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Limiting God

The traditional view of God holds that he is both omniscient and omnipotent, that God created the universe and has taken a keen interest ever since. But how can we actually know this for sure? How can we, with science–civilisation’s finest intellectual achievement–test and probe, and so establish that God is both? In short, we can’t. Physics describes the universe. God, by definition, exists somehow “outside” the universe. Therefore physics, and science more-broadly, cannot describe God. The existence of God is a matter of faith, and faith is the antithesis of science, which is characterised by enquiry and testable theories. (Put simply, science is knowledge through evidence. Faith is belief in the absence of evidence.) We can never prove or disprove the existence of God.

Nevertheless, science can tell us where God isn’t. God isn’t to be found in the creation of the Earth–copious evidence from physics, geology and cosmology tells us of Earth’s 4600 million-year history, from coalescence from interstellar dust to what we see today. To claim, as some creationists do, that the Earth is only about 6000 years old is laughable and naive. If God created Man and gave him intellect and reason, it is a slap in God’s face when people refuse to use their gifts and the evidence all around them to argue against the seemingly miraculous chain of events leading to their existence in favour of the egocentric viewpoint that God created the universe just to put them in it. To claim that God created fossils to mislead us (or to test our faith) is to accuse God of lying to us, something any religious person would outright refuse if it were put in those terms. If you were God, would you want to go to all the bother of creating something extraordinarily complex just so some unimaginative person could deny it?

God is also not to be found in the evolution of life. Evolution is not a matter of faith among scientists–it is a demonstrable fact. Proponents of Intelligent Design, who allow the process of evolution but insist on the hand of God guiding it, are guilty of “argument from personal incapacity,” an error of reasoning one step beyond “argument from personal incredulity.” “Argument from personal incredulity” says “I cannot believe that it is true. Therefore it isn’t.” “Argument from personal incapacity” says “I am not capable of understanding how it works. Therefore it doesn’t.”

No one has put it better than Richard Dawkins in his book The Blind Watchmaker. All that is required in order to understand evolution is to be able to envisage a small-enough change in an organism. If that change is still too big to explain evolution by natural selection, then simply break it up into smaller steps. There is nothing miraculous in this. People who claim that God must have had a hand in evolution, or even in their personal existence, imply an insult to God. Which God is the more remarkable: the one who designed the universe to run without a hitch from the moment of the Big Bang (and who could foresee how evolution would work), or the one who has to keep fiddling to make sure that the whole thing keeps working? The latter is God the Tinkerer, who is seen in the events leading up to Noah’s flood. He made the Earth and saw that it was good, but nevertheless had to pull it apart for repairs when it went wrong. If God is perfect, then why does he have to keep tinkering? If God has any feelings, surely this upsets him to think that people believe he has to keep fixing his mistakes.

Here we have the ignorant defining the behaviour of God. If God had the supreme intelligence to create this extraordinarily-complex universe, then we haven’t the slightest hope of understanding his mind or his reasons. Our brains contain around 10e11 neurons in a volume of about 1 litre. This is an infinitesimal part of the universe–it is not enough to give us the capacity to understand (that is, create an accurate mental model of) the universe, so it is sheer hubris to believe that we can understand God. There are simply nowhere near enough permutations and combinations of neurons to allow us to understand something so big and complex as the universe. To put it another way, we do not have enough brain capacity to create an accurate model of the universe in our minds.

I don’t know whether God exists or not, but I recognise that I can neither prove nor disprove his existence. However (and notwithstanding my criticism of those who try to define God’s behaviour), I can define some limits to his omniscience. To put it simply, God cannot predict the future. Physics shows us why.

The universe consists of something like 10e80 particles, all whizzing around and bumping into each other. As well as the actual particles, uncountable numbers of virtual particles continuously pop into and out of existence in a tiny fraction of a second. Their existence is readily testable, and they have measurable effects. Their appearance is entirely random.

Many philosophers have argued for a mechanistic universe. In such a universe, given the initial positions and trajectories of particles and enough computing power, it is possible to predict any future state. Such a universe also denies free will, a point that has worried a lot of people. But the universe also appears to be random. How do we reconcile these two views? Well, the argument goes that anything that seems to be random becomes predictable if only enough processing power can be thrown at the problem. Surely God has enough? What does a computer (or a mind) that can predict the future of the universe look like? How do you follow the movements of every single particle in the universe? Whatever the system–whether it is the mind of God or God’s hypercomputer–it has to be based on matter or energy (which, as we know, are interchangeable). The simplest way is with the universe itself. The best model of anything is that thing itself. What could be a better model (simulation, “future memory”) of the universe than itself? (The alternative is an even bigger computer to correctly model the universe. If that is the case, then what is the purpose of the universe? Parsimony would suggest that God keeps only the one universe.) But here we run into the first problem: the universe is incomplete. As Gödel showed, any complex system cannot contain a complete description of itself. In practice, this means that if the universe is a computer model of itself, it is incomplete, thus God cannot rely on it to give an accurate description of itself; there remain gaps in God’s knowledge of the universe.

The very smallest meaningful length in the universe is the Planck length, which is 1.1616 x 10e-35 m. No distance smaller than this has any meaning. If we could be precise to a Planck length about the position of an object of a kilogram, Heisenberg’s uncertainty principle tells us that it would be impossible to know whether the object was at rest or traveling at anything up to 3.3 m/s. This is a limitation imposed by the structure of the universe itself. So to assume that God could know to the precision of a Planck length the location of everything in the universe, in order to be able foresee the entire future of the universe, is to say that God cannot distinguish between objects in motion. The very structure of the universe thus places a limit on God’s knowledge of it.

The second problem arises from the entirely random behaviour of the virtual particles. These sometimes collide with real particles, changing their trajectories. If God relies on some model of the universe to predict the future of the universe from the initial states of its particles, the random appearance of virtual particles will completely mess-up any predictions. An obvious objection is that God knows everything and must therefore know all about every random particle that is ever going to appear. But the same constraint that says that he cannot know the motion of objects if he is to know their precise positions also applies to these virtual particles: if he knows their mass then he cannot know how long they’re going to stick around, and if he knows their lifespan, then he cannot know their mass and therefore their effect on any particles they collide with.

This means that God cannot know the future.

So why did God create the universe (if, indeed, he did)? Perhaps to see what happens.

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