2025-08-26 This is IT Consciousness, Many Worlds, and Quantum Computing
Duration: 00:41:07
Transcript
Maciej Kawecki
The brain processes, especially the processes of creation of knowledge, are similar in different universes. Everything we think we understand is, according to this theory, an illusion. Our fundamental theories of physics are reversible in time. If a random process occurs in the brain, for example, some neuron does not work properly, or a cosmic ray hits the neuron, etc., we do something else than we would do. When you find a new proof, different versions of you become more and more similar due to the error correction. Consciousness is a feature of certain computer programs, like the ones we have in our brains. It is not a feature of the brain itself. I am sure that quantum theory will not be the last theory of physics. I am sure that the current theory of evolution will not be the last one. Do you remember the moment when you created the first quantum algorithm theory in the world? Yes. David Deutsch is the creator of the first quantum algorithm in the history of science. He is called the father of quantum computers and designed the first algorithm that exceeds classical approaches. He is the laureate of the most important awards. Breakthrough Prize in Physics, Isaac Newton Medal, and two Dirac Awards. This year he is nominated as the strongest candidate for the Nobel Prize. The channel’s partner is ZenCom, a technology that improves purchases and payments for conscious users who want more and for companies to grow faster.
Maciej Kawecki
And the partner of this episode is SiePomaga.pl
Maciej Kawecki
Mr. Professor, it is a great honor to have you here. Why do you propose infinite parallel universes if you could just have one? You said that it is actually a simpler theory. But how can infinite realities be simpler than just one reality?
David Deutsch
Because the reality that we see is affected by invisible things that we don’t see, and that is the result of an experiment with interference. We have a photon, a single photon, which approaches the barrier with, let’s say, two gaps. And the path of the photon is not the same. The path of the photon coming out of two gaps is not the same as the path of the photon that would come out of the left or right gap. It is different. It is different from both possibilities. And that is because in some universes it goes through the left gap, in others through the right. And they still interfere with each other at the end of the experiment. And this interference shows us that other universes are not only mathematical constructs. They really exist because they have a real physical impact on things that we see.
Maciej Kawecki
When I solve a mathematical problem or do something else, how does it affect the organisation of all other versions of me somewhere?
David Deutsch
The brain is, among other things, a system that corrects mistakes. When we think and there is a possibility that our thinking process will go in one direction or the other, the outcome is not random. If there is a random process in the brain, for example, some neuron is not working properly, or a cosmic ray hits the neuron, etc., we do something different than we would do. For example, in your maths, if we add 7 and 5, you would say 12, but the neuron is hit by a cosmic ray, but you are going to say 13. And with very high probability, you would have said 12, and with very high probability, if you would have said 12, there will be some correction of the error and 13 will be transformed back to 12. This is very important, because it means that brain processes, especially processes of creating knowledge, are being compared across different universes. This is especially true when creating new knowledge. Solving a given mathematical problem may be a mechanical task, it can be done mechanically, but inventing a new element of mathematics, inventing a new proof in mathematics, when you are inventing a new proof, different versions of you become more and more similar because of the error correction that is going on. So, by trying to solve the problem, different versions of you become more and more similar.
Maciej Kawecki
So, as I understand it, it is impossible to test the many-worlds theory. It is impossible to falsify the theory, right?
David Deutsch
That is a mistake. So, first of all, to falsify the theory, you need to run an experiment in which the theory predicts one thing and the other predicts something else. If there is no other theory, there is no other experiment, because it is not a proper test. And the best explanation, when we have only one theory and one explanation, is that the result was an experimental error or the result of multiple errors. The best explanation for the outcome is that it was an experimental error or any number of mistakes, just like when a few years ago certain neutrinos at CERN were said to travel faster than light. And some people asked if the special theory of relativity had failed. No, it would have been repeated in the future, but it was not the case. It would have been repeated only if someone presented a competitive theory to the special theory of relativity, which would contain all correct predictions of the special theory of relativity, but additionally would predict the result for the neutrino. And sure enough, no one actually presented such a theory. After a while it turned out that it was a mistake in the experiment, a rather subtle experimental error, but still a mistake. How could we test the theory of many worlds? What could be its failure? Let’s say we have some other theory. For example, we will say that in a given situation related to quantum computers, as Roger Penrose suggested, if the number of composite superpositions exceeds a certain number, and if the mass of the different branches exceeds a certain amount, then the wave function will not continue to evolve according to the traditional equation of motion, but according to another equation which will make it collapse to one particular state. Now, that means that there is a different result predicted by Everett’s quantum theory compared to this new theory, Penrose’s theory or any other theory that is different from quantum theory. Then what you do is replace the observer with another quantum computer. On this quantum computer we run the AGI program, which is Artificial General Intelligence, which has all the attributes of a person or of any other cognitive thing. Then the observer measures the result. Let’s say that the result may be one of two alternatives, but the result is not the same as the other way around. We know that the result can be left or right, and the computer is instructed to say not left or right, but I saw the result and I know that it is either left or right.
David Deutsch
Now, if Penrose’s theory was true, then the results that the computer would see would be random, randomly left or right, because the coherence was lost randomly left or right, instead of the coherence providing one correct answer. And if Everett’s quantum theory is true, then the answer would be left, for example, whatever was set as the correct answer as part of the quantum interference. Then we reverse the process, which we can do, and if we do it with the help of the device, then we can do it under the condition that we also reverse the memory of the other computer so that it forgets whether it was left or right. I’m sorry that the explanation takes me a little more time. Moving on, the key is that we do not have to erase the memory that we have found one precise value. The computer simply forgot whether it was left or right. So there are two completely different results. One where we will have randomly left and right, and the other where we have the correct left or right. And if we have randomly left or right, then the quantum theory of Everett is failed. Is this the way how quantum computers can shed new light on the nature of reality? Correct. When a quantum computer breaks the codes trying millions of solutions at the same time, where is it actually happening? I don’t think I’ve ever said it proves because I don’t think that these scientific theories can be proven. The point is that this result is not explained by any other theory. By explained, I understand that literally any rival theory cannot explain how this result is created because some variants of quantum theory say that you shouldn’t ask what is happening between the beginning of the experiment and its measured ending. So if they say you shouldn’t ask, it means they have no explanation. In my point of view, it’s not science, it’s not explanation. It’s not explained in any other way than by the unmodified quantum theory, quantum theory of the many worlds of Everett. The same conclusion when we have only two paths like a photon which goes through two holes and then interferes with itself, which also leads to the same conclusion.
Maciej Kawecki
Don’t you think that sometimes such controversial theories can make physics look like a false claim? Well, the charge is often made but it’s simply not true.
David Deutsch
Here is an example, creationists often say that the theory of evolution is false, because nobody has ever seen a living dinosaur and nobody ever sees it. Exactly as in the case of the experiment with photons going through the holes. Although we never saw a dinosaur, we saw the rocks. And rocks are the effect of dinosaurs. They are not dead dinosaurs, they are not made of what a dinosaur is, but they are the effect of the dinosaur on the geological materials after it died. And the only explanation why rock looks as it does is that there was an unobserved dinosaur millions of years ago when there were no people who could see it, an entity which could create theories of biology. And yet, even though there was nobody around, because they affected the things we see, we can deduce that they were there. And again, the theory of dinosaurs has no rival, no other explanation. You can create an explanation saying that you can’t ask that question, but that’s not an explanation. Once you say good theories, it’s not easy to provide good scientific theories, but theories like Freud’s psychology can be used to explain everything. What is the key difference
Maciej Kawecki
Between real science and non-science for you, David Deutsch?
David Deutsch
Well, there are many ways in which there are possibilities of such theorizing that can go wrong and go away from science. The example is what you were talking about, because if theory could explain everything, it would actually explain nothing. Another way is what we mentioned before. This is a kind of opposite of Freudism. If theory is purely predictive, then it also doesn’t explain science and it also isn’t a scientific theory. My favorite example is a magical trick. Let’s say you go to an illusionist’s show and you observe how the illusionist puts the balls on the table, moves them quickly on the table, and then he discovers the ball, and the ball is gone. If you go again the next day, you’ll see how the illusionist does the same thing. You see him doing the same thing maybe every day for a week, and now you’re in perfect condition to predict when the ball will be there and when it won’t be there, but you still have no idea of how that happens. That’s a completely different kind of knowledge, that’s explanatory knowledge, not predictive. Why couldn’t evolution create simple minds that are not predictable? Why are there so many subjective experiences that solve the problems of our mind? Why doesn’t our mind solve the problems of darkness, that is, the inner awareness? Well, the evolution process solved many problems without any explanation. You know, as long as there are no certain… I mean, ordinary problems, not those that engage abstract thinking, abstract mathematics, revolutionize physics. There are fundamental limitations to what evolution is capable of. One major thing it can’t skip is some kind of conceptual gap. If there is an organism that could use some improvement, for example, if a lizard, that really could use if it could breathe fire like a dragon, then the only way that evolution could create a new organism is to have a sequence of organisms in successive generations which would gradually become closer to the ability of the lizard to breathe fire. And every single one of these organisms would have to be a viable organism that would not only have to survive to reproduce, mutate, and so on, but also useful. Because if it’s not useful, then its competitors, because it’s not useful, then its competitor that had a slight mutation would outbreed it. So it’s very difficult therefore for evolution to cross a conceptual gap like that. Whereas thinking we can imagine a flying car. A flying car will not work only because we imagine it. When I was a child I imagined various cars, flying, swimming, underwater. At first I did not try to cross this conceptual gap. But the way that you do bridge it, it’s not by making a sequence of things that start with the first and end with the new ability. You think about how to achieve it. That is the part that explanation has that evolution does not have.
David Deutsch
You claim that all human minds are universal explainers. Yes. Is the human brain able to solve any problems? Well, universal explanation is both about the ability to generate explanations and the ability to understand them. It’s really the same ability, the same ability. Now, this does not mean that in the face of a problem any human mind or any existing brain will manage. It’s a different issue. One of the things that makes most of the problems impossible is that nobody wants to solve them. Nobody wants to find the exact number in a given problem. Only a handful of people want to find out whether Riemann’s hypothesis is true and so on. There are much more, infinite, potential hypotheses that most people will not want to solve. The issue is different. The question is whether we are limited by the construction of our brains in creating knowledge which could exist. Not the kind that could be invented, but the kind that could exist. And the answer is no, as I argue in my book. If there was such a thing that people could not understand but which would still affect us in such a way that we would want to solve it, then if that could not be solved, it would be the same with the belief in the supernatural. We say then that we can understand the universe until this point, but not further. There is no explanation why until this point and not further. Therefore, if something outside of this barrier is affecting us, we cannot understand things that are inside this barrier either. So we come to the opposite. We either have unlimited ability to explain or we have no real ability to explain, because everything we think that we understand is, according to that theory, an illusion in reality. If we have such a gift of explanation why some people are struggling with simple math and others are discovering relativity?
Maciej Kawecki
Why some people struggle with basic math while others discover relativity? How can we be universal when our abilities are so different?
David Deutsch
People struggle with basic math when they try to force them to do it and they don’t want to be, and they don’t want to do it. The key is that they don’t want to do it. They have something different, something better to do, at least something they think is better for them. As I said, very, very few people in the world want to solve the Riemann hypothesis, whether to prove it or to refute it, or just work on it. Very few people want to learn to solve equations. Unfortunately, we have a tradition of education based on forcing people to do things they don’t want to do, which significantly limits creativity. How much it is limited depends on sheer luck mostly. Some people are forced to do things they don’t want to do, and they don’t want to be, and they are forced to do exactly what they want to do. Some of them are forced to do things they can do, but they are not noticed, or punished, and so on. Many people manage to get away with it. Mathematics, for example, I think would be interesting for a much larger number of people than it is now, if they were not discouraged by the coercion of it. Einstein said something like even a hungry wild beast would be discouraged if it was forced to eat it, or something like that. He put it better than I do. So this is true and it’s rather sad. I think if you conduct an interview with someone who has been successful in a given field, whether it’s a man, rather in fields that aren’t socially rewarded, not someone who becomes a professor, but someone who becomes a very, very good, let’s say, model of a match, you will find first of all that they are very interested in it, you will find that nobody forced them to do it. You will find a whole constellation of things that are characteristic of the creativity that happened and usually such a person will say that they were lucky to escape, lucky to be able to continue and acquire the same thing and acquire this great knowledge despite the opposition. Sometimes they may be stopped by forcing them to do this very thing, like that hungry lion.
Maciej Kawecki
What is the function of consciousness, according to you? We see the intelligence without consciousness in machines and probably in some animals. I would like to know that.
David Deutsch
Please note that consciousness is a feature of certain computer programs like the ones we have in our brains. It is not a feature of the brain itself.
Maciej Kawecki
Amazing, because a few days ago in Pasadena I talked to the winner of the Turing Award, Judea Pearl.
David Deutsch
Oh yes.
Maciej Kawecki
He said that consciousness is a scheme of his own programming.
David Deutsch
That is a very deep sounding statement. Judea Pearl is a very deep thinker on this area. He is an example of the difference between prediction and explanation. Not many people can do that. He is a winner of the Turing Award. He is a campaigner for the ideas that explain in contrast to predictions, especially in probabilistic predictions. So yes, I agree, although I am not sure if I can decipher this statement now, but I am sure that he is right.
Maciej Kawecki
You said a few minutes ago that quantum theory is not final. Physics is largely predictive. The constructor theory you work on asks for other possibilities. Can you give an example of what it means? Yes.
David Deutsch
At the beginning I have to say that constructor theory is currently an idea for theory. It is not a theory yet. We are working on it. It is similar to the quantum mechanics theory of Penrose. It is an idea for theory, but it has not yet developed a coherent theory in this form, although it may be able to achieve it. I talked to him about it a few months ago. Good. I will try to explain. I think that one of the interesting ways of explaining why constructor theory may be a better approach is with thermodynamics. In thermodynamics one of the fundamental laws is that entropy increases in the forward direction in time. Entropy does not decrease in the forward direction in time. From the point of view of explanation this is problematic because we know, at least we know that our fundamental theories of physics are reversible in time. If you had the opportunity to look at air particles in this room using a suitable powerful microscope you would see how these particles are reflected from each other. If you recorded and replayed it you would not be able to determine whether you are replaying this film forward or backward. In other words, the forward version is exactly as valid as the backward version. The backward version never appears in reality but the forward version does. It is a sort of a barrier between thermodynamics and the rest of physics. In constructor theory we do not ask what is happening in the given initial condition what we would do with this movie of air molecules. We ask what can be caused by this constructor. The crucial question is what is the reason why the constructor is not able to produce air particles in the first place. The crucial thing is if you have a constructor to produce specific things like a liquid mixture to increase its temperature there is no particular reason in the theory expressed in different versions of the constructor theory which would say that the reverse of this process needs to have a constructor that can do it backwards. There is no mystery here because all fundamental laws in constructor theory are expressed in terms of what can be and what cannot be caused by the constructor. It is completely permissible that the transformation process could be carried out but that it was not possible to carry out the reverse of the transformation. What was the idea born in your head? Well, there were several things that came to me when I was thinking about it and I was somewhat surprised by the fact that I came to the same idea from many different directions. I will tell you about one of them one of these directions when I was writing a philosophical article about why I think that the constructor theory would be a good idea if we could develop it.
David Deutsch
I had a section there entitled motivation and I kept adding more and more motivation there until there were finally 18 of them and that very fact made me think, okay there must be something in it. If the constructor theory does not exist then something else must explain the way in which various problems can be solved by changing the view from the conventional approach to initial conditions, the law of motion and final conditions to what can be achieved and what cannot be achieved. So in constructor theory, if you know that for example something can be achieved, it does not mean that we know how to achieve it and if we already know that something cannot be achieved it does not necessarily mean that we know what stops us. We simply know from the fundamental theory that it is something that results from the fact that one thing must be possible and one thing must be impossible. Can quantum mechanics work without a collapse of the wave function? You are asking whether a theory that does not exist could exist. Logically it could exist as we could say that the world has only been 6,000 years old and there have never been dinosaurs but no one is holding their breath for this theory. In both cases the best existing theory is not only one but it is also extremely effective in predicting the future. I am sure that quantum theory will not be the last theory of physics and I am sure that the current theory of evolution will not be the last one. After all it has been modified several times since Darwin created it until today. I am sure that there will be further improvements in both theories but these improvements will not contain irrational alternatives that are advocated by irrational people. So why did physicists ever come up with irrational theories? This is a bit of a scandal in the history of physics. It was the early 20th century. The trend in philosophy since the late 19th century was towards positivism and then to logical positivism. Both theories wanted to make a comeback in physics
Maciej Kawecki
Without any explanations, only predictions. It was because of the history of empiricism, philosophy of science and so on that the really bad idea came up that science is not about explaining the world but only about predicting it. And that is how it was done. For example when the measurement results in quantum theory were strange and not intuitive they thought, well, we can predict them why do we have to explain them? Let’s not explain them because positivism is serious and even orders us to do that. And then what happened? Some physicists took this view. Some physicists like Einstein opposed it and some like David Bohm tried to take a balanced position.
David Deutsch
But what happened next was not the debate that this theory originally caused but it also took place when physics became more and more important and more and more young people were becoming physicists. You know, there are I don’t know how many more maybe 100 times more physicists than there were in 1900. I don’t know the exact number but it is a huge increase. And they all went through a similar education system in which students asked yes, but how does it come about? Why is the pattern on the screen so similar to the one on the screen? Professors would say if you ask you are not allowed to ask that question or if you ask that question and what’s worse if you ask them you really don’t understand it. And so they shut the students’ mouths and the students later shut their mouths to their own students and it became physics’ irrational tradition. It is very, very gradually changing. Do you remember the moment when you created the first quantum algorithm theory in the world? Yes. Tell me something more about it. Please tell me something more about it. I was just I’m trying to so I often tell the story of how I got interested in the computational properties of quantum theory because a colleague of mine told me that contrary to what I thought the theory of complexity is strongly rooted in physics that the limitations of the theory of complexity what is P and what is NP and similar topics are determined by physics. So I said well, if this is physics you use the wrong physics because they just used the physics of Turing which was classical so I went home and wrote down on a piece of paper what would be the equivalent of Turing’s argument in the quantum world and then I thought to make it an elegant introduction I should prove its universality. I couldn’t prove it and then I realized that to create quantum universality you need some quantum operations not entirely related to quantum. I realized then that there could be a quantum computer which would be more powerful than a classical computer like Turing’s.
Maciej Kawecki
Thank you very much for your time it was a great pleasure and a great honor.
David Deutsch
Same here. Bye bye then.
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