Black holes. One of the universe’s most destructive forces, capable of tearing stars and planets to sheds, and swallowing them whole. Yet, scientists believe they could actually be the key to shaping the many millions of galaxies in the universe, creating and holding life itself. But moreover, scientists believe black holes could finally answer mankind’s most potent question: What came before the Big Bang?
The problem is, researching black holes is near impossible. By definition they are invisible, and current theories that seem to be able to explain everything else in the universe, collapse when applied to black holes.
We know black holes form when the most massive stars reach the end of their life. Red giants explode into a supernova, before finally violently collapsing into a point, creating the black hole. The reason something so small can have such a great gravitational field that not even light can escape, is due to the effect of mass bending space, shown by Einstein’s famous Theory of Relativity. The more massive an object, the more it bends space, like putting a heavy ball onto a trampoline. When this mass concentrates into a small area, the distortion and bending of space greatly increases. As black holes are so small and yet have such large masses, the distortion of space is phenomenal, giving it the quality of the event horizon. Beyond this point, space has bent so much, and the gravitational pull is so large, nothing can escape. A common analogy used by scientists is a waterfall. The closer water is to the drop off point, the faster the current. Once the water flows faster than you can swim, there is no way you’ll ever escape plunging to the bottom, representing the inescapable event horizon of the black hole.
But how can this possibly help scientists find out what came before the beginning of time? Well, it’s all down to the similarities of the black hole, and the big bang theory. According to the accepted current theory, the universe has been expanding for millions of years, and will continue to do so, but this expansion had to start somewhere. The theory states that expansion started from a single point in the universe. A singularity.
The difficulty is that the singularity, the very centre of the black hole, is where physics breaks down completely. It just doesn’t work anymore. Einstein’s Theory of General Relativity perfectly explains the massive, such as the stars and space, but when you put an incredibly large mass into such a small object, something strange happens. According to the theory, the singularity takes up exactly no space at all, and when implemented into the maths of general relativity, we get the answer physicists fear most. Infinity. This would mean that at the centre of a black hole, gravity is infinite, time stops, and physics collapses. The singularity is when our understanding of nature breaks down. So clearly there is a fundamental flaw in physics? Einstein knew of this flaw, but hoped such an object would never actually form, and even wrote a convincing paper proving this. At the time it was reasonable, but in the 1970’s pictures showed thick dense clouds of x-rays which quickly disappeared, giving convincing evidence of what we now know as the black hole.
But general relativity is very good at describing the very large, so to describe the singularity, quantum mechanics was used, which deals with atomic and sub atomic scale objects. But this is not as simple as it seems. Because quantum mechanics describes the minute, it can’t and doesn’t describe gravity, as it makes a negligible effect on atoms. This would normally be irrelevant, but when describing the singularity where gravity is phenomenally strong, the two theories just don’t mix.
To overcome this problem, theorists attempted to extend quantum mechanics to describe gravity, known as Quantum Gravity to try and link the famously incompatible General Relativity and Quantum Mechanics. But when inserted into the equations, again the result came up as infinity. In fact, it resulted in an infinite amount of infinities. Quantum Gravity had fallen apart. The theories were completely incompatible. This told scientists that at best, the theories were just an approximation of the universe. It meant the collapse of all physics as we know it.
Getting quantum mechanics and general relativity to work together has been the biggest challenge for physicists. Finding something to link them, or even finding new theories entirely to explain everything as a whole has been, and still is the current goal of theorists. Although it appears black holes have messed everything up, they represent a marvellous opportunity for physics. If the universe is expanding, then it must once have been more compact. A singularity.
So, if scientists can discover what is happening at the singularity in the black hole, this could help hugely in understanding and unlocking the secrets of what came before the Big Bang. Unfortunately with our current technology, we have only just been able to detect a possible black hole, let alone discover what happens inside one, and even these findings are still not 100% certain. For now, it’s all a big puzzle for the theorists, using clever maths and wondrous ideas to determine what might actually happen at the singularity, and until we can physically research black holes, we can never know for sure. There is hope yet though. Due to the impossible bending of space by a black hole, outside the event horizon, light from stars around the black hole is warped and reflected to produce a ‘halo’, a ring of light surrounding the event horizon. This would be possible to see, so discovering and observing a definite black hole for the first time is possible. Until then, we can only imagine one day, being able to answer the question: ‘What was there, before the Big Bang?’
BBC Horizon, ‘Who’s Afraid Of A Big Black Hole?’
By Will Slack