India's contribution substantial: David Gross

By Gopal Raj

MUMBAI, JAN. 8 ``I truly believe that we are in the middle of a scientific revolution that is akin to the advent of quantum mechanics in the 1920's. When completed, we will not only have a unified theory of all of the forces of nature but we will most likely have a new view of space and time,'' says Prof. David Gross, who has contributed enormously to the development of String Theory. Dr. Gross is participating in the Strings 2001 conference currently in progress at the Tata Institute of Fundamental Research in Mumbai.

Prof. Gross, who is director of the Institute for Theoretical Physics at the University of California, Santa Barbara, is also known for his fundamental contributions to particle physics and quantum theory. He was one of those who provided the explanation for the quixotic behaviour of quarks, fundamental particles which make up the protons found in the nucleus of atoms. Inside a proton, quarks are bound so tightly that they cannot be separated and yet deep inside the proton the quarks move around almost without intereacting with each other. In 1973, Dr. Gross and Dr. Frank Wilczek (and independently Dr. David Politzer) showed that in a certain class of quantum field theories the force between two particles is very strong when they are well separated and that this force weakens as the particles come closer together.

In the realm of String Theory, Dr. Gross was one of those responsible for the `Heterotic String Theory' in 1984, the first string theory which could reasonably realistically model the real world. In String Theory, the fundamental particles which make matter and forces are viewed as vibrating strings. While conventional physics is unable incorporate gravity along with the other fundamental particles, String Theory is able to do so without any difficulty. The hope therefore is that String Theory will be able to provide the unified theory which physicists have been seeking.

String Theory has many hurdles to overcome, observes Dr. Gross. ``We do not yet have the complete theoretical framework that is hinted at by string theory. We lack an understanding of the fundamental formulation of the theory nor do we truly understand its underlying symmetries,'' he told The Hindu.

On the other hand, String Theory was the only one so far which had been able to provide a consistent quantum theory of gravity, Dr. Gross points out. It was also clear that String Theory had the capability to provide all the ingredients of the Standard Model which specifies how the fundamental particles interact and which has been experimentally verified. ``We are, of course, also encouraged by its elegance, mathematical power and by the fact that it contains in such an instructive fashion all of the field theory apparatus that has proved so useful in describing nature,'' he added.

He believes that it would be possible to verify the validity of String Theory in two ways. One way would be if it allowed calculation of parameters in the Standard Model which had hitherto been derived solely from experimental data. He also thought it possible that the next generation of accelerators could see ``stringy effects''.

The Indian contributions to String Theory have been substantial and the Tata Institute for Fundamental Research was a world class center in the field, says Prof. Gross. ``Some of the important advances in recent years have been led by Indian physicists, such as Dr. Ashoke Sen's remarkable insights into string field theory.''

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