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How long do photons last for.?

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  • 5 years ago

    If they are intercepted, they may be absorbed by an atom (whose energy "state" will then change). If they are not intercepted, they will last for millions or billions of years: starlight reaches our naked eyes from the Andromeda Galaxy, 2.5 million light-years away, and if our eyes were more sensitive we would see photons that are even older.

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