Shedding light on black holes

The mathematics and physics underlying black holes is both elegant and excruciatingly technical.

Visual representation of a black hole

In trying to explain quantum aspects of black holes—regions of space where gravity is so strong, even light becomes trapped—scientists have spent many years trying to merge quantum physics with Einstein’s ideas on gravity.

Professor Matt Visser, from the School of Mathematics and Statistics, has been awarded $538,000 of Marsden funding to explore the ‘borderlands’ between gravity and quantum physics.

In 1974, famed physicist Stephen Hawking predicted that black holes aren’t entirely black—they slowly leak radiation, causing them to shrink and eventually evaporate, taking everything inside with it.

But even after 40 years of research, the details of the final stages of this process, when the black hole has become relatively small, continue to generate much heated debate and confusion among scientists.

As black holes get smaller, they also get hotter, Matt explains. “In the last few seconds, 300 tonnes of matter is converted to heat and light, which is a big explosion by human standards.”

Matt, who is a world-renowned expert on the theory of gravitation, will use the funding to research where exactly the Hawking radiation—which is predicted to cause black hole evaporation—is created.

For decades, many scientists believed that the slight differences in ways of defining a black hole were irrelevant, says Matt. But it now appears that the precise technical definition is critically important, as advocated by Hawking. Matt will use a new approach that depends on these subtle differences.

He will also look at thermodynamics, the branch of physics concerned with heat and temperature, providing a careful reanalysis of differences and similarities between black hole and ordinary thermodynamics.

“My contribution is very much on the theoretical side. I’ll be doing a calculation that gets other experts looking in the right direction, which could lead to a better understanding of quantum mechanics and general relativity.”