Daily Archives: February 8, 2010

Recycled Headlines

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The world’s most precise clock

We get this headline every six months or so. The experiment is cool, and drives down the precision to new levels, but I’ll give the standard disclaimer: it’s a frequency standard, not a clock.

The logic clock is based on a single aluminum ion (electrically charged atom) trapped by electric fields and vibrating at ultraviolet light frequencies, which are 100,000 times higher than microwave frequencies used in NIST-F1 and other similar time standards around the world. Optical clocks thus divide time into smaller units, and could someday lead to time standards more than 100 times as accurate as today’s microwave standards. Higher frequency is one of a variety of factors that enables improved precision and accuracy.

Update: an article from Wired which has the virtue of calling it a frequency standard. Unfortunately, it sort of implies that we haven’t already measured gravitational time dilation, which of course we have, and (as I mentioned previously) has even been measured by amateur time nuts.

Double Jeopardy Does not Apply

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Busted more than once.

Skulls in the Stars: Mythbusters were scooped — by 130 years! (Archimedes death ray)

About the same time, however, and in an earlier volume of the Proceedings, I found an article with the title, “On the burning mirrors of Archimedes, and on the Concentration of light produced by reflectors,” by John Scott. This article is also an investigation of a myth that would be tackled some 130 years later by the MythBusters! Apparently the 1870s-1880s were a good era for ‘busting!

The Reckoning is Dead, Jim

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Physics Buzz: Chicken Head Tracking

The technique – which you could generally call “tracking” but is also pretty much the same thing as “dead reckoning” (or is it ded reckoning?) – is utilized by aircraft and some car navigation systems. (I love it when “high tech” turns up in Nature.) The chicken’s body communicates its movements so well with her head, that she can almost instantaneously compensate for her movement of the lower body, and keep her head stationary in relation to her environment. To do this, her body has to have some fixed point, some center, and determine how far her bum has moved away it, then move her head an equal but opposite distance from it. Once again this requires very rapid communication, and then action, on the part of her body.