Week 11 The new Universe

Question 1

what is Cosmic Microwave Background Radiation a result of

Answer 1

it is the result of the afterglow of the big bang

Question 2

what is the CMBR temperature equation

Answer 2

T(t) = T0(1+z)

Question 3

how do we obtain the baryon density of the universe

Answer 3

matter density

Question 4

how do we obtain the photon density of the universe and its equation

Answer 4

we use the blackbody law and the CMBR temperature

η = number density of baryon / number density of photons = ρcrΩ / baryon mass x 1 / photon number density

Question 5

describe the universe 1 second after the big bang

Answer 5

the universe is made up of free protons, neutrons and photons

Question 6

what happens to free neutrons over time

Answer 6

they are unstable and decay

Question 7

what 4 things make up the universe 2 mins after the big bang

Answer 7

proton
deuterium
photon
neutron

Question 8

what are the 4 steps of the deuterium fusion cycle

Answer 8

deuterium –> helium 3 –> tritium –> helium 4

Question 9

why does no more helium fusion occur after 3 mins

Answer 9

the density of the universe is too low

Question 10

how much of the universe density parameter is made up by baryon matter and dark matter

Answer 10

0.2

Question 11

what is responsible for 0.8 of the universe density parameter

Answer 11

dark energy

Question 12

what is the general idea of the De Sitter universe

Answer 12

the universe expands/contracts exponentially

Question 13

what percentage of the universe is baryon matter, dark matter and dark energy respectively

Answer 13

baryon matter = 5%
dark matter = 27%
Dark energy = 68%