Stress–energy tensor

Okay kiddo, imagine you're playing with a bunch of toy cars on a bumpy road. When you push the cars around, sometimes they smash into each other or get stuck in a pothole. Now imagine that instead of toy cars, we're talking about really tiny particles, like atoms or even smaller things called subatomic particles.

When these particles move around in space, they can bump into each other or get trapped by things like gravity. The stress-energy tensor is a way of describing how much force or energy these particles are exerting on their surroundings as they move.

Think of it like a map that tells us where all the bumps and potholes are on the road. By looking at the stress-energy tensor, scientists can understand how gravity is warping space, how particles are moving through it, and how much energy they're carrying with them.

It's kind of like a secret code that helps us crack the mysteries of the universe. Pretty cool, huh?