How Does Gravity Work?

Gravity is one of the four fundamental forces in physics (the others are the strong force, the weak force and the electromagnetic force). It has no effect at subatomic levels, but it determines the motion of planets, stars and galaxies.

It also keeps us from floating away, controls the ocean's tides and guides plant growth. It even keeps Earth and other planets in orbit.

Almost three and a half centuries ago, Isaac Newton revealed that gravity is a universal force that tells massive objects to move. He based his law of universal gravitation on the idea that the force is directly proportional to mass and inversely proportional to the square of the distance between two particles.

Today, gravity is still one of the biggest mysteries in physics. And scientists are still working to answer it.

Why does gravity make things fall?

We all know that an apple falls from a tree and a bicycle labours up a hill, but how does this work?

There's a reason for that: gravity bends and curves the fabric of spacetime.

In fact, spacetime is made up of three dimensions - length, width and height - and a fourth dimension called time. It's a very complicated and fascinating science that's been studied by many great minds over the years, but we still don't understand how it works completely.

In 1915, Albert Einstein proposed a new way of explaining gravity in his theory of general relativity. This was a more accurate description for a lot of things, but it still doesn't explain why some galaxies spin faster than they should.