Albert Einstein

Albert Einstein added a cosmological constant to his equations in 1917 to keep the universe static, and at first dismissed Alexander Friedmann's and Georges Lemaître's expanding solutions. After Edwin Hubble's measurements of receding galaxies, and a visit to Mount Wilson, he publicly dropped the constant in 1931. He also withdrew a mistaken 1936 claim that gravitational waves could not exist once a colleague showed him the error.