7 ms·

A realist takes on quantum mechanics

54 points by jonbaer 8y ago

empath75 8y ago
I feel like when people say ‘realist’ in this context, they mean someone who believes that ordinary intuitions about the way the world works are how the world must work at all levels. And there is no reason to believe that our minds were evolved to understand reality at anything but the macro level. I’ve long thought that the study of physics at the extremes is as much a study of the human mind and what we’re capable of comprehending as it is a probe of fundamental reality. Which is to say that experiments are essentially a chain of processes by which we translate information from whatever we’re studying into a form capable of being understood by our mind — often translating it into something visual so our visual cortex can process it and store it. But I wonder how much is out there that is simply impossible to transform in such a way.
- FakeComments 8y ago
  > I feel like when people say ‘realist’ in this context, they mean someone who believes that ordinary intuitions about the way the world works are how the world must work at all levels. From the article: > Like Einstein, Smolin is a philosophical ‘realist’ — someone who thinks that the real world exists independently of our minds and can be described by deterministic laws. So no, they don’t. Also, realism is consistent with quantum experiment — non-realism is merely an interpretation that’s had more developers work on it, not somehow a proven component of reality. (Commonly called Copenhagen interpretation; MWI and Bohmian are other interpretations; arguably loop quantum gravity too.) I agree with Smolin: non-realism is an extraneous assumption meant to preserve locality, but reality is empirically non-local. Ironically, it’s actually the non-realists who are guilty of what you say — they can’t let go of their Euclidean intuitions, and so come up with nonsense like denying realism. Their entire model is fundamentally predicated on things looking like a smooth Euclidean space at all scales below some threshold — that is, that reality all the way down looks like what we see when we look around. Non-realists insist on a Euclidean world despite contrary experimental evidence. If you view energy as distributed across the topology of your space, which often is radically non-Euclidean, you immediately have realism back — the world just is nothing like what’s in front of your eyes. (Enter loop quantum gravity.)
  - msla 8y ago
    Alternatively, the non-realists prefer to view the Uncertainty Principle as deeply true instead of seeing Special Relativity as deeply false.
    - FakeComments 8y ago
      Yes — so much so, they added it as an extra assumption to their model. The original justification is that we have things like Bell’s experiment that say reality is non-local or non-deterministic, because they exclude local determinism. But since then, we’ve found increasing evidence that it’s non-local, and so the choice made for the Copenhagen interpretation, to preserve locality at the cost of determinism, becomes unjustified. It’s now included as an extra assumption out of tradition, and because no one wants to seriously rewrite things. However, as Smolin contends, that may be a dead-end intellectually and an impediment to unifying QM with relativity. A non-local, but real QM interpretation has a more straightforward paradigm to merge with relativistic gravity: it aligns their models philosophically.
  - TelmoMenezes 8y ago
    > non-realism is an extraneous assumption Realism is as much an assumption as non-realism. It doesn't feel that way, because realism fits the common sense of some evolved monkeys. Common sense sometimes is correct, sometimes is not. It doesn't really mean anything when we deal with these matters. In fact, I would argue that Occam's Razor advises us to prefer non-realism. With non-realism, we are restricted to something we know to exist, by virtue of our human experience: our first-person perception of things. The independent reality, or third-person perspective, is undoubtedly a useful model, but we have no empirical data to suggest it is real. In fact, I would argue that quantum mechanic does raise some serious issues w.r.t. the this model. Btw, this debate is almost as old as human culture. It was already present in Aristotle (materalism) vs. Plato (idealism). You can also find many traces of it in Eastern thought, e.g. the idea of Maya, or the question of: how can you really know if you are dreaming right now? > not somehow a proven component of reality There are no proven components of reality. Proof is something possible in the domain of mathematics, if one accepts certain axioms. Science is not in the business of proving things, it is an empirical endeavor. It gives us theories that resist falsification (until seen) + eternal doubt. Once you abandon doubt, you abandon science.
- naasking 8y ago
  > But I wonder how much is out there that is simply impossible to transform in such a way. Given transformations are mathematical, the only way "phenomena that are impossible to transform" is not the empty set is if there are non-mathematical phenomena. So my bet is that the set is empty.
  - Retra 8y ago
    You can't make that bet. Mathematics is just a language; if there were phenomena that couldn't be explained by mathematics, they could not be explained at all. And we probably couldn't communicate about them in any consistent manner or conceive of them in a useful way. That doesn't mean these things can't exist, only that we could never be rationally justified in saying that they do. Thus it is possible that the true nature of reality is forever beyond the reach of human understanding. Of course, that's almost irrelevant to anyone who's trying to advance human understanding rather than, say, command complete mastery over the universe.
    - naasking 8y ago
      > You can't make that bet. Mathematics is just a language I surely can make that bet! Calling it "just a language" is seriously understating the implications of language. A language is a structured organization of symbols forming a grammar. So basically, mathematics is a description of structure. Everything has structure except a true random number generator. Given the regularity of existence, the unreasonable effectiveness of mathematics, and the fact that a form of mathematical monism adequately explains all of these facts in the most parsimonious fashion, either we are in an exceedingly unlikely zone of stability of a random process (13 billion years running!), or I'm making a pretty safe bet.
      - Retra 8y ago
        A true random number generator definitely has structure. That's the structure in the definition of randomness. And I would not take it as a given that the effectiveness of mathematics is in any way unreasonable.
- tagrun 8y ago
  Realist in this context refers to the belief that quantum mechanics is an approximation of a deeper deterministic theory in which "god doesn't play dice". The underlying theory should reproduce all predictions of quantum mechanics in the relevant limit, so it has nothing to do with human understanding at macro level. Wanting to believe the laws of nature at the lowest level are deterministic is more like a religious belief than anything else at the moment because as of now, there's no experiment which shows that. By the way, people who use quantum mechanics for practical ends tend to not care whether the dice is really real or "emulated" to give the exact same probability distribution, because to them, this is rather a philosophical question with no practical implications.
- wwarner 8y ago
  I'm reading the book. By 'realist', Smolin means that science shouldn't be satisfied with wave function collapse, which he nicely illustrates with Schrödinger's thought experiment of a cat in box. He's not at all disputing that observations of quantum behavior are surprising and counter-intuitive, but he rejects interpretations that require us to distinguish "measurements from other processes in nature".
gus_massa 8y ago
> Smolin concludes with the implications of all this for our understanding of space and time. He suggests that time is irreversible and fundamental, in the sense that the processes by which future events are produced from present ones are truly basic: they do not need to be explained in terms of more basic ideas. Space, however, is different. He argues that it emerges from something deeper. In Special Relativity space and time can be mixed (almost interchangeable), like the x, y and z usual coordinates. If your coordinates and x and t, in a moving system the coordinates x' and t' are x' = something1 * x + something2 * t t' = something3 * x + something4 * t The coordinates in the other system are just linar combinations of your coordinates. So how can be time and space have a different nature?
- inflatableDodo 8y ago
  You can set up the imaginary plane and do transformations like that across it, but imaginary numbers and reals still have demonstrably different natures.
- goatlover 8y ago
  One key difference is that time has a direction from past to future, while space doesn't.
  - echelon 8y ago
    At a cosmic level, space doesn't either. We're all affected by the big bang and can't go back. At small scales there are time-reversible (or symmetric) systems called time crystals. (I am not a physicist, so feel free to refute me.)
  - gus_massa 8y ago
    That is true, but it's not related to this problem. One important point is that you can't replace the "something" in the equation with whatever you like, for example something2 must be always smaller than something1 (if you add a few c here and there to have the correct units). If you select an event (i.e. a particular point of space, in a particular time) there is a cone of future events and a cone of past events and a region with the remainder events. The transformations don't change the future and past cones, but they mix space and time, so they must be mixable.
arbitrage 8y ago
From the article: > The book is, however, upbeat and, finally, optimistic. Unapologetically drawing on historical tradition and even modern philosophy, Smolin proposes a new set of principles that applies to both quantum mechanics and space-time. He then explores how these principles might be realized as part of a fundamental theory of nature, although he stops short of supplying details of the implementation. That's nice. Too bad QM doesn't care about tradition, philosophy, or your feelings. > Smolin concludes with the implications of all this for our understanding of space and time. He suggests that time is irreversible and fundamental, in the sense that the processes by which future events are produced from present ones are truly basic: they do not need to be explained in terms of more basic ideas. Space, however, is different. He argues that it emerges from something deeper. Smolin routinely bullshits, and does not back up much with rigorous theory. He attempts to make a name for himself in a publish-or-perish field by getting his ridiculously unsupported and contrarian ideas traction in the press. In short, he's all talk, with no substance to back it up.
- BenMorganIO 8y ago
  Having read Three Roads to Quantum Gravity, I think there's a lot of substance there. It's a book made to even include high schoolers, so you have to give it some benefit of the doubt. As per the philosophy question, neither classical mechanics, relativity, or even death cares about what we think. What matters here is how we perceive and understand a concept.

54 points by jonbaer 8y ago

I feel like when people say ‘realist’ in this context, they mean someone who believes that ordinary intuitions about the way the world works are how the world must work at all levels. And there is no reason to believe that our minds were evolved to understand reality at anything but the macro level. I’ve long thought that the study of physics at the extremes is as much a study of the human mind and what we’re capable of comprehending as it is a probe of fundamental reality. Which is to say that experiments are essentially a chain of processes by which we translate information from whatever we’re studying into a form capable of being understood by our mind — often translating it into something visual so our visual cortex can process it and store it. But I wonder how much is out there that is simply impossible to transform in such a way.

FakeComments 8y ago
> I feel like when people say ‘realist’ in this context, they mean someone who believes that ordinary intuitions about the way the world works are how the world must work at all levels. From the article: > Like Einstein, Smolin is a philosophical ‘realist’ — someone who thinks that the real world exists independently of our minds and can be described by deterministic laws. So no, they don’t. Also, realism is consistent with quantum experiment — non-realism is merely an interpretation that’s had more developers work on it, not somehow a proven component of reality. (Commonly called Copenhagen interpretation; MWI and Bohmian are other interpretations; arguably loop quantum gravity too.) I agree with Smolin: non-realism is an extraneous assumption meant to preserve locality, but reality is empirically non-local. Ironically, it’s actually the non-realists who are guilty of what you say — they can’t let go of their Euclidean intuitions, and so come up with nonsense like denying realism. Their entire model is fundamentally predicated on things looking like a smooth Euclidean space at all scales below some threshold — that is, that reality all the way down looks like what we see when we look around. Non-realists insist on a Euclidean world despite contrary experimental evidence. If you view energy as distributed across the topology of your space, which often is radically non-Euclidean, you immediately have realism back — the world just is nothing like what’s in front of your eyes. (Enter loop quantum gravity.)
- msla 8y ago
  Alternatively, the non-realists prefer to view the Uncertainty Principle as deeply true instead of seeing Special Relativity as deeply false.
  - FakeComments 8y ago
    Yes — so much so, they added it as an extra assumption to their model. The original justification is that we have things like Bell’s experiment that say reality is non-local or non-deterministic, because they exclude local determinism. But since then, we’ve found increasing evidence that it’s non-local, and so the choice made for the Copenhagen interpretation, to preserve locality at the cost of determinism, becomes unjustified. It’s now included as an extra assumption out of tradition, and because no one wants to seriously rewrite things. However, as Smolin contends, that may be a dead-end intellectually and an impediment to unifying QM with relativity. A non-local, but real QM interpretation has a more straightforward paradigm to merge with relativistic gravity: it aligns their models philosophically.
- TelmoMenezes 8y ago
  > non-realism is an extraneous assumption Realism is as much an assumption as non-realism. It doesn't feel that way, because realism fits the common sense of some evolved monkeys. Common sense sometimes is correct, sometimes is not. It doesn't really mean anything when we deal with these matters. In fact, I would argue that Occam's Razor advises us to prefer non-realism. With non-realism, we are restricted to something we know to exist, by virtue of our human experience: our first-person perception of things. The independent reality, or third-person perspective, is undoubtedly a useful model, but we have no empirical data to suggest it is real. In fact, I would argue that quantum mechanic does raise some serious issues w.r.t. the this model. Btw, this debate is almost as old as human culture. It was already present in Aristotle (materalism) vs. Plato (idealism). You can also find many traces of it in Eastern thought, e.g. the idea of Maya, or the question of: how can you really know if you are dreaming right now? > not somehow a proven component of reality There are no proven components of reality. Proof is something possible in the domain of mathematics, if one accepts certain axioms. Science is not in the business of proving things, it is an empirical endeavor. It gives us theories that resist falsification (until seen) + eternal doubt. Once you abandon doubt, you abandon science.
naasking 8y ago
> But I wonder how much is out there that is simply impossible to transform in such a way. Given transformations are mathematical, the only way "phenomena that are impossible to transform" is not the empty set is if there are non-mathematical phenomena. So my bet is that the set is empty.
- Retra 8y ago
  You can't make that bet. Mathematics is just a language; if there were phenomena that couldn't be explained by mathematics, they could not be explained at all. And we probably couldn't communicate about them in any consistent manner or conceive of them in a useful way. That doesn't mean these things can't exist, only that we could never be rationally justified in saying that they do. Thus it is possible that the true nature of reality is forever beyond the reach of human understanding. Of course, that's almost irrelevant to anyone who's trying to advance human understanding rather than, say, command complete mastery over the universe.
  - naasking 8y ago
    > You can't make that bet. Mathematics is just a language I surely can make that bet! Calling it "just a language" is seriously understating the implications of language. A language is a structured organization of symbols forming a grammar. So basically, mathematics is a description of structure. Everything has structure except a true random number generator. Given the regularity of existence, the unreasonable effectiveness of mathematics, and the fact that a form of mathematical monism adequately explains all of these facts in the most parsimonious fashion, either we are in an exceedingly unlikely zone of stability of a random process (13 billion years running!), or I'm making a pretty safe bet.
    - Retra 8y ago
      A true random number generator definitely has structure. That's the structure in the definition of randomness. And I would not take it as a given that the effectiveness of mathematics is in any way unreasonable.
tagrun 8y ago
Realist in this context refers to the belief that quantum mechanics is an approximation of a deeper deterministic theory in which "god doesn't play dice". The underlying theory should reproduce all predictions of quantum mechanics in the relevant limit, so it has nothing to do with human understanding at macro level. Wanting to believe the laws of nature at the lowest level are deterministic is more like a religious belief than anything else at the moment because as of now, there's no experiment which shows that. By the way, people who use quantum mechanics for practical ends tend to not care whether the dice is really real or "emulated" to give the exact same probability distribution, because to them, this is rather a philosophical question with no practical implications.
wwarner 8y ago
I'm reading the book. By 'realist', Smolin means that science shouldn't be satisfied with wave function collapse, which he nicely illustrates with Schrödinger's thought experiment of a cat in box. He's not at all disputing that observations of quantum behavior are surprising and counter-intuitive, but he rejects interpretations that require us to distinguish "measurements from other processes in nature".

gus_massa 8y ago

> Smolin concludes with the implications of all this for our understanding of space and time. He suggests that time is irreversible and fundamental, in the sense that the processes by which future events are produced from present ones are truly basic: they do not need to be explained in terms of more basic ideas. Space, however, is different. He argues that it emerges from something deeper. In Special Relativity space and time can be mixed (almost interchangeable), like the x, y and z usual coordinates. If your coordinates and x and t, in a moving system the coordinates x' and t' are x' = something1 * x + something2 * t t' = something3 * x + something4 * t The coordinates in the other system are just linar combinations of your coordinates. So how can be time and space have a different nature?

inflatableDodo 8y ago
You can set up the imaginary plane and do transformations like that across it, but imaginary numbers and reals still have demonstrably different natures.
goatlover 8y ago
One key difference is that time has a direction from past to future, while space doesn't.
- echelon 8y ago
  At a cosmic level, space doesn't either. We're all affected by the big bang and can't go back. At small scales there are time-reversible (or symmetric) systems called time crystals. (I am not a physicist, so feel free to refute me.)
- gus_massa 8y ago
  That is true, but it's not related to this problem. One important point is that you can't replace the "something" in the equation with whatever you like, for example something2 must be always smaller than something1 (if you add a few c here and there to have the correct units). If you select an event (i.e. a particular point of space, in a particular time) there is a cone of future events and a cone of past events and a region with the remainder events. The transformations don't change the future and past cones, but they mix space and time, so they must be mixable.

arbitrage 8y ago

From the article: > The book is, however, upbeat and, finally, optimistic. Unapologetically drawing on historical tradition and even modern philosophy, Smolin proposes a new set of principles that applies to both quantum mechanics and space-time. He then explores how these principles might be realized as part of a fundamental theory of nature, although he stops short of supplying details of the implementation. That's nice. Too bad QM doesn't care about tradition, philosophy, or your feelings. > Smolin concludes with the implications of all this for our understanding of space and time. He suggests that time is irreversible and fundamental, in the sense that the processes by which future events are produced from present ones are truly basic: they do not need to be explained in terms of more basic ideas. Space, however, is different. He argues that it emerges from something deeper. Smolin routinely bullshits, and does not back up much with rigorous theory. He attempts to make a name for himself in a publish-or-perish field by getting his ridiculously unsupported and contrarian ideas traction in the press. In short, he's all talk, with no substance to back it up.

BenMorganIO 8y ago
Having read Three Roads to Quantum Gravity, I think there's a lot of substance there. It's a book made to even include high schoolers, so you have to give it some benefit of the doubt. As per the philosophy question, neither classical mechanics, relativity, or even death cares about what we think. What matters here is how we perceive and understand a concept.