Are we there yet?

Some fascinating stuff in this report of studies on the time slowing effects of relativity, which starts with the subheading:

As Einstein predicted, a slow drive or a step up a ladder is enough to warp time.

I think this might explain the common kid’s question while on a drive.

Moving extremely sensitive clocks is how it was tested:

Chou and his team used an optical clock invented in 2005. This uses laser light, which has a frequency some 100,000 times higher than microwaves. Optical clocks are thus tens or hundreds of times more accurate than microwave clocks — NIST's loses less than one second in three billion years.

And here I thought my Pulsar Kinetic (for which I haven't had to replaced the rechargeable battery since I got it about 9 or 10 years) was good. Anyway, this is what they did:

General relativity states that time speeds up for objects as gravity weakens. To demonstrate this, Chou and his colleagues raised one optical clock 33 centimetres above another. The slightly lower gravity at that height meant that compared with the reference clock, the raised clock ticked with a fractional boost in frequency of 4 × 10–17, equivalent to a gain of 90 billionths of a second over 79 years.

To demonstrate special relativity, which says that time slows down for moving objects, the researchers jolted the single atom in their optical clock so that it oscillated at relative speeds of less than 10 metres per second, or 36 kilometres per hour. This time, the clock's ticks seemed to drop by a fractional frequency of almost 6 × 10–16.

Cool.