M5.5 Cosmology

Question 1

Why do near galaxies not follow hubble’s law trend lines

Answer 1

because they experience a stronger force of attraction due to gravity

Question 2

Why do distant galaxies not follow hubble’s law trand lines

Answer 2

because expansion of the universe may not have been constant

Question 3

what is the cosmological principle

Answer 3

On large scales ther universe is uniform
homoogeneous - constant density
isotropic- symmetrical

Question 4

what is the life cycle of a star around the size of the sun

Answer 4

Nebulae
protostar
main sequence star
red giant
white dwarf
black dwarf

Question 5

life cycle of a star around 10 times the size of the sun

Answer 5

nebulae
protostar
main sequence star
red supergiant
Super Nova
Neutron star

Question 6

Life cycle fo a star 25 times the mass of the sun

Answer 6

Nebulae
protostar
main sequence star
red supergiant
Super Nova
Black hole

Question 7

how does a neutron star happen

Answer 7

Main sequence star around 10 times the mass of the sun
the supernova’s core remains intact
when all the fuel is used up the core cools down and the mass of it causese the electrons to fuse with the protons making Neutons

Question 8

properties of a neutrons star

Answer 8

very dense
rotating very quickly
faster the smaller it is
only made of neutrons
emits specific EM waves

Question 9

How does a black hole occur

Answer 9

when the white dwarf after the super nova is greater than 2.5 solar masses
thought to almost be a neutron star with infinite density
gravitational field strong enought to trap light

Question 10

what is a quasar

Answer 10

thought to be galaxies in formation with black holes at the centre

Question 11

what is a nebula

Answer 11

greater force of gravity hence cloud
increase in temperature

Question 12

what is a protostar

Answer 12

not hot enough for fusion
continues to attract mass

Question 13

what is a main sequence star

Answer 13

more density and temperature
Hydrogen fusion can take place
stable pressure and gravity equal

Question 14

what is a red giant and a red super giant

Answer 14

core mostly helium
collapse because not hot enough to fuse helium
outer core is hot enough to fuse hydrogen causing and expanse
cools and contracts until there is just helium left
helium is fused
if red super giant begins to expand and contract again in super nova

Question 15

what is a white dwarf

Answer 15

internal pressue exerted by the attms stops the star collapsing any more
no fusion takes place cools down

Question 16

what is the difference between a white and black ddwarf

Answer 16

black dwarves emit no energy. unlike white dwarfs which are still emitting energy

Question 17

hwo do dwarf stars not collapse any further

Answer 17

electron degeneracy
two electrons cannot exist in the same place

Question 18

what is a supernova

Answer 18

a supernova is when the core collapses after the redsuper giant
but it gets hot enough to

Question 19

what order did the forces split off

Answer 19

Gravity
strong
Weak, Electromagnetic

Question 20

describe what was before planck time

Answer 20

universe ws infinitely small dense and hot

Question 21

Between planck time and 10^-4 seconds

Answer 21

unified force

Question 22

describe the universe 10^-4 seconds after the big bang

Answer 22

10^12 Kelvin
Quarks join to form particles
matter and antimatter annihilate each other

Question 23

describe the universe 10^2 seconds after the big bang

Answer 23

10^9 Kelvin
similar to the interior of a star

Question 24

describe the universe 300,000 seconds after the big bang

Answer 24

3*10^3 Kelvin
electrons combine to helium and hydrogen nuclei
universe becomes transparent

Question 25

What is hubble’s law

Answer 25

recessional speed is proportional to it’s distance from us

Question 26

How is recesional velocity of a galaxy determined

Answer 26

doppler shifted spectral lines of the light emitted from those galaxies