
Physicists have broken the record for the most accurate clock - srikar
http://www.sciencealert.com/physicists-have-broken-the-record-for-the-most-accurate-clock-ever-built
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rubidium
Journal article (paywall):
[http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116...](http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.063001)

There's a team working at JILA in colorado who've achieved something similar
with Strontium:
[http://arxiv.org/abs/1412.8261](http://arxiv.org/abs/1412.8261)

Edit: One of the reasons to build these clocks is to find out if the
fundamental constants really are unchanging. So they build two clocks that
rely on different relations of fundamental constants, and see if the "ticking"
of the clocks changes with respect to each other. See:
[http://arxiv.org/pdf/1407.4408.pdf](http://arxiv.org/pdf/1407.4408.pdf) for
info on that.

~~~
mchahn
> and see if the "ticking" of the clocks changes with respect to each other

Maybe a stupid question. These clocks are so accurate wouldn't the time they
measure vary by changes in the earth's mass and/or rotation speed?

