In his recent book The Grand Design, Stephen Hawking announces, "philosophy is dead." He goes on: "Scientists have become the bearers of the torch of discovery in our quest for knowledge." According to him, scientists will in time be able to explain everything and there is no need for other kinds of thinking (which, it should be noted is in itself an expression of the philosophical position known as scientism).
Hawking, in particular, claims to have solved the age-old problem: "Why is there something rather than nothing?" His answer? M-theory. M-theory spontaneously created the universe out of nothing. It created this universe and countless others. He concludes that M-theory is "a candidate for the ultimate theory of everything... the only candidate."
This assertion prompted the Times newspaper of London to carry a front page banner headline: "Hawking: God did not create the universe." The leading article went on, "Did the universe need a creator? The answer given by Britain's most eminent scientist is a resounding no."
So, what does M-theory look like when written down? No one knows; it has yet to be formulated. It is but a gleam in the eye. If there is such a thing, how could it be verified? It is hard to say. How might one prove the existence of other universes given that we can experience only this one?
But even if the M-theory hypothesis is correct, does it in fact answer the question of "Why is there something rather than nothing?" It would certainly account for the existence of the world. But would it not raise a fresh question: "Where did M-theory come from? What is responsible for its existence?"
This brings us up against what one suspects is a fundamental limitation of the scientific enterprise. The job of science is to describe the world we find ourselves in -- what it consists of, and how it operates. But it appears to fall short of explaining why we are presented with this kind of world rather than some other -- or why there should be a world at all.
Indeed, there is cause to wonder whether science even gets as far as describing the world. For instance, what is the world made of? One might answer in terms of the electrons, protons, and neutrons that make up atoms. But what are electrons, protons and neutrons? Quantum physics shows how they are observed to behave like waves as they move about. But on reaching their destination and giving up their energy and momentum they behave like tiny particles. But how can something be both a spread out wave with humps and troughs, and at the same time be a tiny localized particle? This is the famous wave/particle paradox. It afflicts everything, including light.
The solution given by the Danish physicist Neils Bohr was that one has to stop trying to explain what something, such as an electron, is. Instead, we are confined to explaining how something behaves in the context of a certain kind of observation being made on it -- whether we are observing it moving from one place to another (in which case the language of waves is appropriate), or alternatively observing it interacting on reaching its destination (requiring the language of particles).
We said earlier that the job of science is to describe the world. In order to do this, we have to observe it to find out what kind of world it is. But having made the observations (done the experiments) what we write down in our physics textbooks is a description of the world itself, regardless of whether one happens to be observing it. Bohr, and other adherents to his so-called Copenhagen Interpretation of quantum mechanics, claimed that this was not so. What has been written down is not a description of the world at all, but a description of acts of observation made on the world. All our customary scientific terms such as energy, momentum, position, speed, distance, time, etc. -- they are terms specifically for the description of observations. It is a misuse of language to try and apply them to a world-in-itself divorced from the action of an observation. It is this misuse of language that leads to problems like that posed by the wave/particle paradox. Which is not to say that the world-in-itself does not exist outside the context of someone making an observation of it. Rather, as Werner Heisenberg asserted, all attempts to talk about the world-in-itself are rendered meaningless.
Not that there is anything new in this. The philosopher Immanuel Kant had long ago asserted that one could know nothing about the thing-in-itself. (So much for the death of philosophy.)
Finally we ask whether the scientific enterprise, even in this more limited domain of describing only interactions with the world rather than the world itself, might one day achieve complete knowledge. I think not. After all, what do we do our science with? Our brain. But how come we have a brain? It is something that evolved in response to the need of our ancestors to find food, shelter, and avoid predators. It enabled them to survive to the point where they could mate and pass on their genes. The brain was part of their survival kit. Why therefore should anyone think that such an imperfect instrument should be capable of mastering all knowledge regardless of whether it has any relevance to survival?
And then there are practical limitations. The Large Hadron Collider is 17 miles in circumference. But what if it takes a much larger particle accelerator to discover the last vital piece of the jigsaw puzzle? There is no reason why such a machine should happen to coincide with what we humans on planet earth could physically build.
All we can realistically do is achieve whatever knowledge is open to us to understand. This might well fall short of the expectations of my more optimistic fellow scientists. I think a little humility is in order.