Surprisingly, matter is composed almost entirely of empty space. To understand why this is so, one first has to know a little bit about atoms.
All matter is made up of very tiny units called atoms.
They are much too small to be seen, even with a microscope. That means that there are many more atoms in your little finger than there are people on the entire planet. It was once thought that atoms were solid bits of matter. But, in 1910, Sir Rutherford and two of his students, Mardsen and Geiger, discovered that most of the matter in an atom is condensed at its center, in the nucleus. In fact, more than 99.9 percent of all matter is packed into the nucleus.