The Infinitely Complex Universe

Atoms were once thought to be the indivisible building blocks of matter. An atom was as small as you could get. But now we know that atoms are made up of groups of sub-atomic particles with mostly empty space in between. As it turns out, sub-atomic particles are not solid either. They are believed to be packets of energy. In other words, what we think of as solid matter is actually empty space! What's more, some sub-atomic particles might be like loops of string vibrating in multi-dimensional space. What next? "...And so proceed ad infinitum".