Hello my name is Stephen Hawking, physicist, cosmologist and something of a dreamer. Although I cannot move and have to speak through a computer, in my mind I am free. Free to explore the deepest questions of the universe. Among them the deepest of all, Is there a god who created and controls the universe, from the stars and the planets, to you and me? Finding out takes us on a journey on the Laws of Nature for there I think lies the answer to the age old mystery of how the universe was made and how it really works. Check it out.
I recently published a book that asked if a god created the universe. I caused something of a stir. People got upset that a scientist should have anything to say on matters of religion. I have no desire to tell anyone what to believe but for me asking whether God exists is a valid question for science. . After all is it is hard to think of a more important or fundamental mystery than what or who created and controls the universe.
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 lightening or storms. The Vikings had many different gods. Thor (from whose name we have the day named Thursday) was the god of lightening. Another god Aegir (from whom we have the Aegean Sea) caused stormy seas. But the god they feared the most was named Skoll. He was responsible for the terrifying natural event which we now call a solar eclipse. Skoll was a wolf god who lived in the sky and sometimes he would eat the sun causing the dreadful moment when day turned to night. Without a scientific explanation imagine how disturbing it would have been to see the sun vanish. The Vikings responded in the only way that made sense to them. They tried to scare away the wolf, by shouting incantations at it and praying loudly to Odin their supreme god. The Vikings believed that their actions caused the sun to return. Of course we now know they had nothing to do with it. The sun would have returned anyway. It turns out the universe is not as supernatural or mysterious as it seems. But it takes more courage the Vikings had to discover the truth. Mere mortals like you and I can understand how the universe works. This was realized long before the Vikings, in ancient Greece.
In about 300 BC, a philosopher named Aristarchus was fascinated by eclipses too, especially eclipses of the moon. He was brave enough to question whether they were really caused by gods. Aristarchus was a true scientific pioneer. He studied the heavens carefully and reached a bold conclusion. He realized that 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 instead orbits the sun. In fact understanding this arrangement explains all eclipses. When the moon casts its shadow on the earth that is a solar eclipse, and when the earth shades the moon, that is a lunar eclipse. But Aristarchus took it even further. He suggested that the stars were not chinks in the floor of heaven as his contemporaries believed but that stars were other suns like ours, only a very long 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 achievement for it is these Laws of Nature as we now call them that will tell us whether we need a god to explain the universe at all.
For centuries it was believed that disabled people like me were living under a curse inflicted by God. While I suppose it’s possible I upset someone up there, I prefer to think everything can be explained another way by the Laws of Nature. So what exactly is a law of nature and why is it so powerful? I will show you with a game of tennis. Tennis is governed by two sets of laws. One set is manmade, the rules of the game. They govern things such as the size of the court, the height of the net and what determines if a shot is in or a shot is out. These rules can conceivably be changed if the governing body of tennis so desired. But the other set of laws that apply to the game are fixed, immutable. They govern what will happen to the ball when it is hit. The force and angel of the racket strike determines exactly what happens next. 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 (the Laws of Nature) say it will. And there are many 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 muscles to the speed at which the grass grows beneath their feet. But what is really important is 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 ever be broken. That is 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 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 recently made headlines it is actually an ancient conflict.
Back in 1277 Pope John XXI felt so threatened by the idea of Laws of Nature that he decreed them a heresy. Unfortunately that did nothing to change the law governing gravity. A few months later (during a storm) the palace roof collapsed and fell on the Pope’s head ( and killed him). But organized religion soon found a solution. For the next few hundred years it was simply stated that the Laws of Nature were the work of God, and God could break them if he wished to. This view was further reinforced that our perfect blue planet was quite still at the center of it all, and all the stars and planets rotated around the earth like some carefully designed clockwork. Aristarchus’s idea to the contrary had been long forgotten. But humans are naturally inquisitive and some such as Galileo Galilei could not help but look at “God’s clockwork” once more.
It was the year 1609, and this time the results would change everything. Galileo is the founder of modern day science and one of my heroes. He thought, as I do, that if you looked at the universe closely enough, you could discern what was really going on. He was so determined that he perfected lenses that could for the first time magnify the night sky by 20 times. Carefully, he assembled them into a telescope. From his house in Padua (in Italy) he used this telescope to study Jupiter, night after night, and made a wonderful discovery, three tiny dots very close to the giant planet. To begin with he thought the dots must be very faint stars but then as he watched for a few nights he saw that they moved. And then a fourth dot appeared. Sometimes one of them would vanish behind Jupiter and then reappear. He realized they had to be moons circling the vast planet. Here was proof positive that at least some objects do not orbit the earth. Inspired by this discovery, Galileo went on to prove that the earth must in fact orbit the sun. Aristarchus had been right all along. Galileo’s discoveries triggered a revolution in thought that would ultimately loosen the grip of religion over science. But back in the 17th century they got him into a lot of trouble with the church. He narrowly avoided execution by recanting his so called heresy and was confined to house arrest for the last nine years of his life. Legend has it that even as he confessed his sin he muttered “…but it does move …” Over the next 300 years, as more and more of the Laws of Nature were discovered science began to explain all kinds of things from lightening, earthquakes and storms, to what makes the stars shine. Each new discovery further removed the need for a god. After all if you know the science behind an eclipse you are much less likely to believe in wolf-gods that live in the sky.
Science does not deny religion, it just offers a simpler alternative. Yet several mysteries remain. After all if the earth moves could it be God that moves it? Ultimately did God create a universe in the first place? In 1985 I attended a conference on cosmology at the Vatican in Rome. The gathering of scientists had an audience with Pope John Paul II. He told us that it was OK to study the workings of the universe, but we should not ask questions about its origin for that was the work of God. I am glad to say that I for one haven’t followed his advice. I can’t simply switch off my curiosity. I believe it is a cosmologist’s duty to try to work out where the universe came from. Luckily it’s not as difficult as it seems. Despite the complexity and variety of the universe, it turns out that to make one you need just three ingredients.
Let’s imagine we could list them in some kind of 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 for incredible distances. The second ingredient you need is energy. Even if we’ve never thought about it, we all know what energy is. Something we encounter everyday. Look up at the sun, and you can feel it on your face. Energy produced by a star 93 million miles away. Energy permeates the universe, driving the processes that keep it a dynamic and 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 and more space, and more space stretching in all directions, enough to make your head spin. So where could all this matter, energy, and space come from? We had no idea until well into the 20th 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 remarkable, that two of the main ingredients needed to make a universe, mass and energy, are basically the same thing, two sides of the same coin if you like. His famous equation, E=mc^2 simply means mass can be thought of as a kind of energy and vice versa. So instead of three ingredients we can 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 energy were spontaneously created in an event we now call the Big Bang. At the moment of the Big Bang, an entire universe full of energy came into existence, and with it space. It all inflated just like a balloon being blown 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 that created the energy and the 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 far more of the natural phenomena that terrified the Vikings. We can even go beyond the beautiful symmetry of matter and energy discovered by Einstein. We can use the Laws of Nature to grasp the very origins of the universe and discover if the existence of a 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 taught that you never get something for nothing. But now after a lifetime of work I think that in fact 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 secret lies in one the strangest facts about our cosmos. The Laws of Physics demand the existence of something called Negative Energy. To get your head around this weird but crucial concept let me draw an 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 is not just making a hill, he is 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 principal behind was happened right at the beginning of the universe. When the Big Bang produced the vast amount of positive energy, it simultaneously produced the 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 is in the third ingredient in our cosmic cook book. It’s in space. This may sound odd but due 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 will admit that unless mathematics is your thing, this is hard to grasp but it’s true. The endless web of billions upon billions of galaxies each pulling on one another 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 the energy we see today is like the hill. The corresponding hole or negative side of things is spread throughout space. So what does that mean on 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 negative in the universe adds up to zero all we have to do now is 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 things don’t simply materialize out of the blue. You can’t just click your fingers and summon up a cup of coffee when you feel like one, can you? You have to make it up of other stuff like coffee beans, water, perhaps a milk, and sugar. But travel down into 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 Laws 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, smaller than a proton in fact, this means something quite remarkable. It means the universe itself, in all of its mind boggling vastness and complexity can 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 books. But of course the critical question is raised again. Did God create the quantum laws that allowed the Big Bang to occur?
In a nutshell do we need a god to set it all 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. This explanation is made possible because of something strange about the principle of cause and effect. Our everyday experience makes us convinced that everything that happens must be caused by something that occurred earlier in time. So it’s natural for us to assume that something, perhaps God, must have caused the universe to come into existence. But when we’re talking about the universe as a whole it isn’t necessarily so. Let me explain. Imagine a river flowing down a mountainside. What caused the river? Well, perhaps the rain, rain that fell earlier in the mountains. But then, what caused the rain? A good answer would be the sun, the sun that shone on the ocean and lifted water vapor up into the sky and made clouds. Ok, 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 is the crucial bit. The Laws of Nature themselves tell us that not only could the universe have popped into existence like a proton, and have acquired 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 happed to time at the instant of the Big Bang. Time itself began. To understand this mind boggling idea, consider one of these, a black hole floating in space. A typical black hole is star, so massive 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. Its gravitational field is so powerful it doesn’t only distort and warp 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 it could withstand the extreme gravitational forces, the clock would actually stop. It stops not because it’s broken but because inside the black hole itself, time doesn’t exist. That is exactly what happed at the start of the universe. 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 with the whole universe is in a space so small that it is in effect a single infinitesimally small, infinitesimally dense black hole. And just as with modern day black holes floating around in space, the Laws of Nature dictate something quite extraordinary. They tell us that here too time itself must come to a stop. You can’t get to a time before the Big Bang because there was no “before the Big Bang”. We have finally found something that doesn’t have a cause because there was no time for a cause to exist in. For me this means there is no possibility of a creator because there is no time for a creator to have existed. Since time itself began at the moment of the Big Bang, it was an event that could not have been caused or created by anyone or anything. So science has given us the answer we set out to discover, an answer that took more than three thousand years of human endeavor. We have discovered how the Laws of Nature acting on the mass and energy of the universe, started a process that would eventually produce us, sitting here on our planet, pretty pleased at having worked it all out. So when people ask me did a god create 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, it doesn’t have an edge, so looking for it is a futile exercise.
We are each free to believe what we want and it’s my view that the simplest explanation is 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 no afterlife either. We have this one life to appreciate the grand design of the universe and for that I am extremely grateful.
kwaku ba, January 2012