The Doppler effect was discovered by Christian Doppler in 1842. This effect occurs when the source of wave emission moves closer or farther away from the observer. The waves are compressed when the source moves closer and stretched when the source moves farther away. This phenomenon does not occur, however, when the receiver moves closer or farther away from a stationary source since the waves coming to the receiver are the same in both cases.

Light acts in a similar manner. If the source of light is moving closer to the observer, the light waves are compressed or ‘blue-shifted’; while if the source of light is moving farther away from the observer, the light waves are stretched or ‘red-shifted’. This is the theory. Redshifting has little to do however with ‘age’, or even distance and recession. It is an emanation from the light spectrum at a frequency level. It does not confirm ‘time’ as explained below.

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