Roger Penrose, professor of mathematics at the University of Oxford, has for long been researching revolutionary ideas in physics. His bestselling book The Emperor’s New Mind highlighted his controversial views that to understand consciousness, one must first understand physics, and that computers can never be conscious. He has also been at work on the twistor theory as a step towards uniting quantum mechanics and the general theory of relativity — the so-called Theory of Everything that’s the holy grail of physicists today. He is currently at work on what he terms a ‘‘monstrous book’’ on the work being done in modern physics. Penrose spoke to Mini Kapoor. How far are we from a Theory of Everything? In my opinion physics is a long way from any such thing. If there is such a theory, it will certainly be centuries before we get to it. Many people express what I regard as over-optimism, usually in connection with such theories as string theory or M-theory. I think there are major problems which we are nowhere close to resolving. Like? The most immediate one in my opinion is making sense of quantum mechanics (QM). As it exists today it is not just incomplete, it is inconsistent. It is understood as a theory which deals with small things — atoms and molecules and fundamental particles — and it works extremely well for small things. But one of the rules one adopts in QM is what is called the superposition principle — that means if one thing can happen, or another thing can happen, then you get a whole lot of possibilities in which they both happen at once. Now these things, strange as they may seem, are experimentally well-confirmed for individual particles such as neutrons. But they lead to absurdity if you consider large objects like a cricket ball — and according to the rules that apply to small objects in QM, there is nothing which tells you they should also not apply to a cricket ball. In fact, Schrodinger, one of the architects of QM, took great pains to show how his own equation did not make sense if you applied it to, for example, a cat. There’s the famous Schrodinger’s cat, a theoretical situation in which the cat is alive and dead simultaneously. He was more or less saying, look, this is ridiculous, don’t believe my equation at the level of a cat. Albert Einstein was strongly of the view that QM is incomplete, but you’d find that most physicists who work in quantum theory take the view that it is a question of interpreting the theory appropriately. I think that’s wrong, and we really do need a revolution — a real revolution, and not just tinkering. What would the structure of such a revolution be? The sort of analogy I think one should make here is with gravitation theory. Newton introduced a theory of gravitation, which worked extraordinarily well, was extremely accurate and lasted for hundreds of years without any indication that there should be a modification. But then Einstein had a different way of looking at it — a completely different perspective, you think of space and time as being curved and so on. It gives almost the same answers as Newton’s theory, but it gives slightly different answers for the motion of the planet Mercury, which agrees with what we see. But Einstein’s theory was not tinkering, you see, it was a completely different perspective on gravitational theory. And string theory does not provide an adequate perspective? No, I think there is very little chance. There are interesting ideas in string theory and M-theory which are important mathematically, but there is very little evidence that these ideas have any clear-cut connection to the workings of the physical world. The main problem I have with it is the necessity for higher numbers of dimensions. The twistor theory too, it is hoped, will take us towards a TOE. I’ve worked on it for nearly 40 years now. Again, it’s an area where all of the support comes from its mathematical connections. I will certainly not claim that twistor theory as it stands today represents a TOE. It contains ideas which I think are well-worth exploring. The weakness in it is that it’s not sufficiently developed even to incorporate Einstein’s general theory of relativity, let alone the union between it and quantum theory. It’s motivated partly by the idea that in the union between QM and the general theory of relativity, one needs to change QM as much as to change space-time structure. Whereas many people, including the string theorists, would say what we need is a quantum gravity theory — that means a theory in which QM is left untouched, yet the theory of space-time is changed. The one feature which is very important in twistor theory is the role of complex numbers in dealing with the classical world too, not just in the quantum world. One of the important things one has to do in order to see this, is to say that one of the fundamental things in space and time structure is not the point, but something like a light ray. Do you think we may need a new mathematics to merge QM and the general theory of relativity? I would think so. It’s hard to know because sometimes you’re lucky and the mathematics is there already. Einstein was quite lucky because the kind of mathematics he needed was there, he didn’t have to invent it. Newton had to find it for himself, calculus was not really there. Is there a pattern in nature that’s being probed, or do scientists make sense of nature through theories? This is a big point I certainly have strong views about. We’re searching for what’s there — it’s not that we’re imposing on nature our views of what looks like a nice theory. The pattern is in nature. Although the things we see and understand in nature are importantly incomplete at the moment, this nevertheless reveals deep patterns which are in nature. What does all of this have to do with consciousness? My personal view is that we are not going to understand the deep factor which is involved in consciousness until we can improve our physical picture of what reality is like. And there are important things missing in our picture of reality — the main thing at the present level is QM. I have reasons to believe that whatever consciousness is depends upon this revolution. There is a common view that whatever a brain is doing when consciousness is present is computation. They would say if you have a computer which does the same thing as a brain, then it would also be conscious. There are good reasons to disbelieve this. The quality of understanding is something demonstrably outside the scope of pure computation. Understanding is something that requires awareness. If you believe consciousness is some kind of a feature of a brain activity which is probing what nature is, we have to have a revolution in physics first (before we can fully understand it).
