# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

**Re: Quantum Compass**

**From:**Frank Reed

**Date:**2014 May 16, 12:23 -0700

Bill you asked:

"For the sake of discussion, let's say outer space is 10 K, or 10/273.16

kelvin units. Does on billionth colder than outer space imply 3.66 x

10^-12 K?"

Yes, that's the idea --except that you didn't need to divide by 273. They probably used the cosmic microwave background temperature as a starting point for comparison so the temperature they're describing would be some few nanokelvins (billionths of a kelvin), but since we're only talking order of magnitude here, that's close enough. Now consider this: absolute temperature is directly proportional to mean kinetic energy or, for the same type, molecular speed squared. So 100 billion times lower mean kinetic energy (compared to normal "room temperature," hence the extra factor of 100) corresponds to a molecular speed that's lower by about the square root of 10^11 or roughly 300,000. How fast is that? Well, normal air molecules move at a speed of the same order of magnitude as the speed of sound --necessarily, since sound is transmitted by collisions among molecules. The speed of sound is just about a third of a kilometer per second or nearly enough 300 meters per second. So... that means that the supercooled atoms as described have thermal speeds of something like 1 millimeter per second (order of magnitude). That's slower than a snail. Assuming I did the arithmetic right!

For a navigation connection, check an old edition of Bowditch from, say, 1826 and find out the estimate of absolute zero recommended to celestial navigators in those tables.

-FER

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