Do electrons rotate?

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Offline JP

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Do electrons rotate?
« on: 14/02/2010 07:02:02 »
This topic came up in another thread recently: http://www.thenakedscientists.com/forum/index.php?topic=27444.0

Since it's gotten a lot of discussion, I think it deserves its own thread.  So the question is this: do electrons necessarily rotate?  What kinds of rotation do electrons experience?  Are there physical consequences of these rotations?

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Offline lightarrow

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Do electrons rotate?
« Reply #1 on: 14/02/2010 12:42:24 »
This topic came up in another thread recently: http://www.thenakedscientists.com/forum/index.php?topic=27444.0

Since it's gotten a lot of discussion, I think it deserves its own thread.  So the question is this: do electrons necessarily rotate?  What kinds of rotation do electrons experience?  Are there physical consequences of these rotations?
For what concern me, electrons don't rotate.
As always, in physics this doesn't mean that the opposite couldn't be true one day, but only that, for what we know NOW there isn't any experimentally verified inner rotation.

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Offline Soul Surfer

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Do electrons rotate?
« Reply #2 on: 14/02/2010 13:16:40 »
Electrons possess a quantum mechanical property known as spin which is very similar to rotation but it can have only one of two opposing values usually described as up and down.  This means that electrons are a bit like magnets and tend to like to group in pairs.
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Offline CZARCAR

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Do electrons rotate?
« Reply #3 on: 14/02/2010 16:03:28 »
i contrast this to the actions of a knuckleball in baseball & would guess they gotta have some spin

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Offline lightarrow

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Do electrons rotate?
« Reply #4 on: 14/02/2010 19:30:52 »
i contrast this to the actions of a knuckleball in baseball & would guess they gotta have some spin
Rotation → spin = angular momentum → magnetic momentum (if it's charged).
spin = angular momentum (not→) rotation (in the quantum world).

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Offline Farsight

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« Reply #5 on: 14/02/2010 22:05:03 »
In answer to the direct question "Do electrons rotate?" I'd actually say no. That might surprise you, but I'll come back to it. 

If the question was "Do electrons involve some form of rotational motion" I'd say yes. Electrons do exhibit the properties of angular momentum and magnetic moment, see magnetic moment of electrons and electron magnetic dipole moment. We all know that electron's spin 1/2 isn't the typical spin of say a rotating billiard ball, and precise measurement of say the g-factor confirms this, bringing in the anomalous magnetic dipole moment. However what's called mainstream physics rather gives up at this point, saying "you cannot understand it classically". It doesn't offer an electron model that gives any conceptual grasp of pair production or what the electron actually is, saying instead "it's an elementary particle" or "it's a point particle", missing the fact that the electron can be created and destroyed, and a point particle cannot exhibit angular momentum. Moreover there seems to be a refusal to entertain papers by bona-fide physicists that attempt to offer answers, or at least ideas. Such papers receive little attention, and instead we read of Boltzmann brains, parallel worlds, and other matters for which we have no actual scientific evidence. I find this an extraordinary situation, to say the least.   

I was looking at We Need to Talk About Kelvin: What Everyday Things Tell Us About the Universe by Marcus Chown last week. On page 73 he says "spin 1/2 is something doubly new under the sun". Imagine not being the same person if you turn round once, but only if you turn round twice". He speaks as if there's something miraculous that can never be understood, but I can think of an everyday thing that fits the bill:



The thing is, rotation can be subtle. If I ask you to look at a clock and say "Which way are the hands rotating?", you'd say clockwise. But suppose it was a glass clock, and I took you round the back. Those hands are now rotating anticlockwise. In similar vein if we fly around the equator of the earth, we can easily distinguish between an East→West and a West→East rotational motion. But suppose we added a South→North rotational motion, such that we now head North-West, go round the back of the Northern hemisphere, come down from the North-East to head South-West, then go round the back of the Southern hemisphere and come up from the South-East. We're describing a folded figure-of-8, and we're continuously changing direction. Which way are we spinning? It's difficult to say.

For me, this is enough to look seriously at real rotational motion, like the Williamson / van der Mark depiction below. The dark black line is the figure of 8, but rather than wrapping round a sphere, it and the other trajectory lines delineate a  torus with a spin 1/2 feature like the moebius strip. 

 

So, to return to the original question: "Do electrons rotate?" I'd say no, because the situation is something like a whirlpool where the water rotates. The whirlpool only exists because of this rotation. The whirlpool doesn’t rotate, the water does. After pair production, we don’t see any 511 keV photons conveying energy/momentum at c. Instead we see angular momentum and magnetic moment, et cetera. The scientific evidence seems pretty conclusive, whatever the maths. However you model the electron, that photon is stuck in some kind of 2π loop. Only now we don't call it a photon any more, we call it an electron.

And of course, light travels in straight lines, so yes, we do Need to Talk About Kelvin because of http://www.math.buffalo.edu/~menasco/Knottheory.html. You call it fringe, I call it leading edge, but time will tell as to what it really is.     

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Offline yor_on

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« Reply #6 on: 16/02/2010 19:31:03 »
I agree on that spin is defined as having an 'angular momentum' but there is one important word missing.

. . . Intrinsic . . .

--Quote---

Experimental evidence like the hydrogen fine structure and the Stern-Gerlach experiment suggest that an electron has an intrinsic angular momentum, independent of its orbital angular momentum. These experiments suggest just two possible states for this angular momentum, and following the pattern of quantized angular momentum, this requires an angular momentum quantum number of 1/2.

---End of quote--Electron Intrinsic Angular Momentum

" Ralph Kronig, one of Landé's assistants, suggested in early 1925 that it was produced by the self-rotation of the electron. When Pauli heard about the idea, he criticized it severely, noting that the electron's hypothetical surface would have to be moving faster than the speed of light in order for it to rotate quickly enough to produce the necessary angular momentum. This would violate the theory of relativity."

The definition of intrinsic is as follows " Belonging to a thing by its very nature." In the same way as photons are intrinsically massless and timeless.

"As the name suggests, spin was originally conceived as the rotation of a particle around some axis. This picture is correct in so far as spins obey the same mathematical laws as do quantized angular momenta. On the other hand, spins have some peculiar properties that distinguish them from orbital angular momenta:

    * Spin quantum numbers may take on half-integer values;
    * The spin of a charged particle is associated with a magnetic dipole moment with a g-factor differing from 1.

This is incompatible with classical physics, assuming that the charge and mass of the particle are distributed evenly in spheres of equal radius. Particles with half-integer spin obey Fermi-Dirac statistics, and are known as fermions. They are required to occupy antisymmetric quantum states (see the article on identical particles.) This property forbids fermions from sharing quantum states – a restriction known as the Pauli exclusion principle. Particles with integer spin, on the other hand, obey Bose-Einstein statistics, and are known as bosons. These particles occupy "symmetric states", and can therefore share quantum states. The proof of this is known as the spin-statistics theorem, which relies on both quantum mechanics and the theory of special relativity. In fact, "the connection between spin and statistics is one of the most important applications of the special relativity theory".

So we have a definition coined because it reminded us about angular momentum, not that it was anything like it. So, to treat it as a rotation seems less than correct.
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Offline Farsight

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Do electrons rotate?
« Reply #7 on: 16/02/2010 22:33:02 »
I agree on that spin is defined as having an 'angular momentum' but there is one important word missing.

. . . Intrinsic . . .
That's a cop-out non-answer, yor-on. Really. It's like saying surpasseth all human understanding.

"Experimental evidence like the hydrogen fine structure and the Stern-Gerlach experiment suggest that an electron has an intrinsic angular momentum, independent of its orbital angular momentum. These experiments suggest just two possible states for this angular momentum, and following the pattern of quantized angular momentum, this requires an angular momentum quantum number of 1/2".
No problem with that. The moebius strip exhibits this feature, as does the Williamson / van der Mark and the Qiu-Hong Hu electron models. See http://arxiv.org/abs/physics/0512265 for the latter. This might not be mainstream yet, and it has not yet hit the media or the textbooks. But I assure you, the moot word is yet.  

"Ralph Kronig, one of Landé's assistants, suggested in early 1925 that it was produced by the self-rotation of the electron. When Pauli heard about the idea, he criticized it severely, noting that the electron's hypothetical surface would have to be moving faster than the speed of light in order for it to rotate quickly enough to produce the necessary angular momentum. This would violate the theory of relativity."
There is no surface to the electron, just as there's no surface to an electromagnetic wave travelling through the bulk of space, or to a seismic s-wave travelling through the bulk of the earth. The bottom line is that Pauli didn't understand the electron.

The definition of intrinsic is as follows " Belonging to a thing by its very nature." In the same way as photons are intrinsically massless and timeless.
As above. We do science to understand things, not give up on them. And we do understand why the photon is massless and timeless - you can't change its speed and since it travels at c it is subject to infinite time dilation.

"As the name suggests, spin was originally conceived as the rotation of a particle around some axis. This picture is correct in so far as spins obey the same mathematical laws as do quantized angular momenta. On the other hand, spins have some peculiar properties that distinguish them from orbital angular momenta:

    * Spin quantum numbers may take on half-integer values;
    * The spin of a charged particle is associated with a magnetic dipole moment with a g-factor differing from 1.

This is incompatible with classical physics, assuming that the charge and mass of the particle are distributed evenly in spheres of equal radius. Particles with half-integer spin obey Fermi-Dirac statistics, and are known as fermions. They are required to occupy antisymmetric quantum states (see the article on identical particles.) This property forbids fermions from sharing quantum states – a restriction known as the Pauli exclusion principle2.
It is compatible with classical physics, but not with the rotation of spheres. All you need is a stress-energy rotation in two dimensions. That means the rotational direction constantly changes, which is why you can't say which direction it's going. All you can do to change it is go backwards, then you have the opposite spin. And as for the Pauli exclusion principle, two waves can ride over one another, but two whirlpools cannot overlap. It's a rather simple picture once you see it, and it works.

"Particles with integer spin, on the other hand, obey Bose-Einstein statistics, and are known as bosons. These particles occupy "symmetric states", and can therefore share quantum states. The proof of this is known as the spin-statistics theorem, which relies on both quantum mechanics and the theory of special relativity. In fact, "the connection between spin and statistics is one of the most important applications of the special relativity theory".

So we have a definition coined because it reminded us about angular momentum, not that it was anything like it. So, to treat it as a rotation seems less than correct.
It is angular momentum. And there's magnetic moment in there too. The g-factor is a correction factor, and it's 2.002319. It isn't quite 2, but that 2 should tell you something. As should the fact that the magnetic field is associated with curl aka rot aka rotor. There's definitely something going round and round.

I'm sorry yor-on, but it's not scientific to say it's something intrinsic that we cannot understand. That's not enough to oppose deductive logic backed by evidence and peer-reviewed papers. Look to pair production, where mass and charge and all those electron properties are created by doing something to light so that it no longer propagates linearly at c.

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Offline yor_on

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« Reply #8 on: 16/02/2010 22:56:31 »
Sorry Farsight, Angular momentum might be the word here but the effect seen have nothing to do with angular momentum. Don't let that excite you too much though, as long as your math follows the math used to describe those effects, or have an analogous way to describe them preferably, if you want them to supersede an older idea, with some new experimental evidence to it then that's perfectly cool with me :)

Math and words sometimes seems to have problems 'coexisting'?
As for you saying "I'm sorry yor-on, but it's not scientific to say it's something intrinsic that we cannot understand." I'm afraid I have to state that my opinion is just the opposite :) It's when we have moved from that word to 'knowing' what gives those properties we are truly scientific. 'Intrinsic' is a definition very near to singularities as I see it. There, existing, but very hard to understand for me.

==
And btw, it's not my idea defining them as 'intrinsic'?
« Last Edit: 16/02/2010 22:58:38 by yor_on »
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Offline Farsight

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« Reply #9 on: 16/02/2010 23:38:24 »
It is to do with angular momentum, see the papers for the maths. The whole point is that there is no old idea, and people accept this deficiency whilst making light of the experimental evidence of pair production, angular momentum, magnetic moment, etc. It's all locked away in a blind spot called "intrinsic spin", and people can't see their blind spot. See this quote from that hyperphysics page?

"With this evidence, we say that the electron has spin 1/2. An angular momentum and a magnetic moment could indeed arise from a spinning sphere of charge, but this classical picture cannot fit the size or quantized nature of the electron spin. The property called electron spin must be considered to be a quantum concept without detailed classical analogy".

We all know an electron is not a spinning sphere. But to then say there can be no classical picture is a non-sequitur. The phrase must be considered to be a quantum concept without detailed classical analogy really does equate to surpasseth all human understanding. That's dogma, not science.
« Last Edit: 16/02/2010 23:41:07 by Farsight »

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Offline PhysBang

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« Reply #10 on: 17/02/2010 00:09:26 »
That's a cop-out non-answer, yor-on. Really. It's like saying surpasseth all human understanding.
It would be if his answer wasn't actually based on the experiments that people have done with electrons.
Quote
No problem with that. The moebius strip exhibits this feature, as does the Williamson / van der Mark and the Qiu-Hong Hu electron models. See http://arxiv.org/abs/physics/0512265 for the latter. This might not be mainstream yet, and it has not yet hit the media or the textbooks. But I assure you, the moot word is yet.  
The reason why it is not mainstream is that the proposal you have linked to is something published in a crank journal. There are simply some publications that one cannot take seriously and Physics Essays is one such journal. If someone is publishing their work their, it is almost guaranteed that it is of little or no value.
Quote
And as for the Pauli exclusion principle, two waves can ride over one another, but two whirlpools cannot overlap. It's a rather simple picture once you see it, and it works.
Then demonstrate how it produces the results of QM experiments. That's what "it works" must mean in this context.
Quote
I'm sorry yor-on, but it's not scientific to say it's something intrinsic that we cannot understand. That's not enough to oppose deductive logic backed by evidence and peer-reviewed papers.
The only one here ignoring the science is you, Farsight. For example, you are entirely ignoring the results of the Ster-Gerlach experiments and other experiments that back up exactly what yor-on is saying. Additionally, you have not provided any peer reviewed research to support your opinion, you have only provided a single article on a pre-print archive that is far from peer reviewed, an article that is, at best, printed in a crank journal. A paper with very few citations (2 that I could find). This means it is science that scientists do not take seriously.

We do understand electron spin, we have just been forced to the conclusion that it is significantly different from angular momentum.
Quote
Look to pair production, where mass and charge and all those electron properties are created by doing something to light so that it no longer propagates linearly at c.
If you can show exactly how your idea of pair production recaptures all of the properties of an electron going through a Stern-Gerlach magnet, then go ahead. Let's see how you predict the experimental results that people get every day from these devices and ones like them.

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Offline yor_on

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« Reply #11 on: 17/02/2010 00:39:59 »
Physbang although I agree on physicists being able to manipulate this property in logical (and at times even a-logical:) ways they still haven't made me understand what they really mean by it. I would gladly pass them by (electrons) if I did, but as it is they confuse, as well as fascinate, me with their entanglements etc and the way they are 'quantized' as so much else, ah, down under :).

But Farsight, you will need to be able to explain the properties of an electron going through a Stern-Gerlach magnet too for your proposal to become a theory, don't you agree? Or maybe you already have?
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Offline JP

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« Reply #12 on: 17/02/2010 05:55:57 »
Most of quantum mechanics is really weird, and although we can grasp its mathematics, I don't think anyone can really intuitively understand it.  The way tiny things behave is just so alien to our everyday world.  Spin is an example of one of those things that just doesn't show up in everyday life, but which nevertheless appears to be true.  I don't see why we should really expect things that are extremely far outside of our everyday view of the world to behave in an intuitive manner. 

I think the ultimate test of these theories is (and should be) whether or not they hold up to experimental scrutiny.  So far, spin has done so.  Like other posters here, I'm not sure how the electron model you described, Farsight, would be testable.  If it does predict exactly the same properties that are shown by an actual electron, then it's worth considering further.  However, new proposals in science are everywhere, so its up to the one proposing them to rigorously show how they satisfy existing tests and also how they predict new phenomena or fix problems with the current theory. 

Having said that, I think that the description of an electron (and other fundamental particles) as having sub-structure that geometrically accounts for spin is something that string theory is trying to come up with.  I'm not an expert on string theory, but I know that those who are have demonstrated that it is compatible with current physics, although they haven't come up with new testable predictions yet.

Edit:  I hate to link to the wiki on a point where I'm not very familiar with the subject, but if this is true, it seems to cover most of what your electron model claims to solve, Farsight: http://en.wikipedia.org/wiki/Relationship_between_string_theory_and_quantum_field_theory .  In particular, it explains spin as the rotation of a string, and it would explain pair production as the splitting of these strings.  Maybe someone with a better grasp of string theory could enlighten us further.
« Last Edit: 17/02/2010 06:03:59 by JP »

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Offline yor_on

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« Reply #13 on: 17/02/2010 19:30:29 »
Yes JP, strings might cover it :)

The problem with string theory is how we should see it. It starts from one dimensionality as I understands it?
And I'm lost directly there :)

A one dimensional surface, as observed here in 3D + time?
I say we can pack them on, into infinity, without making them interact.
They are one dimensional after all.
==

And that should also mean that no matter your geometric 'twists and knots' you wont make them 'connect' to another one dimensional plane. Then it might be easier to consider SpaceTime just being one singular 'one dimensional' plane knotted with the help of 'time' and 'times arrow', well, to me that is ::))
==

Two dimensional?
Okay, I can accept that they will interact geometrically from some 'perspective' at the same time as they won't interact (or even be seen to exist) simultaneously for another observer observing them from another position (angle).
===

Although this makes a lot of sense, to me at least.

"renormalization: in particle physics the behaviour of particles in the smallest scales is largely unknown. In order to avoid this difficulty, the particles are treated as point-like objects, and a mathematical tool known as renormalization is used to describe the unknown aspects by only few parameters, which can be adjusted so that calculations give adequate results. In string theory, this is unnecessary since the behaviour of the strings is presumed to be known to every scale."

Yeah, is there anyone here that can relate strings to SpaceTime here?
« Last Edit: 17/02/2010 19:44:24 by yor_on »
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Offline lightarrow

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« Reply #14 on: 17/02/2010 19:55:53 »
Farsight: in addition to the properties you have discussed, the electron model that you propose which dimensions would have? Does the model also predict the wavelike properties of the electron?

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Offline yor_on

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« Reply #15 on: 17/02/2010 20:00:40 »
So, rereading myself. Sure, a one dimensional 'place' knotted by 'times arrow' and 'time' will then have a higher probability to my eyes than the idea of 'dimensions' as something we 'cut and paste' as needed. After all, there are no two dimensional objects inside SpaceTime as I know of?

And to prove that you will need to show me how it will disappear from one angle being in the same 'frame of reference' and at the same time as my coworker on the other side (angle) still can see, as well as 'touch', it?

So is there any string theories that looks at it that way?
I haven't heard of them?
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Offline yor_on

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« Reply #16 on: 18/02/2010 01:35:32 »
On a similar but (maybe this will need a new thread too?) connected thought. How exactly can a electron transition in its orbitals, does it take time? It should, shouldn't it, are there some immediate time when it won't 'exist', that is if I assume that it will be a 'new orbital' made by a 'new electron' created due to interaction with something else. If I move a atom inside a electromagnetic field created by a permanent magnet I will 'transfer energy' to it, won't I? The way i transfer this energy is via 'virtual photons', am I right there? So then this electron orbital will change, right?

So, how does it do it. By destroying one 'electron orbital' and creating another orbital, or by changing the probability of where it is. And does it take time, and is there a moment when it won't 'exist' in between those two orbitals.

'Exist' as I use it here can either be seen as gone, nada, not there at all.. Or as a probability of it being superimposed I guess? Like negated by being at two places simultaneously, which should unbalance it, as it seems to me?
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Offline Soul Surfer

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« Reply #17 on: 18/02/2010 16:16:10 »
The way electrons change their orbitals is very interesting and not well understood, and the way photons of very similar frequencies are produced can be very different.  Let me explain.

When an electron is in a higher energy state above the ground state it will eventually lose a photon and decay to a lower energy state or even the ground state.  These states like nuclear decay have "half lives".  they are also subject to the uncertainty principle (QV)  this means that the shorter the decay time the less well defined is the energy of the photons.  so if you want a very precise frequency with a narrow spectrum line you chose a state with a long life.  The photons produced by  short lived processes have a broad bandwidths and the long lived processes produce a narrow bandwidth photons

It is possible to visualise this by saying that the short lived photons are only a single wave while the long lived ones have many waves in their wave packet.

This effect occurs all the way from radio waves in communications to gamma rays and collections of photons from different processes with the same nominal frequency can gave different bandwidths.

The one and very important feature that I have never had a clear answer for is:-  Is bandwidth an inherent property of a single photon or is it only observable in collections of photons from a particular source?  and I have asked this question of some pretty good scientists.  The only reply i have ever received is That is a good question  I will have to think about it.

I have never been able to think up an experiment that could prove this either way so maybe this question just cannot be answered.
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Offline yor_on

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« Reply #18 on: 18/02/2010 19:19:55 »
Nice answer Soulsurfer, and, ah, I will have to think about it :)

And I mean it sincerely.

F.ex I presume that there is a similarity between the shortlived wavepackets having a broad bandwidth and a virtual photon, in that they also can have a very high energy, a little like virtual photons can have an undefined energy, just because they go under Plancktime? Or am I wrong there?

And that bandwidth here refers to their 'energy', sort of? If I would look at it as a photon? If we were talking about the electrons emitting them I would think of some sort of 'vibrational mode' emitting certain waves?

How is a single photon thought to be able to emit/contain several waves?

As a wavepacket I think I can accept it, even though it seems that if we assume that the shortest 'real' wavepacket possible will have to be at Planck size it then will have a length of '1' but f.ex then containing, how many possible waves?
 
But I have definite difficulties conceptualize it as a photon at the same time?
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« Last Edit: 18/02/2010 19:22:42 by yor_on »
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Offline lightarrow

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« Reply #19 on: 18/02/2010 20:04:38 »
The one and very important feature that I have never had a clear answer for is:-  Is bandwidth an inherent property of a single photon or is it only observable in collections of photons from a particular source?  and I have asked this question of some pretty good scientists.  The only reply i have ever received is That is a good question  I will have to think about it.
I have never been able to think up an experiment that could prove this either way so maybe this question just cannot be answered.
I'm rather sure a physicist told me that single photons have their own coherence and so their own bandwidth.
About an experiment to prove it, I would say fire single photons through a diffraction grating and analyze the spectrum after a large amount of detection events (but I'm not completely sure it would work, anyway).

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Offline Soul Surfer

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« Reply #20 on: 18/02/2010 22:09:27 »
Yor on  the energy of a photon of a given frequency is always the same.  The best way to visualise it is to consider the response of a radio cavity resonator to an impulse  if the cavity has a high Q and is narrow band it rings for a long time before fading if it has a lower Q and a less precise frequency it decays much quicker  this is because for a high q cavity most of the energy is retained each cycle and more escapes from the lower Q cavity
This is analagous to the long transition time and the short transition time.  a narrowband photon consists of many cycles of the frequency of a lower amplitude and takes longer to detect.

Light arrow your experiment would only show that a large number of photons from this source possess a particular bandwidth which is no problem. you need to prove this property for one single photon so you would have to detect the full spectrum of a single photon using your detector and I am not sure if that is possible although i understand that it may now be possible to detect the passage of a photon without destroying it under certain special circumstances and this may be a route to an experiment.
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Offline JP

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« Reply #21 on: 19/02/2010 02:21:54 »
Isn't a single photon by definition a pure frequency? (E=hν)?  Therefore, aren't the finite bandwidth packets released by an atomic process a quantum superposition of photons of different frequencies?  If that's the case, the answer to the bandwidth problem would be that each photon has a well-defined frequency, but that most processes release a spectrum of possible photons (although upon detection you collapse the wavefunction to only measure one).

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« Reply #22 on: 19/02/2010 05:37:18 »
Thank you Soul Surfer and JP. When it come so wavepackets the terminology is unfamiliar to me so anything that can clear that up is appreciated.  Looking I saw a lot of experiments using the term photon wavepacket which was a new experience for me :) I think I'm getting old fashioned, I've always differed between those two.

Never the less it becomes understandable if it, like JP suggests, have to do with 'superpositions' although that gives me another headache as I now start to wonder how and why a, or several', photons would 'join' up like that superimposed. It seems to imply, if so, that you have several processes taking place with the electron simultaneously, it also imply that the electron then is acting in a analogue way, being able to process them at the same time, sort of? Or maybe in a 'self like' way? A little like my thoughts about the 'Rindler observers' all describing different SpaceTimes 'simultaneously', as observed from my frame.

The other way that I like to look at photons is as 'probabilities' and doing so I presume that I might view those 'superpositions' as 'probabilities' instead. Does this make sense? For me personally it becomes easier to understand then, if we assume that it is in the interactions those 'probabilities' finds its expression. But I really have to give you both a lot of kudos for doing your best to 'boink' some sense into my head :)

It's rather hard (to do too), so it takes time.

Which reminds me. I'm still wondering if those orbitals transitions take time?
And if there is a state where they are gone /'superimposed'/not defined?
If there is shouldn't it be measurable?

And considering your question SoulSurfer, from my naive perspective, looking at it as 'probabilities' :) I would say that it will be the interaction that defines what you see. That some interactions are consistent over time is what we build on when we define the math regulating those probabilities. And the question that gives me is if 'interactions' live on a plane of itself :) We like to define it as 'forces' acting on each other creating those 'interactions' but, sh* I don't know ::)) I should have slept longer :)

And that makes me wonder another ting, if it was like this, then the relation would have to be the interaction observed between at least two proceedings/properties as observed in SpaceTime right? So for this to be right there can never be a proceeding initiated and concluded by a proceeding in itself, if I'm thinking right here? Or can there?

« Last Edit: 19/02/2010 06:00:08 by yor_on »
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« Reply #23 on: 19/02/2010 06:20:05 »
Yor_on, when you're dealing with waves, you can choose a wave that has a certain value of some physical parameter you choose.  Let's choose sine waves for an example and define the frequency (i.e. how fast they oscillate).  It turns out that you can use combinations (or superpositions) of these sine waves to make a different type of wave, and conversely you can write a different type of wave in terms of a superposition of sine waves.  Why this is important is that in quantum mechanics, you choose what you want to measure, and then essentially "write" your wave in terms of other waves that have well-defined values of that quantity and then your measurement picks one wave from among these.  It can only pick one answer, so it picks among them randomly (with some rules giving the probabilities of picking each particular answer). 

Here's a short example.  Let's say I want quantum mechanically measure the sine wave frequency of a wave that looks like a sharp step.  To describe this mathematically, I first write it in terms of sine waves with known frequencies.  I can do so as shown in the figure (there are mathematical formulas that tell you how).  To get exactly to the answer, I need to add an infinite number of these, but they get smaller and smaller, so I only show it up to 50 terms here.  Since this is quantum mechanics and I'm measuring sine wave frequency, my measurement you can only get one answer, so my measurement would randomly pick from among the sine waves making it up (all the dashed blue lines in the figures).  (The probability of picking a given sine wave is related to how big [vertically] it is when I add it in the picture.)

So superposition is basically the way you write a complicated wave in terms of waves with well-defined measurable values, and it's important in quantum mechanics because you randomly pick one of the measurable waves when you actually do a measurement.

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« Reply #24 on: 19/02/2010 09:17:15 »
JP you make sense :)
In a slightly weird way ::))

But as I'm, ah, ever so slightly weird myself I think I get it, a very nice explanation. In that motto a superposition will be how you define a given wave by using approximations to narrow it down to a 'best answer'?

But can there be a definite answer to such a procedure, doesn't it just goes on and on?
But very very good explanation of the mathematic principle for it. Sweet one JP.

And a 'wavepacket', if you tried to define it like this, or could I see this as a 'reversed wavepacket procedure' sort of? You should be able to do this both ways mathematically, shouldn't you? I think of a wave packet as what it seems to say, like a 'packet of waves' together.
===

This one though, could you expand on how you mean here?

"Why this is important is that in quantum mechanics, you choose what you want to measure, and then essentially "write" your wave in terms of other waves that have well-defined values of that quantity and then your measurement picks one wave from among these.  It can only pick one answer, so it picks among them randomly (with some rules giving the probabilities of picking each particular answer)."

I'm sort of losing myself in it :)
==

Hey, I know what it reminded me of now :) A analogue signal to digital, right? And that makes sense, it's 'cut outs' right? A way to treat the universe as 'quanta' so to get a 'over see able' system?

Or am I bicycling in the blue younder again? And the 'digitalized' concept here, could that be a conceptual idea of 'photons' from a wave perspective then? I need to get a time machine :) Or find that well of youth.. So I can start all over again :::)))
« Last Edit: 19/02/2010 09:48:53 by yor_on »
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« Reply #25 on: 19/02/2010 10:11:19 »
But as I'm, ah, ever so slightly weird myself I think I get it, a very nice explanation. In that motto a superposition will be how you define a given wave by using approximations to narrow it down to a 'best answer'?

But can there be a definite answer to such a procedure, doesn't it just goes on and on?
But very very good explanation of the mathematic principle for it. Sweet one JP.
In many cases, it does go on and on, like in the case above.  This is one of the cases where physicists can use infinities to do some useful stuff, like keep track of the infinite number of sine waves in my above example.

Quote
And a 'wavepacket', if you tried to define it like this, or could I see this as a 'reversed wavepacket procedure' sort of? You should be able to do this both ways mathematically, shouldn't you? I think of a wave packet as what it seems to say, like a 'packet of waves' together.
A wavepacket is also like what I showed above.  It's a wave of short length that you can break into a superposition of waves just like how I did it above.  You just change the step function I showed to a packet of your choice.  Of course, the recipe for how to add sine functions to get the wave packet changes, depending on the packet. 

Quote
This one though, could you expand on how you mean here?

"Why this is important is that in quantum mechanics, you choose what you want to measure, and then essentially "write" your wave in terms of other waves that have well-defined values of that quantity and then your measurement picks one wave from among these.  It can only pick one answer, so it picks among them randomly (with some rules giving the probabilities of picking each particular answer)."
Quantum mechanics is all about measurements.  It gives you recipes to predict the probabilities of getting different measurements.  Let's say you have a wave function (like the step function I showed above), and you want to predict the probability of measuring a certain value X of some measurable quantity.  Your original wave function usually doesn't have an exact value of your measurable quantity: for example, the step function above doesn't have an exact value of sine-wave frequency since it's not a sine wave, but in quantum mechanics you can still make a measurement of sine-wave frequency and get a single answer.  So how do you make predictions about the answer that you get?

The rule for making that prediction is to write your wave function as a superposition of simpler waves, where each simpler wave has an exact value of the thing you're trying to measure, which is exactly what I did above by writing that step function in terms of sine waves.  Then the probability of making each measurement is the amplitude (in other words "how much") of that particular simpler wave.  So in the example above, the amplitude of the sine waves would correspond to the probability of measuring that sine-wave frequency in an experiment.

By the way, the collapse of the wave function just says that after you make the measurement, your original wave function becomes the one you measured.  So if I measured one particular sine wave, from that point on, my wave function would actually be that sine wave, and the step would have ceased to exist.

Quote
Hey, I know what it reminded me of now :) A analogue signal to digital, right? And that makes sense, it's 'cut outs' right? A way to treat the universe as 'quanta' so to get a 'over see able' system?

Or am I bicycling in the blue younder again?
I think that's a bit of a stretch, since it loses the idea that each simple wave has an exact value of something you're trying to measure.

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« Reply #26 on: 19/02/2010 10:24:00 »
By the way, I'm happy to go on about superpositions and quantum mechanics (I find this stuff really cool), but maybe we should start a new thread if you have more questions, since it's a bit off topic?

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« Reply #27 on: 19/02/2010 19:15:10 »
It's okay JP, i see your point there. Why we started it was when I asked about how to see those wave packets, and I think I've gotten a very good explanation to that :)

And that helps me see how the idea is mathematically. And yes, I agree, QM is really cool :) but (as you said) we might need to steer this back to electrons. So I'm still wondering if those orbitals transitions take time? And if there is a state where they are gone /'superimposed'/not defined? And if there is, shouldn't it be measurable?
===

Why I'm asking it is because I need to know :)

It's about how I should look at electrons in general. As entities or as probability functions (wavepackets). You can look at it this way too. When a electron is alone orbitaling the nucleus its energy is well defined as I understands it? But when together with other electrons their energies seems to become a function of them all? Very confusing :)

And then my question is, can we say that those 'jumps' take a measurable time inside our arrow? Or how should I look at it? As wave functions subtly changing depending on interactions but without any defineable 'transition times'. Don't know if this makes sense at all, but I'm interested in your views.
« Last Edit: 19/02/2010 19:58:16 by yor_on »
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« Reply #28 on: 19/02/2010 22:06:48 »
JP  you already appear to understand Fourier transforms so it is perfectly obvious to you that any wave that starts and stops CANNOT BE A SINGLE FREQUENCY so why are you worried about this?  A single photon cannot possibly be a pure sine wave of a single frequency because such a sine wave goes on (and has gone on)for ever with a constant amplitude and no one ever said it was.  The wave packet has its maximum energy at a particular frequency and tails off  at frequencies on either side of this according to its line width.  (this is a property of a spectrum line that can be predicted from quantum mechanics and measured to show that the prediction is accurate).  You are taking simple descriptions that are approximations used to describe things to scientists who are starting to learn and applying them absolutely.  As you and everyone else should realise.  EVERYTHING IN PHYSICS IS AN APPROXIMATION there are absolutely no absolutes.  These absolutes only exist in mathematics  which is NOT physics.

Nearly all the arguments in these pages are caused by people realising that all approximations fail under certain limiting  conditions and then either trying to apply them beyond their limits of suitability or finding alternative hypotheses to get round the "problem" suggesting that the main core of scientific opinion does not really know what it is talking about.
« Last Edit: 19/02/2010 22:22:10 by Soul Surfer »
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« Reply #29 on: 19/02/2010 22:59:04 »
No disrespect meant here Soul Surfer, but I hope you don't mean me now? I'm fully in agreement with your definition of approximations and the need for understanding why they exist, and as far as I know I'm not trying to go around anything? I just want to see them better, to do that I ask :)

And JP gave me a tool to understand your thoughts better here. I think that he too is aware of that it's only an approximation, but for me and as I guess, for some others :) his description gave me an idea of how they are thought to work.

As for a sine wave not having an end? It will have in its interaction, won't it? As a mathematical concept it won't as it is an idealization of a smooth repetitive oscillation, with the weight put upon 'repetitive'. But what you seem to say here is that a wavepackets then have limits, which they need if they ever will have a resemblance to what we call photons, but it's  mathematically I presume? In which way do those waves in wavepackets then differ from sine waves?

After reading your thoughts I went up to look some more on waves and superpositions . And there they had this definition of a wavepacket?

--Quote--

The regions of large wave amplitude are called wave packets. Wave packets will play a central role in what is to follow, so it is important that we acquire a good understanding of them. The wave packets produced by only two sine waves are not well separated along the x-axis. However, if we superimpose many waves, we can produce an isolated wave packet. For example, figure 1.9 shows the results of superimposing 20 sine waves with wavenumbers k = 0.4m, m = 1,2, \ldots , 20, where the amplitudes of the waves are largest for wavenumbers near k = 4.

--End of quote--

As I said Soul Surfer, I'm not trying to rewrite QM, just trying to see where the ideas stands today.
« Last Edit: 19/02/2010 23:01:05 by yor_on »
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« Reply #30 on: 19/02/2010 23:22:07 »
No I was referring to jPs  apparent insistence that photon wave packets only included a single frequency pure sinusoid.  Note they could contain a single frequency gaussian amplitude modulated sinusoid.  This would produce the normal line widths observed in spectrum lines.  This is probably the best way to imagine what the waveform of a photon is like.

My definition of a photon wave packet is a burst of energy of a specific frequency that starts small builds to a peak and falls away to zero over a specific time period longer than a single wave. This is not like a bell which starts with an impulse and then dies away.  mind you some of the more extreme pulse modulators nowadays can produce light waveforms that are just about a single wave.

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« Reply #31 on: 20/02/2010 01:08:29 »
Soul Surfer I got to admit that I fail to see what a 'single frequency gaussian amplitude modulated sinusoid.' might look like? Can you simplify your description somewhat so I might get an idea :)

If I look at a single photon I would say that it has an energy but no waves. and for it to get a wavelike property you will have to superimpose them in 'place' and possibly 'arrange' them so that they will differ in energy over times arrow?

And for a photon to exist you will need an interaction right? And then an EM field is needed, am I correct? And when you have an EM field and a atom interacting you can't really define it as only a single photon, or can you? Is there any way to guarantee that your wavepacket only will represent a discrete energy level?

(Hey, soon I will decide that there can be no single photons:)
==

As I understand it a photon has no magnetic field (it's zero) and without that how can there be any EM fluctuations? If I want one photon to be representative of waves, won't I need those fluctuations present in times arrow intrinsic to that photon?
==
Awh, this is really confusing. I'm trying to see how a photon can be seen as a wavepacket, and mathematically it seems to work, but only when choosing appropriate 'cutoff's'. Or am I loosing it again ::))
« Last Edit: 20/02/2010 01:48:23 by yor_on »
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« Reply #32 on: 20/02/2010 02:01:31 »
No I was referring to jPs  apparent insistence that photon wave packets only included a single frequency pure sinusoid.  Note they could contain a single frequency gaussian amplitude modulated sinusoid.  This would produce the normal line widths observed in spectrum lines.  This is probably the best way to imagine what the waveform of a photon is like.

Soul Surfer, I agree with you completely, but I think you've misinterpreted what I said.  A photon doesn't have a well-defined spatial representation by its nature, so it can't be a sinusoid.  However, it does have a precise frequency, which has to do with its energy, and is modeled as an excitation of a harmonic oscillator.  (If you've dealt with quantum harmonic oscillators, you know that the frequency of the oscillator isn't sinusoidal.)  You can check a textbook like Mandel and Wolf for details, and some of it is online here.

Is it worth starting a new post about the bandwidth of photons or the photon model?  I don't want to drag this any more off topic.  Soul Surfer, since you had the original question on photons and bandwidth, do you want to do so?
« Last Edit: 20/02/2010 02:15:10 by JP »

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« Reply #33 on: 20/02/2010 02:41:04 »
E = h nu?
But how? Is a relationship the same as saying that "as it exist it must be, at all times"?
Or does it speak about interactions, as that's where we draw those conclusions from as I see it. And from there my next question must become. Can we speak with surety of anything while it's not interacting?

Yeah, I know :)

sleep, right?
==

"higher frequencies mean shorter wavelengths"
So what is the energy of virtual photons in that motto?
Or their frequency?
==

So, if I accept that, photons must have a frequency, right?
And then I will have to state that a single photon oscillates too :)
And from there?

So from being a particle of no geometric size and with a EM field of zero, to a oscillating particle of an extremely short wavelength(?) being well defined in space; And also simultaneously defined to an extremely long(?) wavelength and therefore diffused geometrically. But now definitely of some defined placement in SpaceTime depending on frequency aka energy, even as a photon. My headache is now astronomical :)

And you're right JP, in a way, but it's difficult to discuss electrons without interactions in time :)
==

As if I assume that even if a photon of high energy would be better defined in SpaceTime it would still matter which way I was traveling, and what speed I had relative it, right? And the same goes for its energy. And it can do this without any magnetic field whatsoever. And it won't emit any radiation.
==

Sorry, saw that it wasn't that clear what I meant :)
Hope its reads better now
« Last Edit: 20/02/2010 06:16:45 by yor_on »
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« Reply #34 on: 20/02/2010 17:28:03 »
And there's one more thing that disturbs me. As I understands it we say that virtual photons are under Planck time right? And we use this phenomena for describing a lot of strange possibilities, like being able to get out from a Black Hole. Maybe I'm thinking wrong here but to me there are major differences between macroscopic SpaceTime and what we have under Planck time.

But reading about 'Rindler Observers' and the way their observations will differ from a observer being at rest with f.ex. Earth they , if i got it right, will see virtual particles as being real. That opens major questions for me. For one I can't help wondering about the arrow of time, if I assume that this phenomena now have passed some sort of threshold as it exists continuously in the observations by those Rindler observers? And what should  the definition of inside versus outside our arrow of time be. Why should 'virtual particles' become real particles due to a uniform acceleration. It's like SpaceTime exist on a sliding scale of 'reality'?

But I'm neither doubting photons as particles or as waves. When it comes to wavepackets I've tried to avoid them as I have enough troubles trying to understand photons as particles:) But as wave packets are able to predict a lot of behaviors they are working, right? But I'm still wondering what a photon is? and 'times arrow' too.

When it comes to wave packets I understands that your starting presumptions and definitions are of the utmost importance when it comes to the decide the outcome of a experiment?

--Quote--

Wave packet propagation is a useful technique for solving quantum mechanical problems over a wide range of applications. Since very few quantum mechanical problems can be solved exactly, each propagation technique can only provide an estimate to the actual solution. For a propagation algorithm to be useful it must be fast in addition to being accurate. With most algorithms a high accuracy can be reached by taking a small time step between propagation calculations. However, if the time step is too small too much time is needed to reach a final answer, so a balance between speed and accuracy is needed for each algorithm. In addition, the parameters of the energy spectrum I am interested in calculating must be taken into account, since the energy range of the spectrum determines the maximum time step that can be taken, and the energy resolution of the spectrum determines the length of time that the wave packet must be propagated.

The different propagation techniques I have studied include the Feit & Fleck split operator method, a time dependent modified Cayley method, a second-order differencing scheme, an iterative Lanczos reduction, and a Chebyshev polynomial expansion. Various coordinate systems have been used for the propagations, including normal coordinates, Jacobi coordinates and Radau coordinates. Finally, different methods for calculating the kinetic energy of the system have been explored, including FFT's and various finite-difference schemes.

When normal coordinates can be used, the Feit & Fleck split operator propagation technique, using FFT's to calculate the kinetic energy, is the most robust and fastest of the various combinations studied. However, normal coordinates do not preserve the symmetry of the OClO molecule and therefore cannot always be relied upon to produce accurate results. In such cases Radau coordinates must be used, and in order to reproduce the reflectional symmetry of the angle coordinate a finite-difference scheme must be used to find the kinetic energy, rather than an FFT. We use a 25-point finite difference method because we found it gave the best compromise between accuracy and speed. Since FFT's cannot be used with Radau coordinates the split operator propagation technique is no longer viable; a Chebyshev expansion is instead used to propagate the wave packet.

--End of Quote-- Wave packets

And perhaps?
Back to electrons:)
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« Reply #35 on: 20/02/2010 21:42:49 »
yor-on From your writings in the previous few replies (as opposed to your quotations) it is clear to me that your mental image of electromagnetic waves in general and photons in particular is extremely confused and inaccurate.  A lot of your quotations appear to be either from advanced texts or spoof garbage texts (there are a lot of fake pseudo scientific texts around on the web that look learned but are really just rubbish)  that are not relevant to the problems that you have with understanding. 

I would recommend that you read a good well established basic physics textbook on the topics and try to understand initially classical electromagnetic wave theory and then extend this to the most basic quantum theory.  To go back to square one and put it all in here is more work than I am prepared to do at the moment
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« Reply #36 on: 20/02/2010 22:02:56 »
Well Soul Surfer, your opinion is your own of course. But all together with the way you reacted towards JP I can't say I'm surprised :)

Be cool.
==
Btw: What's so apparently wrong in my comments?
Never said I understood wave packet theory?
I said I tried to stay away from it, more or less :)

As you imply, that may make me a 'fossil' not understanding anything about waves.
Sh* never said I did, you do then :)
Come on Soul Surfer, give your solution to us mortals.

We need it...
« Last Edit: 20/02/2010 22:08:54 by yor_on »
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« Reply #37 on: 20/02/2010 23:11:28 »
Well lets have a go.  You appear to make a lot of categorical statements about electromagnetic waves and quanta please forget all these and we will start from the beginning.

A varying electrical field in space causes an electrical current to flow as space itself is charged up to crate the field.  An electrical current creates a magnetic field.  A varying magnetic field creates an electrical field as the magnetic polarisation of space itself changes.  This is a property of space in the same way as mass and gravitation.  This as Maxwell realised creates the possibility of waves (like waves in the sea) where energy is propagated by moving between electrical energy and magnetic energy within space even when nothing else was present.

The velocity of these waves is determined by the electrical permittivity and the magnetic permeability of free space and is equal to the well known velocity of light.  the wavelength of the waves is defined as in all wave motions by the equation wavelength times frequency equals velocity.  The velocity of the waves is constant for all frequencies in free space.

Wavelengths and frequencies of electromagnetic radiation can vary over a vast range from kilometres as in long waves  through meters and centimetres for TV, phones and microwave cookers  to nanometers for light and very much shorter for X-rays and Gamma rays (ionising radiation).

An electron is a single negative electrical charge  a proton is a single positive electrical charge but much heavier than an electron.

Let us consider (in a purely classical physics sense) what might happen as a single electron approaches a single proton to form a hydrogen atom if the electron has some angular momentum it could go into orbit around the proton like the earth around the sun and let us ignore any motion of the proton around the common centre of gravity.  This could in theory be a stable situation except that the electron as it orbits would create a varying electrical and magnetic field in space and would lose energy by radiating electromagnetic waves and the proton and electron would quickly fuse together but this does not happen.  For certain very specific orbits the electron it is found by experiment that it is stable for quite a long time before it decays and at one particular state the ground state it is permanently stable in the absence of major disturbances.

When the electron moves between  two of the metastable states it radiates a pulse of electromagnetic waves.  this consists of a wave of a particular frequency that starts builds up over a few cycles and then decays taking a time that is related to that particular change.  This pulse of electromagnetic waves which is in effect usually much larger that the atom that originates it because of the wavelength and time it takes to radiate.

Please note again this is all totally classical physics and was in effect observed and accepted long before quantum theory was considered.

The metastable states are a bit like resonant cavities where the electron that is trying all the time to radiate its energy is in effect having energy fed back to it from the fields that it is creating in a continuous feedback loop.

Quantum mechanics just explains this classical process in a slightly different way and allows the energy levels to be calculated to a great degree of accuracy via quantum electrodynamics the most accurate physical theory that we have at the moment.

As an interesting aside let me add one other fact.   It can be observed that although electrons are particles they can also behave like waves and show interference patterns etc.  The wavelength of the waves depends on the momentum (mass times velocity) of the electron.  If one considered the metastable states of the electron and work out the "wavelengths" of the electrons as waves when they are in these orbits you find that the metastable states correspond to whole numbers of wavelengths of the electron that is the electrons are resonant structures then.  Again all this is classical physics and measurable without ant recourse to quantum theory for an isolated hydrogen atom.

Similarly all quantum processes have a solid bedrock in classical physics although once you get more electrons in an atom the calculations become incredibly complex.

Nowadays physics teaching tends to dive straight into quantum processes without fully explaining the classical physics background and this causes severe confusion in some peoples minds.

« Last Edit: 20/02/2010 23:23:28 by Soul Surfer »
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« Reply #38 on: 20/02/2010 23:56:18 »
Soul Surfer, let's call my expressions about photons and wavepackets as born out of frustration here :) And let me add that I'm glad you took it this way.

As for if a photon has a frequency in a mathematical sense bound to it's energy I know, actually I do even though i tend to forget it as i look at it. But what's interest me are those 'single ones' aka 'what the he* is a photon?' and those I think to be non-classical, and in that motto it, to me that is, becomes impossible to understand how they are thought to act as common waves in their single state?

I will read you and see how you think.
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Offline yor_on

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« Reply #39 on: 21/02/2010 03:14:46 »
Thanks for your lecture Soul Surfer. A nice view of a classical approach.
And single photons will in your eyes then be a bell formed (Gaussian)wave packet with its 'cutoff's' decided by what? And should I understand that as a classical approach too?

And your use of 'free space' I assume to include some sort of particles, not being a 'perfect vacuum' as it's normally defined in classical physics? Or do you mean that electromagnetism will propagate in a free space in the classical sense. That's one of my main questions in fact, as if we define that 'space' as containing nothing, and consider an EM wave as something obeying our macroscopic arrow of time (above Planck time/size) then, for this question, I will ignore 'virtual energy/particles'. As I believe that everything needs an interaction (medium if you like) to propagate, be it billiard balls or waves, that one is quite interesting to me?
==

I'm presuming that you are using 'free space' here in the meaning of how it relates to electromagnetic theory (Maxwell). In that idea 'virtual energy or particles' (quantum vacuum) have no place, as I understands it?
« Last Edit: 21/02/2010 03:33:58 by yor_on »
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« Reply #40 on: 21/02/2010 06:26:48 »
Yor_on, the photon picture doesn't have a classical wave model.  It's used because in certain cases, the classical wave theory breaks down.  The link between the two models is mathematically complex.  This is because they simply don't have a nice wave function that you can draw in space.  They have a very precise definition in terms of energy, but it turns out that you can't draw them in space.  A classical wave is a superposition of photons in a particular way, but that's incredibly hard to visualize without a grasp on the mathematics, simply because you can't write down what a photon's wave function looks like in space, whereas you can write a classical wave in space.  It can, however, be done.  (The link above to Mandel and Wolf is a good place to start, but you need to be ready for some heavy math and you want a working knowledge of quantum mechanics.) 

Photons are important because there are cases where knowing about energies is much more important than knowing about what it looks like in space, and there are cases where you can make approximations to get some idea of what they'd look like in space.  However, in most cases, you don't need the photon model.  Even though it should be right, treating most everyday problems in terms of photons is so incredibly complex that no one would want to do it.

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« Reply #41 on: 21/02/2010 10:11:01 »
when I say free space I mean a total vacuum with absolutely no other particles in it.  they only disturb the picture and are not required. a slight lack of perfection i.e. the odd particle does not have any significant effect.

As with an exponential decay the gaussian bell function goes off to infinity mathematically in both directions and is never zero.  physically it becomes to small to matter at a few standard deviations from the peak.   This is the big difference between mathematical things and physical things.

Some of your problems seem to be associated with mathematical absolutes.   in this sense every particle in the universe extends throughout the entire universe in all space and time
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« Reply #42 on: 21/02/2010 10:55:13 »
It suddenly struck me.  maybe you are thinking about what is sometimes called "the quantum mechanical vacuum"  which is a seething mass of virtual particles that only exist within the limits allowed by the uncertainty principle.  This is not what i am talking about because the details of that can never be known in any other way than the statistics of the uncertainty principle.  what I am talking about is the observable classical vacuum of standard physics.
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« Reply #43 on: 21/02/2010 12:39:22 »
But Farsight, you will need to be able to explain the properties of an electron going through a Stern-Gerlach magnet too for your proposal to become a theory, don't you agree? Or maybe you already have?
It isn't my proposal, yor_on. Williamson and van der Mark used to be at CERN. The former is a senior lecturer at Glasgow University, the latter is chief scientist at Philips. Qiu-Hong Hu is a researcher at the University of Gothenburg. Don't let ad-hominems like "crank" deter you. This really is leading edge stuff, see this week's New Scientist and the article on page 15 http://www.newscientist.com/article/dn18526-atom-smasher-shows-vacuum-of-space-in-a-twist.html. Here's an excerpt - it's not done to repeat the whole thing:

Quote
Atom smasher shows vacuum of space in a twist

Ephemeral vortices that form in the vacuum of space may have been spotted for the first time. They could help to explain how matter gets much of its mass.

Most of the mass of ordinary matter comes from nucleons – protons and neutrons. Each nucleon, in turn, is made of three quarks. But the quarks themselves account for only about 1 per cent of the mass of a nucleon. The remainder of the mass comes from the force that holds the quarks together. This force is mediated by particles called gluons.

A theory called quantum chromodynamics is used to calculate how quarks and gluons combine to give mass to nucleons, but exactly how this phenomenon works is not fully understood.

One possibility is that the fields created by gluons can twist, forming vortex-like structures in the all-pervasive vacuum of space, and when quarks loop through these vortices, they gain energy, making them heavier.

Now the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory (BNL) in Upton, New York, has seen signs of such vortices...
« Last Edit: 21/02/2010 12:42:13 by Farsight »

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« Reply #44 on: 21/02/2010 12:50:38 »
Farsight: in addition to the properties you have discussed, the electron model that you propose which dimensions would have? Does the model also predict the wavelike properties of the electron?
It's three-dimensional, lightarrow, like a bagel with a twist only there's no actual surface to it. I wouldn't say the model predicts the wavelike properties of the electron, because that's what we observe. Rather it explains them because it describes the electron as a double-wrapped electromagnetic wave going round and round in a circle.

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« Reply #45 on: 21/02/2010 20:31:41 »
JP you say that "A classical wave is a superposition of photons in a particular way" If I would guess :) then this math describing it is introducing some concept more than just 3D + time. It can't be enough with defining different vectors/tensors, can it?

No SoulSurfer I was thinking straightly 'classically' when I asked you about it, and that's why went some way to define what I meant too. It's easy to see that light somehow can' make it' through space, some of the solutions I've seen suggested is just that "the quantum mechanical vacuum" you thought of. Then you have other solutions too :) that somehow seems to expect both a sink (eye) and a source (sun) present for any 'wave' to exist, meaning that they won't do it until our two prerequisites are fulfilled.

The interesting thing to me is that in a classical sense a vacuum is a 'nothing'. Let's say that you compress it, well, try to compress it :) It will be extremely easy to do so on earth. In fact the energy spent will be to create it, not compress it. So what exactly are those waves propagating through? Is a vacuum a 'medium'? And how, if so, should I understand that 'medium'?

Okay Farsight, keep forgetting that :) So did you find an description of how they explain the properties of an electron going through a Stern-Gerlach magnet?
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« Reply #46 on: 22/02/2010 01:47:55 »
No, I didn't look for it. I know it anyway. That's easy.

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« Reply #47 on: 22/02/2010 02:02:22 »
This really is leading edge stuff, see this week's New Scientist and the article on page 15 http://www.newscientist.com/article/dn18526-atom-smasher-shows-vacuum-of-space-in-a-twist.html.
Why would you post this? This obviously has nothing to do with electrons?
It's three-dimensional, lightarrow, like a bagel with a twist only there's no actual surface to it. I wouldn't say the model predicts the wavelike properties of the electron, because that's what we observe. Rather it explains them because it describes the electron as a double-wrapped electromagnetic wave going round and round in a circle.
So how does this explain the wavelike properties?
No, I didn't look for it. I know it anyway. That's easy.
How can we take this answer seriously? If it's so easy, please demonstrate how your proposal produces the appropriate Stern-Gerlach magnet effects. It looks like you are merely trying to avoid answering the question, but surely that cannot be the case.

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Offline yor_on

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« Reply #48 on: 22/02/2010 02:49:26 »
I know we are getting of course now but I found this experiment when I was searching on experiments done with superimposing photons. Now, before someone tells me that this can't be done :) We have the idea and we use it to explain a lot of things, don't we? Which to me seems to imply that you can't used a 'flawed model' to build further proposals on, right?

The reason why it seems to be hard to do is HUP (Heisenberg's uncertainty principle) as I understands it. "You can't get photons that have perfectly defined position and trajectory. Photons with a perfectly defined trajectory must have an uncertainty in their wavevector direction of zero, which implies that the wavefunction of the photon is an infinite plane wave. Since the wavefunction is infinite in extent, the uncertainty in position is infinite. (by Claude Bile)" Remember that this answer is referring to when 'trying to superimpose photons', and not about superimposing waves.

In this experiment they say some, to me, remarkable things "The physicists allowed the photon to pass through the loop five times. They then found that one of the photons had fanned out into a chain of several wave packets which formed a superimposed state."

So they start with one photon, right? "They create this state by using a polarizer to first generate a photon oscillating in a horizontal or vertical direction. This is then moved to the superimposed state by means of a half-wave plate. The half-wave plate acts, to a certain extent, like the pin of a classical Galton board, except that it does not force the photon to adopt a specific direction but ensures that it figuratively continues to move in both directions." And here they seem to get a superimposition from only one photon. How is that done? Ah well it's the same principle as for creating a entanglement, right. But then we talk about waves, not 'photons'?

By the recirculating of those two 'new photons' superimposed, but going two different paths, one longer than the other, back to the half-wave plate (five times), they at last ends up with how many photons (wavepackets)? they must mean 32 like 2, 4, 8, 16, 32 or? Furthermore, after that first 'superimposition/split' they suddenly refer to them/it as wavepackets, why? Because they were treated as waves in the first 'split'? "They then found that one of the photons had fanned out into a chain of several wave packets which formed a superimposed state." 

'One of the photons'? Not wave packets suddenly but photons? And, one of what? They started with only one photon, superimposed it to ? wavepackets. Do they mean that one of those wavepackets now is treated as a singular photon, that in its turn make that chain they are referring too? Or are they still discussing our original photon, but now superimposed into several? And in the end they use a detector that only registers the photon as a particle, which then will give them, one photon again, right?

So it gives me a headache :)
They 'superimpose' a photon into several, which may be allowed according to HUP? From that they get several superimposed wavepackets but traveling different lengths in time, that then 'transforms' into a photon again, as I understands it?

Source.

If you have any understanding of how this is thought to be done, I'm very interested.
If you understands it that is. I know I don't.
==

And, can you really jump from calling it a photon to a wave, alternative wavepacket, like this?
==

Why I put a question mark after writing 'They 'superimpose' a photon into several, which may be allowed according to HUP?' Is because they call it a photon, not a wave.. to me those have different properties, and what you can observe and do with a wave you can't do with a 'photon', well, as I (still) see it :)

So yeah, I'm an old 'fogey', or 'stofil'  as we say in Swedish :)
==
One last question, how do they 'know' that 'they' take both paths experimentally?
Measuring it? Won't that collapse the 'photons' superposition/wavepackets?
« Last Edit: 22/02/2010 05:57:26 by yor_on »
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« Reply #49 on: 22/02/2010 05:51:50 »
Yor_on, you don't need quantum optics to explain what they did.  A classical version of the experiment could be done by using a pules of light, and splitting it into two parts.  One part takes a longer path than the other and they recombine later on before they hit a detector.  What you'd see is that part of the pulse arrives first while the part that took the longer path arrives later.  It sounds like that's essentially what they did, except they had it working with only one photon at a time so that you could either detect it early or late, rather than seeing both pulses every time.

They don't give a lot of mathematical details on what they're doing and assuming in this problem, so its hard to comment on the wave packet terminology.  You can describe wave packets in terms of non-space variables, which is one way to describe photons, or you can make approximations to based on the fact that it's in a fiber in order to write a spatial wave packet in this case. 

By the way, this site should be useful as an introduction to photons.  If you can understand the basics on that site, you should be a long way to understanding photons and how they relate to classical waves.
« Last Edit: 22/02/2010 05:56:27 by JP »