Why is the Hubble’s law considered a piece of evidence that supports the Big Bang?

Explanation:

Hubble's Law basically states that the greater the distance of a galaxy from ours, the faster it recedes. It was proof that the Universe is expanding. It was also the first observational support for a new theory on the origin of the Universe proposed by Georges Lemaitre: the Big Bang.

Hubble's law is considered the first observational basis for the expansion of the universe, and today it serves as one of the pieces of evidence most often cited in support of the Big Bang model. The motion of astronomical objects due solely to this expansion is known as the Hubble flow

Explanation:

Hubble's law says that the universe is expanding outward. Actually Hubble's law was discovered before the Big Bang theory was formulated. The Big Bang Theory is an attempt to explain the observations that led to Hubble's Law. Before the 1900s the theory was that the universe was eternal and self existent.

The real significance of Hubble's Law is that the Universe is expanding in all directions not just from Earth. This means all matter in the Universe started at one point in space at the time of 'the Big Bang'.

Cosmic microwave background radiation as evidence for the Big Bang and expansion of the Universe. American astronomer Edwin Hubble (the space telescope was named after him) measured the speed of galaxies and their distance from Earth and obtained the following graph.

Almost all astronomers agree on the theory of the Big Bang, that the entire Universe is spreading apart, with distant galaxies speeding away from us in all directions. Run the clock backwards to 13.8 billion years ago, and everything in the Cosmos started out as a single point in space. In an instant,...