Black holes 'important'
Cape Town - A University of Chicago professor studying black holes says they are an important phenomenon and may lead to new understanding of the nature of the "real universe".
"They (black holes) are interesting objects from a fundamental physics point of view and play an important role in astrophysics processes. They help us to understand what's going on in the real universe," Bob Wald told News24 after his lecture at UCT.
A black hole is a region of spacetime where gravity is so strong that nothing - not even light - can escape. They arise in nature as the end products of the complete gravitational collapse of sufficiently massive bodies like stars.
"There are black holes at the centre of most galaxies, and the one at the centre of our galaxy is about four million solar masses," said Wald, who is in SA for the first time, and just recently hiked up Table Mountain.
However, despite being a "perfect absorber of everything", black holes do not swallow up the galaxy because of the speed of bodies around it, much like the Earth doesn't not fall into the sun, despite the latter's gravity.
"Black holes have a finite temperature, despite their gravity. One would think that their temperature should be absolute zero (-273.15°C) but they are subject to quantum effects.
"Given that black holes have a finite temperature, they should evaporate in a finite amount of time," said Wald.
He said that much of the theory around the study of black holes was developed by physicist Stephen Hawking and hopes that observations of black holes will confirm the theory of general relativity.
"I'm still excited by black holes, there's still much to be learned and it might teach one about what's going on. We need to fill in the details of astro-physical processes."
Most remarkable of the theoretical developments is the relationship between certain laws applying to black holes and the ordinary laws of thermodynamics, particularly the fact that - due to quantum processes - black holes "emit" thermal radiation.
Wald said study of physics and cosmology was a popular field of study in the US and attracted good students, illustrating the difference between the industrialised economy and SA as a developing country where there was a chronic shortage of skills.
"The gravitational waves results in about five years excites me - it would be good to confirm the theory. What is needed is a theory that includes general relativity and quantum theory, but there are special difficulties when one tries to formulate a quantum theory of gravity."
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