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Author Topic: What did Bohr actually state?  (Read 6709 times)

Offline ron123456

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What did Bohr actually state?
« on: 12/05/2015 20:32:30 »
Did Niels Bohr actually state that an electron could never ever exist ever between two energy levels at all, or did he really state that it could, but just momentarily? The latter would explain circular (all) light polarization with just using one atom as opposed to a multitude of atoms. Did the word "jump" actually emulate in time from the following statistical Schrodinger model? Perhaps the quantum jump functionally works only because of statistics?


 

Online jeffreyH

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Re: What did Bohr actually state?
« Reply #1 on: 12/05/2015 21:47:23 »
Did Niels Bohr actually state that an electron could never ever exist ever between two energy levels at all, or did he really state that it could, but just momentarily? The latter would explain circular (all) light polarization with just using one atom as opposed to a multitude of atoms. Did the word "jump" actually emulate in time from the following statistical Schrodinger model? Perhaps the quantum jump functionally works only because of statistics?

Everything ultimately boils down to statistics and uncertainty. The only particle that has a definite position and momentum is an unmeasured one. Only we don't know what it is because to measure it is to disturb it. The role of observer dependence in my opinion is an absurdity. If a particle hits a surface it needs no observer to affect the outcome. As for energy levels, they are discrete and quantized.
« Last Edit: 12/05/2015 21:49:50 by jeffreyH »
 

Offline Bill S

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Re: What did Bohr actually state?
« Reply #2 on: 12/05/2015 23:34:59 »
Quote from: Jeffrey
The role of observer dependence in my opinion is an absurdity.

Didn't someone of note say that "an observer is not just a man with binoculars"?  I think what he/she meant was that anything that reacted with something could count as an observer.  Thus, when a particle hits a surface, the surface "observes" the particle.
 

Offline Colin2B

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Re: What did Bohr actually state?
« Reply #3 on: 12/05/2015 23:45:15 »
... The latter would explain circular (all) light polarization with just using one atom as opposed to a multitude of atoms.
Could you explain your assumptions on this in a little more detail please. What does (all) mean?
My understanding is that circular polarisation is not a function of multiple atoms but the photon spin.
Would be interested in your views.
 

Online jeffreyH

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Re: What did Bohr actually state?
« Reply #4 on: 13/05/2015 00:35:43 »
Quote from: Jeffrey
The role of observer dependence in my opinion is an absurdity.

Didn't someone of note say that "an observer is not just a man with binoculars"?  I think what he/she meant was that anything that reacted with something could count as an observer.  Thus, when a particle hits a surface, the surface "observes" the particle.

I can see what you mean and yes in that sense you could state that. However the particle is disturbed by the interaction so the surface would be restricted in the properties it could observe. Motion without collision is determinate but this determinacy is unavailable to detection.
 

Online jeffreyH

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Re: What did Bohr actually state?
« Reply #5 on: 13/05/2015 00:40:20 »
Think of it this way. At extreme levels of uncertainty the wave nature of matter would be chaotic. You wouldn't have a wave to measure, only random fluctuations. All would be noise. This isn't the case This indicates an infinitesimally small uncertainty which could be ignored completely.
« Last Edit: 13/05/2015 00:41:58 by jeffreyH »
 

Offline Bill S

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Re: What did Bohr actually state?
« Reply #6 on: 13/05/2015 01:21:48 »
Quote from: Jeffrey
The only particle that has a definite position and momentum is an unmeasured one.

Does this mean you don't accept that the particle has no intrinsic properties before it is measured? 
 

Offline Colin2B

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Re: What did Bohr actually state?
« Reply #7 on: 13/05/2015 06:42:24 »
Quote from: Jeffrey
The only particle that has a definite position and momentum is an unmeasured one.

Does this mean you don't accept that the particle has no intrinsic properties before it is measured?
Jeffery, is this a typo? Surely we only know a definite position when it is captured/observed/measured.
 

Online jeffreyH

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Re: What did Bohr actually state?
« Reply #8 on: 13/05/2015 12:03:18 »
Quote from: Jeffrey
The only particle that has a definite position and momentum is an unmeasured one.

Does this mean you don't accept that the particle has no intrinsic properties before it is measured?
Jeffery, is this a typo? Surely we only know a definite position when it is captured/observed/measured.

Well if a surface can be thought of as an observer of sorts then so can the universe as a whole. From the perspective of a universal observer all paths are definite as are all momenta.
 

Offline chiralSPO

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Re: What did Bohr actually state?
« Reply #9 on: 13/05/2015 13:22:12 »
Well if a surface can be thought of as an observer of sorts then so can the universe as a whole. From the perspective of a universal observer all paths are definite as are all momenta.

I don't agree with your logic here. The surface is an "observer" due to interacting with the particle. Particles that are not interacting with the universe are not "observed" by the universe, and particles that are interacting are, well, interacting, so uncertainty is still in play. You cannot eat your cake and have it too. It might be possible that everything is purely deterministic, but as far as what we can observe, a probabilistic interpretation fits better, and discussions of what we cannot observe is no longer really physics.

Also, any reference to a "universal observer" is likely to draw fire from students of relativity or QM...
 

Offline Colin2B

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Re: What did Bohr actually state?
« Reply #10 on: 13/05/2015 14:43:36 »
The surface is an "observer" due to interacting with the particle. Particles that are not interacting with the universe are not "observed" by the universe, and particles that are interacting are, well, interacting, so uncertainty is still in play.
I agree. I have a very simplistic way of looking at this. Imagine enemy aircraft coming our way at night. They could be anywhere but probability says they will cluster around military targets etc. we can look for them with antiaircraft missiles and barrage balloons and when we hit one we will know its position exactly, until then we cannot say it has a position. We do however, have some nondestructive techniques like radar. Photon are similar in that detecting them destroys them, we have no radar equivalent. Closest anyone has got is firing single photons parallel to a wire and looking at the effect of the E field on the electrons in the wire.
 

Online jeffreyH

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Re: What did Bohr actually state?
« Reply #11 on: 13/05/2015 21:16:35 »
I take all your points on board.
 

Offline ron123456

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Re: What did Bohr actually state?
« Reply #12 on: 14/05/2015 18:22:37 »
Is it ever possible to forget about Heisenburg?....Colin2B had an initial interesting question....Is circular light polarization a function of one or a multitude of atoms?
« Last Edit: 14/05/2015 19:56:12 by ron123456 »
 

Offline PmbPhy

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Re: What did Bohr actually state?
« Reply #13 on: 14/05/2015 23:49:09 »
Quote from: ron123456
Did Niels Bohr actually state that an electron could never ever exist ever between two energy levels at all, or did he really state that it could, but just momentarily?
You're referring to the Rutherford-Bohr model of the atom (aka the Bohr model). Accepting the nuclear model of the atom in 1911 Bohr forced a connection between the relation E = hf for photons and the Newtonian picture of electrons in orbits around the nucleus. Bohr's two postulate's were

1. An atom has a number of "stationary states."
2. When an atom changes from one stationary state to another, corresponding to a change in orbit  of one of the electrons (i.e. a "quantum jump"), it emits a photon.

The energy of the photon must equal the difference between the stationary states. I.e.

Ephoton = Ei - Ef = hf

So you see, it's not the electron that has only specific values but the atom, i.e. proton/electron system.
 

Offline ron123456

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Re: What did Bohr actually state?
« Reply #14 on: 15/05/2015 13:58:58 »
Is the photon simply not just an electromagnetic pulse with the pulse actually being the particle? From a particle view, the spin of a photon could explain circular polarization, but from the view of an electromagnetic pulse, the quantum jump could only act like an antenna providing linear polarization. The only way to get circular polarization occurring in nature from a wave standpoint and without using indexes of refraction after the fact, would be for the electron to momentarily spiral down via progressively smaller orbits to the lower energy level thus providing a circular polarization of the electric field around the nucleus (half wave dipole antenna) along one axis and linear along another axis. Frequency would be hypothesized to be fixed during the transition. That is my confusion on what Bohr actually stated? This is probably totally incorrect? Maybe the spin of a photon particle occurs for some other reason thus providing the circular polarization? Yes, I am using the old Bohr model as opposed to the Schrodinger wave probability model.
« Last Edit: 18/05/2015 12:43:48 by ron123456 »
 

Offline Colin2B

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Re: What did Bohr actually state?
« Reply #15 on: 15/05/2015 14:44:34 »
. The only way to get circular polarization from a wave standpoint, would be for the electron to momentarily spiral down to the lower energy level  thus provide a circular polarization of the electric field around the nucleus (half wave dipole antenna)
No, you are thinking radio antenna, this is different. The electron doesn't have to spiral at all. It has to do with phase relationship between the electric and magnetic fields. The natural state of a photon is circular polarisation L and R hand (spin1 or -1, no 0 state has been detected). In normal light they come in 50:50 and it's the superposition of the 2 that gives linear polarisation. The radio antenna produces the same in the near field and it is only in the far field that you get linear polarisation when the waves starts to form plane waves.
« Last Edit: 15/05/2015 14:55:58 by Colin2B »
 

Offline PmbPhy

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Re: What did Bohr actually state?
« Reply #16 on: 15/05/2015 16:21:06 »
Quote from: ron123456
Is the photon simply not just an electromagnetic pulse with the pulse actually being the particle?
No. It has properties of being a particle. A collection of photons has the property of being an electromagnetic wave.
 

Offline Phaedrus

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Re: What did Bohr actually state?
« Reply #17 on: 16/05/2015 17:25:13 »
. The only way to get circular polarization from a wave standpoint, would be for the electron to momentarily spiral down to the lower energy level  thus provide a circular polarization of the electric field around the nucleus (half wave dipole antenna)
No, you are thinking radio antenna, this is different. The electron doesn't have to spiral at all. It has to do with phase relationship between the electric and magnetic fields. The natural state of a photon is circular polarisation L and R hand (spin1 or -1, no 0 state has been detected). In normal light they come in 50:50 and it's the superposition of the 2 that gives linear polarisation. The radio antenna produces the same in the near field and it is only in the far field that you get linear polarisation when the waves starts to form plane waves.

Is spin an actual observed property of the photon or is it kind of a mathematical abstraction?
 

Offline ron123456

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Re: What did Bohr actually state?
« Reply #18 on: 16/05/2015 18:29:46 »
Is it possible that the momentum of an EM wave pulse could possibly just be emulating the physical properties of a particle?
« Last Edit: 17/05/2015 05:12:24 by ron123456 »
 

Offline PmbPhy

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Re: What did Bohr actually state?
« Reply #19 on: 16/05/2015 18:52:40 »
Quote from: Phaedrus
Is spin an actual observed property of the photon ...
Yes. It's part of total angular momentum. For a single particle the total angular momentum is spin,
 

Offline ron123456

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Re: What did Bohr actually state?
« Reply #20 on: 19/05/2015 15:11:53 »
Thank you for clarifying how circular polarization works. It is so much easier realizing that Ey vector component of field vector E is a quarter wavelength behind Ez vector component of E due to different speeds (different indexes of refraction along different axis) leading to circular polarization. But like always, I still have an understanding problem. How did the quantum jump generate the original EM sine wave pulse to provide an alternating electric field vector if the electron is just going down to a lower level and not back up?
 

Offline PmbPhy

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Re: What did Bohr actually state?
« Reply #21 on: 19/05/2015 16:39:59 »
Quote from: ron123456
Thank you for clarifying how circular polarization works.
From the content of this post it's not clear to me that you understand circular polarization at all. Where did you get the idea that this is how it works?

Quote from: ron123456
It is so much easier realizing that Ey vector component of field vector E is a quarter wavelength behind Ez vector component of E due to different speeds (different indexes of refraction along different axis) leading to circular polarization.
The problem that you're having is that you're mixing two theories; classical electrodynamics and quantum electrodynamics. You can't confuse the two. And you certainly can't think of a photon as possessing an electric or magnetic field. If you really want to understand photon polarization then you should study these pages;

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

http://en.wikipedia.org/wiki/Photon_polarization#Photons:_The_connection_to_quantum_mechanics

If you have any questions then please feel free to ask. It's expected that you'll have questions so please don't feel shy about asking them. Nobody knows everything, that's for certain. :)

You shouldn't think of photons as being sinusoidal waves or any kind of "sine pulse." A photon does not have an alternating electric field vector. Recall that you asked
Quote from: ron123456
Is the photon simply not just an electromagnetic pulse with the pulse actually being the particle?
to which I responded, No.
 

Offline ron123456

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Re: What did Bohr actually state?
« Reply #22 on: 20/05/2015 17:16:33 »
Thank you PmbPhy for being considerate to answer essentially each sentence ...It was rude of me to start this at this date.....I'll be in the woods for the next three months....I scanned the sites and cannot get back until the Fall...Thx again
 

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Re: What did Bohr actually state?
« Reply #22 on: 20/05/2015 17:16:33 »

 

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