Astro2 Asal Usul Alam Semesta

8/10/2019 Astro2 Asal Usul Alam Semesta

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Astronomi dan astrofsika

2. Penciptaan alam semesta


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Teori menyatakan bahwa alam semesta berasal dari ledakan spontanmateri kecil dengan densiti dan temperatur tinggi

The Big Bang Theory


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Pada 1927,

ilmuan

Belgian,

Georges

Lematre

orang pertamayang

menyatakan

bahwa alam

semestaberasal dari

ledakan atom

purba.

Evidence for the Big Bang


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Photons berubah men"adi

pasangan parti!le(antiparti!le

and )i!e()ersa

E = mc2

*lam semesta awal penuh

dengan partikel dan radiasi

karena temperaturnya yang

tinggi


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The Big Band Theory

endeskripsikan bagaimana perluasan danpendinginan partikel dapat menghasilkan

bintang dan galaksiTeori ini men#elaskan dengan sangat akuratbeberapa aspek alam semesta saat ini


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The Big Band Theory

Teori ini dapat membuat prediksi$prediksi yang dapat diamati melaluiobser!asi% contohnya

1. Radiasi latar belakang gelombang mikro.

2. Reaksi fusi hidrogen menjadi helium


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Bukti odel Big Bang

+ Teori big bang memprediksi bahwa radiasi darialam semesta ketika awala penciptaan masihada hingga saat ini. Ternyata alam semestasaat ini memang diisi oleh cosmic microwavebackground. &arakteristiknya cocok denganBig Bang model.

+ The Big Bang model #uga memprediksi bahwahidrogen mengalami 'usi men#adi heliumselama the era o' nucleosynthesis. Pengamatan#umlah helium di alam semesta mendekatiprediksi nilai dari the Big Bang model.


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Bukti Big Bang

The Cosmic Background Radiation (icrowa!es"

Penias ) *ilson (+,-2" menemukan sinyal isotropikgelombang mikro latar belakang ketika mencobaantena gelombang mikro di Bell abs +,-/. Thenoise ditemukan dari semua arah.

Pada saat yang bersamaan% fsiakawan dari Pricetonmenghitung radiasi dari alam semesta mula. ereka

merekomendasikan radiasi tersebut dapat dideteksimenggunakan antena gelombang mikro

The result was a Nobel Prize in physics for 1978.


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*AP


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Radiasi termal

Perluasan alam semesta menun"ukan radiasi termal pergeseran merah

dari waktu itu men"adi 1%%% kali gelombang lebih pan"ang microwaves)


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Arno Penias and Robert*ilson

+ enemukangelomban

g mikrolatarbelakang

cosmic


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Cosmic Background Explorer

satellitepertama yang dibuat untuk cosmology.Tu#uannya untuk mengin!estigasi cosmicmicrowa!e background radiation(CB" dari alamsemesta dan memberikan pengukuran$pengukuran yangakan membentuk pemahaman kita akan alam semesta
http://en.wikipedia.org/wiki/Satellitehttp://en.wikipedia.org/wiki/Physical_cosmologyhttp://en.wikipedia.org/wiki/Cosmic_microwave_background_radiationhttp://en.wikipedia.org/wiki/Cosmic_microwave_background_radiationhttp://en.wikipedia.org/wiki/Cosmic_microwave_background_radiationhttp://en.wikipedia.org/wiki/Cosmic_microwave_background_radiationhttp://en.wikipedia.org/wiki/Physical_cosmologyhttp://en.wikipedia.org/wiki/Satellite


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Peta CB anisotropy dari data C7B8 spacecra't.



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Edwin Hubble'ound e9perimental e!idenceto help #usti'y ema:tre;s theory.


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s 8!idence

+ ?oppler shi'ting $ wa!elength emitted by something mo!ingaway 'rom us is shi'ted to a lower 're@uency

+ ound o' a fre truck siren $ pitch o' the siren is higher asthe fre truck mo!es towards you% and lower as it mo!esaway 'rom you

+ 5isible wa!elengths emitted by ob#ects mo!ing away 'romus are shi'ted towards the red part o' the !isible spectrum

+ The 'aster they mo!e away 'rom us% the more they areredshi'ted. Thus% redshi't is a reasonable way to measurethe speed o' an ob#ect (this% by the way% is the principal by

which radar guns measure the speed o' a car or baseball"+ *hen we obser!e the redshi't o' gala9ies outside our localgroup% e!ery gala9y appears to be mo!ing away 'rom us $uni!erse is e9panding.


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Big Bang Theory - Evidence for the Theory*hat are the ma#or e!idences which support the Big Bangtheory


Firsto' all% we are reasonably certain that the

uni!erse had a beginning. econd% gala9ies appear to be mo!ing away

'rom us at speeds proportional to theirdistance. This is called


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Third!i' the uni!erse was initially !ery% !eryhot as the Big Bang suggests% we should beable to fnd some remnant o' this heat. Dn +,-/%

Radioastronomers Arno Penias and Robert*ilson disco!ered a 2.62/ degree &el!in ($=/=.6-/ degree Eahrenheit% $263.=2/ degreeCelsius" Cosmic icrowa!e Backgroundradiation (CB" which per!ades the obser!ableuni!erse. This is thought to be the remnantwhich scientists were looking 'or. Penias and*ilson shared in the +,6 4obel Prie 'orPhysics 'or their disco!ery.


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Finally!the abundance o' the light elements


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Synthesis of Helium

The current CB temperature tells us preciselyhow hot the uni!erse was when it appeared.

Dt tells us how much helium was initially

produced.

A helium nucleus contains 2 protons and 2neutrons.

At T F +3++&% nuclear reactions con!ertedprotons into neutrons and back% keeping theirnumbers nearly [email protected] +3+3and +3++&% neutron G proton

reactions 'a!or protons% because neutrons are


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Big Bang theorypredi!tion' 7- /,

2- /e by mass0

at!hes obser)ations

o nearly primordial

gases

Synthesis of Helium


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*bundan!es o otherlight elements agree

with Big Bang model

ha)ing 3.3 normal

matter 4 more

evidence for WIMPS!

Synthesis of Helium


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Dstilah Penting


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Dstilah Penting


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Astro2 Asal Usul Alam Semesta