Let's say you take two conducting plates, each one meter square or so, and put them in deep, deep space. Far enough away that nothing external should influence them, and they're sitting in the near-vacuum of interstellar space. Just to make things easier, we'll say this part of space lacks even the one hydrogen atom per cubic centimeter density of space, and is actually a perfect vacuum. Now, you make one place negatively charged, and the other positive. What do they do? Well, they attract due to electromagnetic forces. Obviously. So let's take away the charge. What do they do? Well, they attract due to electromagnetic forces. Wait, what?