I’ll answer this without looking it up, and then I’ll check myself 😉
There are four fundamental forces that we know in the universe: Gravity, electromagnetism, the weak force and the strong force. These are all described by two great theories of physics: Quantum physics and Relativity.
Quantum physics describes electromagnetism, the strong force and the weak force. Relativity describes gravity.
Really we think that quantum physics should also describe gravity, but we don’t have the final theory yet – quantum loop theory is an attempt to make quantum mechanics work with relativity.
(checks internet) Yay I’m right! Well… right enough!