According to modern physics, we can't push matter to the speed of light. It would slow down (relative to its environment). But theoretically, if matter were to travel the speed of light, would it become energy?
It seems to me that $E = mc^2$ could be rearranged to prove that it would.
If so, what kind of energy would it become, and do we know what that transition would look like?
Would the transition be instant, or is there some kind of transitional state between matter and energy?