red-shift

Question 1

what is red-shift?

Answer 1

• when there is an observed increase in the wavelength of light from most distant galaxies - the further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength

Question 2

what does red-shift provide evidence for?

Answer 2

that space is expanding and supports the big bang theory

Question 3

what does the big bang theory suggest?

Answer 3

the universe began from a very small region that was extremely hot and dense

Question 4

why does red-shift occur?

Answer 4

• if a galaxy is moving away from us, the light waves it emits are stretched
• this means that the light from the galaxy shifts towards the red end of the visible spectrum (or even into the infrared, beyond visible light)

Question 5

how is the change of each galaxy’s speed with distance
evidence of an expanding universe?

Answer 5

• the faster a galaxy is moving, the further it is moving so the more light is red-shifted

Question 6

how does red-shift provide evidence for the big bang theory?

Answer 6

• the red-shift of light from galaxies shows that the universe is still expanding
• if the galaxies are all moving away from each other, this shows that at some point the universe was much smaller and denser

Question 7

how are scientists able to use observations to arrive at
theories such as the Big Bang theory?

Answer 7

• collect data
• peer review
• testing

Question 8

what is dark matter?

Answer 8

an unknown substance which holds galaxies together, but doesn’t emit any EM radiation

Question 9

what do scientists currently think the universe is made up of?

Answer 9

dark mass and dark energy