https://physicsworld.com/a/calculations-provide-insight-into-why-sound-waves-carry-negative-mass/
Calculations provide insight into why sound waves carry ‘negative mass’ Its the phonons that carry negative mass. The polariton is a derivative of the phonon and therefore share this common characteristic. Negative mass is a property that carries with it lots of weird behaviors. This state of weirdness is amplified as these phonons congeal into a condensate which advances this state of weirdness into the macro realm were the weirdness can be fully recognized and appreciated.
