Re: “Accelerate a charge and you’ll get electromagnetic radiation: light. But accelerate any mass and you’ll get gravitational radiation.”
I don’t understand the basic concept here.
Since “charge” is present in all protons and electrons, and since protons and electrons have “mass,” it seems like “acceleration” in some types of “mass” is exactly the same thing as “acceleration” in “charge.”
The confusion arises because we observed the electromagnetic charge first, and when most people hear the word "charge" they think of electric charge, which is only positive or negative. The color charge of the strong nuclear force actually corresponds to three distinct charges, which in some combinations are attractive, in others, repulsive.
Any accelerating charge produces radiation corresponding to the charge. In the case that you're talking about, an accelerating electron will produce both electromagnetic radiation [from its accelerating electromagnetic charge] and gravitational radiation [from its accelerating mass.]
There is another symmetry: in every Lorentz frame [frame of reference in uniform motion -- not accelerating -- with respect to another Lorentz frame] there should also be an analogue of the magnetic component of the electromagnetic field. Consequently, there is also a "gravitational magnetic field." It is extremely weak. Too weak to measure.