Friday, January 07, 2011

The Only Constant Is Change

February's ASTRONOMY magazine features this column by Bob Berman:

The Dimensionless Constant

"Scientists are discovering our universe may not be as invariable as previously thought"

Berman's article describes the work of John Webb and Michael Murphy, who have been searching for changes in the fine-structure value $\alpha$. They are based in Australia, not New Zealand.

"In 1998, New Zealand astrophysicists studied the light from distant quasars as it passed through ancient nebulae. The way the light was absorbed revealed the value of $\alpha$ long ago. They found that in the distant past, the constant was slightly smaller than it is today. The result seemed impossible, and most astronomers simply rejected it.

"This variation in $\alpha$ violates one of the tenets of Einstein's special theory of relativity, which states that a constant must be identical no matter where and when it is measured. One physicist called this discovery "the news of the year in physics." If constants like $\alpha$ really vary, the cosmos loses its homogeneity, and dark matter and dark energy could be different in various places."

The fine-structure value $\alpha$ determines the strength of electromagnetic interactions. For some odd reason this dimensionless value is nearly equal to 1/137. It is given by ke^2/$\hbar$ c, where c is the speed of light. Changing $\alpha$ is a big indicator that the speed of light is also changing.

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4 Comments:

Blogger Kea said...

Oh, my. The Tasman sea is quite wide, you know. But good to see some sense creeping into science journalism.

7:57 PM  
Blogger Ulla said...

http://milan.milanovic.org/math/english/alpha/alpha.html
about the hierarchy of Plancks constants?

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