Red Shift (8.2) (M)

Question 1

What is observed from the most distant galaxies?

Answer 1

an observed increase in the wavelength of light

Question 2

What is red shift?

Answer 2

An observed increase in the wavelength of light from (distant) galaxies

Question 3

What does red-shift suggest?

Answer 3

The further away the galaxies, the faster they are moving due to the bigger the observed increase in wavelength

Question 4

What does an observed increase in wavelength (i.e. red shift) mean on the electromagnetic spectrum?

Answer 4

Dark lines that appear, representing wavelengths absorbed from elements in Sun, shift to red end of electromagnetic spectrum

Question 5

2 things

What does red-shift provide evidence for?

Answer 5

The observed red-shift provides evidence that space itself (the universe) is expanding and supports the Big Bang theory

Question 6

What does the Big Bang Theory suggest?

Answer 6

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

Question 7

What provides evidence that distant galaxies are receding ever faster? i.e. acceleration away from us

Answer 7

observations of supernovae from 1998 onwards

Question 8

What do observations of supernovae from 1998 onwards suggest?

Answer 8

distant galaxies are receding ever faster

Question 9

The change of each galaxy’s speed with distance is evidence of what?

Answer 9

an (ever) expanding universe

Question 10

What led to the development of the Big Bang Theory?

Answer 10

Red-Shift

Question 11

How does red shift provide evidence for the Big Bang model?

Answer 11

Red shift proves that the further away the galaxies, the faster they are moving because of the bigger red shift/observed increase in wavelength (shift to red end of electromagnetic spectrum)

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

Question 12

What is CMBR?

Answer 12

the remains of the thermal energy from the Big Bang, which is spread thinly across the whole Universe

Question 13

How does CMBR provide evidence for the Big Bang?

Answer 13

The Bg Bang theory suggests that Initial heat from the Big Bang should now be thinly spread across the whole Universe

CMBR is detected at a very low temperature

This was discovered after the Big Bang Theory was developed (so provided very strong evidence)

Question 14

There is still much about the universe that is…

Answer 14

not understood

Question 15

2 needed

What are some components of the universe that are not understood that much?

Answer 15

Dark mass (matter) and dark energy

Question 16

What is dark energy?

Answer 16

An unknown form of energy, put forward as a solution to the problem of why the expansion of the Universe is accelerating

makes up 68% of universe

Question 17

What is dark mass (matter)?

Answer 17

An unidentified form of matter that accounts for galaxies rotating faster than their visible mass should cause

makes up 27% of universe

Question 18

Galaxies seem to rotate too (…) for the mass of their stars

Answer 18

quickly

Question 19

What do galaxies rotating too quickly for their mass suggest? How do they know this?

Answer 19

That there is mass in the Universe that is invisible to the instruments used by scientists.

Scientists only know it is there because it has gravity that affects objects nearby

Question 20

What is blue-shift?

Answer 20

A decrease in the wavelength of light observed from a galaxy

Question 21

What does blue-shift suggest?

Answer 21

The galaxy is moving towards us

Question 22

What are the main ideas of the big bang?

Answer 22

all matter concentrated at single point

single massive explosion sent matter outwards

make sure to mention definition above these points

Question 23

The Big Bang is one way of explain the (…) of the universe

Answer 23

origin

Question 24

Give one strength and one weakness of this method to represent the idea of an expanding universe.

Answer 24

Strength: as balloon expands, the dots get farther away representing galaxies moving apart

Weakness: there is a limit to how far the balloon can expand (or dots on only surface, galaxies throughout universe)

Question 25

What may lead to scientists believing one theory over the other?

Answer 25

new evidence/observations that cannot be explained in theory x

Question 26

5 marks - 6 points you could give

Explain, in as much detail as you can, the main scientific theory supporting the big bang theory fo the universe?

Answer 26

• The light we receive from galaxies has been red-shifted
• The greater the distance of the galaxy away from us, the greater the galaxies
• So galaxies must be moving away from us
• The further away the galaxies are, the faster they are moving
• Therefore, the galaxies must have been much closer together in the past
• And initially they would have been located at a single point

Question 27

2 makes - 3 you could give

What should scientists do when a theory is not supported by new data?

Answer 27

• Check data to ensure it is valid
• Repeat experiment to see if results are reliable
• Develop new theories to explain the results

Question 28

3 needed

What information about a galaxy can be found by measuring the size of its red shift?

Answer 28

• The speed of the galaxy
• What direction the galaxy is moving in (towards or away from us)
• The distance to the galaxy