4.8.2 - Red Shift Flashcards
What is the Big Bang theory?
The Big Bang theory suggests that the universe began from a very small region that was extremely hot and dense.
What do observations of supernovae tell us about distant galaxies?
Since 1998 onwards, observations of supernovae suggest that distant galaxies are receding ever faster.
Explain the red-shift of light from galaxies that are receding.
Red shift is a result of the space between the Earth and the galaxies expanding.
This expansion stretches out the light waves as they travel towards us, shifting them towards the red end of the spectrum.
The more red-shifted the light from a galaxy is, the faster the galaxy is moving away from Earth.
Explain that the change of each galaxy’s speed with distance is evidence of an expanding universe.
Distant galaxies are moving away from Earth ; this can be determined by the presence of red-shift.
This means that similarly, the greater the distance a galaxy is from Earth, the greater the speed it is moving away from earth.
This means, since the Earth is not central in the universe, all distant galaxies are moving away from each other ; the whole universe is expanding.
Explain how red-shift provides evidence for the Big Bang model.
The presence of red-shift implies galaxies are travelling away from Earth.
This implies that at one point in time, the galaxy and the Earth were in the same location.
As the Earth has no special place in the universe, this means that the entire universe must have originated from a small region.
Explain how scientists are able to use observations to arrive at theories such as the Big Bang theory.
The presence of cosmic microwave background radiation (CMBR) cannot be explained by the steady-state theory, meaning it disproves this theory.
The presence of cosmic microwave background radiation (CMBR) can be explained by the big bang theory, meaning it provides evidence to support this theory.
