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 ...

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of "Ask a Spaceman" and "Space Radio," and author of "How to Die in Space." Sutter contributed this article to ...