A question and theory about light

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  • #26
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Hi jtbell, thank you for the link. As it happens I've been as baffled as the next man for years about 'locality' and the Aspect et al. results. And anti-particles propagating backwards in time, the 'doppler' effect in photons etc.
I suppose my sense of weirdness has been overworked.

In case you haven't seen this paper, it's worth a long look -
 

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  • #27
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Cybercrypt, your questions about the aether -

So could you explain to me why we KNOW that the ether doesn't exist?... So far I see plenty of material stating for fact that its wrong, but none define why or how this is know as fact. Its just another assumption made based on "non" evidence from what I have seen.

We can't be certain there's no aether, despite none having been observed.

BUT why introduce something you don't need ? All the phenomena we have dealt with so far can be explained with theories that agree with experiment and do not need an aether.

Keep studying. This is a good article -

http://en.wikipedia.org/wiki/Luminiferous_aether
 
  • #28
Cybercrypt, your questions about the aether -



We can't be certain there's no aether, despite none having been observed.

BUT why introduce something you don't need ? All the phenomena we have dealt with so far can be explained with theories that agree with experiment and do not need an aether.

Keep studying. This is a good article -

http://en.wikipedia.org/wiki/Luminiferous_aether

Thanks, I'll take a look

glenn
 
  • #29
DrChinese
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...I would think the only way to truely rule out classical thinking in an experiment such as this would be to seperate two particles and then somehow take them miles apart and reuse the same particles. Changing ones orientation and showing how it effects the one at the other end. But it seems that you have to be very careful not to get mixed up between thought experiments and actual experiments as things seem to get mixed up quite a bit.

I agree that if proven, this would seem to seal the cap on Einstein's old argument against Quantum Mechanics, but I have to say that I've not read about an experiment in which I haven't questioned what was really being observed compared to what was being assumed.

Do you have any more information on experiments that I could read ?

Thanks,

glenn

There have been such experiments. One was performed at Innsbruck with over a kilometer of separation (and other tests have gone even farther):

http://http://arxiv.org/abs/quant-ph/9810080 [Broken]

Here is my web page devoted to Bell's Theorem and related links, which you may find useful:

Bell's Theorem: An Overview with Lotsa Links

Please note that local realistic theories have very specific requirements which are NOT present for orthodox quantum theory. Your idea of the spin being related even after the particles are separated is agreed to by both quantum theory AND classical theory. But what is not agreed is that a specific observation on one is related to the specific observation on the other.

Classical thinking actually leads to very different predictions than quantum theory. A pure classical view consistent with your idea actually leads to a prediction of correlation of .25+(cos^2/2) while the quantum prediction is cos^2. Guess which is actually observed?
 
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I would think the only way to truely rule out classical thinking in an experiment such as this would be to seperate two particles and then somehow take them miles apart and reuse the same particles. Changing ones orientation and showing how it effects the one at the other end. But it seems that you have to be very careful not to get mixed up between thought experiments and actual experiments as things seem to get mixed up quite a bit.

I agree that if proven, this would seem to seal the cap on Einstein's old argument against Quantum Mechanics, but I have to say that I've not read about an experiment in which I haven't questioned what was really being observed compared to what was being assumed.

Do you have any more information on experiments that I could read ?

Thanks,

glenn
Let's not forget about physical results that only have a quantum explanation. Classically, an accelerated charge emits electromagnetic waves, losing energy, so the orbit of an electron as it circles around a proton would be unstable. It'd spiral into the nucleus. Quantum mechanically, you find the position of the wavefunction of the electron by solving Schodinger's equation, substituting the Coulomb potential of the proton into the Hamiltonian in the equation, and you solve for all possible wavefunctions. It turns out that only some wavefunctions are allowed, each with its average distance from the proton and its energy. Furthermore, there is a lowest possible energy, a closest distance the electron can be to the proton. We call it the ground state. According to quantum mechanics, an electron can only emit radiation when it moves between states. Thus quantum mechanics yields the correct answer where the classical prediction fails.
 
  • #31
Hurkyl
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Let's not forget about physical results that only have a quantum explanation. Classically, an accelerated charge emits electromagnetic waves, losing energy, so the orbit of an electron as it circles around a proton would be unstable.
For the record, this may be a very poor choice of example: the SED people seem to have shown that, classically, an electron in a hydrogen atom may remain in (an erratic) orbit about the proton, because, on average, it absorbs as much background radiation as it radiates.

Of course, there are many other examples that do, so far, defy classical explanation.
 
  • #32
I have another question. I'll be finishing up CalcIII in the fall and afterwards need to start either physics classes or chemistry classes. I was wondering which would be more useful towards a better understanding of QM? I'm thinking Chemistry but wanted some input.

Thanks,

glenn
 
  • #33
reilly
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In particle physics, the quantum version of course, we talk about particles -- including photons-, and not much about waves. that's simply because many of the the measuring techniques stem from old classical-physics based instruments. Toward the bottom of the energy chain, we describe electrons going through crystals in terms of waves -- diffraction and all that. The reality, some say, is that sometimes electrons are waves, sometimes particles.However, it is far more appropriate to say that sometimes electrons BEHAVE like particles, sometimes like waves -- as determined by experiment. We really don't have a clue about the structure of electrons; we know a bit about their behavior. (Is water liquid, solid or gas?)

However, the very structure of Quantum Field Theory, directly involves both wave and particle features. QFT is a big word subject, and is considerably more abstract and mathematically sophisticated than ordinary QM. A key difference is that QFT is about particle transformations -- A->B + C --,

electron->electron + photon.

(Yes, I know about energy conservation; it's not important here and now.)

When you work through the problem you find the following: before radiation there was no photon in the system, then there was a photon. How can we deal with this creation process? What physicists did was to invent the answer. Why not invent an operator -- like position or spin - that changes the number of photons or whatever? Thus we talk about a creation operator and a destruction operator. The Lord giveth and the Lord taketh away.

Phew. The deal is that the standard natural mathematical expression of these transformations involves these creation and descruction operators to create or destroy particles in the system. But they do this in association with the particle's wave-function; both notions are there from the beginning. Ultimately, a creation operator creates a particle and a wave together -- there is a great deal of poetic license here.

Nature is weird, and does not always conform to human notions. Sometimes wave behavior, sometimes particle behavior; crazy making. Who knows from?

Why? -- Lot's of history.

Regards,
Reilly Atkinson
 
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  • #34
DrChinese
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In particle physics, the quantum version of course, we talk about particles -- including photons-, and not much about waves. ...

Regards,
Reilly Atkinson

Nice post, reilly! :smile:
 
  • #35
reilly
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