Fellow space-nerds might be quite excited by reports over the last month of a brave group of scientists trying the capture an image of the supermassive black hole sitting in the centre of our twinkly Milky Way. It’s a thrilling proposition for many reasons, but my excitement was piqued further after reading Stephen Hawking’s Black Holes: The BBC Reith Lectures, with an introduction and commentary by David Shukman.
This slim, pocket-sized volume is easy to read in a lunchtime, but might take weeks or years to really comprehend. It illustrates once again that subtle boundary between physics and philosophy – and that black holes are no exception to the true weirdness of quantum physics.
Assisted by quirky illustrations, Hawking and Shukman reveal the complex paradoxes that make black holes so intriguing. The problem at the crux of the discussion is whether or not information – that is data about our universe in the form of physical objects – is destroyed when it is consumed by a supernova. On one side of the fence, you find yourself denying quantum theory; on the other, Einstein’s Theory of General Relativity. A quandary indeed.
But why does it matter whether or not information is destroyed within a black hole? Surely it is all too far away to matter all that much. But here is where Hawking puts the philosophical boot in. The physical laws which operate within our universe contribute to a school of thought called “determinism” – that is, that while we cannot tell exactly what will happen in the future, a rough idea can be determined. if it is possible for information to be lost inside a black hole, however, it would fundamentally undermine the predictability of the universe.
Not only would this affect our ability to foretell the future with any degree of certainty, it would also destabilise our past.
The history books and our memories could just be illusions. It is the past that tells us who we are; without it, we lose our identities.
Comfortingly, Hawking’s theory is that information can be recovered, in a manner of speaking. Less comfortingly, he posits that this is because information may be recorded on the event horizon of a black hole via a complex mechanism involving multiple histories.
As the brave scientists mentioned earlier attempt to take a photograph of that dark and endless eye in the middle of our galaxy, the creeping feeling passes over me that, by gazing into – and perhaps, who knows, beyond – the event horizon, they might just change our concept of reality more than we can guess.
Black Holes: The BBC Reith Lectures by Stephen Hawking was published in the UK in 2016 by Bantam Books, an imprint of Penguin Random House. It was adapted from a series of BBC Radio 4 lectures by Hawking, with introduction and notes from David Shukman.