Redshift

Red shift is a natural phenomenon observed by astronomers observing distant galaxies. The light from sources moving at significant speed away from the observer appear to be lower in frequency. This is easily measured because the emmision and absorbtion patterns for molecules are distinctive. This can provide a means of measuring the speed between the source and the observer.

Edwin Hubble was one of the primary researchers in this area. If the light source is moving towards the observer, a blue shift is seen. Red and blue shifts are a consequence of the Doppler effect on light waves.

One of the most significant consequences of distant galaxies' red shift is that if all of them are increasing their distance from one another, going backwards this leads us to the Big Bang theory.

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For an article about the novel, see Red Shift.