Relativity for Children

Anyone can understand Einstein

I have a ball.

The ball has mass.

Mass tells us how much matter is in the ball. Matter is stuff we can see and touch.

I have another ball! It’s bigger than the first. The bigger ball has more mass. The smaller ball has less mass.

I place the balls on a sheet.

This sheet is spacetime. It is where we live.

When the balls are placed on the sheet, they create indents. They are warping spacetime.

The warp of an object with mass is seen from another angle.

These warps in spacetime create gravity.

The ball with more mass, warps more. The ball with less mass, warps less.

The balls are also spinning on their own axis. They are rotating. They drag space as they rotate.

But the smaller ball is also moving around the bigger one. It is revolving.

The small ball is Earth. The big ball is the sun.

The sun is also revolving! The sun and Earth revolve around the center of our home galaxy, the Milky Way.

I have a marble. The marble is a particle of light.

The marble wants to reach a point beyond the balls.

Light always takes the shortest path to its destination. The shortest path is usually a straight line.

Not anymore. The spacetime has been warped by the sun and Earth. Spacetime is no longer flat, but warped.

Now, the shortest path is a curved line. When the shortest path is a curved line, it is called a…