AST201H1 Lecture Notes - Lecture 20: Nucleosynthesis, 2Mass, Planck (Spacecraft)

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Bryan Gaensler

Document Summary

Imagine dots on an inflating balloon are galaxies: as balloon expands the dots move apart, galaxies does(cid:374)(cid:859)t expa(cid:374)d (cid:271)ut the spa(cid:272)e (cid:271)et(cid:449)ee(cid:374) the(cid:373) do. Instead of visible light, we expect microwave light. Picture from textbook describes beginning of universe: times starts from top to bottom. Figure 12(credit: pearson education: era of nucleosynthesis: entire infinite universe = hot and dense enough for fusion! Figure 13(credit: pearson education) helium & of the mass to be in hydrogen this really is the ratio of hydrogen to helium. 380000 years after big bang, universe cooled enough that plasma became gas. Cosmic microwave background light comes from end of the era of nuclei. Plasma should produce an almost perfect black body. Evidence for big bang: cosmic microwave background: fills the whole sky and has right spectrum as predicted. Evidence for big bang: nucleosynthesis: correct ratio of light elements indicates that universe went through temperatures and densities predicted by big bang.