Hubble’s Law

In 1925, American astronomer Edwin Hubble showed that the galaxies’ speed has a positive relationship with their distances from Earth. This relationship is called Hubble’s Law, and it served as the first observation showing that the Universe is expanding.

When we say that the Universe is expanding, the galaxies move away from us, and even if you are in a different galaxy, you will observe that the other galaxies are moving away from you. It is the space where they are moving that moves, and his also implies that the Universe has no center. The expansion of the Universe is the result of the Big Bang, when the Universe expanded from a high density and temperature state to a less extreme environment.

Einstein’s View on Expansion of the Universe

At first, famous physicist Albert Einstein did not believe that the Universe is expanding. He instead insisted about the static model of the Universe; never changing with time. After Hubble showed him his observations of Hubble’s Law, he changed his mind. For this week, Prof. Goto will discuss more on this, while focusing on Einstein’s biggest blunder about the model that he proposed earlier: the cosmological constant.