What Is the Wave-Particle Duality of Photons in Quantum Mechanics?

[KKHausman]

I have seen a number of discussions and articles regarding the seeming disparity between the behavior of photons through the traditional "two slit" experiment. As I understand this issue, quanta of light will interact in a reinforcing/cancelling wave interference pattern until the apparatus is configured to allow determination of the path taken by the photon. Even when this capability is not used to determine which path has been taken, the quanta now scatter in a particle-like manner.

I have read a number of critical examinations of the variance between these two behaviors, identifying the problem of a photon's ability to follow both paths when no determinism of path is possible while each will follow a single path when the potential is present - even when the photon will not encounter the apparatus allowing this determination until well after passing through the mechanism allowing the photon to pass along one or both paths.

If my understanding to this point is correct, I would offer an observation for consideration: It would seem that a photon, traveling at C, would experience no subjective temporal duration between emission and absorption (based on the relativistic effects on time passage). If this is the case, then both behaviors fit the statement that "a photon will follow all available paths as they will exist between emission and absorption".

Within this model, if no mechanism is present for determination of a photon's path between its emission and absorption, the photon can travel along all possible paths and so generate the interference pattern suitable to a wave. The presence of a mechanism for determination at any point between emission and absorption would then cause the photon to travel along a determinable path, and so generate the observed scattering instead.

It would seem that a photon's period of travel between emission and absorption is more an artifact of our own observational position rather than a state that would apply to the photon's own "subjective" temporal duration (this term is not used to suggest the photon has a cognitive faculty). Unless I have missed something, emission, transit and emission should occur as a singular event without temporal duration existing for the photon.

I would welcome any comments in this regard. Thank you all for your time.

K. Hausman

 

[jdlech]

As I understand it, the photon will never experience time as anything more than a single point. Therefore, time will not exist for the photon. Meanwhile, it will occupy all space from point of origin to point of absorption.

We observers, on the other hand, should see the photon travel at C until it is absorbed. Theoretically, we should never see a photon decay.

What I keep thinking is there should be an antithetical frame of reference to the subjective one. There should be one that sees the electron stay put and occupy all of time.

That should put us objective observers somewhere inbetween the two.

 

[Art]

a question

"As I understand this issue, quanta of light will interact in a reinforcing/cancelling wave interference pattern until the apparatus is configured to allow determination of the path taken by the photon. Even when this capability is not used to determine which path has been taken, the quanta now scatter in a particle-like manner."

How does the photon know what equipment is sufficient to allow it's detection? ie. if one simply eyeballs the experiment we know that would be insufficient to detect it's path whereas a cloud chamber would (I think??) but how does the photon 'know' what equipment is adequate and so 'know' if it should collapse it's wave function?
Art

 

[selfAdjoint]

"As I understand this issue, quanta of light will interact in a reinforcing/cancelling wave interference pattern until the apparatus is configured to allow determination of the path taken by the photon. Even when this capability is not used to determine which path has been taken, the quanta now scatter in a particle-like manner."

How does the photon know what equipment is sufficient to allow it's detection? ie. if one simply eyeballs the experiment we know that would be insufficient to detect it's path whereas a cloud chamber would (I think??) but how does the photon 'know' what equipment is adequate and so 'know' if it should collapse it's wave function?
Art

How does any wave know how to do that? Look at the Huygens construction of double slit interference. Each slit becomes a secondary emitter of waves and their emitted waves subsequently interfere.

 

[MonstersFromTheId]

Can the "twin slit" exper b done at home?

I can see where the answer would be "Of course! Send me a check for a hundred and seventy kay and I'll send you the kit. You'll still need to build a specially isolated room in the basement to use it, but IF YOU ORDER BEFORE MIDNIGHT TONIGHT! We'll include, FOR FREE, a list of qualified contractors in your area to do the work!"

So, assuming I'm NOT Bill Gates, could this experiment be done at home? (Without the risk of my dog losing all her hair and becoming a glow in the dark night light. My significant other would be upset by that. Girls can be such... girls! Hand me that cake pan! This is for SCIENCE dammit SCIENCE!)

 

[selfAdjoint]

The twin slot - actually twin pinhole - experiment for light can be done at home. It invoves a small laser and some tinfoil, and was described in a recent thread somewhenre on these boards. Sorry I can't remembr where; try googling on double slit home.

For electrons it's MUCH harder, and you'ld have to be pretty damn expert to do it. And spend a good chunk of dough.

 

[KKHausman]

"How does the photon know what equipment is sufficient to allow it's detection? ie. if one simply eyeballs the experiment we know that would be insufficient to detect it's path whereas a cloud chamber would (I think??) but how does the photon 'know' what equipment is adequate and so 'know' if it should collapse it's wave function?
Art

My question was in no way meant to ascribe cognitive qualities to the elementary particle or photon involved. In order for definitive transit to be identifiable, some type of state or quality would have to be filtered out or imparted along the path. It is this mechanism, of whatever type, to which I was referring.

K Hausman

 

[KKHausman]

As I understand it, the photon will never experience time as anything more than a single point. Therefore, time will not exist for the photon. Meanwhile, it will occupy all space from point of origin to point of absorption.

We observers, on the other hand, should see the photon travel at C until it is absorbed. Theoretically, we should never see a photon decay.

That follows the thinking which spawned this line of inquiry. If a photon's existence (emission->transit->absorption) exists as a singular event (from the reference frame of the photon), then the options of future and past paths would be more an artifact of observation from the external frame of reference we biological observers inhabit.

An offshoot of this line of reasoning was that the tendency of photons to travel the same velocity within a vacuum regardless of level of energy would seem to support the possibility that we are within a reference frame having a temporal velocity of 1 sec/sec. In this thought experiment, the propagative rate of a photon could be said to result from an expression of its singular existence (emission through absorption) as our own framework "passes along its length."

I look forward to your responses to this line of reasoning.

K Hausman

 

[Art]

My question was in no way meant to ascribe cognitive qualities to the elementary particle or photon involved. In order for definitive transit to be identifiable, some type of state or quality would have to be filtered out or imparted along the path. It is this mechanism, of whatever type, to which I was referring.

K Hausman

I wasn't suggesting that you were suggesting that elementary particles have cognitive abilities. I agree with your proposal that past, present and future are all one and the same for the elemental particle and so I was toying with this hazy idea that in some way the apparatus could be configured to allow predictions of future world events.