One Universe at a Time

The weak force is what causes radioactive decay. It’s also what has made life on Earth possible.

The strong force is a complex interaction that holds nuclei of atoms together. It is also the force that lets stars create the elements we see around us.

Electromagnetism can produce a force between charges or magnets, but it is much more than a simple force.

We often speak of gravity as a force. More accurately it is a feature of spacetime. Even more accurately, we don’t know what it is.

There are four fundamental forces in the universe, and each of them plays a crucial role in astrophysics.