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Britannica editor Erik Gregersen, a white man wearing glasses, holds a microphone in front of a galaxy background. Displayed above him are the phrases: Ask an Editor, and How old is the universe?

How Do We Know the Age of the Universe?

And how do you even start to answer this question?
Encyclopædia Britannica, Inc.
Media Editor: Lauren Sims
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News •

How did the universe take shape? A new simulation offer clues • Nov. 11, 2026, 8:30 AM ET (CNN)
A distant exoplanet mysteriously vanished from sight. Astronomers just discovered why • Nov. 10, 2026, 4:00 PM ET (Space)
Theory predicting an older universe without dark matter or dark energy passes key cosmological tests • Nov. 7, 2026, 9:00 AM ET (Phys.org)
Colliding Stars in Early Universe May Explain Stellar Monsters, Study Suggests • Nov. 3, 2026, 6:12 PM ET (Sci.News)
What ended the 'Cosmic Dark Age'? Astronomers say they're closer than ever to an answer. • Oct. 31, 2026, 11:00 AM ET (Live Science)

Transcript

Erik: The universe is 13.8 billion years old. We know that from observations of the cosmic microwave background, which is the oldest light you can see in the universe. And from that, we can get a very good determination of how fast the universe is expanding. Knowing that number, you can run the movie backward and get an age. My mechanic, you know, like has this thing, you should aim for 200,000 miles on a car. That’s about 13-14 billion inches. If you drove your car ‘til it broke down, every inch you drove would be like a year in the age of the universe. And 200,000 miles is also, you know, a good chunk of the way to the Moon.

Off camera: What kind of car would you drive to the Moon?

Erik: I would drive, I think the largest SUV possible so I could have the most room in it. I don’t know, I’m going to say maybe the Cadillac Escalade. Oh no, no, no, the Hummer. That probably would be the smartest car to drive to the Moon, I think.
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