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2Physics Quote:
"Today’s most precise time measurements are performed with optical atomic clocks, which achieve a precision of about 10-18, corresponding to 1 second uncertainty in more than 15 billion years, a time span which is longer than the age of the universe... Despite such stunning precision, these clocks could be outperformed by a different type of clock, the so called “nuclear clock”... The expected factor of improvement in precision of such a new type of clock has been estimated to be up to 100, in this way pushing the ability of time measurement to the next level."
-- Lars von der Wense, Benedict Seiferle, Mustapha Laatiaoui, Jürgen B. Neumayr, Hans-Jörg Maier, Hans-Friedrich Wirth, Christoph Mokry, Jörg Runke, Klaus Eberhardt, Christoph E. Düllmann, Norbert G. Trautmann, Peter G. Thirolf
(Read Full Article: "Direct Detection of the 229Th Nuclear Clock Transition"

Monday, May 08, 2006

Hydrogen in Far Galaxy

A team of astronomers from European Southern Observatory (ESO) detected the presence of molecular hydrogen in the farthest system ever, an otherwise invisible galaxy that we observe when the Universe was less than 1.5 billion years old (The universe is estimated to be about 15 billion years old). The astronomers find that there is about one hydrogen molecule for 250 hydrogen atoms. This also implies that the gas in this galaxy must be rather cold, about -90 to -180 degrees Celsius. In addition, several lines from 'metals' are also seen, allowing the researchers to deduce the amount of various chemical elements.

The team arrived at this conclusion analyzing light from a quasar located 12.3 billion light-years away. A similar set of observations for two other quasars, together with the most precise laboratory measurements, allows scientists to infer that the ratio of the proton to electron masses may have changed with time (our last posting).

These exciting results will be available in a paper accepted for publication in the Astrophysical Journal Letters ("Molecular Hydrogen in a Damped Lyman-α system at zabs=4.224", by C. Ledoux, P. Petitjean, and R. Srianand).



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