When I say that the universe is 13.77 billion years old, it sounds rather authoritative.

And it's not just because of the values after the decimal point. That just makes it sound precise.

And we're very proud of achieving that level of precision.

Thank you very much.

No, it's the extreme amount of confidence that I can just sit here, look you in the eyes,

and say in no uncertain terms that we estimate the age of the universe to be 13.77 billion years old.

But how? How do we know? Like, really know how old the universe is?

And what does it even mean for the whole universe to have an age? So let's dig in. In today's

episode, I'm going to tell you how we calculate the age of the universe and how we got so dang

confident. And then I'm going

to present three potential challenges to our method of calculating the universe's age.

And I'm going to knock down those challenges one by one with the sheer force of my confidence.

And science, mostly science.

Okay, first objection.

Can the universe really have a clock?

Didn't special relativity, which is kind of important and kind of well tested for over a century,

say that there's no such thing as a universal clock?

When we go way back in time to the pre-Einstein era,

our conceptions of the structure of the universe were rooted in Newton.

How do objects know when and where to interact with each other?

For Newton, what allowed this was a universal clock and a master ruler,

some set of standards against which everything else could be measured.

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