The particles that are in an atom: protons, neutrons and electrons The particles that are in protons and neutrons: quarks The four fundamental forces: gravity, electromagnetism, the strong force and ...

The ancient Greeks speculated that it might be air, fire or water. A century ago, physicists felt sure it was the atom. Today, we believe that the deepest layer of reality is populated by a diverse ...

Scientists imagine virtual particles popping in and out of existence to explain how forces transfer between particles. koto_feja/iStock via Getty Images A clever mathematical tool known as virtual ...

Physicist Richard Feynman invented them to describe the interactions between real particles. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. This ...