Stephen Hawking: from Brief Answers to the Big Questions

“…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 the laws are the work of God, but that is more a definition of God than a proof of his existence…(26).

“I believe that the discovery of these laws has been humankind’s greatest achievement, for it’s 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 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 players’ muscles 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…(27-8).

“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 use 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…(28). I think the universe was spontaneously created out of nothing, according to the laws of science...(29).

“Despite the complexity and variety of the universe, it turns out that to make one you need just three ingredients. Let’s imagine that 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 (29).

“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 at the Sun and you can feel it on your face: energy produced by a star ninety-three million miles away. Energy permeates the universe, driving the processes 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…(30). 

“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. (31).

“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 of the strangest facts about our cosmos. The laws of physics demand the existence of something called ‘negative energy' (30-1).

“To help you get your head around this weird but crucial concept, let me draw on a simple 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 dig 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 (32). 

“When the Big Bang produced a massive 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 (32).

“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 (32).

“I’ll 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 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 (33). 

“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 (33).

“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 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 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…(34).

“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...(34-5).

“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. Its 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…(35-7).

“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, 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 time 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 that there is no possibility of a creator, because there is no time for a creator to have existed in…(37-8).

“[I]t’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 belief 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…(38).

“One day, I hope we will know the answers to all these questions. But there are other challenges, other big questions on the planet which must be answered, and these will also need a new generation who are interested and engaged, and have an understanding of science. How will we feed an ever-growing population? Provide clean water, generate renewable energy, prevent and cure disease and slow down global climate change? I hope that science and technology will provide the answers to these questions, but it will take people, human beings with knowledge and understanding, to implement these solutions. Let us fight for every woman and every man to have the opportunity to live healthy, secure lives, full of opportunity and love. We are all time travelers, journeying together into the future. But let us work together to make that future a place we want to visit. Be brave, be curious, be determined, overcome the odds. It can be done…”(21-2).  (These excerpts are also from Brainpickings). 

Hawking, Stephen. Brief Answers to the Big Questions. New York: Bantam Books, 2018.