Better not tell this to Mitt Romney.
Quantum entanglement shows that reality can't be local
131–140 of 172 posts
Re: Quantum entanglement shows that reality can't be local
#132The way that I best understand quantum entanglement (and maybe someone like jessriedel can correct me if I'm wrong) is thus: You may be familiar with the Schrodinger equation (HΨ = ih' dΨ/dt) or the more accurate time-dependent Dirac equation. In each of these equations is a function called the wavefunction (denoted with Ψ). This function represents the "quantum state" of your system -- in other words, all the inform…
Being requested by name is too ego-boosting to pass up, so let me take a crack at clarifying at least one apparent confusion. > For example, you can measure momentum, position, energy, spin etc... and each of these observables has a different corresponding mathematical operation that you perform on Ψ to get XΨ, where X is the mean value of the observable... >The weird thing though is that what you measure isn't alway…
Great, thanks for the clarifications!
Re: Quantum entanglement shows that reality can't be local
#133Can someone provide or point to a layman's definition of "realism" in quantum mechanics? Recently on a call-in podcast I listen to, a caller has claimed that the following article shows that a) realism has been disproven and b) that proves we are all in a computer simulation: http://physicsworld.com/cws/article/news/2007/apr/20/quantum... >Now physicists from Austria claim to have performed an experiment that rules o…
Philosophically (as written by Einstein, Heisenberg, etc.) there are three assumptions about the world - of which one is broken by the quantum world. We do not know which one. Depending on your interpretation of the Schrodinger equation you can interpret the breaking in any of the three ways. This article says its realism - but as far as I know there is no way to prove its realism and not one of the others. One of th…
Do you have any sources for the separability part? From what I remember, the three assumptions should be realism (the universe would exist even if no one would 'observe' it), locality or counter-factual definiteness - the ability to talk and reason on results of measurements that have not been performed.
Re: Quantum entanglement shows that reality can't be local
#134Can someone provide or point to a layman's definition of "realism" in quantum mechanics? Recently on a call-in podcast I listen to, a caller has claimed that the following article shows that a) realism has been disproven and b) that proves we are all in a computer simulation: http://physicsworld.com/cws/article/news/2007/apr/20/quantum... >Now physicists from Austria claim to have performed an experiment that rules o…
Philosophically (as written by Einstein, Heisenberg, etc.) there are three assumptions about the world - of which one is broken by the quantum world. We do not know which one. Depending on your interpretation of the Schrodinger equation you can interpret the breaking in any of the three ways. This article says its realism - but as far as I know there is no way to prove its realism and not one of the others. One of th…
That's interesting. At first glance, it seems like we invented Separability just to make things easier for us. In my head I'd always assumed that forces diminish continuously; But I guess that's what I get for thinking of force as something different from a particle. If all force is particles, I suppose it makes sense.
Re: Quantum entanglement shows that reality can't be local
#135Earlier quoted context omitted.
This doesn't work because there is no moment at which the state is 'known' or 'detangled'. There is no way to tell, by observing one particle, when the other particle was observed. If there was you could send a signal with it, which would be no good. The universe is a strange place.
Plus the other particle could later be "unobserved" through quantum erasure.. http://en.wikipedia.org/wiki/Quantum_eraser_experiment
Not in the way that you're imagining. Otherwise, you could easily communicate by repeatedly observing and then unobserving until finally you see the bit that you don't want to send, and then you let it be.
Re: Quantum entanglement shows that reality can't be local
#136This is for me the most interesting part of the whole teleportation / entanglement research. When these papers started coming out we debated the notion of 'faster than light' communication. The counter argument was that you had to move the particles apart and that was constrained by the speed of light. Then the question of "when" the state was resolved was pondered. There were two thought experiments proposed at this…
and have the alien equivalent of the FCC come out to the planet to arrest the scientists for transmitting without a license Or the channel is already filled completely with spam.
Maybe they can tell me how to make my jagon bigger.
Re: Quantum entanglement shows that reality can't be local
#137I've always found classical Newtonian physics, the Special Theory of Relativity, and (to a lesser extent) the General Theory of Relativity to be understandable at an intuitive level, but quantum phenomena just baffles me, even when I think I "understand" it. PS. IvoDankolov: I find it difficult or impossible to think intuitively about quantum phenomena.
Quantum mechanics is very simple and intuitive, after you remove the annoying physics (and the long history of misunderstandings that courses in the subject seem duty-bound to cover) from the mathematics. See http://www.scottaaronson.com/democritus/default.html
Re: Quantum entanglement shows that reality can't be local
#138Earlier quoted context omitted.
Philosophically (as written by Einstein, Heisenberg, etc.) there are three assumptions about the world - of which one is broken by the quantum world. We do not know which one. Depending on your interpretation of the Schrodinger equation you can interpret the breaking in any of the three ways. This article says its realism - but as far as I know there is no way to prove its realism and not one of the others. One of th…
Do you have any sources for the separability part? From what I remember, the three assumptions should be realism (the universe would exist even if no one would 'observe' it), locality or counter-factual definiteness - the ability to talk and reason on results of measurements that have not been performed.
Search this article - it explains much of the original rationale:
Re: Quantum entanglement shows that reality can't be local
#139I've always found classical Newtonian physics, the Special Theory of Relativity, and (to a lesser extent) the General Theory of Relativity to be understandable at an intuitive level, but quantum phenomena just baffles me, even when I think I "understand" it. PS. IvoDankolov: I find it difficult or impossible to think intuitively about quantum phenomena.
Let me make it worse. Ever heard of chaotic systems? Any dynamic system that shows extreme sensitivity to initial conditions is chaotic. For instance smoke curling from a cigarette, planetary orbits over time, weather, water dripping from a tap - all of these show extreme sensitivity to initial conditions. Here is the fun thing. In quantum mechanics everything evolves linearly. Therefore extreme sensitivity to initia…
>Here is the fun thing. In quantum mechanics everything evolves linearly. Therefore extreme sensitivity to initial conditions is entirely impossible
I'm not sure if that is true. You can have dense sets created by Linear Operators if you're in a infinite dimensional setting (which you _are_ in QM). That's what Hypercyclic Operators are.
In any case, although the wave function evolves linearly, the _square_ of the wavefunction obviously does not (by the product rule). Since all observations are going to be based on square of the wavefunction, or the product of it with it's gradient, all observable quantities will typically evolve nonlinearly.
Re: Quantum entanglement shows that reality can't be local
#140If you were able to construct a rigid beam 25 million miles long wouldn't you be able to transmit data (push a button) on the other end faster than the speed of light?
It is possible to conceive of violating the known laws of physics if you start by conceiving of an object that violates the known laws of physics. A perfectly rigid beam 25 million miles long would be such an object.
A beam made of matter is not rigid (as we think of the word) on that scale, as others in the thread have pointed out.