Multiple Messengers

When you dig into a curry dish, it’s a feast for all the senses. You see the colorful sauce, smell the spices, then taste the great flavors. In other words, your brain is getting multiple messages — from the eyes, nose, and tongue.

Today, astronomers are getting multiple messages from the universe — messages they see, “touch,” and “hear.” The combination tells them much more than any single message on its own.

They “see” electromagnetic energy. The form we know best is visible light — the wavelengths visible to our eyes. But stars and galaxies also produce other forms of light. They range from radio waves to X-rays and gamma rays.

Astronomers “touch” the universe by catching neutrinos. These ghostly particles are produced in the hearts of stars. They’re also produced in huge amounts in exploding stars called supernovas. In fact, in 1987, the first “message” from a supernova in a nearby galaxy was a small burst of neutrinos.

And they “hear” the universe through gravitational waves. These ripples in space and time are caused by the motions of massive objects. They were first detected in 2015, from the merger of two black holes. Astronomers have heard many more gravitational-wave events since then; more about that tomorrow.

“Multi-messenger” astronomy is especially helpful when astronomers get two or more types of messages from the same event — helping solve some of the mysteries of the universe.

Script by Damond Benningfield