So when I was growing up, there was a phone number that I would dial whenever I was bored, just to have someone to call.

At least once a week, I'd grab the handset off the wall and punch in the 10-digit number.

And that phone number would tell you the exact time, 24-7.

At the tone, Eastern Daylight Time, one hour, 36 minutes, 30 seconds.

Universal time, five hours, 36 minutes, 35 seconds.

Personally, I think I just like punching in the buttons and pretending I had a call to make.

But this was before smartphones, before all of our digital timepieces automatically synced up.

So sometimes the clock in the kitchen read five minutes slower than your bedroom alarm clock,

and it could be hard to figure out what was the accurate time.

So how do we determine the time?

Well, there's an official clock,

and it's located in Boulder, Colorado

at the National Institute of Standards and Technology.

I'm Alexa Lim, and this is Atlas Sbskera, a celebration of the world's strange, incredible, and wondrous places. Join me as we visit the official timekeepers. I'm a ah, ah, uh, uh, uh, I'm Bye-Bah-B-B-B-B-B-B-B-B-ha-B-ha-B-ha-B-ha-ha-ha-ha-ha-ha-ha. Now, if you want to create a super accurate clock, you need to have a really precise measurement of time.

And that standard unit is the second. The National Institute of Standards and Technology, or NIST, is a government agency that sets the standard for measurements that we all go by.

NIST calibrates all sorts of things on its 200-acre campus.

We pass by labs with cryogenic stations measuring voltage, and scientists using tiny sensors

that determine temperature with light.

There's a person who manages a million pound dead weight literally is a million pounds hanging

from a pulley, and it's used, for example, to calibrate the force that a rocket engine can produce.

That's Jeff Sherman. He's a physicist at NIST, and he works in the time division.

I'm the one government employee that actually is paid to sit around and watch the clock.

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