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Menu  Q & A: red shift  Learn more physics!  Browse our 6407
answers by or search term  I know that I’m asking a lot of
questions for one guy but I don’t understand the principles of
Red Shift. It seems very similar to the Doppler Effect so I
can’t understand how physicists say it can work. Light moves
completely differently to sound so how can the same effect occur
in both? - Muhammed (age 17) Sir George Monoux College, London
At least for standard small red shifts, you're right that you
can think of the red shift as a Doppler shift just like for
sound. It doesn't matter that light and sound are different
types of waves. If you're rushing towards the source, you will
encounter the wave fronts more often (at higher frequency) than
if you and the source are at a fixed distance. The same happens
if the source rushes toward you. Of course the opposite happens
if you and the source are moving away from each other.  For big
speeds, of course it does ma