You are going to love this: http://www.leapsecond.com/great2005/ http://www.leapsecond.com/great2005/ The short version is that this guy hauled three cesium a

You are going to love this: http://www.leapsecond.com/great2005/ http://www.leapsecond.com/great2005/ The short version is that this guy hauled three cesium atomic clocks up a mountain while on vacation with his kids. They returned 23 ns older then the guy's wife (who stayed home to study for her nursing board exams). Note that time dilation isn't just caused by motion (special relativity), but also by proximity to a gravity well (general relativity).