20. Cosmology

Question 1

What is the sequence for the evolution of the universe between the big bang and the formation of stars?

Answer 1

Universe starts to expand —> Quarks and leptons form —> Hadrons form -> Nuclei form —> Atoms form

Question 2

Describe how the universe was formed from the big bang up to nuclei formed

Answer 2

1. At big bang universe is a singularity
2. Very dense very hot
3. Start to expand
4. Quarks and leptons form
5. Quarks combine to form neutrons protons and hadrons
6. Nucleons combine to make nuclei

Question 3

What is red shift?

Answer 3

Star/galaxy moving away
(wavelength increases)

Question 4

What is blue shift?

Answer 4

Star/galaxy moving closer
(wavelength decreases)

Question 5

What is bubbles law?

Answer 5

v =H0d (for receding galaxies)

evidence for expanding universe

Question 6

What is the evidence for th big bang theory?

Answer 6

Cosmic microwave background - 2.7K uniform radiation
Redshift of galaxies - supports expansion
Abundance of light elements - H/He ratios match predictions

Question 7

Critical density

Answer 7

if density > critical density = universe collapses (big crunch)
if density < critical density = universe expands for ever