Here’s a question I’ve been hearing regarding Stephen Hawking’s new book, Brief Answers to the Big Questions: What business does a scientist have weighing in on the existence of God? This is asked as if someone who best understands the workings of the universe is utterly unqualified to make statements about its ultimate origins.
It’s surprising that people would resist wanting to hear what the foremost physicist of our times has to say about the origins of our universe. I think the answer is partly that they’re afraid of what he has to say, but that there is a also a deeper psychological explanation.
There’s a relevant fallacy at work here, called the illusion of explanatory depth. Particularly in regard to science, many people feel that they understand complex phenomena with far greater precision, coherence, and depth than they actually do. People have a tendency to overestimate their knowledge and then, when their knowledge breaks down, if they are religious, they simply insert God to fill in the gaps of their own understanding.
But the universe doesn’t work that way. It doesn’t conform to our intuitions. The simple physics of our everyday world do not apply to large scale phenomena (relativity) or small scale phenomena (quantum mechanics). “The universe,” as Neil deGrasse Tyson said, “is under no obligation to make sense to you.”
But it does make sense to the mathematical models of modern physics, to which Hawking is thoroughly familiar and a contributor. And Hawking is not just claiming that God doesn’t exist; he’s claiming that it is utterly incoherent to even propose that God exists, based on our current understanding of these models. He provides two reasons for this.
First, the mathematics of the universe shows that net energy is always zero. Positive energy takes the form of matter, whereas space provides the counter-balancing negative energy. Hawking uses the analogy of making a hill out of flat land. The hole you dig represents negative energy, while the resulting mound of soil that makes up the hill represents positive energy. The universe is like this, with matter and space counterbalancing the possibility for any excess energy. Additionally, quantum mechanics demonstrates that matter can spontaneously arise from nothing under the right conditions, where positive and negative energy counterbalance each other. So, if matter can pop into existence, and no new energy is created in the process, and this all occurs according to fixed laws, then there is in fact no need for a creator.
The second point has to do with the initial state of the universe. Since we know the rate at which the universe is expanding, we can rewind the process to determine that the universe was, at one point, incredibly dense and smaller than an atom. At this point, the laws of quantum mechanics, that show how matter can spring from nothing, with positive and negative energy that sums to nothing, could produce the universe from nothing. Within this singularity, time does not exist. Because time does not exist before the Big Bang, it makes no sense to ask what came before the Big Bang. According to Hawking, the answer cannot be God, or anything else, because asking what came before the Big Bang is like asking where the edge of the earth is. Time itself was created with the Big Bang and is therefore the starting point of all time. Why did the Big Bang happen when it did? That’s an incoherent question, because time itself began at that moment. As Einstein demonstrated, time and space are not absolute.
I fell for this trap myself. I had always asked, what came before the Big Bang? Or, why did the Big Bang happen when it did, and not sooner or later? I didn’t realize that I was asking the wrong question, or asking a meaningless or incoherent question based on assumptions that don’t align with the reality of the actual physics.
Now what about the actual laws of quantum mechanics themselves? Or the existence of the necessary positive and negative energy to begin with? Doesn’t this require a creator? Maybe, and in truth no one can really know. But all that positing a creator does is add additional mystery to the universe, and you can’t solve a mystery by introducing a bigger mystery.
We can always posit the existence of God at whatever gaps we have in our knowledge, but that’s a tiresome game to play. Before we could explain the weather, God determined it. Before we could explain the motions of the planets, God directed it. Before we could explain the complexity and diversity of life, God created it. Whatever gaps we have in our current scientific understanding, God is there as a synonym for our ignorance. But this “God of the gaps,” throughout history, has been pushed farther and farther to the margins. If you extrapolate the trend far enough into the future, he eventually disappears.
Understanding the ultimate origins of the universe may be beyond our powers, but we have to continue to try, because we don’t know what we can discover before we discover it. Claiming the existence of God is just throwing in the towel prematurely.
It’s due time that we admit that the universe operates according to natural laws, and that positing the existence of anything beyond those laws is a relic of our ancient past. Hawking was able to do this, even in the face of death. As Hawking said, “We have this one life to appreciate the grand design of the universe, and for that I am extremely grateful.”