How can motion exists in a void?

Question

Hi. I've been wondering: if we took the smallest particle in the world (whatever it may be, quark or whatever), and we placed it in a complete void (in complete emptiness), how could the particle still be in motion?

Isn't motion interaction, and hence with nothing to interact with motion could not occur?

If that is not the case, please tell me how motion can occur without interaction between two entities.

If motion can indeed only happen through interaction, then does this mean that there is no such thing as a void in our universe, otherwise anything that would end up in the void would cease to exist since it would no longer interact with anything and since interaction = motion and motion as a result defines what is in motion, anything that would no longer be in motion could no longer be defined, as a result it would become nothing since something that has no definition (no motion) cannot be interacted with anymore?

Also, if anyone says "gravitational force would still interact with said particle", then you are saying that gravitational forces travel through voids in order to reach a particle and interact with it, so then gravity is not a "force that reaches out" but more like a distortion of space? Because obviously gravity could not reach out through a void, since a void is nothing, gravity would have nothing to interact with to get all the way to the particle.

Please provide any info and answers that may be useful or that can help me formulate a better question.

Thank you!

Answer 1

Short answer: once an object is moving, no interaction is required to keep it moving.  This is Newton's first law -- an object in motion will stay in motion until acted upon by an external force.  If this particle is in motion, in a void, it will continue to move, without any interactions.

However, the second part of Newton's first law might be what you are asking about -- an object at rest will stay at rest until acted upon by an external force.  

In a slightly different form, your question was asked by lots of scientists until fairly recently.  It was tested by the Michelson-Morley experiment, a result of the findings (roughly, that there were no interactions to move light) was the Lorentz contraction, which is critical to Einstein's Special Relativity.