Optical lattice atomic clock could 'redefine the second' - Page 1
Forum section: electronics / general

author: Unknown
author_rank: Unknown
timestamp: July 10, 2013, 03:07:53 pm
content: http://www.bbc.co.uk/news/science-environment-23231206"For the first time, two state-of-the-art strontium optical lattice clocks are proven to agree within their accuracy budget, with a total uncertainty of 1.5 × 10-16. Their comparison with three independent caesium fountains shows a degree of accuracy now only limited by the best realizations of the microwave-defined second, at the level of 3.1 × 10-16"

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 11, 2013, 08:24:15 am
content: Meh. Does the uncertainty of present reference standards really cause any issues for anybody, outside of the heads of a few academics trying to justify their budget?Whenever I see articles about advances in standards, there is generally an assumption that more accuracy is really necessary. Why?Apparently the reference kilo in France is losing a few micrograms - big deal. Will anyone die?

author: Unknown
author_rank: Unknown
timestamp: July 11, 2013, 10:18:12 am
content: Quote from: mikeselectricstuff on July 11, 2013, 08:24:15 amThe metre standard is derived from time, apparently it's defined as the distance of light travelled in a vacuum in 1/299792458 of a second; also I believe communication companies have to use accurate time at the exchanges to sync the call multiplexing; otherwise they would get all mixed up.The thing is some bits of research might not appear to have any purpose until years later - but like you say some areas of research do appear questionable!

author: saturation
author_rank: Super Contributor
timestamp: July 11, 2013, 04:21:19 pm
content: I'd agree with Mike that many metrology R&D issues are not practical for typical application engineers particularly for consumer products, but there is great value for higher precision in industry specific tasks were EE's work closely with physicists, or metrologist's work in a national standards lab.See the segment on applications and were increase accuracy matters:http://phys.org/news11527.htmlOne that has always intrigued me is if some presumed "constants" actually are not, such as the speed of light. Without the improved accuracy of the "optical" standards clock, the issue regarding 'alpha' would be even cloudier.http://en.wikipedia.org/wiki/Fine-structure_constant#cite_note-36http://www.newscientist.com/article/dn7285-new-twist-in-wrangle-over-changing-physical-constant.html

author: sub
author_rank: Regular Contributor
timestamp: July 21, 2013, 01:15:46 am
content: Quote from: mikeselectricstuff on July 11, 2013, 08:24:15 amTime metrology is really big in VLBI radio astronomy, where you are limited by the length of time for which you can maintain phase coherence. At the moment such sites use hydrogen masers.

author: Stonent
author_rank: Super Contributor
timestamp: July 21, 2013, 02:04:22 am
content: Quote from: mikeselectricstuff on July 11, 2013, 08:24:15 amI don't know about you but when my wife says she'll be out of the bathroom in "just a second", I require 8 significant digits of precision.