4 ms·

what is configuration space

jfengel 5y ago
"Configuration space" means that the state of the world is described by some list of numbers that don't actually correspond directly to locations in space or time. Or even mass or energy. It means that those things aren't really fundamental. What's fundamental is some other set of things that aren't too difficult to work with mathematically, but which don't correspond exactly to anything you're familiar with. The best you can do is to add in "probability functions", such that "state of the world X" means that you'd have some chance of detecting a particle here, and some chance of detecting a particle there, and so on. It's that jump from one to the other that's awkward, and to be honest not 100% understood. But it's actually better understood than a lot of the woo-woo descriptions of quantum mechanics make it out to be. Now, when I said that the math isn't too difficult to work with, that's a bit of a lie. It's all about Simple Harmonic Oscillation, except using complex numbers. That's really not too bad, but it's definitely new.
- lisper 5y ago
  > It's all about Simple Harmonic Oscillation, except using complex numbers And both of those are among the details which can be safely ignored. The only math you really need in order to understand QM conceptually is linear algebra. (And actually, even the harmonic oscillators are not that difficult to understand. If you understand Euler's identity, you're 90% of the way there.)
- ars 5y ago
  > means that the state of the world is described by some list of numbers How is that different from hidden variables?
  - Cookingboy 5y ago
    Yeah I'm honestly not too sure here either, the more I think the more I believe simulation + hidden variables may be the true explanation behind our reality.
  - jfengel 5y ago
    The difference is that they're not localized. It's only local hidden variables that are forbidden by theory. One way to look at it is that every one of those pieces of configuration space apply to all of space and all of time. That's not forbidden. But it also means that these values aren't directly accessible. They can only be partially inferred.
    - Smithalicious 5y ago
      So the universe is governed by inaccessible magic numbers, like a kind of divine DRM?
      - Smithalicious 5y ago
        This is being downvoted, perhaps because I put a humorous analogy in there, but I really am curious, isn't this what is claimed? The "real" ground truth of the universe is "configuration space", which is some kind of mathematical construct, and which can't be perceived directly but only partially inferred? I'd like to know more about this since I have never heard of this concept before and I feel like it has far-reaching implications
        jfengel 5y ago
        It's not quite as dramatic as it sounds. It's a somewhat more mathematically sound way of saying all of the usual stuff about quantum mechanics. It just takes the QM side more seriously, rather than trying to describe it as a bag on the side of classical physics. The unobservable parts are not really any different from indirectly inferred concepts like potential energy. It's just that even seemingly concrete notions like location turn out to be macro scale approximations of this phase space. They're not accessible only because you are a macro scale object. You can very much demonstrate that it's real by simple experiments. You just need to be able to take them seriously, which is unexpectedly difficult because classical physics seems so intuitively obvious.
- jaquers 5y ago
  where & how is the 'configuration' encoded? [we don't know, right] Is this why string theory requires higher dimensions? Also when I see the term 'harmonic oscillations', I think of plucking a string -- it seems so elegant for the physical particles to be manifestations of higher dimensional ~~vibrating~~ oscillating strings :) (thinking of flat-lander analogy) gp's premise about learning with the multi-particle landscape first sort of blew my mind.
  - astrange 5y ago
    https://en.wikipedia.org/wiki/Holographic_principle https://en.wikipedia.org/wiki/Holographic_principle
  - lisper 5y ago
    > we don't know, right Right. > Is this why string theory requires higher dimensions? No. The higher dimensions of string theory are actual physical dimensions. Configuration space dimensions are pure mathematical abstractions, and there are potentially an infinite number of them, one for every degree of freedom in the system. Look up "Hilbert space" if you want the gory details.
    - jaquers 5y ago
      thanks

"Configuration space" means that the state of the world is described by some list of numbers that don't actually correspond directly to locations in space or time. Or even mass or energy. It means that those things aren't really fundamental. What's fundamental is some other set of things that aren't too difficult to work with mathematically, but which don't correspond exactly to anything you're familiar with. The best you can do is to add in "probability functions", such that "state of the world X" means that you'd have some chance of detecting a particle here, and some chance of detecting a particle there, and so on. It's that jump from one to the other that's awkward, and to be honest not 100% understood. But it's actually better understood than a lot of the woo-woo descriptions of quantum mechanics make it out to be. Now, when I said that the math isn't too difficult to work with, that's a bit of a lie. It's all about Simple Harmonic Oscillation, except using complex numbers. That's really not too bad, but it's definitely new.

lisper 5y ago
> It's all about Simple Harmonic Oscillation, except using complex numbers And both of those are among the details which can be safely ignored. The only math you really need in order to understand QM conceptually is linear algebra. (And actually, even the harmonic oscillators are not that difficult to understand. If you understand Euler's identity, you're 90% of the way there.)
ars 5y ago
> means that the state of the world is described by some list of numbers How is that different from hidden variables?
- Cookingboy 5y ago
  Yeah I'm honestly not too sure here either, the more I think the more I believe simulation + hidden variables may be the true explanation behind our reality.
- jfengel 5y ago
  The difference is that they're not localized. It's only local hidden variables that are forbidden by theory. One way to look at it is that every one of those pieces of configuration space apply to all of space and all of time. That's not forbidden. But it also means that these values aren't directly accessible. They can only be partially inferred.
  - Smithalicious 5y ago
    So the universe is governed by inaccessible magic numbers, like a kind of divine DRM?
    - Smithalicious 5y ago
      This is being downvoted, perhaps because I put a humorous analogy in there, but I really am curious, isn't this what is claimed? The "real" ground truth of the universe is "configuration space", which is some kind of mathematical construct, and which can't be perceived directly but only partially inferred? I'd like to know more about this since I have never heard of this concept before and I feel like it has far-reaching implications
      - jfengel 5y ago
        It's not quite as dramatic as it sounds. It's a somewhat more mathematically sound way of saying all of the usual stuff about quantum mechanics. It just takes the QM side more seriously, rather than trying to describe it as a bag on the side of classical physics. The unobservable parts are not really any different from indirectly inferred concepts like potential energy. It's just that even seemingly concrete notions like location turn out to be macro scale approximations of this phase space. They're not accessible only because you are a macro scale object. You can very much demonstrate that it's real by simple experiments. You just need to be able to take them seriously, which is unexpectedly difficult because classical physics seems so intuitively obvious.
jaquers 5y ago
where & how is the 'configuration' encoded? [we don't know, right] Is this why string theory requires higher dimensions? Also when I see the term 'harmonic oscillations', I think of plucking a string -- it seems so elegant for the physical particles to be manifestations of higher dimensional ~~vibrating~~ oscillating strings :) (thinking of flat-lander analogy) gp's premise about learning with the multi-particle landscape first sort of blew my mind.
- astrange 5y ago
  https://en.wikipedia.org/wiki/Holographic_principle https://en.wikipedia.org/wiki/Holographic_principle
- lisper 5y ago
  > we don't know, right Right. > Is this why string theory requires higher dimensions? No. The higher dimensions of string theory are actual physical dimensions. Configuration space dimensions are pure mathematical abstractions, and there are potentially an infinite number of them, one for every degree of freedom in the system. Look up "Hilbert space" if you want the gory details.
  - jaquers 5y ago
    thanks