Question

Edwin Hubble was the first to suggest that the universe is expanding. We can verify his theory by observing the supernovaaccelerationblueshiftredshift of distant stars and galaxies.

Answer 1

If the universe is expanding, this means that all the distances are getting bigger too- those differences are expanding too.

This change in the difference between the galaxies can be measured by the redshift of distant stars and galaxies. -this is the correct answer. The Redshift was already discovered by Hubble.

Answer 2

Before Edwin Hubble's theory, many scientists were confused about whether or not the universe was expanding because back then, there was a paradox of a finite and infinite universe. In 1929, Hubble measured the redshifts and distances of galaxies. When he plotted them against each other, he discovered a pattern that redshifts linearly increased with distance. This meant the universe is expanding.