Astrophysics - cosmology Flashcards
1
Q
main idea behind the Big Bang theory
A
- the universe was created around 14 billion years ago in a hot dense state
- it has expanded since then, cooling as it did so, to form the universe
2
Q
what evidence supports the Big Bang theory?
A
- red shift
- cosmic microwave background radiation (CMBR)
3
Q
What is redshift?
A
- when the wavelength of a source of light gets longer (stretched)
- the light from distant galaxies is redshifted, which indicates that they are moving away from us
4
Q
What is cosmic microwave background radiation (CMBR)?
A
- it is background radiation at 2.7 kelvin (-270 degrees celsius)
- it is radiation coming from all directions
5
Q
What does Hubble’s law state?
A
- the velocity of the galaxy is equal to Hubble’s constant times the distance away from us
- all galaxies are moving away from us, the light is redshifted by various amounts as the galaxies are moving compared to our position
6
Q
What does redshift show about the universe?
A
- everything is moving away from us in all directions
7
Q
What does CMBR show about the universe?
A
- at the very beginning it was very hot and over time it has cooled
- as it gets cooler, the wavelength of the background radiation has increased
8
Q
How does CMBR support the Big Bang theory over the steady state theory?
A
- it confirms that a long time ago, the universe was very hot and full of short wavelength radiation produced by the Big Bang.
9
Q
equation relating change in wavelength, wavelength, velocity of a galaxy and the speed of light
A
- change in wavelength/ reference wavelength = velocity of a galaxy/speed of light
10
Q
what happens to red shift as the distance from the earth increases?
A
- the red shift increases
11
Q
what happens to red shift as the distance from the earth decreases?
A
- the red shift decreases
