If you look farther and farther away, you also look farther and farther into the past. The farthest we can see back in time is 13.8 billion years: our estimate for the age of the Universe. But is it correct? Image credit: NASA / STScI / A. Feild.

Ask Ethan: How Sure Are We That The Universe Is 13.8 Billion Years Old?

Very sure. Here’s how we know.

Ethan Siegel
Oct 28, 2017 · 6 min read

You’ve no doubt heard that the Universe itself has been around for 13.8 billion years since the Big Bang, and that scientists are extremely confident of that figure. In fact, the uncertainty on that figure is under 100 million years: less than 1% of the estimated age. But science has been…