Do phonons for example really have negative mass or does it just seem like they have negative mass? Could one use the negative mass of certain quasi particles to meet the negative energy requirements of warp drives or wormholes?
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2 Answers
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Quasiparticles do not exist physically per se, but are more of a mathematical trick to simplify our models. An excellent example is the "electron hole" quasiparticle, whose physical manifestation is simply the absence of an electron in a Fermi sea. The phonon is also not a physical particle, but is rather a phenomenon which is practical to describe as such.
Such quasiparticles can indeed be considered as having negative mass, but only in the very specific condensed matter context in which they are defined. This has nothing to do with negative mass in the relativistic context you are talking about, and therefore no, it cannot be used to build a warp drive or a wormhole.
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$\begingroup$ Yes. The actual physical basis of phonons is the quantization of lattice vibrations of a solid; no actual physical particles involved. $\endgroup$ Commented Dec 19, 2023 at 17:09
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I can provide a partial answer. Please have a look at Casimir effect. I was shown that under certain circumstances a energy density between two metal plates placed in a vacuum can be negative. This implies a negative mass.
answered Dec 19, 2023 at 7:28
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2$\begingroup$ Why are you talking about photons? They aren't quasiparticles. The OP asks about phonons, not photons. $\endgroup$– PM 2RingCommented Dec 19, 2023 at 7:41
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$\begingroup$ Oh, sorry. I misread. I am deleting respective part. $\endgroup$ Commented Dec 19, 2023 at 14:37