Time for a New Clock

Jonathan Strickland


A couple of weeks ago, I caught an interesting story on NPR about a phenomenally precise clock. It's really well done -- you should check it out. It hits several of the points we made in our own episode about the future of time.

Time is a tricky concept. The experience of time is subjective -- there's no universality to it. I don't just mean our perception that time flies by when we're having a good time and drags to a standstill when things aren't going so well. I mean that time is affected by other stuff -- like gravity. And depending upon that stuff, time will appear to move at different rates from different points of view.

Imagine you built a spaceship that could travel at 99.9% the speed of light and took a little jaunt to Pluto and back. You'd notice something odd when you got back home. Your watch shows that only 11 hours or so have gone by since you left and returned. Time passed for you as it always does. But everyone on Earth claims that more than 10 days have gone by -- a total of around 246 hours have passed. And for them, time went by just the same as it always does. It's only when you compare that you see there was a discrepancy.

Getting back to the NPR story, the piece talks about a new ultra-precise clock at the University of Colorado, Boulder. It's a clock that uses strontium atoms and lasers. It's so precise that it's a good thing there's only one of them or we'd all go bonkers. That's because it keeps time in tiny fractions of a second and the smallest changes can affect it. If you tried to synchronize two or more of these clocks, they'd quickly move out of agreement with each other as conditions changed between them.

Let's say that you have one strontium-and-laser awesome clock at sea level and another sitting on top of Mount Everest. The two clocks would keep time each within their own frame of reference. But these are two different frames! The clocks would be out of synch, each keeping exquisite time for its own location but in disagreement with one another. Has your mind melted yet?

It may turn out that this clock's greatest purpose isn't for measuring time at all but rather as a sensor for gravity. Launching a device like this into space, far from the gravitational influences of larger bodies, it may serve as a gravitational wave detector. And that's pretty awesome.

Want to hear more about the future of time? Check out our episode.