This Is How Astronomers Know The Age Of The Universe (And You Can, Too)
“The reason that we can claim the Universe is 13.8 billion years old to such enormous precision is driven by the full suite of data that we have. A Universe that expands more quickly needs to have less matter and more dark energy, and its Hubble constant multiplied by the age of the Universe will have a larger value. A slower-expanding Universe requires more matter and less dark energy, and its Hubble constant multiplied by the age of the Universe gets a smaller value.
However, in order to be consistent with what we observe, the Universe can be no younger than 13.6 billion years and no older than 14.0 billion years, to more than 95% confidence. There are many properties of the Universe that are indeed in doubt, but its age isn’t one of them. Just make sure you take the Universe’s composition into account, or you’ll wind up with a naive — and incorrect — answer.”
Earlier this year, there was a report that the Universe could have been a billion years younger than we currently think. Many people still think that you can calculate the age of the Universe directly from the Hubble constant. And even though the concept of the age of the Universe is a simple one to understand, the pitfalls are so numerous that even Nobel Laureates can fall into them.