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Cracking the code of the Universe

- Wits Univeristy

A hundred years ago, Albert Einstein published his theory of general relativity.

A hundred years from now, the world might be looking back to today, celebrating the cracking of String Theory.

String Theory is a highly complex theory in physics that attempts to find a solution to the question of why quantum mechanics and Einstein’s theory of general relativity are not compatible.

Where Einstein’s theory of general relativity provides a unified description of gravity as a geometric property of space and time (or spacetime), quantum mechanics provides a description of how fundamental particles build up and create the substances with which we are familiar.

While both these theories are some of the best-tested theories in science, they seem to be fundamentally irreconcilable where they both matter. String Theory establishes a link between particle physics and Einstein’s general relativity.

“This correspondence, which is unexpected and one of the most exciting areas of current research in Theoretical High Energy Physics is the subject of active research by members of the Mandelstam Institute for Theoretical Physics, based at Wits University,” says Professor João Rodrigues, Director of the Institute.

The Mandelstam Institute was established in January 2015 out of what was previously known as the Centre for Theoretical Physics at Wits.

The Institute conducts research in Theoretical High Energy Physics, Cosmology and Quantum Matter and is widely regarded as the leading university-based theoretical physics research group on the African continent.

It consists of 11 academics, eight of whom are rated by the NRF and two of whom hold DST/NRF Chairs. They are Professor Robert de Mello-Koch (Fundamental Physics and String Theory) and Professor Vishnu Jejjala (Theoretical Particle Cosmology).

“We are certainly leaders in the area of Theoretical High Energy Physics/String Theory,” adds Rodrigues.

Named after the eminent South African-born American theoretical physicist and Wits graduate, Stanley Mandelstam, who is currently Professor Emeritus at the University of California, Berkeley, the Institute has eight postdoctoral fellows and close to 30 postgraduate students. It also hosts the Gauteng node of the National Institute for Theoretical Physics.

“General relativity deals with the physics of large scales, and quantum mechanics deals with the physics of small scales, so you don’t need to worry about their incompatibility because one theory is (usually) good enough for your calculation,” says Jejjala.

However, to explain the start of the universe, or the functioning of black holes in space, you need both these theories. “Einstein’s theory tells us everything about how the Universe expands but it doesn’t explain what happened at the instant that the Universe started,” he adds. In this instance, both theories matter, but they don’t speak to each other.

Researchers in the Institute and their peers in the field believe that they are now closer to solving this riddle.

“What has happened is one of the most exciting developments in this field, and that is that there may be a link between general relativity theory and particle physics, which may allow us to understand or figure out a long-standing problem in particle physics, which is the problem of confinement,” says Jejjala.

“In certain settings, gravitational physics and non-gravitational quantum field theories are the same thing.”

While work on String Theory is still work in progress, they are closer to being able to describe the Universe in detail.

“We are certainly not done with quantum gravity or String Theory but it is a very exciting time, in that we are able to begin to address the kind of questions of how the Universe works at a very fundamental level,” concludes Jejjala.