expanding Universe

views updated May 21 2018

expanding Universe Theory of the origin and direction in time of the Universe. Physicists have attempted to explain the red shift phenomenon of some stars as resulting from a single, huge explosion which causes these stars to move away from our section of the Universe. The red shift occurs when, due to the Doppler effect, the perceived wavelengths of light from some stars are lengthened because of their outwards movement. There is also the opposite effect, a blue shift, but this does not occur as often. In 1929 Edwin Hubble demonstrated obsverationally the expansion of the Universe, although Georges Lemaître had suggested the theory in 1927. The idea of the expanding Universe set the stage for the Big Bang theory of the origin of the Universe. In 1998 scientists discovered evidence that the Universe is expanding at an accelerating rate. See also Hubble's law