Speed of light getting faster? Scientists say the speed of light, regarded as a universal constant, may be getting faster. They say it may have been lower as recently as two billion years ago - right here on Earth. The controversial finding is based on re-analysis of old data that has long been used to argue exactly the opposite, reports New Scientist. A varying speed of light contradicts Einstein's theory of relativity, and would undermine much of traditional physics. But some physicists believe it would elegantly explain puzzling cosmological phenomena such as the nearly uniform temperature of the universe. The threat to the idea of an invariable speed of light comes from measurements of another parameter called the fine structure constant, or alpha, which dictates the strength of the electromagnetic force. [ how strongly things are held together - ed@percs] The speed of light is inversely proportional to alpha, and though alpha also depends on two other constants, many physicists tend to interpret a change in alpha as a change in the speed of light. Victor Flambaum of the University of New South Wales in Sydney, says the comparison is a simplification but a valid one. "I can't see a particular mistake," says Flambaum. "However, the claim is so revolutionary there should be many independent confirmations." 01 June '04 http://www.ananova.com/news/story/sm_1007244.html?menu=news.scienceanddiscovery ------------------------------------------------------------- Constant that Isn't Constant Analysis of the light from distant quasars has shown that billions of years ago the laws of physics may have been slightly different. A research team has found evidence that the fine structure constant--which measures the strength with which subatomic particles interact with one another and with light--was different at earlier times in the history of the Universe. The new work, which will appear in the 27 August print issue of PRL, confirms earlier results by the same group, which suggested that six billion years ago the value was about one part in 105 smaller. They now have added more data and have ruled out more potential sources of systematic error. If confirmed by other experiments, the finding would profoundly change our understanding of the evolution of the Universe, but not all experts are convinced. John Webb, of the University of New South Wales in Australia, and his colleagues, focused on the fine structure constant, which goes by the Greek letter alpha, because it has no units and is independent of any measurement system. Its current value of roughly 1/137 could not have been very different in the past, as that would have spelled trouble for our very existence. A variation in alpha by more than a factor of ten would imply that carbon atoms could not be stable, and organic life could not have arisen. The team looked at dark, narrow lines in the spectra of quasars, the highly active, bright cores of galaxies at the farthest reaches of our universe. Gas clouds between Earth and the quasars absorb some of this light and produce the spectral lines. The difference between the wavelengths absorbed by any two elements depends sensitively on the value of the fine structure constant. The researchers accurately measured the absorption wavelengths of several metal atoms in clouds seen at different cosmic times using the HIRES precision spectrograph at the 10-meter Keck telescope in Hawaii. In their 1999 paper [1] the team studied only iron and magnesium, but they have now also looked at absorption lines from silicon and other metals, further increasing their sensitivity and reducing their error bars. They also analyzed 13 potential sources of systematic error and found that none could explain their main result: Alpha is increasing. 9 August 2001 http://focus.aps.org/story/v8/st9 ------------------------------------------------- `Perceptions' note: The evidence in favor of our forecasts is mounting. Forecasts summarized at - www.perceptions.couk.com/verities.html www.perceptions.couk.com/enigmas.html ------------------------------------------------- FURTHER REFERENCES GO - "search perceptions" - in SEARCH-ENGINE file-ID www.perceptions.couk.com/uef/changec.txt