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I didn't think there was such a thing as negative mass. That is, you can hypothetically have gravity that is repulsive, but you cannot have negative mass becaus
by slowmovintarget 3y ago
I didn't think there was such a thing as negative mass. That is, you can hypothetically have gravity that is repulsive, but you cannot have negative mass because mass is a property of matter conveyed by the Higgs field. All matter has some positive value for mass; the measure of the matter's resistance to acceleration.
Photons (a.k.a energy, including radio waves) do not interact with the Higgs field and so have zero mass.
There is no negative Higgs field, and no negative mass.
There's also no ether either as originally constructed (it was ruled out by experiment) but you could be speaking metaphorically.
- scotty79 3y agoSo is it really the energy of coupling between particles and Higgs field (along with other kinds of energy and momentum) that reshapes the spacetime?
- slowmovintarget 3y agoI don't think I know the math well enough to answer the question definitively, but given my surface understanding of the Standard Model and GR... I think so (though I suspect "energy of coupling" is the wrong way to put it).
- andrewflnr 3y agoMost mass of massive objects doesn't come from the higgs mechanism. It's mostly the relativistic mass (?) of binding energy in protons and neutrons. So, I'm not sure the Higgs field needs to be involved at all.
- slowmovintarget 3y agoThank you.
- mnw21cam 3y agoPhotons have zero rest mass. But they're never at rest, they are always travelling at the speed of light. They have mass equivalent to their energy, which is related to their wavelength.
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- slowmovintarget 3y agoI don't think that's the accepted view (that photons have mass). https://profoundphysics.com/why-do-photons-have-no-mass-simple-proof/ https://profoundphysics.com/why-do-photons-have-no-mass-simp... When the velocity is the speed of light, solving the equation of special relativity yields m of zero. We have a successful theory of quantum mechanics which integrates with special relativity, so that definition holds, even if you take the same approach from an Effective Field Theory perspective.
- mnw21cam 3y agoThe article you link starts off by defining mass as rest mass. I think the article shows very clearly that photons have no rest mass, using several different arguments. However, a photon has energy, so therefore it must have not-at-rest mass. The article doesn't really comment on not-at-rest mass. We know photons interact with gravity because of gravitational lensing.
- slowmovintarget 3y agoThe calculation for mass zeros out as c is a divisor. You get zero for one of the coefficients of the mass calculation, which winds up making the whole thing zero. The article doesn't have to comment on not-at-rest mass because the math is clear. As for interacting with gravity, photons move through spacetime, and general relativity shows that gravity is the curvature of spacetime, and photons move on the shortest geodesic for that spacetime.
- andrewflnr 3y agoI'm not enough of a physicist to explain why this framing is wrong, but I took enough physics in college to know it absolutely is wrong. Fun fact from my "Modern Physics" homework: a system of two photons can have mass, if they're traveling in different directions. In parallel though, they're still massless.