# Physics: "Para-gravity" analog to Magnetism?

I’m basing this question on some serious (?) speculation in an early ***Omni ***article. The author may have been wrong, but did not seem to me to be some sort of crank. My interest has been renewed by recent research of gravity waves.

As the Physics experts here know, moving or changing electrical charges sets up electromagnetic waves through space. Because of the relationship between electrostatic forces and magnetism the “disturbance” in the former causes a perpendicular wave of magnetic disturbance. The symmetry is such that this produces a secondary electric disturbance, and so on. Hence the travelling wave function is referred to as an example of electromagnetism. (The unity of the three long-observed phenomena is a pretty modern concept.)

My Physics and Astronomy prof (way back long before the earth’s crust completely cooled) was already interested in grav waves, and preferred the example two charges pushed toward and then away from each other. (He wondered aloud about the possibility of two huge masses being pushed away and toward each other.) The textbook we used stressed two electrodes of opposite charges repeatedly switched. On the atomic level, electrons dropping from an excited state down to the lowest available one are responsible for visible light and other, non-visible examples.

The Omni article offered some way-out speculation on artificial grav, or “anti-gravity”.

It suggested a parallel, so that one could supposedly wrap a coil into a loop and send very dense masses very quickly through it, creating a separate grav field that could be manipulated at will. The article seemed very serious because it outlined two or three tremendous hurdles for this method. First, we are talking about white dwarf densities being controlled. Second, they would have to be shifted at speeds crowding c. (The article outlined two other very speculative or impractical methods.)

My question is about the intermediate possible phenomenon suggested. Do gravitational waves involve a sort of para-gravitational analog at right angles? I cannot recall if the article called them this or something else.

I know enough of Physics that the g force is in many ways different form the e-m force. For one thing, grav is not polar, but always attractive. Also I recall that the hypothetical quantum, the graviton, is supposed to have a spin of 2, instead of 1. I have no idea why it has been worked out this way, but it is a difference I am aware of.

Okay, fight my ignorance, but please be gentle.

Physicists only separate out the electromagnetic field into electric and magnetic parts from habit and historical accident. It’s much easier to work with both of them combined into a single relativistic object called the Faraday tensor. And since gravitational waves are studied almost exclusively by relativists, we just stick with tensors right from the start, without worrying about which parts are “magnetic”. But yeah, you can separate them out the same way you separate the electromagnetic field, if for some reason you really want to.

As for practical applications, don’t hold your breath. Unless you’ve got things moving at a sizable fraction of the speed of light, magnetic effects are always going to be much weaker than non-magnetic effects (and even with high speeds, the magnetic part is always at least somewhat smaller). The only reason we ever notice magnetic effects for electricity is that we have arrangements of positive and negative charges that exactly cancel out all of the non-magnetic effects, and that’s not possible with gravity, since we don’t have negative mass. Worse, even non-magnetic gravitational effects are already incredibly weak, such that you need planet-sized masses to even notice them, so the magnetic effects, being even weaker, will be that much harder to notice.

Just to add to what Chronos has said, the most common name for the effect(s) is gravitomagnetism. If you take general relativity and selectively ignore the non-linear aspects, then you can formulate it in a way that is strikingly similar to electromagnetism. Of course though your selective ignorance of the non-linear aspects means that the linearized theory only provides a good approximation to GR in some circumstances. Gravitational waves are a classic example of the application of linearized GR.

Was that Omni article by Robert Forward? I remember he wrote articles like that for Omni back in the 1970s. Forward was a physicist who did gravity wave research at Hughes Research Lab and also wrote science fiction novels. I believe he was quite careful to get the science right in his science fiction.

It’s too bad Bob Forward did not live long enough to see the LIGO results.

From the Wikipedia link above: “In 2001, Forward received a diagnosis of terminal cancer which gave him enough time remaining to make his farewells and settle any unfinished projects. He died on September 21, 2002.”

Yes, at least I seem to recall that he wrote it.

Forward also wrote a spoof piece for Omni, titled “Static Gravity”. It was a revolutionary concept. This is something that you acquire when you move horizontally. It explains why a fast-walking man is faster than a slow-walking man, who in turn is faster than a man who is standing still. :dubious: