Consciousness is said to be "one of the last great mysteries for science". It is at once the most familiar thing in the world and the most difficult to explain. Oddly enough the great successes of modern neuroscience only seem to make consciousness harder to understand.
The central mystery has fascinated philosophers for thousands of years' that the universe seems to contain two completely different kinds of thing. On the one hand are bodies and brains - physical objects that we can touch and measure' on the other are conscious experiences - private and subjective feelings that we cannot get at directly. We can ask people what they are experiencing, record their words, and measure what happens in their brains, but somehow this doesn't seem to capture the "what it's like" of subjective experience.
Right now, for me, the sky is a very faint pale blue streaked with early morning wisps of delicate pink. But how can science measure this? We can't even tell whether you and I are having the same experience when we both say we are seeing blue. My pale blue might be your bright orange. This "what it's like for me", is what philosophers call "qualia"' the intrinsic properties of the experiences themselves. So the mystery is this - how can a few pounds of living neurons inside a skull create qualia? No one knows.
No one knows, but at least now they are arguing about it. When I started my research, more than 30 years ago, no serious scientist would even admit to an interest in consciousness, and I was very much on my own. I had had many strange experiences and was obsessed with trying to understand them, but the science simply wasn't there to do the job. Then, gradually, I found I was in the midst of a hot topic. Brain scanning and other advances in neuroscience meant we could at last peek inside a living brain, but how could we find consciousness there?
The problem got me hooked, and so I gave up my university ob to read all I could on the sub-ect and write a textbook' a proect that left me well informed but even more baffled. Everyone seemed to disagree. So I decided that I needed to ask the experts what they meant - face to face. I travelled the world talking to some of the world's finest thinkers and put together a book, Conversations on Consciousness.
Perhaps the key thinker in this debate is the young Australian philosopher David Chalmers. I caught up with him in Tucson Arizona where, for many years, he has organised the famous "Toward a Science of Consciousness" conferences. He said that scientists researching vision, memory, thinking or emotions were just tackling "easy problems". Even f they solved all those there would still be something else left to explain - consciousness itself - and this he called the "hard problem".
The phrase stuck, and now Chalmers's hard problem has become something of a Holy Grail for consciousness studies. Scientists and philosophers are falling over themselves to become the one who solves the hard problem. The trouble is, no one knows how to set about solving it.
At one extreme are those who think a revolution in physics is the answer. The Tucson anaesthetist Stuart Hameroff is one such theorist. "Every day," he told me, "I put patients to sleep and wake them up and it's still incredible. You wonder - where do they go?" He has teamed up with the British mathematician, Sir Roger Penrose, to argue that the brain is a quantum computer and the conscious self depends on quantum effects in the micro-tubules - tiny tubular structures inside every cell of the body. They are convinced that this is the way forward, but no one else I talked to shared their enthusiasm.
Far more common are the neuroscientists who think that if we just get on with the "easy problems" we will eventually solve the hard one. …