Scientific American | 2019 Mar 11
Some sounds might possess a tiny but measurable amount of negative gravitational mass
In a paper published in Physical Review Letters, a group of scientists has theorized that sound waves possess mass, meaning sounds would be directly affected by gravity. They suggest phonons, particlelike collective excitations responsible for transporting sound waves across a medium, might exhibit a tiny amount of mass in a gravitational field. “You would expect classical physics results like this one to have been known for a long time by now,” says Angelo Esposito from Columbia University, the lead author on the paper. “It’s something we stumbled upon almost by chance.”
Esposito and his colleagues built on a previous paper published last year, in which Alberto Nicolis of Columbia and Riccardo Penco from Carnegie Mellon University first suggested phonons could have mass in a superfluid. The latest study, however, shows this effect should hold true for other materials, too, including regular liquids and solids, and even air itself. ...
Gravitational Mass Carried by Sound Waves ~ Angelo Esposito, Rafael Krichevsky, Alberto Nicolis
- Physical Review Letters 122(08):4501 (01 Mar 2019) DOI: 10.1103/PhysRevLett.122.084501
- arXiv.org > hep-th > arXiv:1807.08771 > 23 Jul 2018 (v1), 02 Mar 2019 (v2)