Einstein's famous mass-energy equivalence is also a Pythagorean relationpic.twitter.com/JtXG4VipBD
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Einstein's mass-energy relation is presented in pop-culture as E=mc² This is unfortunate: E=mc² is only true for a particle at rest (𝑝=0) For a particle in motion, its energy is given by the relation belowpic.twitter.com/qMfhYozGvh
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There's also the unfortunate fact that some older books make use of the 'relativistic mass', which depends on velocity, in order to make the formula E=mc^2 hold in all situations.
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if you must know .. special relativity is all about "invariants" .. in Minkowski spacetime the invariants are constructed by contractions with the metric tensor ημν in any two frames pμ*p^μ must be equal (since it's invariant).. this in turn means the green equality must holdpic.twitter.com/kXVUzMSRsL
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Part of the popularity of Einstein's equation is the simplified version (E = mc²) because the public can remember it without falling into narcolepsy. Most people don't understand the variables behind it anyway.
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Twice in my life people (nonscientists) have asked me (nonscientist), "If E=mc^2 and a photon has energy, then why doesn't it also have mass?" Me: "That's not the full equation Einstein found. It's a special case for at rest. A photon is never at rest, so you can't use that."
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I've been lied to??
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Hard to market E^2 = m^2 c^4 + p^2 c^2. Same reason PV = NkT fell short of PV = nRT. Doesn't roll off the tongue.
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Ever since I learned of E=mc2 as a kid I wondered about this. Thanks for finally clearing it up for me! :)
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pop culture is not pc
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