6 ms·

Why can't splitting just be creating a new non-local hidden variable by the very action of splitting, carrying the information for the split pair? (And really,

Why can't splitting just be creating a new non-local hidden variable by the very action of splitting, carrying the information for the split pair? (And really, several consecutive splits is just defining the shape/topology of the single, original split non-local variable.)

lisper 10y ago
You're missing the point. Locality, topology, and even geometry are irrelevant. What matters is how many bits of information you would need to specify the path that the photon takes. And the answer is: you need an infinite number of bits. (OK, well, actually you need an unbounded number of bits, which is not quite the same thing. But it's equally implausible.)
- T-A 10y ago
  So if you use an infinite amount of matter to create an infinite number of beam splitters, an infinite amount of energy to move them to an infinite number of positions (which I guess you keep track of using a computer with infinite memory), over (I guess again) an infinite amount of time, then... ... it turns out that you also need an infinite number of hidden variables for the resulting setup to work according to QM? Shocking! :)
  - lisper 10y ago
    Yes. But this specious argument is exactly why I corrected myself and said "unbounded" instead of "infinite."
- SomeStupidPoint 10y ago
  I mean, your argument supposes that the system can't have that many bits -- but doesn't your device to generate arbitrary bits require more bits to be generated than that amount? Your argument sounds like "5 bits is too many bits to have in a system, and my 10 bit device can generate 5 bits!" I guess? But that doesn't really seem interesting to me: impossible outcomes from impossible to construct situations don't matter. Also, any value which can take on an arbitrary real (or even rational) number has arbitrary storage capcity -- and so far as I know, lots of quantum values do.
  - lisper 10y ago
    Did you not bother to read the original article? "Now an international collaboration led by Adán Cabello has invoked a fundamental thermodynamics result, the Landauer erasure principle, to show that systems in hidden-variable theories must have an infinite memory to be compatible with quantum mechanics." All I'm saying is that you don't need thermodynamics to show this. Conservation laws are enough.
    - SomeStupidPoint 10y ago
      My point was your argument doesn't hold, because you cant actually construct a situation in which the system doesnt already have sufficient storage capacity: the inability to require those bits without already having enough bits in the system to store them is pretty important. I don't believe that it can require QM to account for arbitrary memory, without presupposing we have it to construct the device. Hence, impossible constructions dont matter. I have some similar objections to the summary of their paper, but I haven't had time to read it yet. It's possible they address some of them. In particular, measuring from an arbitrary location and an arbitrary number of times sounds like the introduction of the infinity by assumption, rather than by consequence.
      - lisper 10y ago
        I think you're missing the point. It is not that all that information exists, it is that all that information has to exist in a single particle. This is not impossible, but it is implausible.
        SomeStupidPoint 10y ago
        Correction: it has to be accessible to a single particle, but the information could be non-localized across the whole system, since your particle is itself fairly non-localized, and arguably has weakly interacted with the various devices along the way, meaning that Im not sure we can fully disentangle the wave-equation for the photon from the equations for the splitters. This could easily be the photon "borrowing" bits from the splitter, by sharing a non-local value with it, which carries the split path information for both. Which is just to say that the system (in full) has to be able to contain a number of bits sufficient for that, which your setup does.
100ideas 10y ago
"qlosures"

lisper 10y ago

You're missing the point. Locality, topology, and even geometry are irrelevant. What matters is how many bits of information you would need to specify the path that the photon takes. And the answer is: you need an infinite number of bits. (OK, well, actually you need an unbounded number of bits, which is not quite the same thing. But it's equally implausible.)

T-A 10y ago
So if you use an infinite amount of matter to create an infinite number of beam splitters, an infinite amount of energy to move them to an infinite number of positions (which I guess you keep track of using a computer with infinite memory), over (I guess again) an infinite amount of time, then... ... it turns out that you also need an infinite number of hidden variables for the resulting setup to work according to QM? Shocking! :)
- lisper 10y ago
  Yes. But this specious argument is exactly why I corrected myself and said "unbounded" instead of "infinite."
SomeStupidPoint 10y ago
I mean, your argument supposes that the system can't have that many bits -- but doesn't your device to generate arbitrary bits require more bits to be generated than that amount? Your argument sounds like "5 bits is too many bits to have in a system, and my 10 bit device can generate 5 bits!" I guess? But that doesn't really seem interesting to me: impossible outcomes from impossible to construct situations don't matter. Also, any value which can take on an arbitrary real (or even rational) number has arbitrary storage capcity -- and so far as I know, lots of quantum values do.
- lisper 10y ago
  Did you not bother to read the original article? "Now an international collaboration led by Adán Cabello has invoked a fundamental thermodynamics result, the Landauer erasure principle, to show that systems in hidden-variable theories must have an infinite memory to be compatible with quantum mechanics." All I'm saying is that you don't need thermodynamics to show this. Conservation laws are enough.
  - SomeStupidPoint 10y ago
    My point was your argument doesn't hold, because you cant actually construct a situation in which the system doesnt already have sufficient storage capacity: the inability to require those bits without already having enough bits in the system to store them is pretty important. I don't believe that it can require QM to account for arbitrary memory, without presupposing we have it to construct the device. Hence, impossible constructions dont matter. I have some similar objections to the summary of their paper, but I haven't had time to read it yet. It's possible they address some of them. In particular, measuring from an arbitrary location and an arbitrary number of times sounds like the introduction of the infinity by assumption, rather than by consequence.
    - lisper 10y ago
      I think you're missing the point. It is not that all that information exists, it is that all that information has to exist in a single particle. This is not impossible, but it is implausible.
      - SomeStupidPoint 10y ago
        Correction: it has to be accessible to a single particle, but the information could be non-localized across the whole system, since your particle is itself fairly non-localized, and arguably has weakly interacted with the various devices along the way, meaning that Im not sure we can fully disentangle the wave-equation for the photon from the equations for the splitters. This could easily be the photon "borrowing" bits from the splitter, by sharing a non-local value with it, which carries the split path information for both. Which is just to say that the system (in full) has to be able to contain a number of bits sufficient for that, which your setup does.

100ideas 10y ago

"qlosures"