Researchers calculate that sound has negative mass and negative gravity

Next Big Future  August 17, 2018
It is usually said that sound waves do not transport mass. They carry momentum and energy, and lead to temporary oscillations of the local mass density of any region they happen to pass through, but it is an accepted fact that the net mass transported by a sound wave vanishes. Using an effective point-particle theory, researchers at Columbia University have shown that phonons in zero-temperature superfluids have an effective coupling to gravity, which depends solely on their energy (or momentum) and on the superfluid’s equation of state. This effect is completely equivalent to standard refraction in the form of Snell’s law. As a result, in the geometric acoustics limit sound waves do not propagate along straight lines. Because of this, one might be tempted to dismiss any interpretation of this phenomenon in terms of “gravitational mass”… read more. Open Access TECHNICAL ARTICLE