4 ms·

If particles can be in multiple states simultaneously until an observer interacts with them then it seems like a tree could in fact fall in the forest and not m

If particles can be in multiple states simultaneously until an observer interacts with them then it seems like a tree could in fact fall in the forest and not make a sound.

crooked-v 9y ago
Well, no. It's possible that a tree could fall in the forest and make any number of different sounds the specifics of which are impossible to determine until observed, though. Keep in mind, too, that "an observer" includes basically anything interacting with an otherwise closed system, not just a thinking creature.
- jon_richards 9y ago
  >"an observer" includes basically anything interacting with an otherwise closed system, not just a thinking creature. Isn't that a bit of a philosophical debate? It could be that things are only "observed" when their cone of causality reaches a thinking creature. I thought that was half the point of the tree question in the first place.
  - chrischen 9y ago
    That would define reality as thought.
    - jon_richards 9y ago
      Or an ever-permuting mush of probabilities that only becomes "evaluated" when thought experiences it. There's no way to know, but I personally like that interpretation because it meshes well with the idea that our reality is a simulation. No need to waste computation when it's not necessary.
    - coldtea 9y ago
      Which is not that different that "reality as information", which is quite probable. Besides, the actual objective reality/universe could just be a set of hazy possibilities in constant flux. And it's only what WE call "reality" (and consider it as "objective") that appears fixed -- because of how our perception/brain perceives it.
  - Tade0 9y ago
    This is what I hate about the popular understanding of the Copenhagen interpretation. Bohr's original idea was that until there's some interaction it's pointless to assign a specific state - you can only talk about certain probabilities. Schrodinger's cat is not both alive and dead. We know nothing about its current state, only how probable certain outcomes are.
    - frede 9y ago
      The thing about quantum theory is that it's not just about propabilities. The double-slit experiment, for example, cannot be explained by adding propabilities alone. Instead the wave function gets added, with the phase considered. This is why an unobserved quantum state is more than a classical state hidden in a box and why we get results that seem paradox.
    - jon_richards 9y ago
      >Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a locked steel chamber, wherein the cat's life or death depended on the state of a radioactive atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the Copenhagen interpretation implies that the cat remains both alive and dead until the state is observed. Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics. However, since Schrödinger's time, other interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real. I was taught that Schrödinger's Cat was conceived of as intentionally absurd, but that physicists loved it because it pointed out how absurd physics was being. As the other comment said, its not just that a photon might have gone through either slit, it provably went through both.
    - coldtea 9y ago
      >Schrodinger's cat is not both alive and dead. We know nothing about its current state, only how probable certain outcomes are That's the case with any cat we throw in a box and ask somebody to kill it or not based on a dice, and then we visit the place where the box is and open it... In other words, the cat is in a certain state, but we merely don't know which. But this doesn't capture what the Schrodinger experiment is supposed to show. Such an case wouldn't need the experimental apparatus Schrodinger describes either. The core idea of the experiment is that quantum uncertainty is not just of the "we just don't know yet" kind, but of the fundamental "reality is inherently mixed-up and uncertain / many things actually hold at the same time until observed" nature. The purpose of the Schrodinger's thought experiment then is to show how this fundamental quantum uncertainty (i.e. not mere not knowing: actual "fuzzy" reality) "pollutes" the macro world (in this case, a cat). The quantum-based mechanism that releases the poison, is his trick to transfer the uncertainty of the quantum state into the macro world (the box with the cat). (Funnily, Schrodinger's purpose was to discredit this). Those that believe it's clear that "the cat is in one state or another, we just don't know which", haven't understood the problem.
  - thehardsphere 9y ago
    It is not a philosophical debate in the arbitrary way that you suggest. "Observation" and "measurement" are not used by physicists in this context as common words, but as jargon with very precise meaning. Depending on what interpretation of quantum mechanics they're using, the meaning of said jargon could be subject to some debate, but that debate takes place in the context of other premises established in advance. None of those premises involve the magical power of thinking to collapse wavefunctions, because that stems from a common conflation of the Uncertainty Principle, which is a physical phenomenon, and the Observer Effect, which is a product of poor experimental design and can be controlled for.
wanda 9y ago
More like the tree could both fall and remain upright.
StephenMelon 9y ago
A sound is by definition something heard by someone. An unobserved universe doesn’t make sense, trying to conceptualise one would be like arguing about what colour a ganabreeshlach is.
- eth0up 9y ago
  Does a dog-whistle not make an ultrasound? There are many examples and applications where sound has very legitimate but inaudible effects. Perhaps this definition has contenders? Seems to me there are audible and inaudible sounds. And since definitions tend to follow the masses regardless of logic or sensibility, "sound" probably should also mean "appear", as it's become an idiomatic (non literal) term you'll see peppered throughout Hackernews and elsewhere, e.g. "this sounds good; this sounds reasonable;" etc, used to describe one's interpretation of texts, which sans synesthesia, shouldn't be audible.
  - StephenMelon 9y ago
    The original riddle about the tree in a forest is intended to illustrate the difference between philosophical idealism and materialism. A dog whistle depends on the concepts of dogs and whistles, which don’t exist outwith the human semantic framework. Historically, science has been heavily materialist but quantum physics has brought idealism back to the table. Another thought experiment is 2 people at opposite ends of a room that contains a total vacuum. Ignoring breathing difficulties, if one spoke to the other, would he make a sound?
thehardsphere 9y ago
Contrary to popular misconception, the Observer Effect and the Uncertainty Principle are not actually the same thing. The Observer Effect is something that can happen in all sorts of experiments, classical or not, and is a result poor experimental design. The Uncertainty Principle is a quantum mechanical phenomenon that cannot be controlled for, because the uncertainty of a particle's position and momentum is an inherent property of the matter wave nature of quantum objects. Part of this stems from early use of the words "observer" and "measurement" when describing the Uncertainty Principle. Most interpretations of quantum mechanics provide specific definitions of these words which differ from their use in common language. The Many Worlds Interpretation, for instance, has no Observer, and defines a measurement as any thermodynamicly non-reverseable process.
- passwordreset 9y ago
  "The Many Worlds Interpretation, for instance, has no Observer, and defines a measurement as any thermodynamicly non-reverseable process." I'm interested in this, as I previously thought that the actual word "measurement" was still a bit of a mish-mosh for most interpretations. Do you have a reference for this?
  - thehardsphere 9y ago
    I'm mainly operating on what I remember from when I studied this in grad school years ago. This FAQ about MWI seems pretty detailed, and includes references to other sources: http://www.anthropic-principle.com/preprints/manyworlds.html http://www.anthropic-principle.com/preprints/manyworlds.html

If particles can be in multiple states simultaneously until an observer interacts with them then it seems like a tree could in fact fall in the forest and not make a sound.

crooked-v 9y ago

Well, no. It's possible that a tree could fall in the forest and make any number of different sounds the specifics of which are impossible to determine until observed, though. Keep in mind, too, that "an observer" includes basically anything interacting with an otherwise closed system, not just a thinking creature.

jon_richards 9y ago
>"an observer" includes basically anything interacting with an otherwise closed system, not just a thinking creature. Isn't that a bit of a philosophical debate? It could be that things are only "observed" when their cone of causality reaches a thinking creature. I thought that was half the point of the tree question in the first place.
- chrischen 9y ago
  That would define reality as thought.
  - jon_richards 9y ago
    Or an ever-permuting mush of probabilities that only becomes "evaluated" when thought experiences it. There's no way to know, but I personally like that interpretation because it meshes well with the idea that our reality is a simulation. No need to waste computation when it's not necessary.
  - coldtea 9y ago
    Which is not that different that "reality as information", which is quite probable. Besides, the actual objective reality/universe could just be a set of hazy possibilities in constant flux. And it's only what WE call "reality" (and consider it as "objective") that appears fixed -- because of how our perception/brain perceives it.
- Tade0 9y ago
  This is what I hate about the popular understanding of the Copenhagen interpretation. Bohr's original idea was that until there's some interaction it's pointless to assign a specific state - you can only talk about certain probabilities. Schrodinger's cat is not both alive and dead. We know nothing about its current state, only how probable certain outcomes are.
  - frede 9y ago
    The thing about quantum theory is that it's not just about propabilities. The double-slit experiment, for example, cannot be explained by adding propabilities alone. Instead the wave function gets added, with the phase considered. This is why an unobserved quantum state is more than a classical state hidden in a box and why we get results that seem paradox.
  - jon_richards 9y ago
    >Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a locked steel chamber, wherein the cat's life or death depended on the state of a radioactive atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the Copenhagen interpretation implies that the cat remains both alive and dead until the state is observed. Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics. However, since Schrödinger's time, other interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real. I was taught that Schrödinger's Cat was conceived of as intentionally absurd, but that physicists loved it because it pointed out how absurd physics was being. As the other comment said, its not just that a photon might have gone through either slit, it provably went through both.
  - coldtea 9y ago
    >Schrodinger's cat is not both alive and dead. We know nothing about its current state, only how probable certain outcomes are That's the case with any cat we throw in a box and ask somebody to kill it or not based on a dice, and then we visit the place where the box is and open it... In other words, the cat is in a certain state, but we merely don't know which. But this doesn't capture what the Schrodinger experiment is supposed to show. Such an case wouldn't need the experimental apparatus Schrodinger describes either. The core idea of the experiment is that quantum uncertainty is not just of the "we just don't know yet" kind, but of the fundamental "reality is inherently mixed-up and uncertain / many things actually hold at the same time until observed" nature. The purpose of the Schrodinger's thought experiment then is to show how this fundamental quantum uncertainty (i.e. not mere not knowing: actual "fuzzy" reality) "pollutes" the macro world (in this case, a cat). The quantum-based mechanism that releases the poison, is his trick to transfer the uncertainty of the quantum state into the macro world (the box with the cat). (Funnily, Schrodinger's purpose was to discredit this). Those that believe it's clear that "the cat is in one state or another, we just don't know which", haven't understood the problem.
- thehardsphere 9y ago
  It is not a philosophical debate in the arbitrary way that you suggest. "Observation" and "measurement" are not used by physicists in this context as common words, but as jargon with very precise meaning. Depending on what interpretation of quantum mechanics they're using, the meaning of said jargon could be subject to some debate, but that debate takes place in the context of other premises established in advance. None of those premises involve the magical power of thinking to collapse wavefunctions, because that stems from a common conflation of the Uncertainty Principle, which is a physical phenomenon, and the Observer Effect, which is a product of poor experimental design and can be controlled for.

wanda 9y ago

More like the tree could both fall and remain upright.

StephenMelon 9y ago

A sound is by definition something heard by someone. An unobserved universe doesn’t make sense, trying to conceptualise one would be like arguing about what colour a ganabreeshlach is.

eth0up 9y ago
Does a dog-whistle not make an ultrasound? There are many examples and applications where sound has very legitimate but inaudible effects. Perhaps this definition has contenders? Seems to me there are audible and inaudible sounds. And since definitions tend to follow the masses regardless of logic or sensibility, "sound" probably should also mean "appear", as it's become an idiomatic (non literal) term you'll see peppered throughout Hackernews and elsewhere, e.g. "this sounds good; this sounds reasonable;" etc, used to describe one's interpretation of texts, which sans synesthesia, shouldn't be audible.
- StephenMelon 9y ago
  The original riddle about the tree in a forest is intended to illustrate the difference between philosophical idealism and materialism. A dog whistle depends on the concepts of dogs and whistles, which don’t exist outwith the human semantic framework. Historically, science has been heavily materialist but quantum physics has brought idealism back to the table. Another thought experiment is 2 people at opposite ends of a room that contains a total vacuum. Ignoring breathing difficulties, if one spoke to the other, would he make a sound?

thehardsphere 9y ago

Contrary to popular misconception, the Observer Effect and the Uncertainty Principle are not actually the same thing. The Observer Effect is something that can happen in all sorts of experiments, classical or not, and is a result poor experimental design. The Uncertainty Principle is a quantum mechanical phenomenon that cannot be controlled for, because the uncertainty of a particle's position and momentum is an inherent property of the matter wave nature of quantum objects. Part of this stems from early use of the words "observer" and "measurement" when describing the Uncertainty Principle. Most interpretations of quantum mechanics provide specific definitions of these words which differ from their use in common language. The Many Worlds Interpretation, for instance, has no Observer, and defines a measurement as any thermodynamicly non-reverseable process.

passwordreset 9y ago
"The Many Worlds Interpretation, for instance, has no Observer, and defines a measurement as any thermodynamicly non-reverseable process." I'm interested in this, as I previously thought that the actual word "measurement" was still a bit of a mish-mosh for most interpretations. Do you have a reference for this?
- thehardsphere 9y ago
  I'm mainly operating on what I remember from when I studied this in grad school years ago. This FAQ about MWI seems pretty detailed, and includes references to other sources: http://www.anthropic-principle.com/preprints/manyworlds.html http://www.anthropic-principle.com/preprints/manyworlds.html