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

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.