If you had 3 sentences to describe special relativity to someone that doesn't know anything about it and 3 sentences to describe general relativity, how would you describe it? I'm reading Fabric of the Cosmos and trying to get a grip on these theories, just a basic grip, I probably won't delve into it very deep but here is what I can come up with for special relativity: The faster you move through space the slower your time goes. And for general: All the matter in the universe makes gravity which curves through space time, which is why the planets orbit the sun in a curve. Also, even if we are sitting still, we are always accelerating, which is why we feel the force of gravity. The force of gravity is the same thing you feel when you're in a car and the driver steps on the gas.