Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Gordian Knot on 09/01/2012 15:39:40
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I was watching a science program, likely the same one Namaan was watching. And if I am understanding what the narrator was saying correctly (which is a big if!), he made an if/then statement that seemed completely nonsensical to me.
He was talking about whether Spooky Action at a Distance was a real phenomena. That Einstein said it wasn't and Bors championed that it was. Some experiments were run that showed that identifying a particle immediately affected the particle it was entwined with, no matter what the distance.
Which brings me to the disturbing part. I have to paraphrase, but I believe I am stating the narrator's statement accurately. He said that because the two particles did alter simultaneously across vast distances, and Einstein proved that nothing can go faster then the speed of light, that was proof that Bors was right and Spooky Action was a real phenomenon.
HuH???????? It proves nothing of the sort! Just because there is no way the information could have travelled the distance between the two particles slower than the speed of light does NOT automatically mean that Spooky Action is the only alternative to what is happening.
If particle identity can teleport instantly from one to the other simultaneously without any information traveling between them is considered a possibility? Why isn't it equally possible that that information IS passing between, just at speeds much faster than light at the quantum level. Both concepts seem equally far fetched to me. And I do not see any reason to give more weight to one impossibility over the other one.
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THIS JUST IN! The great Apple browser for the iOS succumbs to the TNS quick reply box! I've already crashed it three times trying to select a span of text before realizing why it was happening.
HuH???????? It proves nothing of the sort! Just because there is no way the information could have travelled the distance between the two particles slower than the speed of light does NOT automatically mean that Spooky Action is the only alternative to what is happening.
Then again, "Spooky Action" is a pretty big catch-all for, well, just about anything and everything that can't be explained rationally -_-
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Then again, "Spooky Action" is a pretty big catch-all for, well, just about anything and everything that can't be explained rationally -_-
From a physicists point of view, that is tantamount to saying "We are making this sh!t up as we go along!!!!!
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With an emphasis being on the -_-, it was rather tantamount to saying "Spooky Action" is a funny term given the context.
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I believe that the problem of understanding this process is largely the matter of the way it is described to accent quantum weirdness a instil a sense of mystique.
The simple and understandable reality is as follows. All matter and radiation is essentially a wave process. quantum field theory describes this almost perfectly and is the most accurate theory in any branch of science.
All particles are fundamentally waves and the particle description is just a simplification tad describes reality in the way we see it normally.
When two particles are entangled they both have the same wave function but some of the details of this wave function are not defined until one of the particles interacts and is in fact forced to be defined. This defines the phase of the undefined details in the wave function and this phase change is in effect communicated instantaneously to the other particle.
The instantaneous transfer of phase information in this way can be observed in both quantum and classical situations and as it cannot be used to transmit any information other than what it is required to do it does not contravene any normal laws of nature. So this was one of Einstein's blind spots "spooky action at a distance " is far from spooky but is a general property of waves
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The instantaneous transfer of phase information in this way can be observed in both quantum and classical situations and as it cannot be used to transmit any information other than what it is required to do it does not contravene any normal laws of nature.
Soul, I'm a newbie to all this, and I'm sure that what you said is logical to other people educated in physics. Let me see if I can say this in my own words to see if I get what you are stating.
No other transmission works the way the transfer of phase information does, because it is impossible for it to do so according to the laws of physics. Yet it is perfectly okay to accept that phase information does indeed work this way anyway because, ..... because, ........ it does?
The reason it works this way is because it works this way. To me this does not sound like a statement of science. It sounds like a statement of metaphysics, or perhaps philosophy. I'm missing something here!
So this was one of Einstein's blind spots "spooky action at a distance " is far from spooky but is a general property of waves.
It is? Why? How? I have seen not a single description to explain how this magical transfer
can take place in the one single instance of when transferring phase information, but is otherwise impossible for any other transfer of information.
My head hurts........
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No other transmission works the way the transfer of phase information does, because it is impossible for it to do so according to the laws of physics. Yet it is perfectly okay to accept that phase information does indeed work this way anyway because, ..... because, ........ it does?
The reason it works this way is because it works this way. To me this does not sound like a statement of science. It sounds like a statement of metaphysics, or perhaps philosophy. I'm missing something here!
We could really say the same thing about special relativity as well I think. There aren't many places that attempt to explain the why of 'c' invariance (though I'm currently reading one), but then the why really isn't necessary for it to make logical sense. It makes sense because it's a logical conclusion of a more fundamental framework in physics (Maxwell's equations). That is in fact, simply how the universe works even if it doesn't make intuitive sense. As usual, I'm hopeful that I'm giving technically accurate information here.
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Let me explain a simple experiment well known in microwave engineering. when you get up to frequencies of ten or more gigacycles per second, that is wavelengths of 3cm or less, the normal coaxial cables used for most lower frequency signals start to become quite lossy because the energy has to propagate in an ever thinner conducting layer in the material because of what is known as the skin effect. Equipment then switches to use waveguides in which the energy mostly flows through the space inside of the (usually rectangular) tube. You can visualise this as having a pair of waves zig zagging down the tube and reflecting off the shorter sides (a bit like an optical fibre). the interesting feature of these waveguides is that while the group velocity of the waves propagating down the guide is always less than the velocity of light the phase velocity of the waves is always greater than the velocity of light. Also for a particular frequency as the waveguide is made smaller the group velocity (this is the velocity that information travels at) gets slower and the phase velocity gets faster until at what is known as the cutoff point the phase velocity becomes infinite and the wave stops propagating (except for a highly attenuated signal going straight down the space inside the waveguide with a group velocity of the velocity of light|).
One other point that I failed to stress in my original explanation that every wave function of every particle in the universe in theory extends throughout the whole universe except that for most of the particles and most of the space the probability is so small that it does not matter and has no effect on anything. However when I said that entangled particles share the same wave function I really meant it. The two locations where the particles are most probably to be found and what they are are intimately connected until the definition of one of them forces the other and the link can be largely ignored.
Another way of looking at this is that the universe is simultaneously very large in the dimensions of which we are all familiar but very small in the dimensions that determine the entangled properties of the particles.
All the theoretical physics books talk happily about the extra dimensions that we need to define all the properties of particle wave functions and say that the ones we don't see are in fact very small but they draw a little map of large dimensions with small balls screwed up in side them. The other side of things is a load of tiny dimensions approximating to a singularity with three vast dimensions we call space and one we call time bulging out of them and as there are more small dimensions (at least six and probably a few more according to the theoreticians) than large ones most of the universe is in fact tiny and we are the anomaly! Long may that last!!
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Group velocity can be greater than the speed of light as well for other cases in optics. As far as we can tell, information velocity never exceeds the speed of light, however.
I'm not sure group if either group or phase velocity are good analogies for "spooky action at a distance," though. In classical signals, there is no analogue of wave function collapse, which is what gives rise to this quantum effect.
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Two things, my spelling will most probably sux terribly as I'm on a public computer here, and I will regretfully agree to disagree :)
All respect for SoulSurfers position, but I too find it to be a description of a wavefunction 'collapsing', which makes this spooky action, truly, sp00ky :) to me. And my second point is one that seems to be glossed over when discussing everything as waves, in QM they are quantizised, not so when discussing it classically.
It would be interesting to see a discussion comparing a quantizised wave to some classical wave, and how or what they correspond to eachother in reality, that means measurable, not theoretically.
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Again it may be my age that I am aware of facts that are probably not taught nowadays. in the early days of quantum theory, there was an approach (the De Broglie hydrogen atom) that explained the quantised states of a hydrogen atom as resonances of the matter wavelength of the electron with a proton like a cavity resonator or tuned circuit used in electronics. This caused stable or metastable quantised states to form in a classical picture. The results were not as accurate and much harder to calculate than the later quantum field theory but they show a clear and totally logical bridge between classical (many particle large scale) physics and quantum mechanics. In the early days (pre quark) of trying to understand subatomic particles like mesons these were also described in terms of resonances between interacting matter waves in cavities.
I sometimes feel that the current theoreticians have forgotten this approach to understanding quantum processes and they could gain useful insight by trying to use it to get a grasp on quantum gravity where their current quantum field theory maths breaks down because of their inability to control all the mathematical infinities in the equations.
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interesting SoulSurfer :)
I will need to find some sources for that one. If you know a nice one, please link it for us. It's one of the things that constantly disturbs me, the expected equivalence between 'matter waves' as QM:s quantizised waves and the classical description of 'whole waves'.
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SS, quantum mechanics is still taught in that way. Quantum field theory is a much more complicated area, however, in which you're looking at (among other things) the quantum nature of classical waves. The starting point is still classical (classical field theory), but it's not nearly so intuitive since you're describing the quantum wave nature of what is already wavelike which doesn't have a nice classical analogue (that I know of...)
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How about 'time' JP?
That and 'scales'?
Time breaks down with the scale you study it from, as it seems to me? And they both are described in terms of 'c', as the constant that we cut up in smaller pieces, down to plank size. But then you can study something over a extended time period too, and still see it behave 'quantized', but what you observe is on a very small scale even though your measurements are in a macroscopic milieu, as defined by the macroscopic 'clock' you use to measure it in.
It's somehow like 'times arrow' is our conceptual description of how it works four dimensionally and macroscopically. And it is only natural that we use the macroscopic clocks we have when describing QM. But if it really is a 'four-dimensional and whole' reality, treated as one single description, then 'scales' as when you scale down to measuring QM maybe also should be thought of that way?
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Time or space quantization are beyond quantum mechanics and into the realm of post-quantum theories (i.e. quantum gravity).