What We Cannot Know. Marcus du Sautoy
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For me, the science that I began to learn as a teenager did a pretty good job of pushing out any vaguely religious thoughts I had had as a kid. I sang in my local church choir, which exposed me to the ideas that Christianity had to offer for understanding the universe. School education in the Seventies in the UK was infused with mildly religious overtones: renditions of ‘All Things Bright and Beautiful’ and the Lord’s Prayer in assemblies. Religion was dished up as something too simplistic to survive the sophisticated and powerful stories that I would learn in the science labs at my secondary school. Religion was quickly pushed out. Science … and football … were much more attractive.
Inevitably the questions about my stance on religion would not be fobbed off with such a flippant answer. I remember that during one radio interview on a Sunday morning on BBC Northern Ireland I was gradually sucked into considering the question of the existence of God. I guess I should have seen the warning signs. On a Sunday morning in Northern Ireland, God isn’t far from the minds of many listeners.
As a mathematician I am often faced with the challenge of proving the existence of new structures or coming up with arguments to show why such structures cannot exist. The power of the mathematical language to produce logical arguments has led a number of philosophers throughout the ages to resort to mathematics as a way of proving the existence of God. But I always have a problem with such an approach. If you are going to prove existence or otherwise in mathematics, you need a very clear definition of what it is that you are trying to prove exists.
So after some badgering by the interviewer about my stance on the existence of God, I pushed him to try to define what God meant for him so that I could engage my mathematical mind. ‘It is something which transcends human understanding.’ At first I thought: what a cop-out. You have just defined it as something which by its very nature I can’t get a handle on. But I became intrigued by this as a definition. Perhaps it wasn’t such a cop-out after all.
What if you define God as the things we cannot know. The gods in many ancient cultures were always a placeholder for the things we couldn’t explain or couldn’t understand. Our ancestors found volcanic eruptions or eclipses so mysterious that they became acts of gods. As science has explained such phenomena, these gods have retreated.
This definition has some things in common with a God commonly called the ‘God of the gaps’. This phrase was generally used as a derogatory term by religious thinkers who could see that this God was shrinking in the face of the onslaught of scientific knowledge, and a call went out to reject this kind of God. The phrase ‘God of the gaps’ was coined by the Oxford mathematician and Methodist church leader Charles Coulson, when he declared: ‘There is no “God of the gaps” to take over at those strategic places where science fails.’
But the phrase is also associated with a fallacious argument for the existence of God, one that Richard Dawkins spends some time shooting down in The God Delusion: if there are things that we can’t explain or know, there must be a God at work filling the gap. But I am more interested not in the existence of a God to fill the gap, but in equating God with the abstract idea of the things we cannot know. Not in the things we currently don’t know, but the things that by their nature we can never know. The things that will always remain transcendent.
Religion is more complex than the simple stereotype often offered up by modern society. For many ancient cultures in India, China and the Middle East, religion was not about worshipping a Supernatural Intelligence but precisely the attempt to appreciate the limits of our understanding and language. As the theologian Herbert McCabe declared: ‘To assert the existence of God is to claim that there is an unanswered question about the universe.’ Science has pushed hard at those limits. So is there anything left? Will there be anything that will always be beyond the limit. Does McCabe’s God exist?
This is the quest at the heart of this book. Can we identify questions or physical phenomena that will always remain beyond knowledge? If we can identify things that will remain in the gaps of knowledge, then what sort of God is this? What potency would such a concept have? Could the things we cannot know act in the world and affect our futures? Are they worthy of worship?
But first we need to know if in fact there is anything that will remain unanswered about the universe. Is there really anything we cannot know?
The unpredictable and the predetermined unfold together to make everything the way it is. It’s how nature creates itself, on every scale, the snowflake and the snowstorm. It makes me so happy. To be at the beginning again, knowing almost nothing.
Tom Stoppard, Arcadia
There is a single red dice sitting on my desk next to me. I got the dice on a trip to Las Vegas. I fell in love with it when I saw it on the craps table. It was so perfectly engineered. Such precise edges coming to a point at the corners of the cube. The faces so smooth you couldn’t feel what number the face was representing. The pips are carved out of the dice and then filled with paint that has the same density as the plastic used to make the dice. This ensures that the face representing the 6 isn’t a touch lighter than the face on the opposite side with a single pip. The feeling of the dice in the hand is incredibly satisfying. It is a thing of beauty.
And yet I hate it.
It’s got three pips pointing up at me at the moment. But if I pick it up and let it fall from my hand I have no way of knowing how it is going to land. It is the ultimate symbol of the unknowable. The future of the dice seems knowable only when it becomes the past.
I have always been extremely unsettled by things that I cannot know. Things that I cannot work out. I don’t mind not knowing something provided there is some way ultimately to calculate what’s going on. With enough time. Is this dice truly so unknowable? Or with enough information can I actually deduce its next move? Surely it’s just a matter of applying the right laws of physics and solving the appropriate mathematical equations. Surely this is something I can know.
My subject, mathematics, was invented to give people a glimpse of what’s out there coming towards us. To look into the future. To become masters of fate, not its servants. I believe that the universe runs according to laws. Understand those laws and I can know the universe. Spotting patterns has given the human species a very powerful way to take control. If there’s a pattern then I have some chance to predict the future and know the unknowable. The pattern of the Sun means I can rely on it rising in the sky tomorrow or the Moon taking 28 sunrises before it becomes full again. It is how mathematics developed. Mathematics is the science of patterns. Being able to spot patterns is a powerful tool in the evolutionary fight for survival. The caves in Lascaux show how counting 13 quarters of the Moon from the first winter rising of the Pleiades will bring you to a time in the year when the horses are pregnant and easy to hunt. Being able to predict the future is the key to survival.
But there are some things which appear to have no pattern or that have patterns that are so complex or hidden that they are beyond human knowledge. The individual roll of the dice is not like the rising of the Sun. There seems to be no way to know which of the six faces will be pointing upwards once the cube finally comes to rest. It is why the dice has been used since antiquity as a way to decide disputes,