Indian scientists have achieved what has proved to be an illusive dream for Albert Einstein and generations of physicists.
They have found and proposed an experimental test for the quantum theory of gravity, the first step to unify the forces of nature that rule the universe on a large scale and the quantum forces that govern the atomic world.
"These effects can be observed and is an important step because validating quantum gravity is a necessary step in having a unified theory of forces of nature, which has been the cherished goal of generations of scientists, including Einstein," Dr Pankaj Joshi of the Tata Institute of Fundmental Research, one of the senior authors of the work published in the January 27 issue of Physical Review Letters said in Mumbai Tuesday.
The Indian team is now banking on the upcoming experiments like the Extreme Universe Space Observatory, to be launched by the European Space Agency in 2010, which could help provide a test for the prediction.
After the findings are proved, the scientists would have the real clue about obtaining a full quantum theory of gravity (unification of all forces of nature). It also implied that there can be no naked singularity (a region of infinite density, where a spoonful of matter weighs infinitely heavy), when a star dies and shrinks, or when its stellar fuel is exhausted. It also said Black Holes would not form when stars die in gravitational collapse. The co-authors included Joshi's doctoral student, Rituparna Goswami of TIFR and Parampreet Singh of Pennsylvania State University
Their work showed that a collapsing star did not turn into a black hole or a naked singularity. However, instead it throws away all its matter in the form of an explosive burst, which would look like a flash or fireball in the sky. As such the mathematical solutions to the equations of Einstein's General Theory of Relativity predict the existence of Black Holes as well as naked singularities.
"But that does not mean that these objects occur in the Universe. What we have found is when we apply laws of the quantum theory to Einstein's mode, both the Black Hole as well as Naked Singularity are dispensed, and instead, a burst occurs in the final stages of collapse of the dying star," Joshi said.
The work builds on an extensive study of gravitational collapse of dying stars, that has been carried out at TIFR over past two decades by Joshi and his co-workers. The Loop Quantum Gravity theory, a leading contender for quantum gravity theory, is used here to prove that exploding stars have a distinct observable signature.
A dying star dims before emitting ultra-high energy rays, which could be in the form of neutrino particles travelling close to velocity of light, high-energy Gamma rays, or other forms of a strong burst of radiation such as super-energy cosmic rays, induced by the quantum gravity effects.