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How far will a photon travel in empty space before it decays?
- John gribben (age 39)
A photon is a small bundle of electromagnetic energy. If it doesn’t interact with anything then it just keeps going in a straight line at the speed of light. In empty space the only thing it could decay into, conserving energy and momentum, would be to several other photons. No experiment has ever observed this phenomenon.
(published on 12/01/2007)
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