8 ms·

Why are physicists reluctant to give up the idea of experimenter freedom, as the article says? Is there anything more to it than not wanting to deny free will?

by dash2 6y ago

ddxxdd 6y ago
It's extremely unlikely that the universe compels scientists to make certain measurements at certain times in a conspiracy to make quantum physics look real. https://en.wikipedia.org/wiki/Superdeterminism https://en.wikipedia.org/wiki/Superdeterminism
- miltondts 6y ago
  Why? All physics theories we have are deterministic.* So if we take that to the limit, then we are also deterministic. To me, there is nothing conspiratorial about that. *Yes, quantum mechanics is kind of debatable.. But if I understand it correctly, the actual theory is deterministic. It's just the interpretation of the measurements that can lead to some debate. However they can also be viewed in a deterministic framework, as the link you cite shows.
  - DennisP 6y ago
    "We are deterministic" is no big deal, it's what scientists thought for centuries going back to Newton. In classical mechanics, if you knew the exact state of every particle then you could predict everything. But superdeterminism is nothing like that. It's determinism not based on past states, but based on future states, where the universe prevents anyone from making decisions that would cause them to learn a certain type of information. How would that work?
    - miltondts 6y ago
      Superdeterminism just says that there is no statical independence. Not sure where you are getting the future determines the past from that. However, yes, in a deterministic world there is only one way to get to a certain future, so I guess the future does indeed determine the past. Is that what you mean?
      - DennisP 6y ago
        No, I mean that classical determinism says "here is the current set of particle positions/momentums/etc, so we can work forward and predict everything from that." Superdeterminism says "if you do X then you will learn Y, so you aren't going to do X." That doesn't necessarily mean signals going back in time. It could mean that the initial condition of the universe was set, such that nobody would do X. But that's still a way of the past (initial condition) being determined by the future, even if the future was just predicted via determinism. It makes physics teleological. A common criticism of superdeterminism is that it eliminates falsifiability from science. E.g. to quote physicist Nicolas Gisin, "If we did not have free will, we could never decide to test a scientific theory. We could live in a world where objects tend to fly up in the air but be programmed to look only when they are in the process of falling." https://en.wikiquote.org/wiki/Superdeterminism https://en.wikiquote.org/wiki/Superdeterminism
        miltondts 6y ago
        The rebuttal from someone more knowledgeable in the field than I am: https://youtu.be/YglT09Korr0?t=1115 https://youtu.be/YglT09Korr0?t=1115
        DennisP 6y ago
        So her criticism #3 of essentially my second paragraph is that you can't assume anything, because we don't actually have a superdeterministic theory to evaluate. Maybe there's a dynamic law we haven't figured out that could make it work without initial fine tuning. Fair enough I guess, but I'm not convinced it's a good answer to say "I think a theory with property X is the answer, and you can't criticize it because I have no actual theory with property X." I think it makes more sense to give little credence to superdeterminism until someone comes up with a plausible superdeterministic theory.
  - lisper 6y ago
    > quantum mechanics is kind of debatable No, it isn't. Quantum randomness is of a fundamentally different character than chaos. Bell's theorem (and concommitant experiments) shows that it is not possible for the results of quantum experiments to depend on information that exists in our universe before the experiment was actually conducted. So if the results of quantum experiments are deterministic, the information that determines their outcomes can only exist outside of our universe.
    - kdtop 6y ago
      My understanding was that Bell's theorem rules out hidden LOCAL variables, but doesn't address or rule out hidden GLOBAL variables. Bohmian mechanics haven't been disproven, right?
      - lisper 6y ago
        That's right, except that the opposite of "local" in this case is not "global". (This is physics, not software engineering.) The opposite of "local" in this case is "non-local", which refers to state that propagates faster than the speed of light. Bell's theorem shows that describing reality requires some kind of non-local state. In the case of both Copenhagen and Bohm, that non-local state resides in the wave function. But here's the thing: you cannot know the state of the wave function because of the no-cloning theorem. The best you can do is prepare sub-systems in known states. So QM really is different. You cannot predict the outcome of a quantum experiment even in principle and even with arbitrarily advanced technology.
        AnHonestComment 6y ago
        Okay — but inability to predict doesn’t equate to random outcomes. So it sounds like we all agree you stated an interpretation in excess of demonstrated model.
        bluepoint 6y ago
        Best, most precise and accurate comment. Thank you.
  - ddxxdd 6y ago
    I'm a day late to this immense comment chain, but my point is that Bell's Theorem specifically rules out local hidden variables unless scientists are forced to choose never to conduct an experiment that will expose those local hidden variables. I'm not talking about determinism, I'm talking about Superdeterminism, which is akin to saying that coins will always land heads-up because people are compelled to avoid flipping coins in situations where it will land on tails. Please see my link.
raverbashing 6y ago
It seems to me that issue is simpler than people are making it to be. "Consciousness"/"Observer" etc are too high level concepts to matter there. I don't need to choose the experiment directly, I can make a complicated arrangement that then picks the experiment to be executed. (Let's say, I make a random number based on the current wind speed and I make a mechanical apparatus that throws a die and choose the experiment based on that). Try changing that experimental freedom.
- Quekid5 6y ago
  "Observ(er|vation)" is really one of the worst terms ever in this area. It really is just about the experimenter (plus apparatus) becoming entangled with the experiment -- or entering into a superposition with it, if you will. That's it. No spooky consciousness, etc. goes into it. One's consciousness simply enters into the superposition. (If you can't tell, I fully subscribe to the Many World interpretation. AFAICT it's, by quite a long way, the most parsimonious explanation in terms of extra "theoretical stuff", even if it is "wasteful" in terms of the amount of actual stuff it posits.)
  - tsimionescu 6y ago
    Many worlds doesn't really explain more than other interpretations of standard QM. You still have the problem of why the Schrodinger equation shows you that that a particle has some amitude both here and there, and can interact with other particles both here and there, yet when you experiment you only find it either here or there, never in both places. MWI just posits that the measurement apparatus exists in a single world, while the particles exist in many worlds. But it can't explain this basic fact, like any other interpretation. What we need is an actual new theory that can actually measure what a measurement is (at what precise point the Born rule must be applied, or how can we do without the Born rule).
    - Retric 6y ago
      There are essentially 3 options for Wave function collapse. Their are some hidden variables which means it’s deterministic and there is no amplitudes involved. The universe has some sort of random number generator which determines the outcome. They don’t actually collapse, which is what the many worlds theory essentially posits.
eigenket 6y ago
I add this because no one seems to have mentioned it yet. Without experimenter freedom it is hard to make any inferences from the results of experiment. If the experimental choices you make are correlated with the stuff you're experimenting on in hard to understand ways then the experimental data you gather is essentially meaningless. To make a dumb example, you measure some system and always observe outcome A. You might conclude that A is a property of the system you measured, but it just so happens that your decision to do the experiment is correlated with the system, so it always has A when you measure it, but it has other properties at other times.

Why are physicists reluctant to give up the idea of experimenter freedom, as the article says? Is there anything more to it than not wanting to deny free will?

by dash2 6y ago

Why are physicists reluctant to give up the idea of experimenter freedom, as the article says? Is there anything more to it than not wanting to deny free will?

ddxxdd 6y ago

It's extremely unlikely that the universe compels scientists to make certain measurements at certain times in a conspiracy to make quantum physics look real. https://en.wikipedia.org/wiki/Superdeterminism https://en.wikipedia.org/wiki/Superdeterminism

miltondts 6y ago
Why? All physics theories we have are deterministic.* So if we take that to the limit, then we are also deterministic. To me, there is nothing conspiratorial about that. *Yes, quantum mechanics is kind of debatable.. But if I understand it correctly, the actual theory is deterministic. It's just the interpretation of the measurements that can lead to some debate. However they can also be viewed in a deterministic framework, as the link you cite shows.
- DennisP 6y ago
  "We are deterministic" is no big deal, it's what scientists thought for centuries going back to Newton. In classical mechanics, if you knew the exact state of every particle then you could predict everything. But superdeterminism is nothing like that. It's determinism not based on past states, but based on future states, where the universe prevents anyone from making decisions that would cause them to learn a certain type of information. How would that work?
  - miltondts 6y ago
    Superdeterminism just says that there is no statical independence. Not sure where you are getting the future determines the past from that. However, yes, in a deterministic world there is only one way to get to a certain future, so I guess the future does indeed determine the past. Is that what you mean?
    - DennisP 6y ago
      No, I mean that classical determinism says "here is the current set of particle positions/momentums/etc, so we can work forward and predict everything from that." Superdeterminism says "if you do X then you will learn Y, so you aren't going to do X." That doesn't necessarily mean signals going back in time. It could mean that the initial condition of the universe was set, such that nobody would do X. But that's still a way of the past (initial condition) being determined by the future, even if the future was just predicted via determinism. It makes physics teleological. A common criticism of superdeterminism is that it eliminates falsifiability from science. E.g. to quote physicist Nicolas Gisin, "If we did not have free will, we could never decide to test a scientific theory. We could live in a world where objects tend to fly up in the air but be programmed to look only when they are in the process of falling." https://en.wikiquote.org/wiki/Superdeterminism https://en.wikiquote.org/wiki/Superdeterminism
      - miltondts 6y ago
        The rebuttal from someone more knowledgeable in the field than I am: https://youtu.be/YglT09Korr0?t=1115 https://youtu.be/YglT09Korr0?t=1115
        DennisP 6y ago
        So her criticism #3 of essentially my second paragraph is that you can't assume anything, because we don't actually have a superdeterministic theory to evaluate. Maybe there's a dynamic law we haven't figured out that could make it work without initial fine tuning. Fair enough I guess, but I'm not convinced it's a good answer to say "I think a theory with property X is the answer, and you can't criticize it because I have no actual theory with property X." I think it makes more sense to give little credence to superdeterminism until someone comes up with a plausible superdeterministic theory.
- lisper 6y ago
  > quantum mechanics is kind of debatable No, it isn't. Quantum randomness is of a fundamentally different character than chaos. Bell's theorem (and concommitant experiments) shows that it is not possible for the results of quantum experiments to depend on information that exists in our universe before the experiment was actually conducted. So if the results of quantum experiments are deterministic, the information that determines their outcomes can only exist outside of our universe.
  - kdtop 6y ago
    My understanding was that Bell's theorem rules out hidden LOCAL variables, but doesn't address or rule out hidden GLOBAL variables. Bohmian mechanics haven't been disproven, right?
    - lisper 6y ago
      That's right, except that the opposite of "local" in this case is not "global". (This is physics, not software engineering.) The opposite of "local" in this case is "non-local", which refers to state that propagates faster than the speed of light. Bell's theorem shows that describing reality requires some kind of non-local state. In the case of both Copenhagen and Bohm, that non-local state resides in the wave function. But here's the thing: you cannot know the state of the wave function because of the no-cloning theorem. The best you can do is prepare sub-systems in known states. So QM really is different. You cannot predict the outcome of a quantum experiment even in principle and even with arbitrarily advanced technology.
      - AnHonestComment 6y ago
        Okay — but inability to predict doesn’t equate to random outcomes. So it sounds like we all agree you stated an interpretation in excess of demonstrated model.
      - bluepoint 6y ago
        Best, most precise and accurate comment. Thank you.
- ddxxdd 6y ago
  I'm a day late to this immense comment chain, but my point is that Bell's Theorem specifically rules out local hidden variables unless scientists are forced to choose never to conduct an experiment that will expose those local hidden variables. I'm not talking about determinism, I'm talking about Superdeterminism, which is akin to saying that coins will always land heads-up because people are compelled to avoid flipping coins in situations where it will land on tails. Please see my link.

raverbashing 6y ago

It seems to me that issue is simpler than people are making it to be. "Consciousness"/"Observer" etc are too high level concepts to matter there. I don't need to choose the experiment directly, I can make a complicated arrangement that then picks the experiment to be executed. (Let's say, I make a random number based on the current wind speed and I make a mechanical apparatus that throws a die and choose the experiment based on that). Try changing that experimental freedom.

Quekid5 6y ago
"Observ(er|vation)" is really one of the worst terms ever in this area. It really is just about the experimenter (plus apparatus) becoming entangled with the experiment -- or entering into a superposition with it, if you will. That's it. No spooky consciousness, etc. goes into it. One's consciousness simply enters into the superposition. (If you can't tell, I fully subscribe to the Many World interpretation. AFAICT it's, by quite a long way, the most parsimonious explanation in terms of extra "theoretical stuff", even if it is "wasteful" in terms of the amount of actual stuff it posits.)
- tsimionescu 6y ago
  Many worlds doesn't really explain more than other interpretations of standard QM. You still have the problem of why the Schrodinger equation shows you that that a particle has some amitude both here and there, and can interact with other particles both here and there, yet when you experiment you only find it either here or there, never in both places. MWI just posits that the measurement apparatus exists in a single world, while the particles exist in many worlds. But it can't explain this basic fact, like any other interpretation. What we need is an actual new theory that can actually measure what a measurement is (at what precise point the Born rule must be applied, or how can we do without the Born rule).
  - Retric 6y ago
    There are essentially 3 options for Wave function collapse. Their are some hidden variables which means it’s deterministic and there is no amplitudes involved. The universe has some sort of random number generator which determines the outcome. They don’t actually collapse, which is what the many worlds theory essentially posits.

eigenket 6y ago

I add this because no one seems to have mentioned it yet. Without experimenter freedom it is hard to make any inferences from the results of experiment. If the experimental choices you make are correlated with the stuff you're experimenting on in hard to understand ways then the experimental data you gather is essentially meaningless. To make a dumb example, you measure some system and always observe outcome A. You might conclude that A is a property of the system you measured, but it just so happens that your decision to do the experiment is correlated with the system, so it always has A when you measure it, but it has other properties at other times.