Michio Kaku interview: The physicist who sees the future of everything

Born in 1947 to Japanese-American parents in San Jose, California, Kaku’s journey into physics began in high school, when he built a particle accelerator in his garage. Inspired by Albert Einstein’s unfinished quest for a unified theory, he has since become a co-founder of string field theory, a prolific science communicator, and the author of several bestselling books. His latest book, Quantum Supremacy (2023), takes readers deep into a revolution, already underway, that promises to reshape civilization.

For Kaku, the line between physicist and communicator doesn’t exist. His passion lies in translating the abstractions of physics into a language easily understood by the masses. Through books like Physics of the Impossible (2006), The Future of the Mind (2014), and The God Equation (2021), he has helped millions grasp concepts once confined to laboratories and lecture halls. On radio, television, and stages worldwide, Kaku speaks about quantum physics, time travel, space exploration, and artificial intelligence with a clarity and charisma few scientists possess.

In this interview to The Federal, Kaku returns to his lifelong devotion to physics, describing it as his ‘home’. Communicating science to the public, he says, is his hobby. He speaks with both excitement and caution about the dawn of quantum computing, which, he argues, has the potential to solve every major global problem — from disease to climate change — but also to undermine encryption and digital security.

Kaku warns that those who first achieve quantum supremacy may not reveal it, making us vulnerable without even knowing it. On Einstein, he reflects with humility: the great scientist’s belief in determinism may have been wrong, as quantum mechanics teaches us that the universe is fundamentally uncertain. He also defends science fiction, not as fantasy, but as a speculative playground that often anticipates real innovation. The future, Kaku insists, is not only closer than we think — it’s already here. Excerpts from the interview:

You’ve spent a lifetime bringing the mind-bending ideas of physics to the public. When you look back, do you see yourself more as a scientist pushing the frontiers of knowledge or as a communicator ensuring that the wonders of science reach everyone? Or are they inseparable in your mind?

First and foremost, I’m a physicist. If you were to read my mind, you would see equations dancing in my head all the time, always debating different concepts of physics. It’s my home. That’s where I mentally live. And of course, as a byproduct of this, I like to engage other people. Now, it turns out that many physicists have hobbies. Some of them play the violin, like Einstein. Some of them go mountain climbing. Some of them go skiing, like Niels Bohr of quantum theory. My hobby is to communicate physics to other people, and so first and primarily, my concern is physics itself. Researching cutting-edge physics that puts us to the edge of what we know. And instead of climbing mountains, instead of skiing, I like to engage with people by talking to them in plain English. So it’s a hobby, basically.

You often speak about the promise of quantum computing — how it could revolutionise everything from medicine to climate science. But with that immense power comes risks, like breaking current encryption systems. Do you think we’re ready for the ethical and security challenges this technology will bring?

Probably not. In other words, right now, we realise that anyone who can break a computer with another quantum computer can steal the crown jewels of that nation. So the CIA, the FBI, they’re all worried about the fact that a third party can swipe all the secrets right from their noses, and we would be helpless to stop it. And also, if someone finds the code to break into other people’s computers, they’re not going to tell people. We will never know that somebody has broken into everyone’s computer on the planet Earth. They’ll simply do it and keep it a secret, because then people will continue to put more secrets on their damaged network. And so it means that people will keep it a secret once they attain quantum supremacy and can crack into other people’s computers. That’s the dangerous part. In other words, we can be vulnerable and not even know it.

Your fascination with Einstein’s unfinished work shaped your career. But if Einstein were alive today, witnessing the advancements in string theory and quantum physics, do you think he would be satisfied with where we are — or would he still be restless, searching for something beyond?

Well, Einstein’s life was such that he believed in something called determinism, that the laws are fixed, and we essentially are like puppets, uncles, dancing on this stage called reality. Quantum mechanics says no. Quantum mechanics is uncertain. You don’t really know where you are located in the universe. So if Einstein were still alive, he may have doubts. He may still have doubts about quantum theory, which is based on uncertainty, but the bottom line is measurement. Quantum mechanics is measurable. We measure it to one part in eight decimal places, and so we know that quantum mechanics works. So Einstein might have been wrong in this situation. He was of the old school where everything is deterministic. In quantum mechanics, everything is uncertain.

Science fiction and speculative ideas have fuelled real scientific breakthroughs, and you’ve often explored this intersection. But do you think pop culture’s portrayal of futuristic technologies — like AI, space travel, and time manipulation — helps or hinders public understanding of what’s actually possible?

Some people think that science fiction is just science, and they laugh and they giggle and they say it’s usually silly stuff. Fifty years ago, the science fiction then is all fact now. Back then, going to the moon was considered impossible. Talking about supersonic travel, talking about satellites whizzing around the planet Earth, sending things to Mars, and so on and so forth — it was a dream. And now, of course, all that’s reality. And so I think there is a tendency to pooh-pooh science fiction, but remember that everything that is possible may eventually come to fruition if there’s a will behind it. And that’s what we see. We see a lot of the stuff of science fiction becoming science fact.

You’ve worked on string field theory, a framework within string theory, which aims to unify the forces of nature. But with competing theories like loop quantum gravity and new ideas emerging, do you still believe string theory holds the key to the ‘God Equation’? Or is physics at an impasse?

I think that string theory is the only theory which has defeated all criticism, except, of course, the ultimate test of testability. There are other pretenders to the crown. We have loop quantum gravity, which probably does not work. I’ve looked at mathematics, and it simply does not give you all the subatomic particles of today. String theory gives you all the subatomic particles of today, and even more. Yes, in fact, that’s one of the criticisms of string theory — yes, that not only do we get our universe, we also get other universes which don’t exist yet. While loop quantum gravity does not have that capability. And so of all the different contenders to the crown, only one theory allows you to get what is called the Standard Model of particle physics, and that is string theory. It has no rival.

With AI advancing at an unprecedented pace, there’s a growing fear of machines surpassing human intelligence. You’ve spoken about this in your books, but do you believe AI will ever truly replicate human creativity, intuition, and consciousness — or will it always be a powerful tool rather than an independent thinker?

Well, right now, robots have the collective intelligence of a cockroach. We don’t have to worry about them in the sense that cockroaches are not going to take over the world anytime soon. However, artificial intelligence technology is moving at a rapid pace, especially if we get quantum computers that would increase the power of a computer by a factor of millions of times. Once we start to get quantum computers, it may be possible to create a mind that is superior to the mind of a human being. That is a distinct possibility that you can’t rule out. Now, some people think that by 2045, robots will be smarter than us. I don’t think so, because Gordon Moore’s Law is slowing down. Moore’s Law says the computer power doubles in 18 months, but that’s slowing down. So I don’t think that robots are going to take over anytime soon, but if you extend the timescale a bit into the next century, then yes, I think there is a possibility that robots could become smarter than us at that point. One possibility is to merge with them. In other words, instead of fighting them off altogether, which may be impossible eventually, why not merge with them? Why don’t we become superhuman? Okay, why don’t we have the ability to thrive on Mars and Venus?

You’ve described the universe as a ‘chess game where we are just learning the rules.’ Given all that we’ve discovered — dark matter, black holes, the expansion of the universe — what do you think is the next big piece of the puzzle that could redefine everything we know?

Well, as you correctly pointed out, string theory does give us our universe. String theory does give us the particles that we see in nature. The problem is it gives you more than that. It gives you universes that we don’t see, and it simply means that there are probably other universes, other universes with different laws, but we have bifurcated from them. We’ve split off from them. So we think there are other universes where the laws of physics are different. However, we cannot communicate with them. And so it means that it’s an untestable proposition. And so at the present time, we don’t know. All we know is what we see around this universe, and that rules out many of these other universes, but only temporarily, because who knows? Maybe these universes exist in another dimension. We live in three dimensions, or four if you include time, but there are other dimensions that could be perpendicular to ours, bubbles floating in hyperspace, and these bubbles could also be expanding, but in a different dimension.

Many people see physics as abstract or distant from everyday life, but your work makes it relatable. What’s the one mind-blowing scientific concept you wish everyone could truly grasp — something that, if understood, could change how people see the world?

Well, I think the thing that really blows people’s minds is the question of probability—and whether our universe is alone. We think our universe is alone, but there may be other universes compatible with the laws of physics as we know them, equally probable. Why shouldn’t they also exist? We need to consider that there could be other versions of “you” in other universes. We like to think we’re unique. “I’m me, and that’s it.” Period. End of the story. But there could be other versions of you, equally real, in parallel universes. Steve Weinberg, winner of the Nobel Prize, likened it to radio. You tune into one frequency, and you don’t hear the others. Now replace “radio” with electrons. Electrons also vibrate, just like radio waves. So we exist in one frequency of vibrating electrons. But electrons can vibrate in other ways, meaning there could be other universes made of electrons vibrating differently. So, in your living room, there could be other radio stations — you just can’t hear them. In your bedroom or your living room, there could be dinosaurs. There could be pirates. All sorts of parallel universes — but you've decoupled from them. You no longer vibrate in unison with the dinosaurs. Therefore, they’re there — you just can’t interact with them. Sorry about that. (laughs)

Your journey — from building a particle accelerator in your garage to becoming a leading physicist — feels almost cinematic. Do you think young minds today still have that same opportunity for raw, hands-on scientific curiosity, or are we losing something in an age of digital learning and instant information?

Well, I think it’s a combination of both — we’re flooded with different kinds of information, and we have to decide what is true, what is important, which way should I go? When I was eight years old, all the newspapers were dominated by the fact that a great scientist had just died, and on his desk was a book, and that book — I wanted to know what was inside that book. That book was supposed to be the Theory of Everything. I went to the library. I found out who this man was. This man was Albert Einstein, and he left a book on his desk which he could not finish. Yes, he tried, but he failed to finish that book. So I said to myself, that’s what I want to do. I want to finish that book. Now we want to make sure that young kids today have that same feeling — I want to finish that book. That book is unfinished. I want to finish it. Whatever the theory is — about life, about people, about atoms — we want to make sure that people have a chance, the opportunity, as children, to dream about fulfilling their dream of filling the gap, that is, establishing the theory and finishing the theory once and for all.

You’ve spoken about the possibility of extraterrestrial life and even suggested that if aliens exist, they’re likely far more advanced than us. If contact happens in our lifetime, what do you think is the best and worst-case scenario for humanity?

Well, if you walk down a country road and see a bunch of ants, your first urge might be to step on a few of them. But what if those ants are us, and the one stepping on them is an extraterrestrial? You may not like the idea of an extraterrestrial stepping on your world — but that’s a possibility. We can’t ignore the possibility that there are other civilizations more advanced than ours. So far, we have no empirical evidence of this. However, it would take a Type III civilization to reach us from a distant star. A Type I civilization is planetary — it controls all the energy of its planet. A Type II civilization controls the energy of its star. A Type III civilization controls the energy of its galaxy. Once you reach Type III, you can visit star systems throughout the Milky Way. We, by the way, are at zero — we can barely get off the Earth. If aliens visit us from outer space, they’re probably Type II — more likely Type III. They can travel through galactic distances. So we have to realize: yes, there’s a possibility they’re out there. So why don’t they plunder us, like our civilizations did in history? And the question is — why should they?