All matter in the universe is not made up solely of energy. Matter and energy are distinct concepts, although they are related through the famous equation E=mc², which describes the equivalence of energy (E) and mass (m) in the context of relativity theory.
Matter refers to the physical substance that occupies space and has mass. It consists of elementary particles such as protons, neutrons, and electrons, which are further composed of even smaller particles like quarks and leptons. Matter is characterized by its mass and the interactions of its constituent particles through fundamental forces like gravity, electromagnetism, and the strong and weak nuclear forces.
Energy, on the other hand, is a fundamental property of the universe that can exist in various forms, including kinetic energy, potential energy, thermal energy, electromagnetic radiation (such as light), and many other forms. Energy is associated with the ability to do work or cause changes in the physical system.
In accordance with the principle of conservation of energy, energy can be transformed from one form to another, but it is not created or destroyed. In physical processes, matter and energy can be interconverted, as indicated by Einstein's equation E=mc². This equation shows that mass can be converted into energy and vice versa under certain conditions.
So while matter can be converted into energy and energy can be converted into matter, they are distinct concepts, and not all matter in the universe is exclusively made up of energy. Matter and energy coexist and interact in various forms throughout the universe.