The Why Files The Why Files -- whyfiles.org

It's about time

POSTED 25 AUGUST 2005
Got the time?
Do you assume time tomorrow will be like time today? Sorry to break the news: You can't take time for granted. Sure, we'll see how you can count seconds with hairsplitting accuracy. But time itself is about as reliable as a creaky old pendulum clock.

Looking at time is trying to see air.Here's one beef: Time slows under intense gravity and extreme velocity. You get near the speed of light, and time just about stops. And you don't have to take our word for it. Albert Einstein, icon of modern physics, figured this one up, and nobody's done anything but prove him right.the whyfiles wild and whacky wall clock

We always assumed that time, like tide, waits for nobody -- then we learned that on Dec. 31, 1998, scientists spliced in an extra second because the Earth was running slower than the atomic clocks.

Shows you who's boss.

We clocked The Why Files at their favorite pursuit: Making trouble.

The starting gun
Remember 2000, the year the computers didn't crash because the Y2K problem a) got solved in the nick of time, or b) proved to be the perfect tool for separating fools from their money? You mighta thought Y2K was the start of a new millennium, the anchor point for our calendar, and the launching pad for millenialists.

You got that last one right, but what about the other two?

Year 2000 wasn't the start of anything, but rather was the end of the second millennium. The third millennium actually started in 2001, which, if not exactly a round number, is 2000 years after the calendar began -- in year 1.

Man in plaid lightly brushes metal clock.1952 -- NIST completes the first accurate measurement of the frequency of the cesium clock resonance. The apparatus for this measurement is named NBS-1. Photo: NIST

Believe it or not, people argue about this stuff, even including some people who aren't drunk. But if you do the math, you see the second century began in 101, and the second millennium in 1001. If you take it from there, you'll figure out jolly quick when the third millennium commenced.

The problem is that we've grown accustomed to saying a century starts in the "00" year, when it really starts in the "01" year.

If this bugs you (and why wouldn't it?), look at the bright side: 2000 was the first (and last) year in the 20th century that actually began with "20"!

You said something about atomic clocks. How do they tell us what's the time?

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