They are nothing more than additional space dimensions, like the 3 dimensions we are all familiar with. Think of a really long straw. From far away, it looks like any beings on that straw can only go back and forth along the straw in one dimension. But close up it’s possible to see that there is a second dimension *around* the straw. Superstring theory basically says the universe is actually like that, with 3 large dimensions we can freely move around in, and 7 additional curled up dimensions (+ time, obviously) that are just as real as the regular 3, just really really tiny.
Latest Answers