Non-Locality

[Bu🤠ns]

I just finished up Quantum Psychology and I really enjoyed RAW's illustrations on non-locality.  I'd like to get a wider perspective on this subject so would anyone please describe this idea and it's inverse, locality, in their own terms?

[ñͤͣ̄ͦ̌̑͗͊͛͂͗ ̸̨̨̣̺̼̣̜͙͈͕̮̊̈́̈͂͛̽͊ͭ̓͆ͅé ̰̓̓́ͯ́́͞]

[Requia ☣]

um,  wtf is non locality?

[Bu🤠ns]

So you're saying there's a Hidden Variable or what?

[Bu🤠ns]

um,  wtf is non locality?

That's what I'm asking?

In physics, the principle of locality states that an object is influenced directly only by its immediate surroundings. Experiments have shown that quantum mechanically entangled particles must violate either the principle of locality or the form of philosophical realism known as counterfactual definiteness.

In physics, nonlocality is a direct influence of one object on another distant object, in violation of the principle of locality.

To me this, to a degree, sounds like:

B̖̭̼͖͈̫̤̱͉̪͖̍ͨ̓̓͋̾̽ͧ̌̏ͫ͐̕Lͩ́̇͂͒ͮͮ̑̾ͪ̑̋̿̚҉҉̴̵͚̯͇̗̞̫̹̫̥͍̞̯ͅĄ̧̱͔̞̜̭̖͖̯̣̋̐ͥ͆̅̒ͯ̓̽͆͌̈́̔͑̓ͥͦR̛̮͍̣͈͑ͪ̾̄ͣͨ͊͘͠͞͝G͕̼̖̭̖̦͙̥̱̩͕͔̫̾̈ͥ̏̇ͨ̌̍̎ͩ̽̕H̸̸̨̩̟̼͈̞̻ͪ̈̉͑̀͟ͅB̛̞̝̪͎̝̯̣̙̯͍̭̱̭͇̰̒ͧ͒͊̇̄ͧͩͫ͗̆̚͝À̴̧̡̗̝̙̥͔̲̞̘̦̲͉̩̣̺̺ͤ͒̆ͣ͑͋͜Ľ̫͖̩͔͚͓̖̘̭̰͚̰̻̜̣͊̈̏̀̓̀̑̿́͜ḫ̲͎̩̞̭͍̰̻̣̬͇̹̠̉̎̏͂̋̅ͬ̃̚͞͡I̛͈̣͕̮̻͕͓̳̭̲̟̰̠̪͗̅ͯ́A̐ͬͫ̓̉̽̐ͬ̒͛ͬ̒̑̔̏ͩͦ̚͏̢̰̘̳̞̼͔̳͇̗ͅB̵̨͙̘̭͚̣̯̝̜͙̤̗̣͕̯͖̥̮͗̋̏̌̔͗̄̓ͬ̉́͞͡B̡̪͕͓͇̜̩͕̪̳̗̫̐̍͒̆̒̒͋͆̍͊̅̈ͩ̋̾̎̀͜͟͞L̟͇̫̝ͧ̋̒͋ͮ͋͛̾ͧ͊̎́͌́͘̕͢A̿́́ͬͫͮ̋ͤ̔̓̐ͯ̾ͧͮ̉̉ͦ҉̙̦̟̮͍̺͠͠ͅH͎̜̰̮̩̒͋̌ͦͧ̚͠B̵̸̩̩̹̭͚͌ͥͨ̓̃͐̚͢ͅA̛̙̻̞̙̯͖̪͙͈̙͔ͥ̊͌ͥ̂̍ͥͨ̋̄͛̀̕͠͡H̷̡̢̫͇̝̙͕ͩ̒̋̋̊̑ͪ͒̅̍́ͫ̌͐ͮ̐͟Ļͯ͛̀̎̍̅ͣͨͭ͏̟͇͉͖̻͍͔͚̼̟̥̤ͅÃ̹͉̼̫͍̥̥͔ͥ̋̆̍͋̑ͦ̊͘͞L̵̸̡̉̉̉ͨ̉̚͏̴͖̞̥̤͓͉͖͙̮̤͕̗͉̲H̷̙͎̖̪͈͕͙̹͇̭̟͇͎͔̫̪͔ͣͩͯͫ̊ͥ͂ͮ͂̊̋̊̾̂́ͧ̀̚͟B̧̢̧̘̖̻̦̻̝̣̩̙͉͆ͪ̍̉͋̀̿ͤͨͬͣ̈́̿̄̆ͬ̇́͢͜A͈̦͔̲̤ͮ͑̇̓͑̽̽̌͜͢L̷̳̫̤̘͔͎͎̰̩͇͕̗͚͔̘ͤ̓̊̉́ͪͭ̀̊̉ͫ̚͘͢͞͡H̶ͩ̏̇̅ͭͪ̈́͏͎̱̮̗͇̝B̴̷̷̨̡̖̳̹̥̥̫͓̝̼͊ͫ̏ͩͨͭ̓́ͮͤͪ̑̎̔ͫ̓̓ͅĄ̸̶͈̱̜̟͈̲̝͓̱͕̱̩͍̖̜̖̞ͨͥ͒̊̓ͫ̓͐ͤ̏ͤ͒ͨ̑̉͆͟͞L̍ͥͤͣ͆̇̾̀ͩͬ̽͑̊͞͞҉͇̗̦̼̟̼̩Ȟ̸̴̴̻͕̩̩̰̭̻̦͌̉ͭ̏̈́̐ͨ̄̈͐ͧ͞A̵̳̙͍̤̘̣͚͎͈̼̳ͬ̈́̊̓͆̀̕͢H̢̨̯̪̘̟̬̯̺̯̐̈́̅̆̑̈́̀A̷̰̰̹̤̮̦ͬͤ́̓͌͛ͬ͂ͬ̀̇̾ͬ̑̓͌͊ͫ͢Bͤ͋͒͌̿̍ͨ̇̑͂͌̾͐̃͏̢̝̙͔͚͎͉͔͓̤̣͉̝̩̪͙͔̯̀͞A̵̧̲̼̬̦̠̟̱̣̓ͯ͆̋ͮ͛̒ͦͯ̊́̀͊̀ͮͩͮ̀̋L̸͛̊͛̅̓ͮ̽͋̽ͬ̉͏̴̨̛̩̠̗̘̯̰̞͙̙̮̼͙Y̢͂́̓̅̏̇͑̅̉̓͛̎͝҉̜̜̮̘̠̤̬̰̦̠̳̤̣͞A̧̝̞͚̤͚̥͗ͪ̓͋̐̍̾̕͘͞A̴̛̞͓̼̯̫͔͍̭̣͋́͐̆͌͑͂ͣ̒̾ͫ̈́͆̚.̶̘͙̰̘͖ͬ̂̐ͭ͌̆̊͆̇̆ͦ̚̚͘ͅ.̷͓͔̳͍̯̥̲ͪ͛͆͌̅ͯ͒ͨͣ̋͌̉ͩ̏̃̏ͯ͊͢ͅ.̴̴͎̳̤͐ͥ̋͐̎̒̂̑ͫͧ͆ͧ̃͛̏̉.̷̨̯̫̲͓̱̗͉͍̖̹̼͚̻͎̬̺̳͕̞̏ͣ̄̍ͧͥ̈́̀́.̡̨̲̣̦̞̣̹͒͌̋ͨ̔̍ͭ̒̉̃̒̓̃ͅ

[rong]

i thought non-locality was when you had to dial a "1"

[Bu🤠ns]

[PeregrineBF]

Note: The following is wrong in several ways. But it should be good enough to get an intuitive understanding of the terms, though not their actual application.

Locality: You touch the rock, you push, the rock moves back. You had to touch it to get it to move.
Non-Locality: You wave your hands. Without any other interaction (no wind, touching of the rock, etc) the rock moves. Some things in quantum mechanics seem to do this.

The EPR paradox is a classic example of non-locality: Two physicists entangle two particles (decay a spin-zero particle into two spin-one-half particles that don't interact with each other after the decay). Since the spins must add up to 0 (spin is conserved) one spin will be +1/2, the other -1/2. Until they are measured quantum mechanics says they are in both states. EPR thought that, since measuring collapses the superposition, then measuring either particle would collapse the superposition of the other, causing it to be set to a given state. Since that could go faster than light it would violate relativity, and thus be wrong. They, however, were wrong, since no actual information is transmitted, and the second observer has no way to know if he was actually the second observer and not the first. They can't even tell if there was an initial superposition.

[rong]

since most of "reality" is empty space, couldn't you argue that all actions are a mix of local and non-local (mostly non-local)

[Kai]

Note: The following is wrong in several ways. But it should be good enough to get an intuitive understanding of the terms, though not their actual application.

Locality: You touch the rock, you push, the rock moves back. You had to touch it to get it to move.
Non-Locality: You wave your hands. Without any other interaction (no wind, touching of the rock, etc) the rock moves. Some things in quantum mechanics seem to do this.

The EPR paradox is a classic example of non-locality: Two physicists entangle two particles (decay a spin-zero particle into two spin-one-half particles that don't interact with each other after the decay). Since the spins must add up to 0 (spin is conserved) one spin will be +1/2, the other -1/2. Until they are measured quantum mechanics says they are in both states. EPR thought that, since measuring collapses the superposition, then measuring either particle would collapse the superposition of the other, causing it to be set to a given state. Since that could go faster than light it would violate relativity, and thus be wrong. They, however, were wrong, since no actual information is transmitted, and the second observer has no way to know if he was actually the second observer and not the first. They can't even tell if there was an initial superposition.

Wouldn't it be that they are not actually in both states but until we measure we can't tell what state they are in?

Kai,

Once again thinks that the "schrodinger's cat" argument is complete bullshit.

[Requia ☣]

No, its actually both states.  Um, I'm not sure how to explain it for spin, but I can explain it for position.

If you send photons at a plate with two slits, it'll make a pattern on the other side in accordance with wave mechanics.  This happens even if you send one photon at a time through, which means the photon has to pass through both slits, like a wave would.

If you try to measure which slit the photon passes through, then A) you can tell it only passes through one slit, and B) the pattern on the other side is a particle pattern.   This happens with anything sufficiently small as well.  So these wave particles actually exist in a kind of haze, which is quite big (macroscopic even, though barely), until they can't anymore, and then they act like particles.

The same general thing applies to spin states (LMNO may be able to fill you in on how the experiment is done for spin states).

the cat thing *is* bullshit though, the cat has a *lot* of atoms in it, all of which will gleefully measure the position of their neighbor, so the cat is in a known state, even if it never interacts with anything outside the box.

The thing to remember is this is the normal way of the universe.  All this being in one place at a time and being in one state at a time thing cats and ping pong balls do it an aberration brought on by having too much stuff in one place.

[Kai]

I'm throwing up my hands and knowing that although I'll never really understand this in any manner that makes sense, neither will any other person. Its all placing terms and metaphors to activities which defy human ability to place terms and metaphors. I mean, what it really comes down to is that photons are energy and we only describe them as particles and waves because we can't possibly come up with any other way to picture and describe energy except by how it seems to interact with so called matter.

Which gets to the point where I'm not sure anything really exists at all in this reality that it seems to be and I'm just fooling myself to avoid barstools.

[PeregrineBF]

"Schrödinger's cat" was an argument Schrödinger made to disprove QM. Quantum mechanics is highly unintuitive. There is some agreement on how to interpret the math, but it's not 100%.

The math works out that it's in both states, and the math is incredibly accurate, and it's impossible to measure that it's in both states since doing so collapses it.

since most of "reality" is empty space, couldn't you argue that all actions are a mix of local and non-local (mostly non-local)

Not so much. See, it may be empty space but the fields (EM, gravitational, strong & weak nuclear) can interact through it. Non-locality comes into play only when the two things can't possibly interact, e.g. 2 photons moving straight away from each other can never interact, since they travel at the speed of light & nothing can get from one to the other.

Not all interpretations of QM require superpositions. Many Worlds, for example, just says that when something would be in a superposition there are really multiple universes created, one in each possible state. Measuring something in a superposition simply tells you which of those universes you are in, and you can never access any of the others.

Kai, I call that the argument of convenience. It's convenient to believe that reality is real, since even if everything is an illusion being hit with a barstool still hurts. Thus, believe reality is real.

[Golden Applesauce]

Kai - physicists used to just take the position that arguing over where a particle was before it was measured was just philosophical wankery, since by definition, you can't tell where something is before you measure its position.  So one group claimed that the particle really was at point A before you observed it at point A, another that it was distributed probabilistically over an area and the measurement somehow caused the wavefunction to collapse to point A (Copenhagen Interpretation) and the rest just refused to answer.

Then John Bell came along and showed that it makes a testable, measurable difference whether Theory 1 or the Copenhagen interpretation was correct, and that experiments actually supported the Copenhagen Interpretation over the idea that the particle was really there all along.

Sorry, I'm only in the 2nd week of my QM course so I don't really understand it that well either.

[Kai]

Okay, when you say "distributed probabilistically over an area" I visualize a fuzzy ball similar to an electron cloud probability field, that the energy is in this fuzzy sphere, and that the measurement causes that fuzzy sphere to collapse to a point.

Thats how I'm visualizing it. Fuzzy spheres of gray light that collapse to a point when interacting with other fuzzy spheres of gray light.