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I just encountered the wikipedia article on phonons, which says that these quasiparticles represent vibrations through matter. Wikipedia says that Phonons have negative mass and negative gravity.

But then the article says that "In 2019, researchers were able to isolate individual phonons without destroying them for the first time." The citation is:

Enamul Haque and M. Anwar Hossain. (2018). prediction of phonon-mediated superconductivity in XBC (X= Mg, Ca, Sr, Ba) Arviv.org, Retrieved November 27, 2018

So do these things actually exist? Or, rather, do mainstream physicists think that they exist? They clearly exist in PDF files.

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    $\begingroup$ Define "exist". $\endgroup$
    – safesphere
    Commented Feb 4, 2020 at 17:54
  • $\begingroup$ "exists" means... are they really there? Is there a thing? Or is it just a concept? $\endgroup$
    – vy32
    Commented Feb 6, 2020 at 4:37

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Phonons are an established concept. There is usually no reason to consider how they couple to gravity, which means that they are considered as massless.

Never mind what wikipedia says about negative mass. There was a reference to phys.org that recounted this arXiv paper. I read the introductory paragraph:

[P]honons in zero-temperature superfluids have an effective coupling to gravity, which depends solely on their energy and on the superfluid’s equation of state. For ordinary equations of state, this coupling corresponds to a negative effective gravitational mass: in the presence of an external gravitational field, such as that of Earth, a phonon’s trajectory bends upwards.

So it is similar to an air bubble in water: goes up in gravity. That is completely mainstream.

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