Tom sent in this letter to Physics Today, he used an atomic clocks to show his kids they’d get an extra 22 nanosecond from relativistic time dilation… I’m a little skeptical since the difference would be super tiny, but have a gander – it’s pretty neat –

I enjoyed Daniel Kleppner’s Reference Frame about the relativistic effects of elevation on precise clocks (PHYSICS TODAY, March 2006, page 10). He would be amused with an experiment I did with my kids last year.

The year 2005 was the widely publicized 100th anniversary of Einstein’s first paper on relativity and the lesser-known 50th anniversary of Louis Essen’s first cesium clock. To celebrate, I created Project GREAT (General Relativity Einstein/Essen Anniversary Test), perhaps the first “kitchen science” relativity experiment.

As a collector of vintage and modern atomic clocks, I discovered it was possible, using gear found at home, to convert our family minivan into a mobile high-precision time laboratory, complete with batteries, power converters, time interval counters, three children, and three cesium clocks (see photograph). We drove as high as we could up Mount Rainier, the volcano near Seattle, Washington, and parked there for two days. The trip was continuously logged with the global positioning system; the net altitude gain was +1340 meters.

An adventure in relative time-keeping – Physics Today March 2007 – [via] Link.

Project GREAT – General Relativity Einstein / Essen Anniversary Test – 3 kids, 3 cesium clocks, a family road trip to measure relativistic time dilation – Link.