What if matter is just another type of wave? Matter could be just another type of energy; a wave doubled over itself (into a loop) held together by strong force could form the elemental particles. This is slightly different from the string theory. Matter, I find, is a surprisingly difficult concept. If atoms are 99.9999...% matter, what is matter? If we could form a ball of pure matter, it would take the matter of the entire universe just to form one as big as a golf ball (...I think.) But, on a microscopic scale, what would pure matter be? Pure, simple existence? So matter = wave. This makes particle-wave duality make a lot more sense, too. Thoughts, anyone? I posted this in a similar forum once, but I didn't get the information I was looking for.
When you say a pure ball of matter is I assume you mean matter that has no space between the atoms. There are no atomic structures like this but the material of a neutron star fits the bill. The matter in a neutron star is ultra dense - it is made from essentally pure mater with no space between the subatomic particles. A 5cc sample of the interior a neutron star has a about the mass of mt everest. In quantum physics it is known that mater has a wavelike nature. Electrons (which are matter) when shot through a diffraction grid will produce an interference pattern that is a result of the wavelike nature of the electrons. Look up the "Schrödinger equation" on google.
