Fittingly for someone dedicated to pondering the puzzle posed by consciousness, philosopher David Chalmers possesses an unusual and fascinating mind.
For a start, he excelled at maths when he was young, earning a bronze medal at the fiendishly cryptic International Mathematical Olympiad.
"I had a very strong interest in the sciences in general, but maths was number one," he said. "Philosophy — I don't think I really knew what it was at that point."
As a boy he also had synaesthesia, meaning that music produced strong colour sensations in his mind.
"A lot of things were just kind of boring greens and browns but every now and then something would be bright red. I remember Here, There and Everywhere by The Beatles was bright red."
Professor Chalmers, who was born in Sydney and brought up in Adelaide, today works out of New York University and is one of the world's pre-eminent philosophers of mind, best known for breathing new life into an old conundrum.
He calls it the hard problem of consciousness.
Simply put, the hard problem asks the following question: how can the machinery of the brain (the neurons and synapses) produce consciousness — the colours that we see, for example, or the sounds that we hear?
Look at a brain scan and you will see nothing resembling consciousness. Brains, in fact, do not appear particularly remarkable — which makes the fact that they are even more exceptional.
"The really hard problem of consciousness is the problem of experience," Professor Chalmers wrote in a landmark 1995 paper. "When we think and perceive, there is a whir of information-processing, but there is also a subjective aspect."
"It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises. Why should physical processing give rise to a rich inner life at all? It seems objectively unreasonable that it should, and yet it does."
In short, why should moving parts produce perception and sensation? And why should only brains (as far as we know) be responsible for consciousness?
Car engines are sophisticated systems, albeit far less complicated than brains, yet not one has ever shown the vaguest inclination of wanting to drive.
To claim that pain is nothing more than a configuration of molecules in our heads seems to ignore the fact that pain actually hurts.
In the 1950s, philosophers at the University of Adelaide were at the forefront of attempts to tackle such problems. A later generation of so-called eliminative materialists (most notably Patricia and Paul Churchland) were more radical.
Eliminativists claim that brain states do not merely generate conscious experiences, but literally are them. Daniel Dennett, who debated Professor Chalmers in a now notorious showdown in the Arctic Circle funded by a Russian entrepreneur, has even claimed that consciousness itself is an illusion.
The reality of experience, however, tends to refute this idea.
It seems that there is a hole in our scientific picture of the world, what philosopher Joseph Levine called an "explanatory gap".
When I spoke to Professor Chalmers ahead of his recent talk at the Australasian Association of Philosophy, he went so far as to call the hard problem "the number one unanswered scientific challenge of our time".
Sci-fi and the path to philosophy
Professor Chalmers grew up in a house filled with books. An avid reader, he was drawn to the science fiction of Asimov, Heinlein and Arthur C. Clarke.
Those authors posed deep questions about the world, about reality, and about the relationship between human beings and machines.
"The problem of consciousness certainly comes up from thinking about robots," Professor Chalmers said.
"Could a robot be conscious in the way that a human being is, or do you need a special biology to be conscious? I was always on the side of the robots. That's not to say there's no mystery about consciousness."
Professor Chalmers went to Unley High School where he was a few years behind former prime minister Julia Gillard. At university, he studied mathematics — first in Adelaide, then at Oxford.
An encounter with Douglas Hofstadter's classic book Godel, Escher, Bach deepened his burgeoning passion for philosophy, and he decided to switch fields.
"I had zero demonstrated talent at philosophy so there was no particular reason to think I'd be any good at it. It was a bit of a leap of faith."
He recalls a conversation he had with his father, who was a professor of medicine at Flinders University, as he was making the transition.
"He was a bit worried about the whole philosophy thing," Professor Chalmers said. "He's a scientist ... and then for me to be wanting to be veering off into philosophy.
"He told me 'don't tell me you're going to spend your life looking for the soul!'"
Panpsychism and the fundamental laws of consciousness
Professor Chalmers believes one possible answer to the hard problem is a view known as panpsychism. It sounds spiritual, but it isn't.
According to panpsychism, consciousness may be a fundamental property of reality in the same way as space and time.
"We're not going to reduce consciousness to something physical ... it's a primitive component of the universe," he said.
"But that frees us up to search for the fundamental principles that govern it. In physics, we don't try and explain space and time in terms of more fundamental things. We just find the laws that govern them."
Professor Chalmers retains a love of science, despite the hostility sometimes shown by scientists towards his own discipline. In recent years, theoretical physicists have been especially critical of philosophy. Lawrence Krauss is one. Stephen Hawking is another.
"You get a few people with strongly expressed opinions about this," he said. "Often they don't know so much about philosophy. Certainly Stephen Hawking doesn't.
"A lot of the great philosophers of the 20th century have actually been scientists. Einstein was a great philosopher in his way, as well as people like Heisenberg and Schrodinger. Some of the best philosophical conversations I've had have been with scientists."
Neuroscientist Giulio Tononi is among those to have piqued Professor Chalmers' interest. Dr Tononi has developed what has come to be known as Integrated Information Theory, which attempts to measure consciousness using maths.
Professor Chalmers does not believe Dr Tononi has solved the hard problem, but thinks he may be closing in on significant new insights about the connections between mind and matter.
"He takes the attitude of presupposing the existence of consciousness as basically a fundamental component of reality, as I do, and [tries to] find the fundamental laws that link it to physical processing," Professor Chalmers said.
"For him, these principles that connect integrated information and consciousness are kind of like fundamental laws of physics, and that's roughly the view that I think you have to take too."
Is Trump proof we are living in a simulation?
Lately, Professor Chalmers has been thinking about technology and virtual reality, and whether we are all living in some kind of simulation.
He is far from alone in flirting with the idea — technologist Elon Musk, nuclear physicist Zohreh Davoudi, philosopher Nick Bostrom, futurist Ray Kurzweil and cosmologist Alan Guth are all enthusiasts.
Unsurprisingly, Professor Chalmers invokes The Matrix. But it is a train of thought that has taken him into the realm of current affairs.
Professor Chalmers has speculated that recent seismic political events may be evidence of the mischief, or cruelty, of whoever has programmed our universe.
"I started joking around saying 'various things have been happening lately — Donald Trump, Brexit'," he said.
"[Maybe] the simulators are just messing with us. Maybe someone thought at one point 'let's just run a simulation on the counterfactual hypothesis — what if Donald Trump had been elected?'"
During my interview with Professor Chalmers, I suggested that incessantly thinking about the mind, the brain and the nature of reality was enough to drive anyone mad. But as we were getting up to leave, I asked him more seriously whether there would come a point in his life when he would accept he would never answer the hard problem. Could he simply let it go?
"I'm an optimist so I would like the problem to be solved," he replied.
"It could be decades. It could be centuries. At the end of the day, it's possible we'll never have a satisfactory solution but I don't think we're yet in a position to say that.
"Maybe once we develop amazing artificial intelligences they'll be better than us at everything, including philosophy. Maybe they'll be the ones that come up with a solution."