Latest / Daniel and Kelly’s Extraordinary Universe / What is Relational Quantum Mechanics?

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What is Relational Quantum Mechanics? · Daniel and Kelly’s Extraordinary Universe

0:01
Speaker 1: Hey, it' Jorhan Daniel here, and we want to tell
0:03
Speaker 1: you about our new book. It's called Frequently Asked Questions
0:06
Speaker 1: about the Universe because you have questions about the universe,
0:09
Speaker 1: and so we decided to write a book all about them.
0:12
Speaker 1: We talk about your questions, we give some answers, we
0:14
Speaker 1: make a bunch of silly jokes as usual, and we
0:17
Speaker 1: tackle all kinds of questions, including what happens if I
0:20
Speaker 1: fall into a black hole? Or is there another version
0:22
Speaker 1: of you out there that's right? Like usual, we tackle
0:25
Speaker 1: the deepest, darkest, biggest, craziest questions about this incredible cosmos.
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Speaker 1: If you want to support the podcast, please get the
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Speaker 1: book and get a copy not just for yourself, but
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Speaker 1: you know, for your nieces and nephews, cousins, friends, parents, dogs, hamsters,
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Speaker 1: and for the aliens. So get your copy of Frequently
0:42
Speaker 1: Asked Questions about the Universe is available for pre order now,
0:46
Speaker 1: coming out November two. You can find more details at
0:49
Speaker 1: the book's website, Universe f a Q dot com. Thanks
0:53
Speaker 1: for your support, and if you have a hamster that
0:55
Speaker 1: can read, please let us know. We'd love to have
0:57
Speaker 1: them on the podcast. We all know that quantum mechanics
1:10
Speaker 1: can't be quite right. I'm not talking about the counter intuitive,
1:15
Speaker 1: probabilistic aspects of it that it forced us to accept
1:18
Speaker 1: that the world we live in is fundamentally weirder than
1:22
Speaker 1: we have ever imagined. Probabilities and correlations and uncertainty is no.
1:27
Speaker 1: Those bits are probably right, But there's a problem at
1:30
Speaker 1: the heart of quantum mechanics, one that has baffled physicists
1:34
Speaker 1: and philosophers for nearly a hundred years, and that may
1:38
Speaker 1: take another hundred years to solve. But some recent ideas
1:43
Speaker 1: maybe showing us a path forward, even if it's a
1:46
Speaker 1: stranger path. Then we imagine, Hi, I'm Daniel. I'm a
2:05
Speaker 1: particle physicist and a professor at u C Irvine, and
2:08
Speaker 1: I'm still confused by quantum mechanics. Confused but not frustrated,
2:13
Speaker 1: You might say, I'm deliciously confused. What could be more
2:17
Speaker 1: delightful than grappling with the deep mysteries of the nature
2:20
Speaker 1: of reality, seeing the truth written down in cold black
2:24
Speaker 1: and white and mathematical equations, and struggling to gain an
2:27
Speaker 1: intuition to incorporate those alien concepts into our human brains.
2:32
Speaker 1: After all, that is the deepest goal of physics, and
2:36
Speaker 1: that's the goal of our podcast. Daniel and Jorgey explain
2:40
Speaker 1: the university production of My Heart Radio, in which we
2:43
Speaker 1: tackled the biggest and hardest and nastiest and funnest of
2:46
Speaker 1: questions of the universe, the ones that make your brains twist,
2:50
Speaker 1: the ones that slip away from you just as you
2:53
Speaker 1: thought you had figured them out, the ones that might
2:55
Speaker 1: elude humanity for centuries or forever. We don't show away
3:00
Speaker 1: from any questions on the podcast, but we seek to
3:02
Speaker 1: approach them and explain our knowledge and our ignorance to you.
3:07
Speaker 1: My friend and co host Jorge is on a break,
3:09
Speaker 1: but I have a special treat for you. We are
3:12
Speaker 1: very lucky to have as a guest one of my
3:14
Speaker 1: favorite physicists, one of my favorite writers, and one of
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Speaker 1: my favorite writers about physics, truly a poet of science communication.
3:23
Speaker 1: Today we'll be talking to Carlo Rovelli about some of
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Speaker 1: the problems at the heart of quantum mechanics and explaining
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Speaker 1: a lesser known but absolutely fascinating alternative version of quantum mechanics.
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Speaker 1: So today on the podcast, we'll be answering the question
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Speaker 1: what is relational quantum mechanics? So it's my great pleasure
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Speaker 1: today to introduce Professor Carlo Rovelli. He's a professor of
3:51
Speaker 1: physics in Marseille, and he cut his teeth and made
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Speaker 1: his name for himself developing theories of quantum gravity, mostly
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Speaker 1: loop quantum gravity. If I understand correctly, he also became
3:59
Speaker 1: a household name. Is the author of the book Seven
4:02
Speaker 1: Brief Lessons on Physics, which sold more than a million
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Speaker 1: copies and was translated into forty one languages. I've read
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Speaker 1: it and enjoyed it immensely and heartily recommended to you. Today,
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Speaker 1: Professor Rivelli is here to talk to us about his
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Speaker 1: new book, Hell Go Land and a fascinating alternative take
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Speaker 1: on the measurement problem in quantum mechanics. Professor Velli, welcome
4:19
Speaker 1: to the podcast, and thank you for joining us. Thank
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Speaker 1: you question that it's a pleasure in the honor of
4:24
Speaker 1: being here, wonderful. Well. I always love talking about quantum
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Speaker 1: mechanics and puzzling over it with other people. I feel
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Speaker 1: like every time I talk about quantum mechanics with somebody else,
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Speaker 1: I think of a new question I've never thought of before,
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Speaker 1: or a new angle on it, or a new mystery
4:38
Speaker 1: frankly like a new corner of my mind that I
4:41
Speaker 1: haven't ever really examined, and I get confused, and so
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Speaker 1: it's always fun to figure things outside of on the fly.
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Speaker 1: So today we wanted to talk about your new book
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Speaker 1: and Hell Go Land, And the book essentially lays out
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Speaker 1: for lay audience this idea of relational quantum mechanics, sort
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Speaker 1: of a new interpretation on quantum mechanics. And the first
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Speaker 1: question for you I have is if you could describe
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Speaker 1: for us what is the problem that relational quantum mechanics solves, Like,
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Speaker 1: why do we need another quantum mechanics interpretation? What is it?
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Speaker 1: At the heart of relational quantum mechanics is trying to
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Speaker 1: do One of the difficulties the problem of quantum mechanics
5:16
Speaker 1: is to say exactly what the problem is. So quass mechanics,
5:21
Speaker 1: on the one hand, it's extraordinary successful, is used in
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Speaker 1: a lot of our technology, is used a lot of
5:28
Speaker 1: our understanding of the world world. We explain with quantum
5:31
Speaker 1: mechanics the basics of chemistry, basic apastrophysics, all sorts of stuff,
5:37
Speaker 1: and it works. It works fantastically. On the other hand,
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Speaker 1: there is a persisting, mysterious aspect about this theory. It's
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Speaker 1: a theory that it's a it's sort of formulity differently
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Speaker 1: than previous basic physical theories. This difference puzzles everybody, and
5:54
Speaker 1: this is where the problems can in because the scientists
5:57
Speaker 1: disagree about how to think abou quantum mechanics. If you
6:01
Speaker 1: if you want to, if you go to a physicist
6:03
Speaker 1: conference and you want to really start a furious discussion,
6:08
Speaker 1: just like drop the question at the banquets, say oh,
6:11
Speaker 1: by the way, what do you think going to mechanics,
6:14
Speaker 1: And ten minutes later everyone's screaming against everybody. But is
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Speaker 1: this a conference of philosophers or physicists in your mind? No,
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Speaker 1: No physicist physicist physicism, including the one to say there's
6:23
Speaker 1: no problem at all, what are you talking about? And
6:25
Speaker 1: that they say, of course there's a problem. You know,
6:29
Speaker 1: where is the problem? I mean, how how can we
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Speaker 1: characterize the problem? Well? Sort of all physical theories from
6:35
Speaker 1: saying Newton or maybe even before from the card or
6:38
Speaker 1: even from Aristotle all the way to Maxwell and Twinstein,
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Speaker 1: special activity, general activity, electro dynamics. The theories describes the
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Speaker 1: systems and just the sens the system with some variables.
6:52
Speaker 1: I don't know a pendulum. It's a physical object and
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Speaker 1: the variable is the angle with the vertical and tell
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Speaker 1: you how this variable ease and evolves. Given something that
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Speaker 1: you know at the beginning and you know where it is,
7:05
Speaker 1: you know the velocity, and then you have you have
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Speaker 1: any questions that tell you how the variable changes continuously
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Speaker 1: in time. So of course this allows assume ex predictions
7:13
Speaker 1: because we can measure the position. The velocity doesn't close
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Speaker 1: our eyes with two seconds, open again and the new position.
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Speaker 1: New velocity can be predicted by the theory because they
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Speaker 1: tell us exactly how it moves in time. So that's
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Speaker 1: how Newton physics works, or Maxwell theory works of ice.
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Speaker 1: Since theory works well probamical, it does not work this way.
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Speaker 1: That's the point. It works in a completely different manner.
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Speaker 1: It does not tell us what happens at the pendulum
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Speaker 1: while he's moving. It only tells us the prediction without
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Speaker 1: saying what is in between. And if you try to reconstruct,
7:50
Speaker 1: what is this in between? So the data that you
7:54
Speaker 1: know and the prediction that you make, all devils go loose,
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Speaker 1: namely every stray. Things happen, and people disagree about what
8:02
Speaker 1: happened in between in between, you mean that moment when
8:05
Speaker 1: you close your eyes and you're trying to use physics
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Speaker 1: to predict the future exactly. So typically think about quantum
8:11
Speaker 1: mechanics in this way. I mean, you make a measurement,
8:13
Speaker 1: that's the language which is used. They'll certainly makes a measurement,
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Speaker 1: and you make a prediction of what's going to happen
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Speaker 1: at the next measurement sometime later, and the prediction is binger.
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Speaker 1: It works. I mean, it tell us exactly what we see,
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Speaker 1: but if you ask what happened in between, it's confusing.
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Speaker 1: And the reason it's confusing one way of presenting it,
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Speaker 1: one of the many ways of presenting it is the following.
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Speaker 1: If you have a particle, an electron, or a little
8:40
Speaker 1: mole for that, or an atom remocal, and you throw
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Speaker 1: it in some way, then going to mechanics tell you
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Speaker 1: where it's going to be, or at least probility distribution
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Speaker 1: of what's going to be. Because the prediction about the
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Speaker 1: mechanics and probabilistics are not not exactly that's one of
8:53
Speaker 1: the corrector is still going to mechanics, but it's telling
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Speaker 1: me the sort of probility going to be here that
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Speaker 1: you're probably going to be here, to be going to
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Speaker 1: be here. Then in between, what happens to the mathematics
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Speaker 1: is the particle opens up in a wave. It's it's everywhere,
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Speaker 1: and with this way you compute the different probabilities, so
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Speaker 1: the particles at the same time many positions in the mathematics.
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Speaker 1: So some people say, okay, so the particle isn't many,
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Speaker 1: it's a wave, it's all over. But then when you
9:23
Speaker 1: look at the particle is not a way. It's in
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Speaker 1: a single position. So other people say, no, come on,
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Speaker 1: I mean, we look at the particle is always a particle.
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Speaker 1: When we look where it is, it is always in
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Speaker 1: one point. But when you compute how it goes from
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Speaker 1: from here to here, it's not in one point. And
9:40
Speaker 1: if you assume that it is in one point, you're
9:43
Speaker 1: led to make some kind of mistakes and things like that.
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Speaker 1: So it's capable of making predictions, concrete predictions, or be
9:49
Speaker 1: can compared to measurements. But to make those predictions you
9:52
Speaker 1: need this intermediate step, which seems sort of nonsensical and
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Speaker 1: conflicts with our sense of like what is real in
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Speaker 1: the universe around exactly. So, but the real problem, it's
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Speaker 1: the thing people are debating with is what does it
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Speaker 1: mean that the theory describe what we measure. That's why
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Speaker 1: it's called the measurement problem. In a sense, it's like
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Speaker 1: when we measure something special happened, But we are not special, right,
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Speaker 1: We are just you know, piece of the universe like
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Speaker 1: any others. So the standard formulation of quantum mechanics, the
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Speaker 1: one reading textbooks, it's only in terms of the observer
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Speaker 1: and the measurement, which is fine as long as you
10:31
Speaker 1: don't ask, what about the physics of the observer? What
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Speaker 1: about the observer itself isn't to observe itself a quantum system,
10:39
Speaker 1: so it should be described the quantum mechanics as well,
10:42
Speaker 1: so it should also open up on it like a wave.
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Speaker 1: But that's it, and that's where people start disagree. And
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Speaker 1: some physicists thinkly, yes, we do. We do our waves
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Speaker 1: the multiple copies of Daniel and me and Carolo and
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Speaker 1: some versions of us, some some some answers are given,
10:58
Speaker 1: is some other versions of different. It is given because
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Speaker 1: we're a wave of different configurations of ourselves. Other people think, no,
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Speaker 1: come on, that's not a good way of thinking about reality.
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Speaker 1: And that's where the the disagreement start. So the disagreement
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Speaker 1: is realized in the number of so called interpretations of
11:15
Speaker 1: quanto methadnics ways to make sense about this funny story
11:18
Speaker 1: about the observer and the measurement and on the market
11:22
Speaker 1: that there are many but maybe three or four or
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Speaker 1: four or five which are dominant, and many variants of
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Speaker 1: these which is pretty different from one another, and give
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Speaker 1: a profoundly different picture of reality. And that's the beauty
11:34
Speaker 1: of the story. It's not just a technical thing about
11:37
Speaker 1: using the theory. In fact, it's not the technical thing
11:39
Speaker 1: about using Everybody agrees on using the theory, but everybody
11:41
Speaker 1: disagrees on if you want on what happens between the measurements,
11:45
Speaker 1: that's what way you're putting it. So I think it's
11:47
Speaker 1: really fascinating that it's so important to us to understand
11:51
Speaker 1: what happens when we're not looking. Right. Clearly, physics takes
11:55
Speaker 1: it very important to predict what happens when we look,
11:57
Speaker 1: because it's very practical. We need to know how trans
12:00
Speaker 1: star's working, whether our airplanes will fly. But when we're
12:02
Speaker 1: not making measurements, where we're not looking, when we're not
12:05
Speaker 1: watching the universe, we still want to know what is real,
12:08
Speaker 1: what is going on? We want to have like a
12:09
Speaker 1: model in our minds of how the universe works. Are
12:13
Speaker 1: we still doing physics in that case there's that philosophy
12:15
Speaker 1: or do you think they're you know, forever intertwined. I
12:17
Speaker 1: think they're forever intertwined, and I think they should be
12:20
Speaker 1: forever intertwined, because it's precisely by asking those kinds of
12:24
Speaker 1: questions that in the past physics has made the big jumps. Um,
12:32
Speaker 1: let me make an example of maybe two. What example
12:34
Speaker 1: is is the Earth the center of the universe. This
12:38
Speaker 1: was a huge debate at the time of between Copernicus
12:42
Speaker 1: and Newton. It's it's it's a center of debate, and
12:46
Speaker 1: nobody could say that this was not a scientific debate,
12:48
Speaker 1: because that's the debate that started that allowed Newton to
12:52
Speaker 1: do new to mechanics and allowed Galileo to understand the
12:56
Speaker 1: Gali little relativity, and this debate on on which Kepler BILLT.
13:00
Speaker 1: Kepler was a strenuous defender of the idea that there
13:05
Speaker 1: is not the center the universe. The universe is not
13:07
Speaker 1: the center. Going around the said, but if you think
13:09
Speaker 1: for a moment, is this Earth as the central universe?
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Speaker 1: A scientific question in the sense of something we can
13:16
Speaker 1: test them, of course not. There's no way of testing.
13:20
Speaker 1: There's no there's no operational meaning, there's no measurement that
13:23
Speaker 1: I can make that can distinguish if there Earth is
13:27
Speaker 1: the central universe. So it is not because you know,
13:30
Speaker 1: I mean it can stay somewhere and see moving. But
13:32
Speaker 1: what does it mean if I am moving, I see
13:34
Speaker 1: I I see the center moving. So it's really a
13:38
Speaker 1: non empirical question. And yet it's a profound way scientific question.
13:44
Speaker 1: Why because it gives a different way depending if you
13:48
Speaker 1: answer one way or the other. If you start by
13:50
Speaker 1: thinking there Earth is the center, everything goes around that all.
13:53
Speaker 1: If you start by allowing there is to be one
13:55
Speaker 1: of the things moves, so you go to a completely
13:57
Speaker 1: different way for conceptualizing reality, and one which worked very well.
14:02
Speaker 1: The other was bad. It was not the good one.
14:04
Speaker 1: So I think this is one of the aspect of
14:07
Speaker 1: science which I think is often misunderstood. They would say,
14:11
Speaker 1: sciences is not just about you know, close your eye,
14:15
Speaker 1: make make a model, make mathematics, make a measurement, make
14:18
Speaker 1: a prediction, and that's it. Science is about understanding reality,
14:22
Speaker 1: meaning building up a conceptual structure, the way you're thinking reality,
14:27
Speaker 1: how to put things in cases. One way of putting
14:30
Speaker 1: things in cases is in one case there's the Earth
14:33
Speaker 1: and in the other the celestial bodies, the sound, the wound,
14:37
Speaker 1: the planets, the stars, and then you throw that away.
14:40
Speaker 1: That's that's that. That's not the right characterizasue. The right
14:42
Speaker 1: way is there are stars, the planets, and then there
14:46
Speaker 1: are satellites. Do something different and that's works really different,
14:50
Speaker 1: and boom, we understand the universe better. So I think
14:53
Speaker 1: there are questions which are not directly empirical but are scientific,
14:58
Speaker 1: and I think the interpetitional quantum mechanics turn out something
15:01
Speaker 1: like that, Namely, one way you're thinking about the story
15:04
Speaker 1: will turn out to be useful on the long run.
15:20
Speaker 1: So then let's dig into the details of the different interpretations,
15:24
Speaker 1: just to recap for our listeners, what exactly is the
15:26
Speaker 1: problem that we're trying to solve here. The way I
15:28
Speaker 1: think about it sometimes is that we have these particles,
15:30
Speaker 1: and our mathematical model of them is that they are probabilistic.
15:33
Speaker 1: They can have the probability to be doing one thing
15:35
Speaker 1: or another thing. But of course that's not what we
15:38
Speaker 1: measure when we measure something, it does either one thing
15:41
Speaker 1: or the other. And the question is, how do you
15:43
Speaker 1: go from being probabilistic to being sort of classical. And
15:46
Speaker 1: you know, it seems arbitrary to say I'm making a
15:49
Speaker 1: measurement now or I'm not making a measurement, And you
15:52
Speaker 1: can ask questions like, well, when it interacts with other particles,
15:55
Speaker 1: why isn't that a measurement? Or if I'm making a
15:58
Speaker 1: measurement and I'm using a stick, and you know the
16:00
Speaker 1: tip of that stick is made of quantum mechanical particles,
16:03
Speaker 1: So why doesn't it just interact with my stick the
16:05
Speaker 1: way it interacts with other quantum mechanical particles and maintain
16:08
Speaker 1: it's probabilistic nature. And you know, people think about like
16:11
Speaker 1: do you have to have a conscious observer involved? But
16:13
Speaker 1: there's all sorts of fun things that you can dig
16:15
Speaker 1: into there. And had a fun conversation with the author
16:18
Speaker 1: of What is Real, which people can also dig into
16:21
Speaker 1: if they're interested in more details on what the measurement
16:23
Speaker 1: problem is. And the classical approach to people take this
16:26
Speaker 1: Copenhagen interpretation seems sort of arbitrary. It says that you know,
16:30
Speaker 1: the wave function moves by the shorting air equation, and
16:33
Speaker 1: it's smooth and continuous, and then boom, all of a sudden,
16:36
Speaker 1: when there's a measurement, everything collapses. But it doesn't tell
16:38
Speaker 1: you what a measurement is, right, And so there's this
16:41
Speaker 1: deep question still the heart of the most common interpretation.
16:45
Speaker 1: And let's listener as the podcast can also check out
16:47
Speaker 1: our episodes on the Many World's interpretation. But today I
16:50
Speaker 1: want to talk about your idea or this concept of
16:52
Speaker 1: relational quantum mechanics. So how does relational quantum mechanics deal
16:56
Speaker 1: with the measurement problem in a way that's different from
16:59
Speaker 1: this our try obviously unworkable approach of the Copenhagen interpretation.
17:03
Speaker 1: Yea very good and I think this is a nice
17:06
Speaker 1: way of putting the question. Let's take a let's take
17:10
Speaker 1: a concrete case. Was simplest the quantum mechanical experiment and
17:14
Speaker 1: measurement that we can make. We can take an atom,
17:16
Speaker 1: radioactive atom, right, just a piece of a block of
17:21
Speaker 1: radius radius uranium. They waited there and you put around
17:25
Speaker 1: it some detectors of radiation, you know, the guide detector,
17:29
Speaker 1: the click when when a radiation arrives to wait for
17:32
Speaker 1: a while and after a while, one of these clicks
17:35
Speaker 1: flink okay, and then you say, okay, the atom has
17:38
Speaker 1: emitted a radiation and it has been detected by these detectives.
17:42
Speaker 1: This is the fact. Now, how do we describe this
17:45
Speaker 1: in the equations? What we do when we do want
17:48
Speaker 1: to mechanics, we pretend that this radiation is some particles
17:52
Speaker 1: that are inside trapped inside the atoms, and they have
17:56
Speaker 1: a wave that describe them is a wave the way
17:58
Speaker 1: functions describes them and never automatics. These waves leaks out
18:03
Speaker 1: from the atom or from the nucleus of the atom
18:07
Speaker 1: slowly and continuously, and it's all over so and slowly.
18:11
Speaker 1: The imagine that this this wave continuously leaking out. So
18:15
Speaker 1: there's this continuously wave that around spherical and go out.
18:20
Speaker 1: So each one of the detectors is touched by these waves.
18:23
Speaker 1: Goes on. Then at some point the measurement happened. As
18:27
Speaker 1: you say, something happens. We go from this quantum wave
18:32
Speaker 1: to a classical factor, which is one single detector that happened,
18:36
Speaker 1: and this is a measurement. Now, different interpretation try to
18:40
Speaker 1: fill up the story in different way. Let me just
18:42
Speaker 1: compare to one or two interpretation. What is the many
18:47
Speaker 1: world interpretation that you mentioned, and the other is the
18:49
Speaker 1: Copenagen interpretation that dimension the many world, in a sense
18:52
Speaker 1: is the most radical idea of taking away very seriously,
18:56
Speaker 1: the Copenaga interpetition is the one we study at school,
18:58
Speaker 1: the one the teacher tell you tell you how to use.
19:01
Speaker 1: So the many one interpretation says that there's this wave
19:04
Speaker 1: that come out and you see only one detector clicking.
19:08
Speaker 1: But why do you see one the technical clicking, Because
19:11
Speaker 1: in reality, you yourself are a wave. Okay, So you,
19:16
Speaker 1: yourself are a superposition of different you like the particle
19:20
Speaker 1: and different positions in a superposition different positions. So it's
19:23
Speaker 1: not true that there is one detector that clicks. All
19:26
Speaker 1: the detectors clicks, but you yourself interacting with these detectors
19:30
Speaker 1: split up in one you that sees this the technical clicking.
19:35
Speaker 1: One UITs is that the tector clicking. One U that
19:38
Speaker 1: is that the technical clipping, and so on. Okay, So
19:41
Speaker 1: now you would imagine that the wave contains copies of you,
19:46
Speaker 1: and the reason you've seen one and not the others
19:48
Speaker 1: is only because you happen to be one copy of
19:51
Speaker 1: you and not the other copies of the other. Now
19:53
Speaker 1: does this work. Yes, it works. Is it plausible, Well,
19:57
Speaker 1: it sounds very implausible, extremely implosed. Well, the problem is
20:01
Speaker 1: everything you do with pant the mechanics sounds implausible. So
20:03
Speaker 1: many people say, Okay, we have to accept this, that
20:06
Speaker 1: in reality we live in immense waves, that the copies
20:09
Speaker 1: and copies of ourselves, and that's the many world interpetation.
20:12
Speaker 1: Can I ask you a question actually about that many
20:14
Speaker 1: world interpretation? There is something about that that's never set
20:17
Speaker 1: right with me. But maybe it's very naive and and
20:19
Speaker 1: that's this you say that there are many, many copies
20:22
Speaker 1: of me, And so it breaks the problem of why
20:25
Speaker 1: is this one detector clicked by saying it's not just
20:27
Speaker 1: that one detector clicked, all of them have clicked, just
20:29
Speaker 1: in other versions of the universe. But that doesn't make
20:33
Speaker 1: all the versions of the universe equal or on the
20:35
Speaker 1: same footing. Because I'm in this one, you know, this
20:38
Speaker 1: is the one that I feel is the truth that
20:41
Speaker 1: I'm making the measurement in. And that's different from the
20:44
Speaker 1: other ones because I'm not in those other ones. And
20:46
Speaker 1: maybe there are other means in the other ones. And
20:48
Speaker 1: let's say that they're you know who I actually am.
20:51
Speaker 1: But this is the one that I'm experiencing, and so
20:53
Speaker 1: it still feels to me like it has a special place.
20:56
Speaker 1: Is that a naive concern or is that something that
20:58
Speaker 1: you think many worlds can address. It is a concern
21:02
Speaker 1: because about many words plays exactly on the fact that
21:06
Speaker 1: there is a contingency in who you are, which is
21:09
Speaker 1: hard to making, not either informals or in words, and
21:15
Speaker 1: it is left a little bit vague into that. So
21:19
Speaker 1: it is a concern that some philosophers have raised about
21:24
Speaker 1: about many worlds. All right, Well, as long as philosophers
21:26
Speaker 1: agree with me, then i'm solid. Okay, Yeah, but you know,
21:31
Speaker 1: you can always find a philosopher that has a low
21:35
Speaker 1: bar apparently. All right, so that's the many worlds interpretation.
21:39
Speaker 1: Let's go to the cobanagen which is what you said
21:41
Speaker 1: at school, okay, The communities says, well, there are special
21:44
Speaker 1: things which observers, okay, which are classical, namely a big,
21:50
Speaker 1: big compared to to the quantum phenomena. It's when you
21:55
Speaker 1: don't see quantum phenomena because they're too subtle for you.
21:58
Speaker 1: They are not visible to you there because you're too
22:00
Speaker 1: heavy to see quant phenomena. To isolate things, you go
22:03
Speaker 1: to small things, so they are classical ob genia many
22:06
Speaker 1: all the ones around us, and there is a classical
22:09
Speaker 1: So forget quantum mechanics. About this. When a quantum system
22:12
Speaker 1: interacts with the classical world, bingo, that's a measurement. And
22:17
Speaker 1: this works in practice very well. That's what we do
22:22
Speaker 1: in the laboratory. But in theory it obviously does not
22:25
Speaker 1: work because what is a classical system? But we I
22:29
Speaker 1: am many electrons and protons, and each one of them
22:32
Speaker 1: it's a quantum particle, so each one has a wave,
22:35
Speaker 1: so I have a big wave. I am a quantum
22:37
Speaker 1: system in a sense copenagen it's a works with an
22:43
Speaker 1: approximation saying, well, imagine that your theory is wrong for
22:48
Speaker 1: big things, forget about it, and still use it for
22:51
Speaker 1: small fixed And you know that's why it appeals to
22:54
Speaker 1: everybody who does not want to ask questions. And you can,
22:58
Speaker 1: but if you don't ask sans, you don't get answers.
23:01
Speaker 1: I mean, on those sides of scientists about asking questions,
23:04
Speaker 1: A lot of scientists who say, as well, I don't
23:06
Speaker 1: want to care about that. There were more in the past,
23:08
Speaker 1: in the sixties and the seventies, in the eighties, I
23:11
Speaker 1: would say the majority of physicists would have said, oh,
23:15
Speaker 1: come on, just use the theory. It works very well.
23:18
Speaker 1: Nowadays there are less and less people who do that,
23:20
Speaker 1: so I would say the large majority of people agree
23:24
Speaker 1: that there is something to say better here. So let's
23:26
Speaker 1: come to relationship quantum mechanics. What does the relational quantum
23:29
Speaker 1: mechanics says about that? It says that all systems are quantum,
23:33
Speaker 1: and that's the first assumption. Let's see that we're, as
23:38
Speaker 1: far as we know, quantum mechanics the best ecup, but
23:40
Speaker 1: we haven't about the world. So after to disconfirm all
23:43
Speaker 1: systems have led to So that's already in contradiction with
23:47
Speaker 1: Copenhagen interpretation that says like I am classical and you
23:50
Speaker 1: are classical. It says everything is made of quantum. Even
23:53
Speaker 1: classical objects are just like massive quantum objects. This is
23:56
Speaker 1: just what quantum objects look like when they're really big, exactly.
24:00
Speaker 1: So therefore there is nothing which is an observer, but
24:02
Speaker 1: by itself, nothing that separates an observer in the sense
24:06
Speaker 1: of quantum mechanics from a piece of stone. Of course,
24:11
Speaker 1: you know, there the people who have eyes, the machines,
24:16
Speaker 1: there are things that store information, but that's irrelevant here.
24:21
Speaker 1: The point is in a relational quantum mechanics. That's the
24:24
Speaker 1: suggestion of relational quantum mechanics that the measurement happens in
24:28
Speaker 1: some sense every time two systems interact. But the actual
24:34
Speaker 1: element of reality which is realized in the interaction, so
24:37
Speaker 1: that when the detector clicks or the particle is here
24:41
Speaker 1: is here because they see here, the particle hits another particle,
24:45
Speaker 1: and therefore it has a specific position that has to
24:48
Speaker 1: be soked, not as a property of the particle by itself,
24:53
Speaker 1: but as a proper relational property of the particle and
24:57
Speaker 1: the system it is interacting with in relation to the
25:00
Speaker 1: thing during the measurement, exactly innovation to the same door
25:03
Speaker 1: and literally which could be anything. We can be another
25:05
Speaker 1: party in a sense. So therefore, the central idea of
25:10
Speaker 1: religion wanto mechanics is, let's be radical in the following sense.
25:14
Speaker 1: We describe the world in terms of systems, particle, electron,
25:17
Speaker 1: et cetera. And these have the properties variables that describe them,
25:22
Speaker 1: But these variables don't describe how the system is, it interacts,
25:26
Speaker 1: how the system interact with something else. Okay, so for example,
25:29
Speaker 1: we have a particle and it's flying along and it
25:32
Speaker 1: has a certain way function for things that might do,
25:34
Speaker 1: and Copenhagen interpretation says it stays probabilistic until something classical
25:39
Speaker 1: interact with it. Relation or quantum mechanics says it can
25:43
Speaker 1: collapse when it interacts with anything, but that collapse is
25:47
Speaker 1: different for depending on who is interacting with it. So
25:49
Speaker 1: if it interacts with this particle might collapse in this way.
25:52
Speaker 1: If it interacts with somebody else, that might collapse in
25:54
Speaker 1: another way. In that sense, it's also sort of like
25:56
Speaker 1: a branching of what reality is real, because what is
26:00
Speaker 1: real now depends on who is doing the measurement. Is
26:02
Speaker 1: that right? That's exactly correct. So the so called collapse
26:05
Speaker 1: of the way function is by itself, something which is
26:09
Speaker 1: relative to the system against which the particles is interacting,
26:13
Speaker 1: which doesn't need to be a macroscopical object, doesn't need
26:17
Speaker 1: to be anything special. It's anything but this. The subtlety
26:23
Speaker 1: is the following. I suppose the particle interact with my machine,
26:25
Speaker 1: my detector, okay, and I am I am a distance
26:32
Speaker 1: and the two are not interacting with me. So with
26:35
Speaker 1: respect to me, there is no collapse happening. So the
26:40
Speaker 1: way the particle and the machine are gonna manifest themselves
26:44
Speaker 1: to me later on if they interact with me is
26:47
Speaker 1: still computed with quantum mechanics. So if I want to
26:50
Speaker 1: compute what happens with respect to me, I still use
26:54
Speaker 1: the way function of the particle and the way function
26:57
Speaker 1: of the machine, because the machine is quite mechanical, I think.
27:00
Speaker 1: So for example, I'm here talking to you, so I'm
27:03
Speaker 1: measuring you. I'm collapsing your way function. But our listeners
27:06
Speaker 1: have not yet heard this podcast, so from their point
27:09
Speaker 1: of view, you and I are still in some uncollapsed
27:11
Speaker 1: quantum state, and only when they hear this does it
27:15
Speaker 1: collapse into an actual stream of words. So for us
27:18
Speaker 1: it is collapsed, but for them it's not yet collapsed exactly.
27:21
Speaker 1: So I believe that this is coherent. This can be
27:24
Speaker 1: made clearing by going into details. It offers a possible
27:27
Speaker 1: solution of the puzzle quantum theory. This is a relation
27:31
Speaker 1: with dempetition. It does require it has a cost. There's
27:34
Speaker 1: a conceptual cost, because as you said, reality is a
27:38
Speaker 1: little bit more subjective. No subjective relative. I'll come back
27:42
Speaker 1: to the difference subject in relative. So it weakens realism
27:47
Speaker 1: in a sense, but it's still a realistic interpetation. So
27:50
Speaker 1: I think that this cost is more worthwhile paying for
27:57
Speaker 1: being fruitful for the future of physics than imagining that
28:01
Speaker 1: there are many copies of myself, or than not asking
28:05
Speaker 1: the question when you come to the subtle team. In
28:07
Speaker 1: your example, you talked about you and me and the
28:11
Speaker 1: listeners all people. Okay, that's fine, but the key intuition
28:17
Speaker 1: of relationship about the mechanics that this has nothing to
28:19
Speaker 1: do with people. That's the key point. And that's a
28:22
Speaker 1: big difference with respect also with coping again in a sense, right,
28:26
Speaker 1: this is nothing to do with subjectivity. That's it to
28:29
Speaker 1: do the subject. But factly you and I are are
28:32
Speaker 1: subject of perceptions as need to do. You would also
28:34
Speaker 1: work if you and I were dogs or bananas or particles, right, exactly,
28:39
Speaker 1: the same mathematics work, exactly as I'm the same story
28:42
Speaker 1: would work. And to make an example of this, because
28:45
Speaker 1: I think that you know, relative to observer observable are
28:51
Speaker 1: often misinterpreted as subjective while it's just relational. For instance,
28:57
Speaker 1: there's a very well known example of relational notion in
29:01
Speaker 1: physics which students struggle at the beginning when they encounter
29:06
Speaker 1: it the first time, because it's very contin intuitive if
29:09
Speaker 1: you think at the beginning, which is velocity. When we
29:11
Speaker 1: study Galian theory a Newton theory, we learn that velocity
29:17
Speaker 1: is not absolute, velocity is relative. So what is the
29:21
Speaker 1: velocity of the moon. Well, depend there's the velocity of
29:26
Speaker 1: the moon we respect to this Earth, the velocity of
29:28
Speaker 1: the moon we respect to the Sun. The velocity moon
29:30
Speaker 1: we respect to the center of the galaxy, the loscy
29:33
Speaker 1: moon respect to the cosmic microwave background average. Which one
29:38
Speaker 1: is the true one? Well, no, it's a velocity. It's
29:43
Speaker 1: a notion that pertains the two objects, the moon and
29:46
Speaker 1: something else. It's always velocity of the moon with respects
29:49
Speaker 1: something else. We sort of know that, right, because when
29:51
Speaker 1: we say don't move, we know that don't move is
29:55
Speaker 1: relativitally to something. For instance, if you're in a train
29:59
Speaker 1: and your little daughter is jumping around and you say
30:02
Speaker 1: don't move, you don't mean that you little daughters to
30:05
Speaker 1: jump out of the train and don't cove with respect
30:07
Speaker 1: to the earth. Right, you mean don't move respect to
30:11
Speaker 1: the train. And she understand correctly right that she should
30:14
Speaker 1: soon move respect the train and she's just still moving
30:17
Speaker 1: very fast because the train is running. So we understand
30:20
Speaker 1: that velocities are it's it's a relational notion. But this
30:24
Speaker 1: is nothing to do with subjectivity, right because if I
30:26
Speaker 1: say that the moon has a velocity respect to the sound,
30:29
Speaker 1: I'm not saying that the Sun is a subject that
30:33
Speaker 1: sees the moon and perceives something. Is nothing to do
30:35
Speaker 1: with that, nothing to do with mind subjectivity, Just physics,
30:39
Speaker 1: pure physics. There is a quantity to velocity which doesn't
30:44
Speaker 1: depend on one thing. It depends on two things, the
30:47
Speaker 1: Moon and the Sun. And it's velocity the relative velocity
30:50
Speaker 1: of the two, say how they move respect one of that.
30:52
Speaker 1: So that's a big philosophical step, right, You've sort of
30:54
Speaker 1: taken away from the moon the fact that it can
30:57
Speaker 1: have a property called velocity. Say, you can't have a
31:00
Speaker 1: property called velocity. Only a pair of things can have
31:02
Speaker 1: this property. A single object cannot. And the sort of
31:06
Speaker 1: the mental game i'd like to place to imagine, like
31:08
Speaker 1: a particle in an empty universe, can it have a velocity? Well,
31:11
Speaker 1: it has no meaning to have a velocity if you
31:13
Speaker 1: are the only thing in the universe, right, And so
31:16
Speaker 1: I want to also ask you about this concept of cost.
31:18
Speaker 1: You're talking about the cost of a theory, and so
31:21
Speaker 1: here is that the cost you mean that you're like
31:23
Speaker 1: now changing philosophically what it means to be real that
31:26
Speaker 1: no longer can you include in your sort of you know,
31:29
Speaker 1: category or your index of what it means to be
31:32
Speaker 1: that you have a certain velocity that you've like taken
31:35
Speaker 1: that away from objects. Yes, this is the course, and
31:38
Speaker 1: I think you said it very cleanly. It's a deep
31:41
Speaker 1: philosophical point when we realize that velocity is not a
31:45
Speaker 1: property of an object you need another object, is a
31:48
Speaker 1: property of two objects. A quantum mechanics in a sense.
31:52
Speaker 1: The phone suggestion that we in this em better quantum
31:54
Speaker 1: mechanics if we just interpreted all properties, all variable in
32:00
Speaker 1: this way, not just velocity. Okay, any variablity, even think
32:05
Speaker 1: about a system only makes sense if you if you
32:11
Speaker 1: have another system. You're saying it's this is a variable
32:14
Speaker 1: with suspect to this other system. And what you mean
32:16
Speaker 1: is that there was an interaction to these two systems
32:19
Speaker 1: and that variable was realized in this interaction. Namely, describe
32:23
Speaker 1: the way one system affected the other one. And can't
32:25
Speaker 1: you use even the same language. Because now we talked
32:27
Speaker 1: about velocity. We say velocity of the moon as measured
32:31
Speaker 1: by an observer on the Sun, or as measured by
32:33
Speaker 1: observer on the Earth. Now you can say the location
32:36
Speaker 1: of this particle or the color of this particle as
32:38
Speaker 1: measured by this observer versus as measured by that observer exactly.
32:56
Speaker 1: Now you went strongly in saying, does this mean that
32:59
Speaker 1: reality itself it's relative to um? I hesitate. Namely, the
33:06
Speaker 1: same reaction could have been raised against the Galileo and
33:12
Speaker 1: Newton when they started using velocity. In this sense, I
33:18
Speaker 1: think that the reality of the motion of the moon
33:21
Speaker 1: and velocity of the moon and the Sun and things,
33:24
Speaker 1: in spite of what we have understood about relativity velocity
33:28
Speaker 1: is still very solid. Still we still have a realistic
33:32
Speaker 1: interpretation of motion, and so I would like to think
33:36
Speaker 1: about relational quantum mechanics as a realistic picture. So reality
33:41
Speaker 1: is there, it's I mean, things are there, and then
33:44
Speaker 1: there's nothing to do with us. Of course, we are
33:47
Speaker 1: just a part of nature. Is not that nature is
33:49
Speaker 1: a part of our mind. That's my naturalism if you want.
33:54
Speaker 1: But the way reality is is subtle. According to quantum
33:57
Speaker 1: mechanics can be described. Reality can be described by systems
34:01
Speaker 1: that have a properties relative to other systems. So then
34:05
Speaker 1: can you have something which exists by itself like imagine,
34:09
Speaker 1: you know, the sort of simple example I mentioned earlier.
34:11
Speaker 1: For velocity, a single particle an empty universe can't have
34:14
Speaker 1: a velocity. Now you said that everything is relation on
34:18
Speaker 1: the way velocity is. Does that mean a single particle
34:21
Speaker 1: in an empty universe does not exist or cannot have
34:24
Speaker 1: any properties because it would need something else in order
34:27
Speaker 1: to measure it. Can a single particle universe exists? No,
34:30
Speaker 1: if quantum mechanics max is the correct description of the units.
34:33
Speaker 1: And in fact that can be said in a beside
34:35
Speaker 1: the way. There's a philosopher which is Madorato who is
34:39
Speaker 1: elaborated much on that, saying, if we take relationhp quantum
34:43
Speaker 1: mechanics correctly, we cannot talk about the quantum state of
34:46
Speaker 1: the universe. We cannot state of the quantum state of everything.
34:50
Speaker 1: We cannot even talk about the description of the universe
34:53
Speaker 1: because the scripture universe needs to be if you use
34:57
Speaker 1: this way of thinking, a point of mechanics scripture relatively
34:59
Speaker 1: to something else. So in the moment in which you're
35:02
Speaker 1: saying the description units, so you're assuming there is something
35:05
Speaker 1: outside that is looking at the universe. Well you can,
35:08
Speaker 1: but then in your reality there is something else in
35:10
Speaker 1: addition to what you just called the universe a moment ago.
35:14
Speaker 1: For instance, the famous way functional units, what is it
35:17
Speaker 1: is a mathematical object that allows you to predict what
35:22
Speaker 1: you would measure if you are outside the universe to
35:25
Speaker 1: interact with it. But then it's not the universe anymore
35:28
Speaker 1: because there is something else outside the universe interacting with it.
35:31
Speaker 1: So there's the way functional use is meaningless. It's always
35:35
Speaker 1: the way function of something. I was hoping to use
35:38
Speaker 1: that example to lead you down the garden path to
35:41
Speaker 1: admit that means the universe can't exist, but you just
35:43
Speaker 1: went straight there and said, if this is true, then
35:47
Speaker 1: we don't have a meaningful concept of what the universe is.
35:51
Speaker 1: I mean, isn't that a problem? I mean, if we
35:53
Speaker 1: want a theory of reality that tells us what is happening,
35:56
Speaker 1: doesn't it need to also allow us to think about
35:59
Speaker 1: what reality is. I think that it's a deeper point
36:03
Speaker 1: one of the things we have understood more and more
36:06
Speaker 1: in modern physics, but also another realm of modern culture
36:10
Speaker 1: is that we're always part of the story. So we
36:13
Speaker 1: see reality from we think, not from outside in completely
36:17
Speaker 1: different parts of our culture. First this this was famously
36:20
Speaker 1: an immense issue and toropology, right, you want to describe
36:23
Speaker 1: a society. When the Europeans went around the world to
36:26
Speaker 1: try to describe societies objectively, um, non European societies, maybe
36:33
Speaker 1: I don't know some people in their matson and then
36:36
Speaker 1: they re allies that they were not doing nothing objectively.
36:40
Speaker 1: They were just comparing their own culture with the culture
36:42
Speaker 1: of these people. In some of they were interacting with
36:45
Speaker 1: these people and not being outside a cultural scheme, but
36:50
Speaker 1: doing something and olmously interesting, not something that lacked value,
36:56
Speaker 1: but that was not a stepping out from what is
37:00
Speaker 1: being described. And I think physics to some extent has
37:04
Speaker 1: encountered the same set of problems. Namely, we described the
37:09
Speaker 1: universe from within. We are part of the universe. What
37:12
Speaker 1: physics tell us is if I encounter this, I know
37:17
Speaker 1: what I can expect, and I know what a what
37:21
Speaker 1: I can expect, what kind of things aide around me.
37:24
Speaker 1: But the idea that physics give a list of all
37:28
Speaker 1: or everything existing with the state, it's a first of all,
37:32
Speaker 1: totally unplausible by itself, right, I mean, how many stars
37:36
Speaker 1: there are in the universe, and how many atoms in
37:39
Speaker 1: each one of these stars? So it's just totally outside
37:42
Speaker 1: or a capacity. But even in principle, what does it mean.
37:45
Speaker 1: I mean, physics is all in the form if this,
37:48
Speaker 1: then that, right, If I found this pendulum in this way,
37:53
Speaker 1: then it's going to move that like that. It's model,
37:56
Speaker 1: as the philosopher says. So it's always a story of
38:00
Speaker 1: out given some initial conditions, this is what I expect
38:03
Speaker 1: to happen, given some data, this is what comes later,
38:07
Speaker 1: and then it tells what kind of atoms are around,
38:09
Speaker 1: the forces are around. But we shouldn't expect from physics
38:13
Speaker 1: the total novel of the universe. That's what everything is
38:17
Speaker 1: in the universe. That's at all the state of the universe.
38:20
Speaker 1: Why it's not that's far outside our capacities, And probably
38:26
Speaker 1: I would say it's meaningless because of what we said before,
38:30
Speaker 1: because that would be an issue that God might have
38:33
Speaker 1: if he or she exists seeing from the units from
38:37
Speaker 1: the outside, not of all our business. And I think
38:39
Speaker 1: this makes exactly the point that you were talking about earlier,
38:43
Speaker 1: that we want to know the answers these the philosophical questions,
38:45
Speaker 1: because they tell us which questions then makes sense to
38:49
Speaker 1: ask which questions have answers, and which questions are even
38:52
Speaker 1: relevant to think about. I think that's some of the
38:54
Speaker 1: most important reason why physicists need to think about philosophy.
38:58
Speaker 1: And I know that you talked about the mechanics a lot,
39:00
Speaker 1: and you're quite an expert on this, So I want
39:02
Speaker 1: to try to ask you a question that maybe nobody
39:04
Speaker 1: has asked you before, put you on the spot, and
39:06
Speaker 1: and that's this. Have you thought about what it might
39:08
Speaker 1: be like to talk about physics or quantum mechanics with aliens?
39:14
Speaker 1: Imagine that we have meet extraterrestrial physicists, right, and we
39:19
Speaker 1: go and we we say with to them whole you
39:21
Speaker 1: must know the secrets of the universe because you figured
39:23
Speaker 1: out how to travel here from distant stars. Do you
39:25
Speaker 1: think there's any possibility that we would be asking the
39:28
Speaker 1: same questions or that their answers to our questions would
39:31
Speaker 1: make any sense to us. Do you think that the
39:33
Speaker 1: way that we look at the universe is sort of
39:35
Speaker 1: the way Europeans, you know, looked at other cultures. Do
39:39
Speaker 1: you think that's deeply imbued with our human bias, or
39:41
Speaker 1: do you think that we are probing something universal which
39:44
Speaker 1: should be part of sort of like some galactic physics project.
39:47
Speaker 1: Great question. A bit of both, but more of the
39:49
Speaker 1: first and the second. That's my answer. There is a
39:52
Speaker 1: precise sense in which what we discover in science is
39:55
Speaker 1: it's just two in universal mean. I don't think this
39:59
Speaker 1: can be denied, and people who denied it, I think
40:02
Speaker 1: have a toak way of denying it, and don and
40:05
Speaker 1: physics in some sense, it's true. It works described reality.
40:08
Speaker 1: It's I mean, the fact that everything is made by
40:11
Speaker 1: atoms and there are ninety and so kind of different atoms.
40:15
Speaker 1: That's a fact. It's like when you you know, when
40:18
Speaker 1: you go down the street and you see that you
40:21
Speaker 1: know your three friends are in the cafe. That's a fact.
40:24
Speaker 1: It's true. And I believe that science is a higher
40:28
Speaker 1: level of understanding. Fact is the way humankind organizes an
40:33
Speaker 1: understanding of reality better and better. But from this, to
40:38
Speaker 1: have the idea that there is a unique, clearly path
40:43
Speaker 1: to the perfect description of reality and we are on need,
40:46
Speaker 1: or even that we're close to the end of it,
40:49
Speaker 1: that seems to me unbelievably full of self pretension, and
40:54
Speaker 1: I see no sign that we're close to that. And
40:59
Speaker 1: we have a sort of experiment of that because we
41:02
Speaker 1: know what asked centurists, scientists thought, and we do know
41:07
Speaker 1: that some of the things that we know would be
41:10
Speaker 1: meaningless for them, It would not answer their questions in
41:15
Speaker 1: really going in a different direction, which does not mean
41:17
Speaker 1: that they are better than us. We are better than
41:19
Speaker 1: them because we know what they are in some objective sense,
41:24
Speaker 1: and the objective sense is that if both one came alive,
41:27
Speaker 1: and if I could have enough time also want to
41:30
Speaker 1: me sitting here, I believe that I could slowly arrive
41:32
Speaker 1: to convince him that there are a lot of interesting
41:34
Speaker 1: things he doesn't know. So I think it's the same
41:36
Speaker 1: with some aliens. If some millions would come, I wouldn't
41:40
Speaker 1: be surprised if they have a completely different story. And
41:42
Speaker 1: it might be possible that we just don't understand one
41:44
Speaker 1: another because the story is two different. It might be
41:48
Speaker 1: different because they have a different way of perceiving reality. Right,
41:51
Speaker 1: we view reality on the basis of what useful to
41:53
Speaker 1: our They're being an evolution, not on the basis of,
41:56
Speaker 1: you know, some contient rationalism or simply even if they
42:00
Speaker 1: had the same senses, because culture of them was going
42:04
Speaker 1: in other directions. But I believe there is communication, right,
42:08
Speaker 1: Cultures communicate, So maybe with this aliens we could learn
42:14
Speaker 1: to communicate. And we were very surprised of learning completely
42:18
Speaker 1: different perspectives. If they are more advanced than us in
42:21
Speaker 1: some sense, or maybe they will be surprised to learn
42:24
Speaker 1: something from us, or maybe both. So in other ways,
42:26
Speaker 1: I don't think there is a path to tools, and
42:28
Speaker 1: they would know everything we know any more. Maybe they
42:31
Speaker 1: would never think about quantum mechanics and we teach them
42:33
Speaker 1: quanto mechanics. That was fantastic. You're right, it's a relationship.
42:38
Speaker 1: But will send you to meet the aliens and how
42:40
Speaker 1: they don't eat you. There is a greater novel, The
42:43
Speaker 1: Dark Clouds The Black Cloud, in which there is this
42:47
Speaker 1: it's a huge cloud that come towards the sermon and
42:51
Speaker 1: somebody realizes that it's actually intelligent something down there, and
42:55
Speaker 1: it's uh, and somebody realized that it is going to
42:57
Speaker 1: be a disaster for the Earth is going to exactly
43:00
Speaker 1: edge of the sound. And somehow so the scientists arrived
43:03
Speaker 1: to communicate and so gently convinced this cloud to leave
43:08
Speaker 1: us alone. But then there is one scientist so too.
43:12
Speaker 1: I don't remember. That's the Wait a minute, I want
43:13
Speaker 1: to learn everything you know, So the cloud answer, well,
43:17
Speaker 1: it's tandrous. I mean your little brain. But they really
43:22
Speaker 1: wanted to so they can say, okay, if you really want, so,
43:25
Speaker 1: I think it's two of them. They sit around the screen, okay,
43:30
Speaker 1: and the screens start flickering, and they just look at
43:32
Speaker 1: this at the beginning. At the beginning, they don't understand,
43:34
Speaker 1: but then they start understanding, and then finally they start learning,
43:39
Speaker 1: and then they're lost because then they're considered fool and
43:42
Speaker 1: they're putting all the psychotic hospital and the body knows what.
43:47
Speaker 1: That's the danger of talking physics with aliens is you
43:50
Speaker 1: can see reality, so clearly the humans can no longer
43:53
Speaker 1: relate to you. So let me bring it back to
43:55
Speaker 1: one last question about relational quantum mechanics. What you're proposing
43:58
Speaker 1: here is really a ratheric of departure on a way
44:01
Speaker 1: of seeing the universe, imagining that objects don't contain on
44:05
Speaker 1: their own properties, but that these things are just dependent
44:09
Speaker 1: on pairs, essentially things that are measuring other things. So
44:12
Speaker 1: my question to you is that how could we know
44:14
Speaker 1: if this is true. Is there some experiment we can do?
44:17
Speaker 1: They could tell us, look, Copenhagen fails here and we
44:20
Speaker 1: need relation or quantum mechanics, or we can dispense with
44:23
Speaker 1: the many worlds, like is this something which can only
44:25
Speaker 1: ever be a philosophical conversation among physicists motivating our questions
44:29
Speaker 1: about reality, or is this something we can actually one
44:32
Speaker 1: day put to the test. I don't see any way
44:35
Speaker 1: it could put to the test. There's some interpretation quantum
44:39
Speaker 1: mechanics that assume that quantum mechanics actually wrong, and so
44:43
Speaker 1: they can be tested because you can do an experiment
44:45
Speaker 1: to see where the quantum mechanic is wrong right, And
44:48
Speaker 1: they're very interesting. And so far many of these tests
44:51
Speaker 1: have been done and quant mechanics always going to be right,
44:53
Speaker 1: and all alternative from the moment have been all eliminated.
44:57
Speaker 1: But the various interpretation like many world or de bullyable,
45:01
Speaker 1: the pilot wave interpretation, hidden variables or relationship quantum mechanics,
45:04
Speaker 1: which I think are the main one. So cubans maybe
45:08
Speaker 1: in one sense, they are not distinguishable in an empirical way,
45:13
Speaker 1: as as far as I know, nobody has come out
45:14
Speaker 1: with experimented distinguished them, and in a sense studying them,
45:18
Speaker 1: there's no experiment making a difference, So how would we know, Well,
45:22
Speaker 1: I think exactly the same way, which we finally all
45:25
Speaker 1: agree that the Earth is not the center of the universe,
45:28
Speaker 1: even if there is no experiment that tells us that
45:31
Speaker 1: the Earth is or is not the center of the universe,
45:34
Speaker 1: because there's no way to measure just what the center
45:38
Speaker 1: the center units, namely, the progress of science will work
45:43
Speaker 1: better with one conceptual scheme than the other. I do
45:46
Speaker 1: quanta gravity my main the reason I got into the
45:50
Speaker 1: issue of integrational quantum mechanics, and the mechanic goes back
45:54
Speaker 1: to the nineties. In fact, my first papers on that
45:56
Speaker 1: in the late nineties, and then other people can and
46:00
Speaker 1: have developed it and in recent years have been a
46:03
Speaker 1: much stronger increasing interest in it. And it's not isolated
46:08
Speaker 1: because there are the people who are very similar ideas,
46:11
Speaker 1: So which why is really part of a little group
46:14
Speaker 1: of interpretation just similar in some sense, maybe with different emphasis,
46:20
Speaker 1: different tone. I'm thinking of writings by Zeilinger, by Chancellor Bruckner,
46:27
Speaker 1: by Richard Haley and another. There are a number of
46:30
Speaker 1: ways of going in the same direction, so in my
46:33
Speaker 1: own work and trying to put up a quantic see
46:35
Speaker 1: of gravity, I found that this way of thinking, it's
46:38
Speaker 1: much more helpful when you don't have space, you don't
46:42
Speaker 1: have time to locate things, you don't have the observer.
46:46
Speaker 1: This relational way works well. And one reason it works well,
46:49
Speaker 1: it works through well well with general activity, where location
46:52
Speaker 1: is relations. Nothing has a position to be somewhere. It's
46:56
Speaker 1: only meaningful if you're some well respect to something else.
46:59
Speaker 1: And now the things start staying together well, because to
47:04
Speaker 1: be next to something is possibility of interacting with something,
47:07
Speaker 1: so you can exchange information with something. That's what we're
47:10
Speaker 1: talking about in physics, this being next to one another
47:13
Speaker 1: and exchanging something, rather than having, you know, it becomevast
47:18
Speaker 1: there and placing things and saying that's that's what reality is.
47:21
Speaker 1: So I hope that the discussion about indevidual quadema is
47:25
Speaker 1: going ahead. It's not blocked, it's not the same as
47:28
Speaker 1: thirty years ago. And I think that with the new ideas,
47:31
Speaker 1: with the new things being discussed, at some point it
47:34
Speaker 1: will become more and more clear that one way of
47:37
Speaker 1: viewing things it's productive. It works. It doesn't require us
47:40
Speaker 1: to assume things which are absurd, but it does require
47:44
Speaker 1: us to assume things which are necessary to make in
47:48
Speaker 1: sense of reality. Wonderful. Well, that's a fascinating insight into
47:53
Speaker 1: how we might make steps forward. And I agree with
47:55
Speaker 1: you that it makes sense to unify quantum mechanics with
47:59
Speaker 1: relativity if quantum mechanics itself becomes sort of relativistic, not
48:03
Speaker 1: in the sense of things moving at very high speeds,
48:06
Speaker 1: but in the sense that the objects and the quantities
48:08
Speaker 1: we measure themselves are relational or relative to other objects.
48:13
Speaker 1: So that makes a lot of sense. Well, thanks very
48:15
Speaker 1: much for this fascinating conversation, really stimulating, you know, about
48:19
Speaker 1: quantum mechanics and physics and relativity and of course aliens
48:22
Speaker 1: and philosophy. I want to thank you very much, and
48:25
Speaker 1: I want to point our listeners to your book Health
48:27
Speaker 1: Go Land, which has just come out recently, and it's
48:29
Speaker 1: fascinating read on these ideas and how they were developed,
48:33
Speaker 1: and people who are interested in digging more deep into
48:35
Speaker 1: them might encourage you to check them out. So Carlo,
48:38
Speaker 1: thanks you very much for joining us on the program today.
48:40
Speaker 1: Thank you. Emaually, that's what's great. Thank you. Thanks for
48:51
Speaker 1: listening and remember that Daniel and Jorge explained. The Universe
48:54
Speaker 1: is a production of I Heart Radio or more podcast
48:57
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