The ever-unreachable now

December 12th, 2007

“Each atom has its own spectral signature,” says Hollberg. Calcium resonates to red, ytterbium to purple. At their most ambitious, NIST scientists hope to wring 10^-18 out of a single trapped mercury ion with a chartreuse light — slicing a second of time into a quadrillion pieces.

At that level, clocks will be precise enough that they’ll have to correct for the relativistic effects of the shape of the earth, which changes every day in reaction to environmental factors. (Some of the research clocks already need to account for changes in the NIST building’s size on a hot day.) That’s where the work at the Time and Frequency Division begins to overlap with cosmology, astrophysics and space-time.

[Wired, Full article]