Wednesday, February 08, 2006


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Indian physics trio rewrites singularity, death of stars
Stars don’t die the way Einstein said they do
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Posted online: Wednesday, February 08, 2006 at 0214 hours IST

MUMBAI, FEBRUARY 7: From Room A-255 at Mumbai’s Land’s End, a bold new idea that questions the fundamental physics of a dying star four to five times the mass of our sun—as Albert Einstein knew it—has come to international notice. The Tata Institute of Fundamental Research (TIFR), located at Land’s End, terms the idea ‘‘an achievement that proved to be an elusive dream for Einstein’’— to unify the forces of gravity and quantum mechanics. And, on January 27, the work made it to the international journal, Physical Review Letters.

The trio of cosmologists who think Einstein would be ‘‘amused’’ are Pankaj Joshi, a physics professor who has studied dying stars for two decades at TIFR; Rituparno Goswami, a 30-yr-old TIFR doctoral student who got past his PhD viva last week; and Parampreet Singh (30) of the University of Pennsylvania.

A year after they bonded over physics at a Jaipur conference, the trio has proposed that the dramatic end of such a dying star is explosively different from theories that classical physics has stood by since Einstein.

‘‘It’s an exciting development at the very foundation of all of black hole physics,’’ says Joshi. ‘‘Our test predicts that a dying, shrinking star of a mass four or five times more than the Sun, goes dim. In its last microseconds, it throws away all its matter in an explosive burst that can be observed like a flash or fireball.’’

That’s not how Einstein’s classical theories described it. Rather, the general theory of relativity predicts that these stars, instead of exploding, would turn into a naked singularity—a very dense region where a spoonful of matter weighs infinitely heavy.

But when the team applied laws of quantum gravity to Einstein’s model, there was no naked singularity. ‘‘We had not anticipated a star burst of radiation,’’ says Joshi. ‘‘We have not solved the problem or got details of the emissions, which could be super-energy cosmic rays or gamma rays. But what we predict can be a good test for quantum gravity.’’ This proposed experimental test for quantum gravity is the first step to unify the forces of gravity that rule the universe and the quantum forces that govern the atomic world.

‘‘The team claims the phenomenon will be observable, that makes it exciting,’’ says TIFR Director Shobo Bhattacharya. ‘‘Understanding collapsing stars is part of frontier physics."


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