Things are made of small bits. Some of the bits are made of even smaller bits. There are many different kinds of bits. Even light is made of very small bits flying very fast. If we look carefully at the smallest kinds of bits they look like little points. But we don’t really know if this is true, because the bits are very small and it is hard to look at things that are so small.
It turns out that we know how to make most things out of point-bits, but one thing is hard. We know everything falls down — or actually everything always falls towards everything else. The force that does this is hard to make out of little point-bits — if we try to do this we get too many little point-bits flying around. There is one way to fix it: we realize that the little bits are actually not points but long things! The long things are wrapped tight and it is hard to see them because they are so small and a very small wrapped long thing looks just like a point.
But then the long things make fun things happen. The force that makes things fall comes out! Wow! And all kinds of other things too! In fact all the different kinds of bits that we see come from just one kind of wrapped long thing moving in different ways. This is great! One idea explains many different things and so we are happy. There are some little problems still but we are working hard and it is possible that everything around us — in space, near by, all of it — can be understood from one simple idea of wrapped long things.”
— Nabil Iqbal. I study string theory.