Eli5 How do we know gravity isn’t just magnetic


This is boggling my mind as to why shouldn’t this be a main theory to explain gravity. I also know nothing about physics so what would I know.

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Because all matter, even without an electric charge, exerts a gravitational force on all other matter. Neutrons have no charge, but are still exerting a gravitational effect on other matter

Magnetism acts with very specific behaviors, especially with relation to electric current.

Gravity does not interact with things, including electric current, in the same manner as magetism.

They explain different phenomena. We observed that *all objects with mass* attract one other, with the strength of the attraction being proportional to the masses of the objects, and we named this phenomenon gravity.

We also observed that *some objects* exert a force on other objects that can attract or repel, and that this force is not directly tied to the mass of the objects involved. We also discovered that moving these objects can create an electric current, and that electric currents can exert a force back on these objects. We named this phenomenon electromagnetism.

Electricity and electromagnetism both produce forces over distance, but other than that they have little in common and they’re easy to tell apart. Gravity only attracts, while magnetism can repel. Gravity is always on and has no connection to electricity. Gravity is also much, much weaker overall, and only dominates the universe because most objects are electromagnetically neutral.

The simple answer is that gravity and magnetism affect different things in different ways. There are things affected by gravity but not magnetism, gravity is only (as far as we can tell) a pulling interaction while magnetism is more of a twisting thing.

The more complicated answer is that there is a whole load of research going on at the moment into trying to connect magnetism and gravity together.

Two hundred years ago magnetism and electricity were viewed as completely different things, but eventually it became clear they were different aspects of a combined electromagnetism interaction.

In the 60s and 70s the electroweak interaction was developed (winning the 1979 Nobel Prize in Physics) – a way of combining electromagnetism and the weak interaction, showing that in certain situations (at very high energies) these two interactions turn out to be the same thing.

Since the 70s there has been a push to develop a “Grand Unified Theory” – a way of combining the electroweak interaction with the strong interaction (the other interaction in the “Standard Model” of physics); it seems like these interactions might also combine at even higher energies, but getting anything to those energies is practically impossible for now, making it very difficult to do any research. There are some interesting ideas, though, for GUTs.

And finally, getting a confirmed GUT is seen as a key step in developing a “theory of everything” (or TOE – physicists love silly acronyms), which would combine gravity with whatever the GUT proposed as a unification of the electroweak and strong interactions. For now, though, there are no candidate TOEs that seem to hold up.


So it wouldn’t be that gravity is magnetism, but that maybe gravity and magnetism might be different aspects of the same thing. But no one is close to showing that.

We actually managed to unify electricity, magnetism, and even the weak nuclear force very beautifully within a single theory, so this is not a crazy question. Einstein famously (and fruitlessly) pursued a unified description of electromagnetism and gravity for much of his life.

Ultimately, we have an extremely successful theory that describes magnetism and a separate extremely successful theory that describes gravity. Currently we do not have a description that unites them. We don’t know if such a description exists. If it does, it must only be relevant in highly exotic situations (for example, really high energies) that we have not been able to reproduce in experiments.