A paper in Nature is getting some press, for having calculated "the pressure distribution inside the proton".(adsbygoogle = window.adsbygoogle || []).push({});

But the theory behind the calculation seems a little odd. Apparently the data pertains to the scattering of an electron from a quark via the exchange of two photons. But each photon has spin 1, so that adds up to spin 2 like a graviton... and then there's talk about gravitational form factors, as if there are sufficient formal similarities with the two-photon electromagnetic form factors (?) that gravitational calculations can be transposed to the electromagnetic context.

I'm not at all saying this is impossible, but I am a little skeptical. Does anyone have an informed opinion on the validity of this work, and its methods?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# A Pressure in the proton, from gravitational form factors?

Have something to add?

**Physics Forums | Science Articles, Homework Help, Discussion**