US astronomer, who discovered Hubble's law and established the reality of the expanding universe on experimental evidence.
The son of a lawyer, Hubble studied law at the University of Chicago and Oxford University. An excellent athlete, he fought against the French boxer Georges Carpentier and was offered a match with the world champion, Jack Johnson. Hubble began to practise law in 1914 but the attraction of astronomy became too strong and he returned to the University of Chicago, where he gained his PhD in 1917. After a year's military service in France, Hubble joined the Mount Wilson Observatory in California, where he spent the rest of his life.
Using measurements of galactic red shifts obtained by his colleagues at Mount Wilson, Hubble found that there was a linear relationship between the velocity of the receding galaxies and their distance from the earth. Hubble thus demonstrated the reality of the expanding universe. He went on to use this linear relationship, since known as Hubble's law, to measure the universe. He assigned to the knowable universe a radius of about 18 billion light-years and an age of about 2 billion years. Both figures have been revised by a factor of about 10 since Hubble's death but the principles he laid down remain unchanged.
Subjects: Astronomy and Astrophysics.