"Because in Cyberspace, no one can hear you scream."
Friday, December 02, 2005
(Red Orbit) After 31 years of tracking the light- output of a burnt-out star from telescopes at McDonald Observatory, astronomer S.O. Kepler of Brazil's Universidade Federal do Rio Grande do Sul and a slew of University of Texas colleagues have found the most stable optical clock in the heavens. [...]
The star in question is a 400 million-year-old white dwarf called G117-B15A, located in Leo Minor. Its pulses of light are so regular that it loses one second in 8.9 million years. This makes the pulses of G117 more accurate and much more stable than the ticks of an atomic clock, Kepler said.
Other astronomers have pointed towards other pulsars (millisecond ones) that have a better "time keep" than G117. Although this may be the case, Kepler argues those pulsars are unstable, and would thus break down eventually making them unreliable. G117 has proven itself by its track record, providing a constant rhythm for at least 20 years.
(Red Orbit) The reconnaissance of G117 continues. "My students will be observing G117," Kepler said. He traces the "family tree" from Rob Robinson, to John McGraw, to himself, to his Brazilian graduate student Barbara Castanheira, who is spending a year visiting The University of Texas at Austin.
Although quite impressive, G117, which loses a second approximately every 9 million years, has been defeated by NIST F1, an atomic clock on Earth. NIST F1 accuracy is nearly seven times greater than G117 (it can maintain its time keep for 60 million years) and will probably maintain its rank as the universal clock for the next million years--that is if is still around in a million years.
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