well
here is the deal
atoms are made of protons neutrons and electrons, protons and neutrons being the subatomic particles located in the nucleus. This is where an atoms mass comes from, as, compared to protons and neutrons ( which are basically the same mass) electrons have an extremely small mass. electrons are also very very far away from the nucleus with respect to their size. Liken it to a golf ball in the middle of a football field. So what is an atom mostly made of? Empty space. THEORETICALLY if you ,,for example,,leaned up against a wall for an infinite amount of time, you would pass right through it. Now we all know that wouldn't happen, but, in theory, it is not impossible. String theory has to do with what the actual subatomic particles are made of. This is where my knowledge stops.