Hi, I'm Ira Flato. Last week, we visited Boulder, Colorado as the guests of KUNC, and we saw a ton of great

stuff, in fact, too much stuff to fit in just one hour of our program. Ironically, the segment we

didn't have enough time for was about time. So here's a special extra for you podcast listeners, a conversation about measuring

time and how to do it better. This is Science Friday. I'm Iroflato coming to you from the

Chautauqua Auditorium in Boulder, Colorado. In Alice in Wonderland, when the White Rabbit appears before he startled Alice saying,

Oh dear, oh dear, I shall be too late,

Lewis Carroll is expressing for all of us, I think, our deep-seated feelings about time.

It's slipping away, You never have enough.

And, oh, just how accurate is my watch? No one is more fixated with time than those who study it.

Researchers are obsessed with measuring it as accurately as possible down to the billionth, the trillions,

or more of a second. And Boulder is a great place

to have a conversation about time, because did you know that one of the most accurate clocks in the

world, the official clock for the United States, is secreted behind locked doors right here in

Boulder? And spoiler alert, it does not look anything like the wind-up pocket watch

carried by the White Rabbit. Dr. Liz Donnelly is the head of the Time and Frequency Division

of the National Institute of Standards and Technology, NIST here in Boulder. She's in charge of both maintaining and distributing the U.S. official time and researching ways to do it better.

Welcome to Science Friday.

Nice to have you here.

We visited, I had a chance to visit NIST yesterday and you showed us some of your clocks,

including something called a cesium fountain clock.

Yes.

What is, can you describe that?

...