Explaining the Fundamental Forces

Illustration showing the four fundamental forces of the universe: (From Top Left) Gravity, Electromagnetism, and the Strong and Weak Forces. MARK GARLICK/SCIENCE PHOTO LIBRARY/GETTY IMAGES PLUS; ADAPTED BY L. STEENBLIK HWANG

Forces are all around us. The force of gravity holds Earth in orbit around the sun. The force of magnetism makes bar magnets attract iron filings.