red-shift

Question 1

what is red-shift

Answer 1

an observed increase in the wavelength of light from distant galaxies

Question 2

what 2 things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?

Answer 2

• the further away a galaxy is, the faster it is moving

- the further away a galaxy is, the greater the observed increase in wavelength

Question 3

what does red-shift provide evidence for?

Answer 3

• provides evidence that the universe is expanding

- supports the big bang theory

Question 4

what does the big bang theory suggest?

Answer 4

the entire universe started from a very small, hot and dense region in space

Question 5

compare the observed red-shift of 2 galaxies, one further away than the other

Answer 5

• the galaxy that is further away is travelling faster

- the observed red-shift is greater the further away it is

Question 6

what did scientists observe to provide evidence that the universe is expanding at an ever faster rate?

Answer 6

they observed supervoae, which suggested that galaxies are moving away at an ever faster rate

Question 7

prior to observations of supernovae, what was believed about the rate of expansion of the universe and why?

Answer 7

• the rate of expansion was expected to occur at an ever slower rate
• it was thought that gravitational forces would cause this slowing down

Question 8

what 2 ideas could explain the universes ever increasing rate of expansion?

Answer 8

• the existence of energy and mass that we cant detect, known as dark matter and dark energy
• these ideas are still being developed by scientists are not yet fully understood