Can Quanta Change Color?

[El Hombre Invisible]

Take an individual photon particle from the CMB. Given we know it started off very Blue with a high energy (In wave talk, that means high frequency). Now that it has reached us, it is very Red, down into the microwave frequency band, better stated as a particle with lower energy. Still moving at the same speed of c, we might even say the particle has a lower ‘apparent mass’ based on E=mcc.

This really does seem to be the part you're stumbling over. The photon being emitted from whatever distant galaxy it came from has the exact same photon energy we measure it as in our frame of reference. Viewing it from one frame of reference alone, the photon does not 'change colour' between emission and absorption. The change is due to change of reference frames alone. We look at stars of a similar size closer to us and measure 'bluer' light, and know then that the light from the more distant star has been red-shifted. But the frame in which the closer star is at rest (in which we could accurately measure the energy of the emitted photon) is NOT the same frame as that in which the more distant star is at rest.
It is due to this change of reference frame that the photon energies appear to change. In reality, in our reference frame (i.e. the one in which we are at rest), the photons emitted from stars AT ANY DISTANCE have the same energy that we measure them at. A microwave photon detected by us in a given frame coming from a distant galaxy was emitted as a microwave photon in that frame. It does not change.

 

[RandallB]

Doppler shift it. When you do that and remeasure ... in the hamiltonian, it isn't the same ... NOTHING to do with "photon stretching", etc. A photon isn't defined by its size ...

You can dress it up with all the math you want, but to "Doppler Shift" any part of a “particle“, stretching & changing the energy, then you are selectively treating that part of it like a wave. Just because you define the rules to say you can not stretch a point particle and then mathematically go ahead and stretch it anyway does not give you the right to claim a particle view only analysis of the event.

In my opinion a complete particle view only explanation has yet to be done here, no more than it has been done for Young’s double slit without inserting the uncertainty principle to stand in for not using waves.

RB

 

[ZapperZ]

You can dress it up with all the math you want, but to "Doppler Shift" any part of a “particle“, stretching & changing the energy, then you are selectively treating that part of it like a wave. Just because you define the rules to say you can not stretch a point particle and then mathematically go ahead and stretch it anyway does not give you the right to claim a particle view only analysis of the event.

In my opinion a complete particle view only explanation has yet to be done here, no more than it has been done for Young’s double slit without inserting the uncertainty principle to stand in for not using waves.

RB

I'm not dressing it up with the math, because the WHOLE thing started with the hamiltonian in the first place! So how can you dismiss it as being nothing but mathematical dressing? The energy level of an atom IS an agreement between the hamiltonian and the experimental observation. If not, you know NOTHING about the kind of atom that is emitting so-and-so spectra.

It is also definitely a lot more valid to deal with rather than a "handwaving" argument of "stretching" that is not based on ANY physics. Can you give an exact citation where such a thing has been described and formulated?

Furthermore, I was explaining why you were "bastardizing" what I mentioned earlier. It had nothing to do with what you had in mind. It certainly does not contain any "stretching" effects of any photons, thank you. If you wish to do such a thing, you cannot piggyback onto what I have described. You will have to make things up on your own.

Zz.

 

[Miserable]

Substitute the words "Doppler shift" for "Lorentz transform". You can now use all the above arguments without ever needing to refer to a wave.

 

[RandallB]

Guys, I’m not the one stretching anything,
But using “Doppler Shift” or "Lorentz transform" on a point particle IS.
I’m not saying you don’t get accurate answers or good predictions. Just that is not a clean and complete purely particle view.
If you don’t see that, then your not seeing the forest for all the trees in the way.

RB

 

[ZapperZ]

Guys, I’m not the one stretching anything,
But using “Doppler Shift” or "Lorentz transform" on a point particle IS.

Can you derive on here how a Lorentz transformed photon is stretched, especially when the dimension of a photon at a particular frequency is undefined?

Zz.

 

[RandallB]

Can you derive on here how a Lorentz transformed photon is stretched, especially when the dimension of a photon at a particular frequency is undefined?Zz.

?
I’m the one saying a particle should not be “stretched” at all! Your the one using (Doppler, Lorentz, Hamiltonian) whatever in a non-particle way to do just that (post #19). So of course I cannot explain it – the point is no one can.

I much prefer the particle view myself, and in the long run that it has the best shot at giving us a better understanding of physics. But we will never improve the use of the particle view if we don’t recognize where it is incomplete.

RB

 

[ZapperZ]

?
I’m the one saying a particle should not be “stretched” at all! Your the one using (Doppler, Lorentz, Hamiltonian) whatever in a non-particle way to do just that (post #19). So of course I cannot explain it – the point is no one can.

Read again. I said if you view an atom that is dopper-shifted, the potential that you have to put in for the Hamiltonian is NOT the same spherical potential that one solve normally. It is BASED on this that one gets a different energy state that would produce a transition corresponding to the photons being observed. At no point did I infer any "stretching" of any kind. You did!

Best explanation I saw was Zapper Z: “.. doppler shift the whole atom(photon), and THEN, recalculate the apparent energy”
Two ways to do this:
Conceptually just, stretch out the size of the individual photon particle (vs. atom) like the wave ring from dropping a stone in a smooth pool of water.
OR, use the doppler frequency change ratio figured from a wave view and just jam it into a formula to refigure and adjust the individual photon energy change over time or distance.

I never invoked any stretching, either conceptually or mathematically. You did. You were the one who equate a Lorentz transformation/Doppler shift to "stretching".

Zz.

 

[RandallB]

And as I said in my post that you did not include in quoting me
"but still a wave view for both"
I’ll go with your definition, stretching and Doppler shift are different things and you way define how.
But both are wave based and not particle views.
That was the point.
If they were you would be able to draw for me what photon looks like at different energies, no one can.
RB

 

[El Hombre Invisible]

But we will never improve the use of the particle view if we don’t recognize where it is incomplete.

I really don't get what you think is incomplete. As far as I can tell, you've taken the wave model of light and a property (the Doppler effect), then tried to apply it to the particle model, when in fact the same phenomenon in the particle model is described by another mechanism (relativity). Whichever model you want to use, you have a description of the phemonenon you wish to describe. But you can't take unobservable aspects unique to one of them and try to seek an explanation for them in the other - they are different models. Trying to fit a square peg into a round hole does not constitute a paradox.

 

[ZapperZ]

And as I said in my post that you did not include in quoting me
"but still a wave view for both"
I’ll go with your definition, stretching and Doppler shift are different things and you way define how.
But both are wave based and not particle views.
That was the point.
If they were you would be able to draw for me what photon looks like at different energies, no one can.
RB

Eh?

When I dopper-shift an atom, where exactly does the "wave picture" comes in?

Zz.

 

[Hans de Vries]

RandallB,

We were discussing Cosmological Redshift here, which is not caused
by the doppler effect in modern interpretations and has nothing to do with
Special Relativity or the Lorentz transformation.


There are three totally different reasons why photons get redshifted:

1) Doppler Redshift, caused by a moving object. emitting light
2) Gravitational RedShift, from the escape out of a gravitational field.
3) Cosmological Redshift, (Hubble) caused by the expansion of space.



The paradox you were mentioning (what happens with the energy) does not
exist in Doppler redshift, so I suppose you want to discuss the Cosmological
redshift according to Hubble's law.

There is quite some difference between the Doppler and Cosmological
redshift. If the Hubble effect was the result of the doppler effect then the
Cosmic Background Radiation would not continue to get lower and lower in
frequency.

I found this old thread from Marcus:

https://www.physicsforums.com/showthread.php?t=2825&goto=nextnewest

A few other useful links:
http://curious.astro.cornell.edu/question.php?number=278
http://www.astro.ucla.edu/~wright/cosmology_faq.html#FTL

Regards, Hans

 

[RandallB]

RandallB,
We were discussing Cosmological Redshift here,

That OK, if this thread has changed that's fine we can leave it on red shift
All I'd done is addressed the orig line of questions El H and Adrin had on how to understand a particle "changing color" that all. And why they would find no simple answer, because it is a PARADOX.

I'm guessing it will stay a paradox till the Wave / Particle duality paradox is resolved. Thats all.

Other that using assumtions made from a wave view doing a doppler shift of an "atom" or a photon just cannot be done or diagramed.

So continue with the Cosmological Redshift discussion.
I'll make a prediction there on the expansion of space, I think time we will find if it is there at all the Hubble constant is actually very small, less than 5.
Yes, I understand most disagree, so only Time will tell.

RB

 

[RandallB]

you can't take unobservable aspects unique to one of them and try to seek an explanation for them in the other - they are different models.

Correct, that's why you shouldn't accept using doppler shift as an acceptable solution if you want to stay only in the particle view.

 

[ZapperZ]

I'm guessing it will stay a paradox till the Wave / Particle duality paradox is resolved. Thats all.

I am sure that, having done QM rigoriously, you would have noticed that in QM, there is no such thing as a "wave/particle duality". There is only ONE description of light (and electron, and proton, and neutron, etc) in QM, not two different ones for particle and for wave.

Thus, where is the "paradox" when there is no "duality"?

Zz.

 

[RandallB]

Zz
You can not be saying you’ve never heard of duality.
So it’s just within QM that we cannot have duality?
Maybe by QM’s definition of it’s self, that it doesn’t use “wave” functions. But the results coming out of QM using Cosine Squared or Sin Squared -- that tells me the wave function is just hidden from view in there. Which is part of why what happens to an individual particle is so hard to describe completely. And using “Doppler Shift” is just a part of getting wave results out of QM.

So for me, I like the view from Quantum Physics as larger than just QM, that can recognize a paradox when looking at Quantum Mechanics. But I can understand how the view from within QM with only the QM rules etc. to go by or “QM trees” can block the view of the “Forest” of the full view of Quantum Physics. And a paradox is not seen and maybe doesn’t matter from inside QM. I just like the view of the whole forest rather than only the trees of QM.

If my view starts to produce better results I’ll let you know.

RB

 

[selfAdjoint]

the results coming out of QM using Cosine Squared or Sin Squared -- that tells me the wave function is just hidden from view in there.

The "duality" is not a property of the particle, but of the observation, The state of the particle is represented by a ray in some vector space over the complex field, Because QM is unitary, and since conservation of probability implies the observable operators have determinant +1, the group of L.T's generated by the observables is some extension of U(1), so complex functions like e^{i\phi t} come into play. You CAN interpret these functions as defining a wave - that's how Schroedinger started out - but you don't HAVE to. You can just take them to be complex functions. They are only connected to events in spacetime by the Born rule. Mystique of waves does not really seem appropriate.

 

[ZapperZ]

Zz
You can not be saying you’ve never heard of duality.
So it’s just within QM that we cannot have duality?

You shouldn't be asking this IF you have done any formal work in QM.

The "duality" that most people have used is because the CLASSICAL IDEA of "wave" and "particle" are two different things. We have no such thing in QM. We have been taught by our classical observation that there is a "wave" property, and there is a "particle" property, and they are incompatible with each other.

ALL of the wavelike and particlelike property can be described by QM with just ONE single formulation. PERIOD!

Don't take my word for it. Look for yourself.

Zz.

 

[RandallB]

... so complex functions like e^{i\phi t} come into play. You CAN interpret these functions as defining a wave - that's how Schroedinger started out - but you don't HAVE to. You can just take them to be complex functions. They are only connected to events in spacetime by the Born rule.

And yet we come down to needing to modify a point particle, a photon and as Zz put it:
“A photon isn't defined by its size, and certainly was NEVER defined by its longitudinal size.”
But one of the things that describes the photon is it's Energy that has changed. Describing that change or the energy in a point particle with nothing to reduce, stretch, or Doppler Shift is not simple. Even if in QM I can work out the change in energy using, complex functions connected in space-time by the Born rule, the change in the point particle comes with no real description how the photon should look different.

I know this leaves me back in the dark ages with Einstein, accepting Quantum Physics as an approach, but not able to accept or “spooked by” Quantum Mechanics.

I could even bail myself out and just use “String Theory” and define the photon as in our three dimensions as a point particle, but allowed to be or at least move about in one or more extra dimensions in a manner to account for the Energy. There allowance for reducing the size, shape, and/or timing of that part of the photon to account for holding, reducing, stretching, or Doppler shifting the energy and it’s changes can be described. This is likely at least part of what the string idea is trying to accomplish, but it strikes me as a bit too contrived for the convenient results.

So that leaves me stuck at the same place Einstein was, wondering about a undefined variable - – all I can do is work on it.

RB

 

[ZapperZ]

And yet we come down to needing to modify a point particle, a photon and as Zz put it:
“A photon isn't defined by its size, and certainly was NEVER defined by its longitudinal size.”
But one of the things that describes the photon is it's Energy that has changed. Describing that change or the energy in a point particle with nothing to reduce, stretch, or Doppler Shift is not simple. Even if in QM I can work out the change in energy using, complex functions connected in space-time by the Born rule, the change in the point particle comes with no real description how the photon should look different.

I know this leaves me back in the dark ages with Einstein, accepting Quantum Physics as an approach, but not able to accept or “spooked by” Quantum Mechanics.

May I suggest you go to a library, and read Ref. [1] and [2], unless you prefer to be stuck in the dark ages.

Zz.

[1] D. Benredjem et al. J. Phys. B: At. Mol. Opt. Phys. v.34, p.1369 (2001).
[2] L. Parker, Phys. Rev. Lett v. 44, p.1599 (1980).

 

[RandallB]

May I suggest you go to a library, and read Ref. [1] and [2], unless you prefer to be stuck in the dark ages.

[1] D. Benredjem et al. J. Phys. B: At. Mol. Opt. Phys. v.34, p.1369 (2001).
[2] L. Parker, Phys. Rev. Lett v. 44, p.1599 (1980).

Unfortunately the Libraries I have access to only have online access to the past 12 months of those Pubs.
I’m sure the details on “Doppler Shift and Freq. redistribution …” must do a good QM job of explaining the changes in photons without “incorrectly” referring to stretching of photons as some physicists sometimes do. Notably as astrophysicists Lineweaver and Davis of Mount Stromlo in Australia did in Scientific American March 2005. In their sidebar on page 41 where the correctly refute “Tired Light”.

Although they are not commenting on QM. I accept the result of “individual photons get stretched (thereby losing energy)” as the best description we have, AND a paradox, until a more complete description than QM, can be found. In my opinion it's only from inside QM that this can be seen as not a paradox.

So in that search for a more complete or even correct description of Physics, I simply choose work from the view of those “Dark Ages”. As in the Opinion by Lee Smolin “Why No New ‘Einstein’?” Physics Today June 2005 p56; we need a few more people outside the box questioning the foundation of QM, which I do. I believe a new approach with the objective of combining Quantum and Classical Physics without the uncertainty of QM has the best chance of solving the Paradox’s. Although just making up some “Meta-Physics” seems to be an easy and rather popular thing for many to do these days. I’d rather see a scientifically testable well thought out solution to the issue. Proving to be a bit of a challenge I admit. Still, I’m betting on me and I feel good about my chances and my approach.

RB

 

[El Hombre Invisible]

Well, I'm sure we all look forward to toasting your success.