How do we know gravity is not just a large scaled electromagnetic force?

[jaydnul]

I mean, you can only start to see the effects of gravity when a large amount of matter is in one place. What if all the electric or magnetic fields in every single atom of that planet or star or black hole, ect... combine into one large field, big enough to create what we know as gravity?

 

[Nessdude14]

Gravity is independent of electric charge or magnetic polarity. This means that you can have a mass with 0 electric charge, but still have a large gravitational force. If you have the same mass of 100% charged particles, the gravitational force will be the same as the mass with 0 charged particles.

 

[mfb]

- If Earth would have a significant total charge, the "gravitational attraction" would depend on the charge of objects. It does not. In particular, ions with opposite charge should feel an opposite force - which is wrong.

- Contact two metallic objects. They are now uncharged or have the same type of charge (-> repulsive force). They will attract due to gravity.

- Earth and moon attract each other. If this would come from an electric charge, they would have opposite charge. In the same way, sun and Earth would need opposite charge, therefore moon and sun would have the same charge and a repulsive force between them. This is wrong, their force is attractive, too. You can do the same as lab experiment with 3 objects.And if you propose some new force just depending on the total amount of charges (which was actually discussed at some point in the past, but did not work):
- Objects with a different (total charge)/(total mass) ratio would fall with a different acceleration. They do not.
- General relativity would not work in this way. You would not get the same deflection / red shift of light and so on.

 

[Cobalt214]

According to Heim Theory, gravity can be counteracted by electromagnetic means. That does not, however, mean that gravity is an electromagnetic force.

Electrical circuits are found in relatively strange places, such as the one between Saturn's Northern Pole and Enceladus. That is also found in conjunction with a magnetic field.

So, in answer to your question, as far as we know, gravity is not an electromagnetic force.