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Q & A: red shifts

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Most recent answer: 10/22/2007
Q:
radio waves were picked up in 1965 which were thought to have been produced by the big bang. the theory was that these waves started out as higher frequency waves (gamma) and over the billions of years became radio waves. Does this happen to all lightwaves ? If a star is too far away does light in the ’visible light’ range deteriorate too, preventing us from ever ’seeing’ it?
- Paul Martin (age 24)
Ireland
A:
First, a small correction. Most of the Cosmic Microwave Background did not start off as gamma rays but at much lower frequencies- in and around the range of visible light.
Yes, the same 'red shift' from high to low frequencies happens to starlight. Some distant galaxies are known with redshifts of around a factor of two. This stretching of the light wavelength can be pictured as driven by the stretching of our expanding space.
Of course, we have infrared instruments that can pick up light red-shifted out of the visible range.

Mike W.

(published on 10/22/2007)

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