The Four Fundamental Forces.
There are four fundamental forces that play into describing how the universe works. These forces are the strong force, weak force, electromagnetic force and the gravity force. All of these work together to show how they demonstrate energy in the universe. The strong force has the strongest attraction out of all of them, hence the name. Its job is to bind together protons and neutrons to make a nuclei. The weak force, instead of holding things together, it helps in things falling apart or decaying. Unlike the strong force and the weak force, the electromagnetic force has an infinite spectrum. This force can attract or repel and is all the electronic and magnetic forces combined together. Most the forces we see throughout the day is cause by electromagnetic forces. The gravitational force is always trying to pull two forces together. Object are always pulling on each other, although its not quite as noticeable with smaller masses and over a long distance, but it's always there.
Unlike general relativity, quantum mechanics describes the universe down to the microscopic level. instead of things following a straight path or a simple curve in the space time, it shows how energy and light works in waves. This theory is a lot more chaotic and complex in it's own ways. Just by the fact that something can have the same chance at being in one place, as it can in the other place. It can be based off probability rather than just ceasing to exist in one spot for certain.