DIMENSIONS OF SPACE

We have the four dimensions that we are familiar with: length, width, height, and time.

These are the dimensions that we use to measure things in our everyday life, and they are also the dimensions that Einstein used to describe his theory of relativity.

Relativity tells us how light and gravity behave in our universe, and it needs four dimensions to work.

But some physicists think that there are more dimensions than just four. Why?

They are trying to find a way to unify relativity with quantum mechanics, which is the theory that describes the behavior of tiny particles like atoms and electrons.

Quantum mechanics and relativity don't agree with each other, so some physicists hope that by adding more dimensions, they can find a common ground.

One of the most popular theories that does this is called string theory.

String theory says that everything in the universe is made of tiny vibrating strings, and these strings can vibrate in different ways depending on the number of dimensions they have.

String theory also says that there are 10 dimensions of space, plus one dimension of time, making 11 dimensions in total.

Why can we only see three?

Two possible answers to that:

• The extra dimensions are very small, so small that we can't see them or measure them. They are curled up into tiny loops called Calabi-Yau shapes, and they only affect things at the smallest scales.
• We live on a 3-dimensional slice of a higher-dimensional space, like a piece of paper in a book. This slice is called a brane, and all the particles and forces that we know about are stuck on this brane, except for gravity.

Gravity can leak into the other dimensions, which is why it is so weak compared to the other forces.

So, space might have 10 dimensions, or maybe even more, depending on what theory you believe.