Oldest surviving light reveals the universe's true age

Ancient light from the Big Bang has revealed a precise new estimate for the universe’s age: 13.77 billion years, give or take 40 million years.

The new estimate, based on data from an array of telescopes in the Chilean Atacama Desert, also weighs in on one of the most important disagreements in astrophysics: How fast is the universe expanding? Described in two scientific papers, the new result gives a significant boost to one side of the disagreement, though the physicists couldn’t prove the other side of the dispute wrong.

Here’s the problem: Physicists need to understand the universe’s expansion rate to make any sense of cosmology — the science of our whole universe’s past, present and future. They know that a mysterious substance called dark energy is causing the universe to expand (at an ever-increasing rate) in all directions.. But when astronomers point their telescopes into space to measure the Hubble constant (H0) — the number that describes how fast the universe is expanding at different distances from us or another point — they come up with numbers that disagree with each other, depending on the method they use.

One method, based on measurements of how fast nearby galaxies are moving away from the Milky Way, produces one H0. Another method, based on studying the oldest light in space, or cosmic microwave background (CMB), produces another H0. This disagreement has left scientists wondering whether there’s some important blind spot in their measurements or theories, as Live Science previously reported. These new results seem to show that there weren’t any measurement errors on the CMB side.