Michio Kaku has an extraordinary mind. It loves nothing better than occupying itself untangling the mathematics of subatomic strings vibrating in 11 dimensions. “My wife always thinks something strange is happening because I stare out the window for hours,” he says. “That’s all I’m doing. I’m playing with equations in my head.” In his day job, Kaku works at the very fringes of physics. He made a name for himself as co-founder of string field theory, which seeks to complete Einstein’s unfinished business by unifying all the fundamental forces of the universe into a single grand equation. He regales the public with tales of multiverses, hyperspace and visions of a better future built by science.
Hyperbole is part of his style. He once urged humanity to consider escaping our universe, which several billions of years from now will be in its last throes, by slipping through a wormhole. Hardly a pressing concern for today, but such proclamations lasso attention and get people to think big.
Kaku certainly thinks big in his latest book, and there’s plenty of hyperbole. But The Future of the Mind is somewhat of a surprise. What is a theoretical physicist doing writing a book about the mind – a topic usually reserved for neuroscientists, psychologists and philosophers? As a philosopher myself I was curious to see if a physicist could shed some photons on the problem. I took the opportunity when he was in Sydney spruiking his new book to find out.
Kaku is short in stature but his personality fills the room. Eyes are drawn to the sharp-suited figure with the shock of white hair, and that melodic voice filled with earnest urgency. It’s hard to resist the limitless passion for wonder. Sitting with him in a corner of the Pullman Hotel across from the green expanse of Hyde Park, I ask him what drew him to write about the mind.
“There are two great mysteries that overshadow all other mysteries in science,” he starts, slipping into his signature avuncular lecturer’s tone. “One is the origin of the universe. That’s my day job. However, there is also the other great mystery of inner space. And that is what sits on your shoulders, which believe it or not, is the most complex object in the known universe. But the brain only uses 20 watts of power. It would require a nuclear power plant to energise a computer the size of a city block to mimic your brain, and your brain does it with just 20 watts. So if someone calls you a dim bulb, that’s a compliment.”
I’m not convinced Kaku has ever been compared to a low wattage bulb. However, I’m immediately struck by how firmly he sees the mind through the lens of the physical. This places him squarely on one side of a centuries-old debate about the nature of the mind. In one corner are those who assert that the mind is nothing more than physical processes – electrical impulses cascading throughout the brain. In the other corner are those who hold that the mind is something above and beyond the physical – that it is made of stuff not found on any periodic table, with properties that can’t be described in physical terms. It’s a debate close to my heart – my honours thesis grappled with the possibility that the mind can be explained in physical terms alone. Kaku, it seems, thinks it can.
As a physicist, Kaku works a lot with models. His job consists of abstracting various chunks of the world and compressing them into cogs in a grander equation. A model, if it is good, should neatly predict future phenomena.
Kaku sees the mind as essentially a model-making machine. Except that the cogs of consciousness are various parameters of the world, like temperature or position, and the model is used to direct behaviour to accomplish very biological goals like hunting prey, dodging predators and winning a mate. No airy-fairy philosopher stuff like thoughts and experience and free will.
Kaku outlines levels of consciousness that correspond to different degrees of complexity, from the simplest things like plants at Level 0 to we humans on Level III. The big difference with us is that we are self-aware. “Human consciousness is a specific form of consciousness that creates a model of the world and then simulates it in time,” he writes in the book. “This requires mediating and evaluating many feedback loops to make a decision to achieve a goal.”
There’s something appealingly tractable about Kaku’s theory, particularly for a cynical philosopher who’s often up to his neck in qualia – a word for when words fail to describe the indescribable features of conscious experience, like trying to describe the redness of a red rose or the ache of new love. But I can’t help but think that his is a theory of cognition, not a theory of consciousness. It describes the information processing that goes into producing behaviour, which is undoubtedly the chief function of the brain, but it doesn’t seem to account for the fact that all this model making coincides with a supremely subjective experience. As the American philosopher Thomas Nagel put it in the 1970s, there’s something it feels like to be a conscious being.
David Chalmers, Director of the Centre for Consciousness at the Australian National University in Canberra, puts it a different way. He draws a distinction between what he called the “easy problem” of consciousness, which is explaining how electrical impulses racing through a network of neurons can produce behaviour, and the “hard problem”, which is explaining how on Earth that network can ever produce something like the redness of red. Chalmers imagines a being that does all the information processing we do, and which can make the kinds of decisions we make, but doesn’t have any conscious experience, no “qualia”. If such a being is at all possible, then it suggests a complete theory of the mind needs to talk about more than just information processing and brains. It needs to talk about conscious experience too.
I ask Kaku about the conspicuous absence of consciousness in his theory and he hastens to dismiss the problem, borrowing another analogy from science. “It used to be that the question of ‘what is life?’ dominated and paralysed biology for decades. Now the question is irrelevant. We now know there are gradations – we have different kinds of viruses, different forms of life. So biologists no longer ask the question ‘what is life?’, because it turned out to be many layers of a continuum.
‘Quantum mechanics is perhaps the most philosophical of all sciences.’
“It’s the same thing about ‘what is redness?’, ‘what is a sunset?’, ‘what is a sensation of ecstasy and thrill?’ or ‘what are qualia?’. Today that absorbs a lot of philosophers’ attention, but I think that just like ‘what is life?’, that will disappear.”
His counterpoint to Chalmers’ thought experiment of a thinking being without qualia is a thought experiment of his own. One day, he muses, “we will have a robot that understands red in ways a hundred times richer than any human. We will have a robot that can tell us the electromagnetic spectrum of red, that can give you all the sensations of red for different kinds of animals, a richness of red far beyond any human’s. And then the robot will say, ‘do humans understand red?’, and it will say, ‘obviously not’.”
I’m not sure Chalmers would be convinced the existence of this robot would mean we’ve solved the hard problem, but that’s a philosophical conundrum Kaku is confident will simply fade in time. Not that he’s taking a swipe against philosophy, as theoretical physicists have been apt to do, “Steven Weinberg, Nobel Prize winner, wrote a book [Dreams of a Final Theory], and he had a chapter against philosophy. He basically denounced philosophers for putting us on the wrong track, giving us dead ends, and conundrums and paradoxes that were really just plays on words. But after reading that chapter you realise: this is the deepest philosophy of all. So simply by attacking philosophy, you become the enemy. You become a philosopher.”
Indeed Kaku points out that philosophy-bashing physicists really are treading on thin ice, “quantum mechanics is perhaps the most philosophical of all sciences”.
Like philosophy, quantum mechanics is rife with conjectures about how the world might be. Maybe there’s just one universe or perhaps a multiverse of countless others, but there’s a lack of the concrete evidence that tells us
which of these conjectures, if any, is true.
Nevertheless Kaku maintains his characteristic optimism that physics will ultimately prove its theories. “In my years as a physicist I’ve noticed that sometimes experiment and theory chase each other,” he says. “When I was a kid, the strong force gave us thousands of sub-atomic particles. J. Robert Oppenheimer, the father of the atomic bomb, said that the Nobel Prize in Physics should go to the physicist who does not discover a new particle this year. We were drowning in data, but we had no theory. Most of my career was spent in that kind of climate. Now it’s flipped,” he says.
“Now, we have the theory of the strong nuclear force, it’s called quantum chromodynamics. And we have theories of quantum gravity. All of a sudden the theory has outraced the data. But does that mean the theory is wrong? No! It just means that we humans are limited by what our gross domestic product can create in terms of atom smashers. It has nothing to do with the correctness or incorrectness of string theory.
“The difference between physics and philosophy is that string theory is testable, believe it or not.”
This gives a hint as to why Kaku chose to write a book about the mind right now. After centuries of armchair speculation and coarse poking and prodding, finally physicists have gotten involved and brought their rigour – and their tools – to the field. They invented the new gizmos that are opening a window into the brain: magnetic resonance imaging, positron emission tomography, electroencephalography, computed tomography, magnetoencephalography and transcranial magnetic stimulation, to name but a few. “In the last 10 years we’ve learnt more about the brain than in all of human history combined. And it’s all because of physics,” says Kaku.
His book is filled with tales of scientists watching people’s “thoughts” on a computer screen – of moving objects with the power of the mind – and transmitting one person’s ideas to another. And the most remarkable feat according to Kaku? “As I was writing the book last year, the announcement was made at Wake Forest University and University of Southern California in Los Angeles that they’d been able to record a memory and upload that same memory. This is incredible. I was saying that very soon we’ll have that capability, and they did it as I was writing that chapter!”
Kaku envisages a world where our new insights into the workings of the brain enable (almost) unbelievable feats. We will enhance our intelligence to super-Einsteinian levels. We will encode the billions of connections in our brains and upload that information into computers, effectively hitting ‘CTRL-S’ on our personalities and consciousness (whatever the latter is). We will beam that information to other planets via laser, loading our minds into robots on the other end to explore the cosmos like a legion of sentient Mars rovers. There’s nothing in the laws of physics that explicitly says we can’t do any of these things, so they simply become engineering problems.
Of course, if the mind is nothing more than information and physical processes, that means we can create artificial minds as well, although Kaku acknowledges we’re still decades away from building a Level III mind that can think like us.
“We made a mistake 50 years ago,” he says. “The mistake was to assume the brain is a computer. So what is the brain? The brain is a neural network of some sort. It’s a learning machine. It rewires itself after mastering a task. Your laptop today is just as stupid as it was yesterday. Your laptop never gets smarter, but brains do. That’s why it’s so hard to create machines that can mimic the brain.”
‘We’ll put a chip in their brain – a failsafe button – so we can just shut off these monkey-like robots if they start to get too intelligent for their own good.’
Naturally, he’s confident it can be done, it’s only a matter of time and money. Which is probably a good thing, because if we create something that has a Level III mind – something that thinks, desires and that can reproduce like we do, something that competes with us for resources – well, we’ve all read enough science fiction to know how that plays out. But Kaku’s not perturbed.
“First of all, robots are not going to take over any time soon. They have the intelligence of a cockroach – a retarded, lobotomised, stupid, idiotic cockroach. They can barely walk across the road.
“But I assume in the coming decades they will be as smart as a mouse, then as smart as a rabbit, then as smart as a cat, a dog and eventually – maybe by the end of the century – a monkey. I think at that point they are potentially dangerous so we’ll put a chip in their brain – a failsafe button – so we can just shut off these monkey-like robots if they start to get too intelligent for their own good.”
But then there’s the question of what to do when they go beyond simian intelligence? What if they become smarter than us? Again, Kaku’s infinite optimism means he’s unperturbed by the prospect of super-intelligent robots roaming around eyeing our stuff. “What do we do? We merge with them,” he says. “Otherwise they could literally become smarter than us, put us in zoos and throw peanuts at us.”
Let’s just hope they want to be merged with.
There can be little question that Kaku’s is an extraordinary mind. But it’s also the mind of a physicist. So it’s entirely natural he would look at the mind firmly through the lens of the physical. And there is certainly a part of my mind that is enticed by his infectious confidence in physics. However, I still can’t quite shake my doubts that even the most penetrating brain scanner will ever truly lay bare the deepest mysteries of consciousness. Then again, after centuries of abstract speculation by philosophers, perhaps Kaku’s refreshingly concrete approach is precisely what we need to unravel the secrets of this extraordinary thing we call the mind.
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