I was asked to explain my understanding of superstring theory (such as it is) on the weekend, particularly the aspect where there is a fundamental limit to the size of objects, that is, why there can be a string, but nothing below a string.
If I'm understanding correctly, what happens is that to get down to a certain size, you need a smaller and smaller amount of energy embodied in a particle. That is, the less energy in the particle, the smaller it can be. However, strings are wave-forms such that if you go below a certain size you must increase the amount of energy in order to constrain them to that amount of space, but by putting that energy in, you wind up increasing the size of the string.
I know that's not right, but she just asked for what I thought it was about, so there. Guess I should read more about it one of these days.