ALL THREE of these problems is to introduce a period of rapid, exponential expansion, early on in the Universe. We call this "Inflation". Inflation would have to blow the Universe up from a very tiny size about e 60 times, to make the entire CMB sky that we measure causally connected. It would also turn any curvature that existed in the early Universe and super rapidly expand the radius of curvature, making everything look geometrically flat. It would ALSO wash out any primordial density of exotic particles, because all of a sudden space is now e 60 times bigger than it is now.

This sudden, powerful expansion of space would produce a stochastic gravitational wave background in the Universe. These gravitational waves would distort the patterns we see in the CMB. These CMB distortions are what BICEP and a whole class of current and future experiments are trying to measure.