Later On

A blog written for those whose interests more or less match mine.

Measuring time by measuring mass

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This seems quite weird, but apparently it in theory works—though not in practice, given that its precision as a clock is about a hundred millionth that of the best atomic clocks now in use. Still, it’s intriguing. Reported in Science News by Andrew Grant:

It’s part clock, part scale: A newly developed atomic clock measures time based on the mass of a single atom. The research, published online January 10 in Science, is controversial but could provide scientists with more precise methods of measuring both time and mass.

“This is the first clock based on a single particle,” says Holger Müller, a physicist at the University of California, Berkeley. “Its ticking rate is determined only by the particle’s mass.”

The idea for the clock stemmed from the quantum principle that particles also behave as waves, and vice versa. In particular, Müller and his colleagues wanted to determine how frequently the wave form of a single atom oscillates, a quantity that in quantum mechanics is inherently linked to the atom’s mass. Then the researchers could use those oscillations like swings of a pendulum to create a clock.

The snag in Müller’s plan was that it’s impossible to directly measure the oscillation frequency of waves of matter. The frequency of these waves is about 1025 hertz, 10 orders of magnitude higher than that of visible light waves. So Müller and his colleagues came up with an apparatus that creates two sets of waves — one based on a cesium atom at rest and another on the atom in motion. The researchers measured the frequency difference between the waves and then used that number, a manageable 100,000 hertz or so, to calculate the much larger oscillation frequency of cesium at rest. . .

Continue reading.

Written by LeisureGuy

11 January 2013 at 10:33 am

Posted in Science

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