Is there a God?
By Stephen Hawking
Science is increasingly answering questions that used to be the province of religion. Religion was an early attempt to answer the questions we all ask: why are we here, where did we come from? Long ago, the answer was almost always the same: gods made everything. The world was a scary place, so even people as tough as the Vikings believed in supernatural beings to make sense of natural phenomena like lightning, storms or eclipse. Nowadays, science provides better and more consistent answers, but people will always cling to religion, because it gives comfort, and they do not trust or understand science.
A few years ago, The Times newspaper ran a head-line on the front page which said ‘Hawking: God Did Not Create Universe’. The article was illustrated. God was shown in a drawing by Michelangelo, looking thunderous. They printed a photo of me, looking smug. They made it look like a duel between us. But I don’t have a grudge against God. I do not want to give the impression that my work is about proving or disproving the existence of God. My work is about finding a rational framework to understand the universe around us.
For centuries, it was believed that disabled people like me were living under a curse that was inflicted by God. Well, I suppose it’s possible that I’ve upset someone up there, but I prefer to think that everything can be explained another way, by the laws of nature. If you believe in science, like I do, you believe that there are certain laws that are always obeyed. If you like, you can say that the laws are the work of God, but that is more a definition of God than a proof of his existence. In about 300 BCE, a philosopher called Aristarchus was fascinated by eclipses, especially eclipses of the Moon. He was brave enough to question whether they really were caused by gods. Aristarchus was a true scientific pioneer. He studied the heavens carefully and reached a bold conclusion: he realized the eclipse was really the shadow of the Earth passing over the Moon, and not a divine event. Liberated by this discovery, he was able to work out what was really going on above his head, and draw diagrams that showed the true relationship of the Sun, the Earth and the Moon. From there he reached even more remarkable conclusions. He deduced that the Earth was not the center of the universe, as everyone had thought, but it instead orbits the Sun. In fact, understand this arrangement explains all eclipses. When the Moon casts its shadow on the Earth, that’s a solar eclipse. And when the Earth shades the Moon, that’s a lunar eclipse. But Aristarchus took it even further. He suggested that stars were not chinks in the floor of heavens, as his contemporaries believed, but that stars are other suns, like ours, only a very long way away. What a stunning realization it must have been. The universe is a machine governed by principles or laws – laws that can be understood by the human mind.
I believe that the discovery of these laws has been humankind’s greatest achievements, for its these laws of nature – as we now call them – that will tell us whether we need a god to explain the universe at all. The laws of nature are a description of how things actually work in the past, present and future. In tennis, the ball always goes exactly where they say it will. And there are other laws at work here too. They govern everything that is going on, from how the energy of the shot is produced in the player’s muscle to the speed at which the grass grows beneath their feet. But what’s really important is that these physical laws, as well as being unchangeable, are universal. They apply not just to the flight of a ball, but to the motion of a planet, and everything else in the universe. Unlike laws made by humans, the laws of nature cannot be broken – that’s why they are so powerful and, when seen from a religious standpoint, controversial too.
If you accept, as I do, that the laws of nature are fixed, then it doesn’t take long to ask: what role is there for God? This is a big part of the contradiction between science and religion, and although my views have made headline, it is actually an ancient conflict. One could define God as the embodiment of the laws of nature. However, this is not what most people would think of as God. They mean a human-like being, with whom one can have a personal relationship. When you look at the vast size of the universe, and how insignificant and accidental human life is in it, that seems most implausible.
I used the word ‘God’ in an impersonal sense, like Einstein did, for the laws of nature, so knowing the mind of God is knowing the laws of nature. My prediction is that we will know the mind of God by the end of this century.
The one remaining area that religion can now lay claim to is the origin of the universe. But even here science is making progress and should soon provide a definitive answer to how the universe began. I published a book that asked if God created the universe, and that caused something of a stir. People got upset that a scientist should have anything to say on the matter of religion. I have no desire to tell anyone what to believe, but for me asking if God exists is a valid question for science. After all, it is hard to think of a more important, or fundamental, mystery than what, or who created and controls the universe.
I think the universe is spontaneously created out of nothing, according to the law of science. The basic assumption of science is scientific determinism. The laws of science determine the evolution of universe, given its state at one time. These laws may, or may not, have decreed by God, but he cannot intervene to break the laws or they would not be laws. That leaves God with the freedom to choose the initial state of the universe, but even here it seems there may be laws. So God would have no freedom at all.
Despite the complexity and variety of the universe, it turns out that to make one you just need three ingredients. Let’s imagine that we could list them in some cosmic cookbook. So what are the three ingredients we need to cook up a universe? The first is matter – stuff that has mass. Matter is all around us, in the ground beneath our feet and out in space. Dust, rock, ice, liquids. Vast clouds of gas, massive spirals of stars, each containing billions of suns, stretching away from incredible distances.
The second thing you need is energy. Even if you’ve never thought about it, we all know what energy is. Something we encounter every day. Look up the Sun and you can feel it in your face: energy produced by a star ninety-three million miles away. Energy permeates the universe, driving the process that keep it a dynamic, endlessly changing place.
So we have matter and we have energy. The third thing we need to build a universe is space. Lots of space. You can call the universe many things – awesome, beautiful, violent – but one thing you can’t call it is cramped. Wherever we look we see space, more space and even more space. Stretching in all directions. It’s enough to make your head spin. So where could all this matter, energy and space come from? We had no idea until the twentieth century.
The answer came from the insights of one man, probably the most remarkable scientist who has ever lived. His name was Albert Einstein. Sadly, I never got to meet him, since I was only thirteen when he died. Einstein realized something quite extraordinary: that two of the main ingredients needed to make the universe – mass and energy – are basically the same thing, two sides of the same coin if you like. His famous equation, E=mc2 simply mean that mass can be thought of as a kind of energy, and vice versa. So instead of three ingredients, we can now say that the universe has just two: energy and space. So where did all this energy and space come from? The answer was found after decades of work by scientists: space and time were spontaneously invented in an event we now called the Big Bang.
At the moment of the Big Bang, an entire universe came into existence, and with it, space. It all inflated, just like a balloon being blow up. So where did all this energy and space come from? How does an entire universe full of energy, the awesome vastness of space and everything in it, simply appear out of nothing?
For some, this is where God comes back into the picture. It was God who created the energy and space. The Big Bang was the moment of creation. But science tells a different story. At the risk of getting myself into trouble, I think we can understand much more the natural phenomena that terrified the Vikings. We can even go beyond the beautiful symmetry of energy and matter discovered by Einstein. We can use the laws of nature to address the very origins of the universe, and discover if the existence of God is the only way to explain it.
As I was growing up in England after the Second World War, it was a time of austerity. We were told that you never get something for nothing. But now, after a lifetime of work, I think that actually you can get a whole universe for free.
The great mystery at the heart of the Big Bang is to explain how an entire, fantastically enormous universe of space and energy can materialize out of nothing. The secrete lies in one of the strangest facts about our cosmos. The laws of physics demand the existence of something called ‘negative energy’.
To help you get your head around this weird but crucial concept, let me draw on a simply analogy. Imagine a man wants to build a hill on a flat piece of land. The hill will represent the universe. To make this hill he digs a hole in the ground and uses that soil to build his hill. But of course he’s not just making a hill – he’s also making a hole, in effect a negative version of the hill. The stuff that was in the hole has now become the hill, so it all perfectly balances out. This is the principle behind what happened at the beginning of the universe.
When the Big Bang produced a massive amount of positive energy, it simultaneously produced same amount of negative energy. In this way, the positive and the negative add up to zero, always. It’s another law of nature.
So where is all this negative energy today? It’s in the third ingredient in our cosmic cookbook: it’s in space. This may sound odd, but according to the laws of nature concerning gravity and motion – laws that are among the oldest in science – space itself is a vast store of negative energy. Enough to ensure that everything adds up to zero.
I’ll admit that, unless mathematics is your thing, this is hard to grasp, but it’s true. The endless web of billions up billions of galaxies, each pulling on each other by the force of gravity, acts like a giant storage device. The universe is like an enormous battery storing negative energy. The positive side of things – the mass and energy we see today – is like the hill. The corresponding hole, or negative side of things, is spread throughout space.
So what does this mean in our quest to find out if there is a God? It means that if the universe adds up to nothing, then you don’t need a God to create it. The universe is the ultimate free lunch.
Since we know that the positive and the negative add up to zero, all we need to do now is to work out what – or dare I say who – triggered the whole process in the first place. What could cause the spontaneous appearance of a universe? At first, it seems a baffling problem – after all, in our daily lives thing don’t just materialize out of the blue. You can’t just click your fingers and summon up a cup of coffee when you feel like one. You have to make it out of other stuff like coffee bean, water and perhaps some milk and sugar. But travel down to this coffee cup – through the milk particles, down to the atomic level and right down to the sub-atomic level, and you enter a world where conjuring something out of nothing is possible. At least, for a short while. That’s because, at this scale, particles such as protons behave according to the law of nature we call quantum mechanics. And they really can appear at random, stick around for a while and then vanish again, to reappear somewhere else.
Since we know that the positive and the negative add up to zero, all we need to do now is to work out what – or dare I say who – triggered the whole process in the first place. What could cause the spontaneous appearance of a universe? At first, it seems a baffling problem – after all, in our daily lives thing don’t just materialize out of the blue. You can’t just click your fingers and summon up a cup of coffee when you feel like one. You have to make it out of other stuff like coffee bean, water and perhaps some milk and sugar. But travel down to this coffee cup – through the milk particles, down to the atomic level and right down to the sub-atomic level, and you enter a world where conjuring something out of nothing is possible. At least, for a short while. That’s because, at this scale, particles such as protons behave according to the law of nature we call quantum mechanics. And they really can appear at random, stick around for a while and then vanish again, to reappear somewhere else.
Since we know the universe itself was once very small – perhaps smaller than a proton – this means something quite remarkable. It means the universe itself, in all its mind-boggling vastness and complexity, could simply have popped into existence without violating the known laws of nature. From that moment on, vast amounts of energy were released as space itself expanded – a place to store all the negative energy needed to balance the book. But of course the critical question is raised again: did God created the quantum laws that allowed the Big Bang to occur? In a nutshell, do we need a God to set it up so that the Big Bang could bang? I have no desire to offend anyone of faith, but I think science has a more compelling explanation than a divine creator.
Our everyday experience makes us think that everything that happens must be caused by something that occurred earlier in time, so it’s natural for us to think that something - maybe God – must have caused the universe to come into existence. But when we’re talking about the universe as a whole, that isn’t necessarily so. Let me explain. Imagine a river, flowing down a mountainside. What caused the river? Well, perhaps the rain that fell earlier in the mountains. But then, what caused the rain? A good answer would be the Sun, that shone down on the ocean and lifted water vapor up into the sky and made clouds. Okay, so what caused the Sun to shine? Well, if we look inside we see the process known as fusion, in which hydrogen atoms join to form helium, releasing vast quantities of energy in the process. So far so good. Where does the hydrogen come from? Answer: the Big Bang. But here’s the crucial bit. The laws of nature itself tell us that not only could the universe have popped into existence without any assistance, like a proton, and have required nothing in terms of energy, but also that it is possible that nothing caused the Big Bang. Nothing.
The explanation lies back with the theories of Einstein, and his insights into how space and time in the universe are fundamentally intertwined. Something very wonderful happened to time at the instant of the Big Bang. Time itself began.
To understand this mind-boggling idea, consider a black hole floating in space. A typical black hole is a star so massive that it has collapsed in on itself. It’s so massive that not even light can escape its gravity, which is why it’s almost perfectly black. It’s gravitational pull is so powerful, it warps and distorts not only light but also time. To see how, imagine a clock is being sucked into it. As the clock gets closer and closer to the black hole, it begins to get slower and slower. Time itself begins to slow down. Now imagine the clock as it enters the black hole – well, assuming of course that it could withstand the extreme gravitational forces – it would actually stop. It stops not because it is broken, but because inside the black hole time itself doesn’t exist. And that’s exactly what happened at the start of the universe.
In the last hundred years, we have made spectacular advances in our understanding of the universe. We now know the laws that govern what happens in all but the most extreme conditions, like the origin of the universe, or black holes. The role played by time at the beginning of the universe is, I believe, the final key to removing the need for a grand designer and revealing how the universe created itself.
As we travel back in time towards the moment of the Big Bang, the universe gets smaller and smaller and smaller, until it finally comes to a point where the whole universe is a space so small that it is in effect a single infinitesimally small, infinitely dense black hole, floating around in space, the laws of nature dictates something quite extraordinary. They tell us hat here too time itself must come to a stop. You can’t get to a time before the Big Bang because there was no time before the Big Bang. We have finally found something that doesn’t have a cause, because there was no time to a cause to exist in. For me this means that there is no possibility of a creator, because there is no time for a creator to have existed in.
People want answer to big questions, like why we are here. They don’t expect the answer to be easy, so they are prepared to struggle a bit. When people ask me if a God created the universe, I tell them that the question itself makes no sense. Time didn’t exist before the Big Bang so there is no time for God to make the universe in. It’s like asking for directions to the edge of the Earth – the Earth is a sphere that doesn’t have an edge, so looking for it is a futile exercise.
Do I have faith? We are each free to believe what we want, and it’s my view that the simplest explanation is that there is no God. No one created the universe and no one directs our fate. This leads me to a profound realization: there is probably no heaven and afterlife either. I think believe in an afterlife is just wishful thinking. There is no reliable evidence for it, and it flies in the face of everything we know in science. I think that when we die we return to dust. But there’s a sense in which we live on, in our influence, and in our genes that we pass on to our children. We have this one life to appreciate the grand design of the universe, and for that I am extremely grateful.
From Brief Answers to the Big Questions by Stephen Hawking， John Murray Publishers (2018) |
2021/3/25 23:34
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2021/3/26 01:45
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