THE DOPPLER EFFECT

1 mark · Easy

State one argument, based on the past evolution of the universe, that supports the Big Bang theory.

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Galaxies appear to be moving away from each other, so if we go back in time, they all must have come from the same point.

Also accept: The universe is expanding, suggesting it began from a single point.

Common mistakes: Giving an argument unrelated to the universe's past evolution.

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Marking points

B1 · 1 mark · States that expansion suggests galaxies started from a single point in the past.

Worked solution

If the universe is expanding, then in the past all matter must have been concentrated in a very small space, supporting the idea of the Big Bang.