Brief review of cosmology Universe is expanding Δλ/λ ∝ d Hubble's law (1929): v = H d Edwin Powell Hubble (1889 -1953) the first observaonal evidence of Big Bang theory Big Bang • 1927 Georges Lemaître (1894 – 1966) • Einstein general relavity • homogeneous and isotropic universe Alexander Friedman • (cosmological principle) (1888 – 1925) • Friedmann's equaons - descripEon of the universe from the Big Bang onwards • Fred Hoyle – 1949 Sir Fred Hoyle (1915 - 2001) universe is isotropic and homogeneous in space and Eme • 1964 – Arno Penzias and Robert Wilson – discovery of Cosmic Microwave Background radiaon – CMB – with T=2.725 K • distribuEon and evoluEon of galaxies Big Bang nucleosynthesis • Alpher-Bethe-Gamow • predicts quanEty of 4He, 3He, 2H in 7Li with respect to 1H • dependance on η=nB/nγ ← CMB ⇒ mass % • 75% H • 25% 4He, (~) • ~ 10−4 2H, (OK) • ~ 10−4 3He • ~ 10−10 7Li, 7Be (2x) 1. beginning to inflaon – Planck epoch: 0-10-43 s, T~ 1034 K - gravitaon decouples GUT 10-38 s – strong interacEon decouples→ huge amount of energy released → Inflaon: grows in size by a factor of 1035 2. electroweak epoch: 10-38 to 10-10 s phase transiEon, soup of elementary parEcles: photons, gluons, quarks weak and EM interacEon decouple 3. par?cle epoch: 10-10 to 1 s quarks and anEquarks annihilate symmetry breaking → residual quarks→ maer Hadron epoch: from 10-6 to 10-5 s, T~ 1015 K: quarks → hadrons unstable decay, p and n remain Lepton epoch: most leptons and anEleptons → annihilaon → residual leptons 4. from 1 to 100 s - n ↔ p + e +!νe + -(m_n-m_p)/kT n + e ↔ p +!νe nn/np =e - n + νe!↔ p + e at T~ 10 GK stops: nn/np =0.223 neutrons: β decay with τ=617 s 5. 3 - 20 min when T decreases to ~ 1 GK deuterons are produced: 2 p+n ↔ 1H+γ rao p:n at the end: np:nn=7:1 → nHe:nH=1:12 or. mHe:m=0.25 2 n + p → 1H + γ. 2 3 2 3 1H + n → H + γ in 1H + p → He + γ. Finally, 4He is produced: 2 2 4 3 4 1H + 1H → He + γ, He + n → He + γ and 3H + p → 4He + γ. atomic nuclei: most n bound in He, very lifle in Lithium, Beryllium, Deuterium nuclei • no elements > Be • because no stable nuclei with A=5 or 8 (see triple alpha process) • Universe conEnues expanding • comparisson with observaons: • WMAP • 10.000 years: end of radiaon era, beginning of maer dominated era • 380.000 years: T~3000 K – atoms form, maer and radiaon dcouple – universe becomes transparent→ CMB • >400 Myr: formaon of stars, galaxies, planets... .