This is believed to be true. But when you break down matter what do you get? Atoms, and when you break those down? Protons, neutrons, electrons, and when you break those down? quarks, and some other tiny stuff. But what about when you break those down? You will reach a point where it cant be broken down, where there are a few charged paricles wizzing around. When you break these down do you know what you will find? Energy. Energy is the nothing that makes up everything. Energy is undestroyable so you cant even break it down. It is unfathomable, the powers of energy. (Pardon the pun). You are right, to our knowledge it is not matter, but how many dimensions are there? 3? More? we don't know, so maybe we haven't found all the states of matter yet. So maybe it is. Remember: A closed mind lets in no air.

There is a lot more here. just 150 years ago physics had no good way of explaining atoms. Maybe energy is something we thought it wasn't. Maybe it is another dimension, like x,y,z. But what is the parralel? Most dimensions tend towards symmetry, meaning that x,y,z, and even time move at the same pace. Is energy different? No, if you have the same reaction with the same numbers of atoms the same energy level will be present. Meaning that Energy is measurable, like the popular E=MC^2 equation. Energy is not random, it is symmeterical, so it could very well be a dimension.