# Do these PR Letter authors suggest sound transports mass, or only that it can be a source of gravitation?

Question: Do the authors of this PR Letter suggest sound transports mass, or only that it can be a source of gravitation?

The Phys.org article More evidence of sound waves carrying mass says:

Using effective field theory, they showed that a single-watt sound wave that moved for one second in water would carry with it a mass of approximately 0.1 milligrams. They further note that the mass was found to be a fraction of the total mass of a system that moved with the wave, as it was displaced from one site to another.

Importantly, the researchers did not actually measure mass being carried by a sound wave—they used math to prove it happens.

I'm having trouble understanding that. "carry with it a mass" and "displaced from one site to another" sound to me like the Phys.org article is suggesting that the sound is transporting mass from point A to point B. But that's not what I get from reading the actual paper:

Phys.org links to the open access Phys Rev Letter Esposito, Krichevsky, and Nicolis 2019 Gravitational Mass Carried by Sound Waves:

Conclusions.— We showed that contrary to common belief, sound waves carry gravitational mass in a standard Newtonian sense: they are affected by gravity, but they also source gravity...

Another possibility might be to consider seismic phenomena. The wave generated by an earthquake of Richter magnitude m=9 carries an energy E ∼ 10$${}^{18}$$ Joules which, for c$${}_s$$ ∼ 5 km/s, corresponds to M ∼ 10$${}^{11}$$ kg, and a change in gravitational acceleration δg ∼ 10$${}^{-4}$$ nm/s$${}^2$$. Atomic clocks and quantum gravimeters can currently detect tiny changes in the gravitational acceleration, up to fractions of nm/s$${}^2$$ [26–28]. Given the rapid improvement of these techniques, one can imagine that in the not-too-distant future they will reach the sensitivity needed to detect the gravitational fields of seismic waves