The universe is made of matter, normal matter is the matter we understand. Normal matter makes up only around 5% of the universe. The rest – about 70% is dark energy, and 25% dark matter. We have no idea how dark energy or matter work, we only know it’s there. To understand them we may have to throw Einstein’s theory of relativity out the window, as his theory on gravity holding the universe together doesn’t seem to apply to 95% of our universe.