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A comment on Einstein's description of gravity just got much harder to beat. Parent comment

Re:Einstein's description of gravity just got much harder to... by pja on Saturday October 03, 2020 @05:20AM (#24670730)
Energy gravitates. Photons have energy, therefore photons gravitate. Photons only have zero /rest mass/, not zero total mass.
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Re:Einstein's description of gravity just got much harder to... by brabel on Saturday October 03, 2020 @10:11AM (#24672195)
Photos by definition don't have a rest mass because they are never at rest. They must always travel at the speed of light, which means they don't experience time, so rest does not even make sense for a photon.
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Re:Einstein's description of gravity just got much harder to... by jlokier on Saturday October 03, 2020 @11:46AM (#24672770)
That makes sense in English, however "rest mess" is also a technical and mathematical term, and in that terminology it has the value zero for photons.
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