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The speed of light
(lemmy.nz)
A place for majestic STEMLORD peacocking, as well as memes about the realities of working in a lab.

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I think you are stating that backwards.
You can definitely say that everything with mass has energy. And yeah the two are kind of interchangeable.
But that does not mean that a photon HAS mass. It just means that we can calculate how much mass its energy is equivalent to.