Bernardo ~

 Quantum theory deals with “observations”. An observation is an interaction. During the period between two observations there is a probability wave, which is unobserved and in principle unobserveable. A “photon” is a phenomenon associated with an observation; when light interacts with “matter” energy is exchanged in discrete units E = hν. We interpret that by saying that an electron in the matter has absorbed or emitted a “photon”.

 However, it seems to me that the idea of an unobserved photon traveling as a discrete individual “particle” is not correct and leads to paradoxes.

 In a diffraction experiment (Young's slits) in which a pulse of light with energy E = hν is emitted and strikes a screen, we have two observations which we can describe as the emission of a photon and the later absorption of a photon. It is tempting to interpret that as a single photon − “the same” photon − that has traveled from the emission event to the absorption event. This leads to the meaningless puzzle about which slit the “photon” traveled through. What has traveled is not a “particle” but an electromagnetic wave that carries information about the various probabilities about where an absorption event is likely to take place. There is no observation between emission and absorption. Even if the experiment takes place in a medium, so that we know that there are interactions between the light and the medium as the light is traveling, and quantum theory can in principle take that into account probabilistically, none of this is observed. It seems to me that the idea of an unobserved photon traveling as an individual “particle” is not correct.

 Consider the Doppler effect. Light emitted at frequency ν is absorbed at a different frequency ν′. It is tempting to speak of “photons gaining or losing energy” while they are traveling. Many physicists do speak like that − as if photons were individually distinguishable particles when they are traveling unobserved. I feel that this is a very misleading way of thinking.

 Incidentally, I have trouble understanding what you mean when you say that “…the assumption of photon individuality could have misled the MM experiments…” (?) − the Michelson-Morley experiment was many years before quantum theory introduced the photon concept.

Dear Mohamed:

There are two aspects to my question:

1.       Is it true that photon experiments assume photon individuality? And if so, has individuality been proven? Or can it be proven?

2.       If light does not require a medium to travel (it only requires an electromagnetic field), then the usual conclusions can be accepted, but if a light beam is a sequence of interactions (a discrete-event path) then are the same conclusions acceptable?

For example, the MM experiment tried to prove that light traveled through a stationary medium (the vacuum/aether) and its results were interpreted to mean that such medium was not required (or non-existent).  But, that is because they assumed the light medium was stationary.

If light travels as an event path —through matter by means of atomic transitions—, then the medium was moving with the earth and the results would then be null, as obtained.  The null results could then be interpreted as an indication of the discrete-event path nature of light.

I’m not asserting that light travels as a discrete-event path.  I’m proposing that it may and that the assumption of photon individuality could have misled the MM experiment’s results and many others.

Your opinions, to all, please,

Regards,

Bernardo.

Yuriy:

Why couldn’t two different photons appear to be entangled, if there is some nonlocal, infrareal accountant, keeping track of the currency?

Bernardo.

Please pardon my ignorance, I’m a systems engineer; I just have a very difficult time understanding how there can be “conservation” laws without some “accounting” somewhere.

Dear Yuriy:

Very nice of you to take the time to look up the book in Amazon.  I will love to read it.  Thanks.

Getting back to my original question, if we ignore the “accounting” part of my answer, which I assume deals with the hidden variables issue, this leaves us with the caveat, as you put it, with the process of quantum decoherence hiding individuality.

If photon individuality may not be fully established, what are your thoughts on the consequences on photon experiments, as I pointed out?

Thanks again,

Bernardo.

 According to Wikipedia, Bell’s theorem states that:

No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics.

If that’s right, I interpret it to mean that any physical theory of hidden variables must be nonlocal, in order to reproduce all the predictions of QM.  If that’s the case, what’s wrong with my idea of nonlocal (infrareal) “accounting” to debunk individual photon entanglement?

Bernardo.

Bernardo ~

 Quantum theory deals with “observations”. An observation is an interaction. During the period between two observations there is a probability wave, which is unobserved and in principle unobserveable. A “photon” is a phenomenon associated with an observation; when light interacts with “matter” energy is exchanged in discrete units E = hν. We interpret that by saying that an electron in the matter has absorbed or emitted a “photon”.

 However, it seems to me that the idea of an unobserved photon traveling as a discrete individual “particle” is not correct and leads to paradoxes.

 In a diffraction experiment (Young's slits) in which a pulse of light with energy E = hν is emitted and strikes a screen, we have two observations which we can describe as the emission of a photon and the later absorption of a photon. It is tempting to interpret that as a single photon − “the same” photon − that has traveled from the emission event to the absorption event. This leads to the meaningless puzzle about which slit the “photon” traveled through. What has traveled is not a “particle” but an electromagnetic wave that carries information about the various probabilities about where an absorption event is likely to take place. There is no observation between emission and absorption. Even if the experiment takes place in a medium, so that we know that there are interactions between the light and the medium as the light is traveling, and quantum theory can in principle take that into account probabilistically, none of this is observed. It seems to me that the idea of an unobserved photon traveling as an individual “particle” is not correct.

 Consider the Doppler effect. Light emitted at frequency ν is absorbed at a different frequency ν′. It is tempting to speak of “photons gaining or losing energy” while they are traveling. Many physicists do speak like that − as if photons were individually distinguishable particles when they are traveling unobserved. I feel that this is a very misleading way of thinking.

 Incidentally, I have trouble understanding what you mean when you say that “…the assumption of photon individuality could have misled the MM experiments…” (?) − the Michelson-Morley experiment was many years before quantum theory introduced the photon concept.

Eric:

My apologies, I did not express myself properly.

I did not mean to associate the concept of photon with the MM experiment; I meant to associate the concept of the individuality of the two (singular) luminous events assumed to travel through a vacuum, as in the MM experiment.  In other words, if a beam of light is a sequence of events (observations), and those events are intertwined (interacting) with matter, then the MM experiment could be interpreted to suggest that the luminous medium is matter, not the vacuum, thus concluding that the isotropy of the speed of light could be the same as the isotropy of the speed of sound in a giant moving air balloon measured with equipment travelling with the balloon.

The following may be hard to prove, but it could be that the observed/assumed isotropy of the speed of light may be due to the isotropy of the number of atoms per unit distance in outer space.

Besides, the speed of light in a vacuum may be a misnomer, because an unobservable is probably atemporal also (what I call infrareal, as belonging to the infrastructure of reality), thus making the concept of speed meaningless.  In order to prove/disprove this, of course, we would have to design an experiment that measures the time interval —which may be null— between two perfectly isolated emitting/absorbing atoms/events…  I rather let the design of that experiment rest for now.

I gather though, that you tend to agree with me that the lack of photon individuality (many intermediate photons) can change the interpretation of a photon experiment.  Is that correct?

Regards,

Bernardo.

Bernado ~

Thanks for the clarification.

You say “…concluding that the isotropy of the speed of light could be the same as the isotropy of the speed of sound in a giant moving air balloon measured with equipment traveling with the balloon.”

I agree; the Michelson-Morley experiment in itself does not rule out the existence of a “luminiferous ether”, it shows only that the laboratory in which the experiment was carried out is at rest with respect to the postulated “ether”. We can imagine that the ether surrounding the Earth’s surface takes part in the motion of the Earth. However, M-M is not the only experimental evidence for the constancy (and hence isotropy) of the “speed of light in a vacuum”.  If the ether surrounding the Earth were being dragged along with the earth then the paths of light rays from distant stars would be dragged along with it and the stars would be seen in their true directions − there would be no “stellar aberration”.

As we know, Lorentz was able to “save” the ether theory by postulating that the ether interacted (in a mysterious unexplained way…) with material objects, making lengths dependent in a precise way on their velocity relative to the ether − in a such a way that the null result of the M-M experiment could be accounted for even if the apparatus were moving relative to the ether. Einstein arrived at the same transformation law that Lorentz had deduced, by the much simpler and more plausible postulate that the speed of light in a vacuum is a universal constant c, not a “relative” speed. (So far as I know, the M-M experiment played little or no part in the considerations that led Einstein to his Theory of Relativity, which is a consequence of accepting the correctness of Maxwell’s electromagnetic theory.)

When Lorentz formulated his explanation the unit of length (a "meter") was defined to be the length of a particular metal rod. It was at that time possible to conceive that the unit of length might be dependent on velocity relative to an "ether". The present definition of the unit of length (a meter) is “the distance that light (in a vacuum) travels in a specified number of seconds". It follows that, in terms of the units in which all physical theories and experiments are now expressed, the speed of light in a vacuum is always everywhere and in every direction the same number of “meters per second”, by definition. The way physical laws are expressed is dependent on our choice of units. The modern international system of units renders the "ether" concept, and in particular  Lorentz’s explanation, meaningless.

“I gather though, that you tend to agree with me that the lack of photon individuality (many intermediate photons) can change the interpretation of a photon experiment.  Is that correct?”

Yes, that’s correct    (-:

No we do not make that assumption-and, in quantum mechanics, that assumption is meaningless, because photons follow Bose-Einstein not Boltzmann statistics. The only meaningful statement is that *one* photon is absorbed and *one* is emitted-but there's no way to state that it's the ``same'' photon.

Stam:

I guess we, is too many people.  Maybe I should rephrase my original question to: Have designers/interpreters of photon experiments, in the past, assumed that the source…?  With the question rephrased, I gather your answer to mean that physicists may have, but no longer assume that.

If that’s the case then, should we no longer, for example, interpret the MM experiment as proof of the non existence of the ether and of the isotropy of the speed of light in a vacuum, but as simply an indication that the light medium could be matter (air) or that the true nature of light is not quite yet understood?

As you pointed out, “The only meaningful statement is that *one* photon is absorbed and *one* is emitted-but there's no way to state that it's the ``same'' photon.”  With that in mind then, I believe the interpretation of other photon experiments should also be carefully revisited, not just the MM.  Case in point, double slit experiments, as Eric Lord pointed out.

Bernardo.

The question seemed interesting, but the thread of discussion seems like a fantasy discussion of how many angels can dance on the head of a pin.  And what does Michaelson-Morley have to do with it?  That is a classical experiment with waves, not individual photons.  One can modulate a signal on a wave group if desired and stamp it with an identifying number.  Case dismissed.

In some ways I agree with Eric.  But I believe it is possible to give additional explanation, which amounts to re-phrasing Bernardo's question.  There is the old problem which I'll rephrase to show how it affects this question:

I hope I've managed to confuse you guys as much as you confused me with your answers.  ; )

Just to confuse matters further, consider again the double slit with photons, in the case where one photon at a time is allowed in the experiment.  It not only knows whether the "other" slit is open, it knows the exact geometry of it, of all the walls on both sides of the experiment, all the electromagnetic properties and arrangements of all the atoms.  It knows all this without ever interacting with it, apparently.

Over time, statistically, it will all be interacted with.  But not that particular photon which was absorbed at the detector.  Regardless of its identity or whether it was the same as the photon emitted, it is the same energy.  Because only so much energy was emitted and all was absorbed at the detector.

How does it know?

• It can't really retain information from the interactions had by previous photons, because you might change whether the slit is open or closed.
• My own supposition is that the field does interact with everything, but that the energy is absorbed and re-emitted, much like a photon traveling through a medium that slows it down, and the quanta you measure is only the one time it gets absorbed and not re-emitted.

This is mainly to agree with Robert Schuler and Eric Lord. When a photon travels through air, or any other medium, the electronic transitions of which are far from the frequency of the incident photon, then the amplitude that a photon should be absorbed by an air molecule and then re-emitted is quite small Additionally, such a process is elastic, so it cannot be used as a proxy for measurement. There is thus no influence on the outcome of a two-slit experiment.

As for Michelson-Morley, its original purpose was, indeed, to decide whether the ether was dragged along with the Earth or not (that was Michelson's stated purpose). The result he found, he interpreted as essentially total ether drag. This, however, was felt by the theorists at the time to be an unacceptable explanation: Several experiments, such as aberration, aberration in water-filled telescope and Fizeau's experiment spoke against this interpretation. Michelson-Morley can be interpreted in several ways, but it is not possible to give an interpretation of all other experiments in non-relativistic terms. In particular, time dilation experiments, such as those performed with muons, seem hard to reconcile with any non-relativistic theory.

OK guys, I asked the question in order to get answers, so I’m getting them.

I can understand why this thread of discussion may have seemed as fantasy to someone who has been immersed in the subject for years, perhaps most of his life, so thanks for your sincerity Robert.  Having said that, I will try to elucidate as much as I can about my question, in appreciation of your comments.

Robert, you will note that in the explanation detail of my question, its validity is expressed as conditional, so if the question is invalid, it’s neither fact nor fiction and we should address that.  Nevertheless, the intent of the question is about experiments dealing with light and their interpretations, not about photons, waves, fields, information packages, etc., thus the relation to the MM experiment.  My mistake for using the word photon as if that were the only manifestation of light.

On second thought, maybe the multiple manifestations of light are what make the question valid.  Regardless of that, what I’m trying to understand is the following:

1.       If light is considered a wave or field, its information is carried from beginning to end, touched only by the apparatus, yielding a particular set of interpretations of the experiment.

2.       If light is a flow of photons, particles, information, etc. , some kind of a flow of packages interacting freely with the apparatus plus other matter, manifesting and de-manifesting themselves as they interact (that does look like some kind of a dance, doesn’t it :), their behavior would appear to be much more complex, interpretable only by statistics, yielding then a different interpretation set.

So which one is it?  If it’s both, which interpretation set do we accept?  The interpretation sets could be mutually exclusive.

To add to the confusion, we can throw in locality and non-locality yielding other sets of interpretations.

Personally, I feel comfortable with the idea of photons as information packages, with some infrareal accountant keeping track of the currency, without worrying too much about the carrier at this moment.  Probably because of my experience as a software engineer. But that’s just a preference.

On the other hand the idea of a field makes me uneasy, because, as far as I know, no one seems to know what it is or how it interfaces (attaches) to the rest of the structure of reality.

But, to get back to the subject at hand, I would like your opinions on the validity of the original question.

Thanks for your help,

Bernardo.

Everything depends on a specific character of experiment.

Suppose that I place a field detector in the wave field flow. Suppose that my detector can absorb the wave energy but it can absorb it by small portion. So it will absorb one portion and indicate the first "click". I will see this click and will think that it was one photon. But this click was not the characteristic of wave field but the characteristic of my detector. However, I can say that I detected a particle.

So I mean that separation of wave field properties and particle properties strongly depends on properties of my detector.

To say more, as soon as I detect a particle (get one "click" from a given direction on my detector) this particle does not exist any more, it exited my detector and transformed to other type of energy. So I can only suppose what were the particle (or the wave field) reflections, interactions and transformations.

So the picture of the phenomenon in my mind depends mainly on my education and my phantasy.

In attempting to answer Bernardo’s question it had crossed my mind that (as Stam pointed out) the fact that photons obey Bose-Einstein statistics renders meaningless the question of whether an an absorbed photon is “the same photon” as the one that was emitted − photons are not individually distinguishable entities. However, electron beams show the same diffraction effects as light beams, though electrons don’t obey Bose-Einstein statistics. Similar effects confirming de Broglie’s theory of “matter waves” have been observed in Young's slit experiments with quite large “particles” such as whole atoms, ”small” molecules such as “Bucky balls” and, more recently, molecules consisting of as many as 8oo atoms (http://arxiv.org/abs/1310.8343).

This suggests that the question of whether any entity is “the same” from moment to moment is meaningless!

http://arxiv.org/abs/1310.8343

Bernado says "So which one is it?" (wave or particle).  This is the question of wave-particle duality, which has been a puzzle and debated since the dawn of quantum mechanics.  An introductory discussion can be found at https://en.wikipedia.org/wiki/Wave%E2%80%93particle_duality 

Eric, that was the point I was trying to make with the anecdote about whether my wife is the same girl I married.  In using both language and mathematics we are only approximating reality.  Identity is a good approximation for large objects, though not perfect since most of the cells in my body change over time.  It is even a good approximation for large photons (gamma rays).  

Now what you refer to about the Bose statistics, they are usually explained by claiming the non-identity of photons.  But as we see this has nothing to do with the double slit experiment for which we can use Buckyballs.  Whether the Bose business is accurately reflected by using the approximate language (or math) term "identity" is something I'm not sure about.  There might be a better explanation.

In classical physics the state of an isolated system is regarded as something precise: all its characteristics are in principle if not in practice accurately knowable. The “laws of physics” then completely determine the precise state at a later time.

Because of the uncertainty relation between pairs of conjugate “observables”, quantum mechanics implies that the precise state of a system is in principle unknowable. However, it seems to me that the further conclusion, that conjugate parameters (I won’t call them “observables”) cannot simultaneously exist with precise values “in reality”, is not warranted.

Let us suppose then, that at every instant a system is in a precise state − a classical state. But the evolution of the system is not deterministic because the Heisenberg uncertainty principle ensures that the state at a given instant cannot uniquely determine the state at a later instant − "decisions" are made; it is as though Nature makes a random selection from the statistical possibilities, at each instant. (God playing dice…).

This viewpoint removes the idea that quantum physics is about “observing” and “measuring” − an idea that creates puzzling questions about whether “consciousness” is involved (the paradox of Schrödinger’s cat), or how physical processes can manage to carry on when they are not being "observed". In any quantum mechanical experiment the apparatus and the experimenter are part of the system, not separate from it.  The “detection of a photon”, for example, is just an interaction, no different in principle from all the interactions between light and “matter” that have taken place unobserved prior to the detection.

I hope what I’m trying to say is clear (and that it makes sense…)?

Hi Eric,

Personally I think von Neumann's idea about consciousness was unprofessional.  We should be able to replace the human experimenter with a good A.I. that can choose experiments and make observations but is not necessarily conscious.

I am not sure why you feel so strongly that "conjugate parameters (I won’t call them “observables”) cannot simultaneously exist with precise values “in reality”, is not warranted."

We have, I believe, several versions of quantum theory, at least one of which is deterministic (de Broglie-Bohm).  It is not the most popular interpretation at the moment, but no one can measure the relevant parameters to disprove it.

As far as I know, and I'm not a QM expert, all versions of QM are non-local, though only statistically so.  Remi Cornwall thinks he can disprove the No Communication Theorem, but there are some strong caveats on what is possible with his method, even if he could demonstrate it.  It is not communication like we think of it normally.

The idea of being able to generate or recover any state interests me, by repeatedly measuring conjugate parameters.  If we measure position precisely, we have no idea of momentum, and vice versa.  The measurement of one scrambles the other.  If we make the two measurements repeatedly, this has a measurable physical effect.  If you determine the position of a particle, the momentum is not just unknown, it is scrambled from whatever the last measurement of momentum was.  So the measurement has a physical effect.  By alternating measurements, you can eventually achieve any momentum (or position) state of the particle that you wish.

Now we sneak up on what I think is an error in Schrodinger's cat experiment - though since Schrodinger intended it to appear ridiculous, maybe this is what he intended people to think.  It is commonly said the state function of the cat contains equal parts live and dead cat.  There is an implication that there is a conjugate parameter to the live-dead axis.

Some have pointed out this allows resurrection of the dead.  We look in the box and let's say we find the cat dead.  If we can measure the conjugate parameter, the state of the cat would again be scrambled and we'd have a 50% chance of finding it alive.  If we keep repeating this, we can come arbitrarily close to a 100% chance of restoring life to the cat.

It seems to me one either has to accept that there is such a conjugate parameter, or conclude that Schrodinger's setup is flawed and the cat does not have a live-dead quantum state, that parameter is not a quantum parameter.

The only thing I have ever been able to come up with for a conjugate to live-dead is identity.  Which is related to our conversation because we have been discussing identity.  If you measure "which cat are we talking about?" then of course you may find it alive again.

Given that a cat has nine lives, can we calculate the probability of whether it is the same cat tomorrow that it was today?

Michael:

I like your answer, because it addresses part of the point of my question.

If I use wave detectors in my experiment, it will yield wave-interpretations, wave-conclusions and wave-related proofs.  But if I use particle detectors, it will yield particle-interpretations, particle-conclusions and particle related proofs.  So, do I conveniently or unknowingly choose the right detector to prove my theory?  Conveniently, of course not, unknowingly, not nowadays either.

So as an example again, and this is just an example, the MM experiment is a wave-detector experiment, designed, as F. Leyvraz pointed out, “to prove ether drag”, assuming that waves need an ether or “something” to travel through, therefore they “concluded total ether [or “something”] drag”.

In their defense, they were not aware of particle behavior at that time, put if they had done a particle-detector experiment, they would have concluded that matter was the medium, or that their measurements were all done in the proper frame, thus nullifying the experiment.  No one would have been the wiser about ether drag.

Thanks for your answer,

Bernardo.

Eric:

I agree with you completely with respect to your last comment, except for a minor issue with the part where you state that “the question of whether any entity is “the same” from moment to moment is meaningless!”, because you need to clarify it with; if the particles obey Bose-Einstein statistics…  If they don’t obey Bose-Einstein statistics, the question still stands.

Thanks for your answer and the reference, I’ll take a look at it.

Bernardo.

Robert:

I know what wave-particle duality is about.  It’s probably my favorite subject, so thanks for the reference, I’m sure I’ll enjoy it.

But I need to clarify that my statement, "So which one is it?", was placed in the context of “So which one is it?  If it’s both, which interpretation set do we accept?” which I intended to mean, which interpretation do I choose? , not is it a wave or a particle?  As a matter of fact, I believe that every observable object is a wave packet or a conglomerate of wave packets, which always behave as wave packets, but that we normally observe as “particles” because of their “packet configuration” and because that’s the way humans have evolved to observe the rest of reality.  But that’s not part of this thread.

By the way, the concept “individuality” is well defined, my question deals with the ability to determine if the source photon is the same as the target, which apparently is not possible when observed statistically.

Thanks,

Bernardo.

Dear Robert ~

Thank you for the detailed and thought-provoking response to my post − which was a search for answers rather than a well thought out statement.

Like you, I don’t see myself as in any way “a QM expert”. I know the subject well enough to see that as a computational method it is mathematically logically sound and that its predictions have always turned out to be empirically verified (even when they seem weird!). What disturbs me (along with many others) is that I have no conceptual grasp of what this it is telling us about the nature of “reality”. It seems to me that this confusion is coming at least partially from the terminology − QM is presented as a theory concerning “observables” − a theory of what can be known experimentally, not a satisfyingly consistent picture of  what is actually going on “in reality”.

Quantum physicists (the “experts”) speak of an “observation” or a “measurement of an observable” as if it that were something that acts on and interferes with a system or process and radically alters the state of the system or process. They call that “ the collapse of the wave-function”. In truth, however, in any experimental set-up the apparatus and the physicist performing the experiment are an integral part of the system. An “observation” (for instance the detection of a photon, the measurement of the spin of a particle, the act of looking in a box to see whether a cat is dead or alive, etc) is an interaction taking place within the system. We need to ask what kind of interaction that is. What kind of interactions can radically change the state of a system − can “collapse the wave-function”? If no unobserved interactions are admitted into that category it would seem that we are left with only two possibilities, neither of which are conceptually satisfying:

either the wave function collapses when information enters the “consciousness” of a conscious observer (Wigner, von Neuman, etc) or the wave function never collapses (the “Many Worlds” hypothesis).

Should physics concern itself only with the mathematical predictions of the outcome of experiments (“shut up and calculate”) or should we require of it a satisfying intuitive understanding of the nature of physical reality? Inroads into the latter requirement seem to me to be missing from quantum theory in its present form.

                     __________________________________________

 Incidentally, Schrödinger’s cat doesn’t trouble me. The radioactive atom in that thought experiment is never in a superposition of states. At every instant it has either decayed or it has not. It is only our knowledge of the state of the atom that can be expressed as a "superposition of states". Hence “the cat” also is never in a superposition of states. Only the knowledge (based on known probabilities) of whether it is dead or alive is a superposition.

Eric:

My intent here is to comment on your post according to my beliefs on the behavior of reality and not as true statements of fact.  All my comments therefore, should only be taken in the context of my understanding of reality. 

The following is a short blurb on that understanding.

I believe all objects are in what you refer to as, a classical state, not at every instant of time, but at discrete points in time (time is discrete also).  It is only at these points in time that reality is expressed (manifested).   Reality is expressed in sets of time intervals (timeframes).  While a timeframe is being expressed the next set is being prepared.  Please don’t ask me where and by whom, because although I may have some ideas, they can only be speculations.  By the way, I implemented this type of process for vibration and acoustic testing, at NASA, when I wore moderate long hair and younger man clothes.

Within the above context and in order to maintain compatibility with Relativity and QM in general, it occurred to me that the expression process (the collapse of the wavefunction) uses some kind of Hermitian (orthogonal) function, such as the Fourier transform.  You can gather from this, that QM and Relativity would not have to be radically modified in their structure but only in their understanding. Nowadays, this same type of process is almost ubiquitous in the inner workings of almost all forms of digital reproduction —as in playback of digitally recorded reality— of sound, music, videos, computer games, computer simulations, etc.

With that in mind let’s continue with my examination of your comments.

On the uncertainty principle.  The uncertainty principle is not about uncertainty, but about the constraints inherent to the orthogonal transformation implemented in the expression of reality.  If one variable has a particular value, the other cannot exhibit a certain range of values in the next timeframe, not because it has been observed, but because their conjugate relationship does not allow it.  We all know that the uncertainty principle is closely related to the Fourier transform.  As a matter of fact, the Fourier transform actually imposes an “uncertainty principle”.  I believe that this type of constraint is characteristic of all Hermitian functions; I have to admit that it’s been a while since I was up the curve on time series analysis and orthogonal functions.

On observing and measuring. I fully agree with you. Because, if the uncertainty principle is not about uncertainties but about mathematical constraints, it says nothing about the act of observing and measuring.  What it does say is that if the wavelength (the spread, not the position) of a wave packet is known, its next (timeframe’s) angular momentum has to be expressed with a value satisfying the Heisenberg uncertainty relation.  It also says that the particle-like-position of a wave packet is undefined, although it lies within its spread.  I haven’t given Schrodinger’s cat much thought, but I suspect the concept dies, not the cat.

On consciousness.  I’m very sure that individual consciousness is part of the expression of reality, but not all of it, the mere exhibition of non-locality tells us that there is some infrareal system (for lack of a better word) keeping track.  I believe that the problem with the examination of the concept of consciousness is that, consciousness is so intertwined with the process of the acquisition of time (expression), that they just blur together in the mind, without conclusion.  Could this mean that consciousness is a Turing machine?  Let’s not go there.

On photon detection.  Full agreement.

By the way, pardon me for the use of the infrareal word, but I found that the infrareal qualifier —as in, part of the infrastructure of reality, but not of it— fits a very large number of concepts in physics, concepts such as, wavefunction, collapse of the wavefunction, expression, unobservable property, consciousness, atemporal property, photon, field, entanglement, physical law, hidden variable, etc. I could go on and on.  I like to use the infrareal qualifier because it can group all of the above concepts and properties, thus saving on words and clarifying their nature.

I guess that wasn’t such a short blurb after all, but I’m just taking advantage of the wonderful opportunity that RG gives us to test our ideas.

Regards, Bernardo.

Let me try to comment on the double-slit experiment, without referring directly to the question.

Most of the ``interesting'' double-slit experiments are made in the regime in which only one photon goes through the slits at a time. So in such cases, which conceptually are the interesting ones leading to questions such as ``how does a single photon, which thus must have gone through one of the slits, know about the other?

By the way, what do I mean when I say: ``one only has one photon at a time''? We have a source of many photons (typically a laser source, so they are identified by having a very well-defined frequency) hitting an attenuator, in which most are absorbed and only a select few get into the apparatus. The length of the apparatus is L, so a photon will cross it in a time L/c. If now the detector detects photons with a certain probability p (which can be measured independently), then we can, from the number of detections made in one second, deduce the number of photons that passed through the apparatus in one second. From that we obtain the number of photons passing through the apparatus in a time L/c. If that number us much less than one, there is only one or no photon in the apparatus at a any given time. This makes the whole question of statistics superfluous. Similarly, when you do double slit experiments with buckyballs, it is very much one at a time.

So now, can it happen that a photon scatters (which is the language I prefer for the expression ``is absorbed and then re-emitted'') on some gas molecule? Certainly. There are then two possibilities: either the scattering is elastic, that is, the molecule is unaffected by the scattering, and so is the photon. In such a case, interference is not affected. On the other hand, you can have inelastic scattering, in which the molecule is affected by the process. This would, I believe, destroy the  coherence and the interference would disappear. But an optical photon has no way to scatter inelastically with air, hence the experiments can be performed in air.

F. Leyvraz:

I think we are getting closer to the point of my question.

Before I ponder on your answer, let me make sure I understand all of it.

Are you telling me that laser light cannot have inelastic scattering with air, but it can have elastic scattering?  If that’s the case, is that the reason why we can see the beam as it passes by?  Does the scattered light we see have the same original frequency?

Bernardo.

Bernardo ~

"Does the scattered light we see have the same original frequency?"

Some of the scattering is inelastic. This accounts for observed frequency shifts in scattered light  (the "Raman effect").

Barnardo ~

Congratulations on your excellent “short blurb”. You have expressed with precision and convincing detail what I was struggling to say in a rather vague way. The blunder in my comment that you were responding to was, of course, the phrase “at every instant”. I actually come back in order to delete my post in order to resubmit after giving more thought to the idea of “discrete jumps” in the evolution of a process, but then I found your response!

Let me quote from something I said on another RG discussion board a while ago:

“Before a measurement is made, all we know are the probabilities of various outcomes. The actual outcome is in principle unpredictable. Let us imagine that, beyond our reality is a meta-reality [Barnardo's "infrareality"] wherein something like a random number generator selects the result whenever a measurement is made. A fanciful scenario, but not in conflict with QM as we know it.”

 A useful analogy (for me…) is to think of the physical world as like a computer animation − something like Conway’s “game of Life”. Physicists are like people watching the screen as the image changes frame by frame, and that is all they have access to. For them, that is observed reality. To begin with they know nothing of the algorithm that generates each image from the previous image(s). They have to deduce it from their observations of the activity on the screen. They eventually deduce quite a lot about it (their deductions are the "laws of physics") including the realization that there is a subroutine in the algorithm that employs a random number generator. This, of course, is an analogue of quantum-mechanical indeterminism

 But now there arises a disturbing corollary:

“…suppose that the random number generator is actually a pseudo-random number generator. That wouldn’t make any noticeable difference, would it? But a pseudo-random number generator produces numbers that only seem random – there is in this case an unobservable deterministic process going on behind the scenes. This line of thinking suggests that QM as we know it could conceivably arise from a deterministic process. That looks suspiciously like a “hidden variables” scenario. Can anyone tell me what, if anything, is wrong with it?”

The word "random" as actually used in physics, computer science, and economics is imprecise in subtle ways, and apparently an approximate model.

Some examples: ...

Let me explain the significance of a random walk, which may not occur to you if you have not studied economics.  An ordinary Gaussian distribution has an average value and a standard deviation that are not time changing.

But a random walk with a certain Gaussian distribution, let's say, changes with each new data point.  That is, each new data point is a new average, and future values are expected in a distribution about that.  So the central value wanders over time in an unpredictable way.  For a century you may have values of some economic parameter, like the DJIA, in the range of 100 to 1000.  Then in a single decade it wanders up to 15,000 and that is the new expected central value.  But the standard deviation may collapse from +/- 75% in a decade to +/- 20%.

It is widely known that market data is unpredictable (efficient market theorem), but it does not have the well behaved characteristics of a quantum state distribution.

F. Leyvraz:

I have no problem rationally accepting photons or Bucky balls interfering, because I believe everything is waves, it’s the individual self-interference that puzzles me, but I guess I’m not alone.

When I phrased my question, it was my hope that the “angels dance”, as Robert Shuller put it, i.e., some form of scattering, was what had been muddling our reasoning about self-interference, but that hope was dampened a bit after reading your comments about the different scattering-with-air possibilities.

Then I read Eric Lord’s comment on the Raman Effect, looked it up in Wikipedia and began to wonder again.  You see, I remain unclear as to what happens between the source and the slits, a bit more unclear about what happens at the slits, but not at what happens at the detector.

What stumps me is that, as Eric Lord pointed out, scattering cannot possibly be a muddling factor with Bucky balls.  In the mean time, the scattering of photons, in photon experiments, still remains as a possibility because there is a small chance that two different processes, with the same result, may be occurring.

Nevertheless, does anyone know of any double-slit experiments performed in a vacuum?  It would be interesting to know if it makes a difference.

Eric:

Thanks for the nice compliment and the up-vote, they are always appreciated.

By the way, your reference to the Raman Effect was very helpful.  Thanks again.

Your proposal of some reality outside of our reality is exactly what I propose and attempt to discern in my monographs on the infrastructure of reality.  I call it infrareality to allude to the supporting structure of our reality, that upon which our reality is based.

We are not the only ones proposing this of course, there are an increasing number of scientists and engineers thinking the same way.  I suppose the numbers are increasing, because nowadays we are fully immersed in technologies that are very tangible examples of immaterial realties, that is, digitally recorded realities, later played back (reconstructed) by physical systems (photos, music, television, movies, etc.).  As you probably know, all of these technologies are subservient to the Nyquist-Shannon sampling theorem, which is a Fourier transform based theorem.  Why is that not a surprise?

My favorite metaphor when explaining infophysical (short for information physics) reality is basically the same as yours, a computer screen; the hardware screen is infrareality, reality is the display and we are part of the display, not the screen.  So, no disagreement with you there.

Your corollary is in no way disturbing to me.  I used pseudo-random number generators before, to simulate random vibration and acoustic noise of rocket take-off for environmental testing at JPL.  The noise generated was indistinguishable from true random noise.  Using pseudo-random number sequences is simple —a couple of lines of code, depending on the language used— and very efficient.  I used more than two lines in my pseudo-random generator because they were written in assembly language; the rest of the code was not that simple, because it required the use of the Fast Fourier transform in both directions and that was a while ago.  At that time, it was fascinating to see how a sequence of numbers can get so physical.  Nowadays, it’s simply commonplace.

I think the disturbing part of your corollary is that it implies that reality may be immaterial.  Most people don’t like to believe in that possibility, because it is contrary to the way we observe the world.  If reality is immaterial it is still physical, because physical is what we observe.  Infophysics, like QM, is a set of mathematical models, yet no one accuses QM of being immaterial, but what can be more immaterial than mathematics?

Getting back to my question, I’m still stumped as to how a single wave packet can self-interfere.  I suspect it has to do with the HUP, but I can’t visualize it yet. I will let you know if I get unstuck.  Perhaps you or anyone at RG can help.

Regards, Bernardo.

Bernardo:

``Are you telling me that laser light cannot have inelastic scattering with air, but it can have elastic scattering? If that’s the case, is that the reason why we can see the beam as it passes by? Does the scattered light we see have the same original frequency?''

Light can scatter quasielastically from air. In particular, what you see from the beam is, I would guess, very close to elastic scattering. But since these are strongly deviated from their path, they would presumably not appear in the interference. However, the size of the effect should be borne in mind: the light scattered from a laser beam is *very* much less than the beam itself. So the number of photons affected by scattering in the double slit experiment is presumably negligible.

Summarizing, I don't think scattering can explain the peculiarities of the double slit experiment. Rather, it is a problem: if there is too much scattering, the interference phenomenon disappears.

F. Leyvraz:

OK, let’s eliminate scattering, your arguments are very reasonable, thanks.

 Do you have any ideas about what causes the peculiarities?  What’s the accepted view?

The accepted view is that a quantum system is not described in terms of a wave, or for that matter a classical particle, but a state. A state is a complex valued function of all the coordinates of the particles composing the system. As long as a system remains isolated, the evolution of its state is deterministic. Thus, if we prepare a hydrogen atom in its ground state, we know it will stay there forever. If we prepare it in some excited state, we know it will be in some kind of superposition as time proceeds. All this is deterministic.

Once, however, that one part of the system comes to interact with a larger system---what is known as a classical system---then generally uncontrollable things happen and the system's evolution is probabilistic. In particular, measurement must be of this kind.

In this sense, as long as we have a single photon, the state of this photon is a complex state function, susceptible of displaying interference (for a single particle, saying that we are dealing with a ``wave'' might barely work. But it becomes inacceptable for even a two photon system, where entanglement arises, which is not something one can describe in the usual ``wave'' framework. It is best to think of an abstract ``state'', which behaves in any ways comparably to a wave, but which is by no means a wave in physical terms). The photon's state cannot be compares to a particle, however, and there is no way of meaningfully deciding through which slit it went. But when the photon hits the detecting screen, the detectors are a complicated classical system, so that the photon is detected in one particular position with a probability proportional to the intensity of the state at this position.

It should be emphasized that the photon always is detected entirely in one place. There is no such thing as a photon being detected half in one place and half in the other. This is one major difference between a wave and a photon. Further, you can put detectors on the slits, but then you necessarily destroy the interference. You can also devise more complex experiments, in which you get some knowledge about the slit, and yet maintain some diffraction.

Over all I think it is very difficult to express such things entirely honestly without the help of the mathematical formalism. This is far from saying ``shut up and calculate'' but rather ``calculate, and you may end up knowing what to say''.

F. Leyvraz:

I can appreciate the conundrum as you struggle to digest it for me.  Thank you very much for your sincere effort.  I really appreciate it.

I see why, there are so many very heated threads in RG —and I imagine elsewhere— discussing this type of problem.

Please don’t be concerned about being interpreted as saying “shut up and calculate”; you have been very gracious, well intended and patient with me.

The following goes for all of you who have tried to help me:

It’s too late for me to start “calculating” as F. suggests, so I apologize for having to disappoint you.

A physical process, as you know, can be modeled in many ways, that’s why I will continue to try to understand reality as a discrete-event model, which is much closer to my experience.  Who knows, maybe I can come up with some solutions to the conundrum.

This does not mean that I will not try to interpret your points of view.  I want you to know that I’m sincerely grateful for your efforts in answering my question.

If someone else has anything to add, please do so.  I would be extremely grateful.

Best Regards, Bernardo.

Actually, my final paragraph, rather than a criticism, was meant to express my own dissatisfaction with what I had written. It was the best I could do, but I realize it remains largely hard to understand and unsatisfactory.

Feynman's QED: the strange theory of light and matter, makes a serious attempt to explain quantum electrodynamics, hence photons, without too many formulae. That might be a good place to start.

F. Leyvraz:

Thanks, you did great.  I will look into Feynman’s book.

Bernardo.

The question of Bernardo initiated me to view the problem from another side meaning the design of systems and the influence of interaction of their components following the basic laws of thermodynamics. However the question of radiation - is it now a particle or a wave - is fascinating but it doesn't say anything about the possible energetic analysis of the system. As an engineer I am not very deeply informed about the fields most of you are working on, but anyway I believe that system analysis and thermodynamics can give an additional view that might be helpful for better understanding. If we consider that there is a unique equation system describing all phenomena connected with the described effect (wave or particle) than we should have a sort of instable equilibrium (bifurcation point) where an unknown effect of a lower order than the described effect itself forces the system to switch in the one or in the other direction. For this simple statement we don't need to know this equation, we should only assume that it is there and allows this bifurcation point. If we now compare the experiment with or without an observer there is an indication that there must be a reason why the behavior change from wave to particle or vice versa. If we further introduce a balance border around the entire experiment light in to light out where the possible observer (if he is part of the experiment) is inside the system border than we have to ask what might be the interaction between the experiment and the observer. Necessarily the experiment influences the observer because it increases his order of information by one bit at the minimum. The thermodynamic quality of one bit is defined by the change of information entropy of the observer. Thus we have to supply to the observer the reversible work that equalizes this change of entropy inside the observer. Assuming that the only source of supply is the incoming light - otherwise the observer is not an observer - the energy of the outgoing light must be reduced by this reversible work at the minimum. Interesting expansions could be the interaction of the observer with environment outside of the common balance border (experiment and observer) and the consideration of possible irreversible effects. So far the considerations of an interested amateur in that field. Anyway for me this view looks that simple that I am wondering not to hear very much about similar discussions. Especially if we look on technical or biological systems the generation and transport of information has the same value as the conversion of substances and energy and its transport however on different levels of energy. So do we have in nature also an “internet of things” that could could contribute to explain some questions we are discussing here? Or is there something wrong?

Bernardo,

I cannot agree with Eric Lord's comment. Basically quantum optics is governed by the rules of classical electrodynamics. When some optical workshop manufactures any of the items used in a quantum optical experiment, polarizing beam splitters, lenses, prisms etc. it applies these rules. All one has to keep in mind in interpreting photon experiments is simply this: The probability-(density) of the photon in question being somewhere in space  is essentially given by the density of the classical electromagnetic energy , divided by the frequency of that wave (wave packet) times Planck's constant. In an individual experiment the photon takes only one path along one "flowline" of the associated Poynting vector, in the following experiment, under the same conditions, it  will follow another flowline . What one sees in the plane of a monitor behind a two-slit diaphragm are the incoming photons one by one, each of which has followed a different trajectory in accord with the above probability rule. The diffraction pattern is the result of many traces that these incoming photons have left. The occurrence of the pattern reflects classical electrodynamics at work! What is wrong with such an interpretation? Where are the contradictions? We should really stop this puristic drive not to use simple pictures if elements of these pictures are not accessible to measurement. After all, the complex-valued wave function of an electron cannot be measured and still it constitutes the center of quantum mechanics.

Lothar,

My question is not about diffraction or interference, we know that happens without a doubt, what my question does try to address is a concept that keeps lurking around in particle optics, namely self-interference, which is a non-intuitive (unexpected) concept, to say the least.

A probabilistic answer to self-interference, such as by QED, even if it does predict it —I don’t know if it does—, tells us very little about the process itself.  Knowing the probability of occurrence of a traffic accident at a particular street corner, although very useful, tells us very little about why they happen or how to prevent them.  Insurance companies may be satisfied with the prediction, but not traffic control.

The problem that I am concerned with —at least with the two-slit experiments that I have examined— is that the experimenters implicitly or explicitly assume self-interference, observe it (or what it appears to be) and then conclude it happens.  This only convinces me that self-interference appears to occur, not that it does.

If each particle has a single “flowline” as you stated —a statement that I believe to be true—, then we should just accept that fact and look for the “self-interference” effect somewhere else.  That to me is much more feasible and reasonably acceptable.

Bernardo.

Dear Bernardo,

I am still not quite sure whether I understand the central point of your qualms concerning self-interference. As I explained already in my previous answer, I think that the physics of quantum optics is primarily governed by classical electrodynamics. I am appending a PDF-file on spontaneous light emission which is mostly an excerpt from my  article "Quantum Mechanics without Fairy Tales", not yet published. I demonstrate that the emission of light from an atom follows - apart from the role of the electron - classical electrodynamics. Hence, the outgoing light which contains only one photon,  is an ordinary  wave packet. The fact that it contains a photon (very likely as a point-like particle) cannot be proven, i.e. also QED cannot prove it. It constitutes a fundamental assumption. When you now let the wave packet enter a two-slit diaphragm you get diffraction, involving interference (which you might call "self-interference"), solely as a consequence of classical electrodynamics. One can calculate the classical energy density of the entire wave field that has built up for this array of an emitting atom and a diaphragm. This energy density divided by Planck's constant times the frequency of the wave has to be interpreted as the probability density of the point-like photon contained in the wave packet as it moves from its atomic source through the diaphragm and finally to the monitoring screen. That means: the photon cannot occur where the wave field has zero amplitude and therefore zero energy density. But this is not a property of the photon, only a property of the classical wave field.  I hope that this comment can be of some service to you.

Lothar 

Thanks Lothar, I will consider your comments and your appended reference.

Bernardo.

To all:

First of all, I would like to thank you for your helpful answers.  Your ideas clarified many concepts in my mind that have helped me to better understand particle-wave duality in general.  I know I have not added any more comments to this post since October last year but I have been writing three monographs on matter-waves.  The following are some realizations to which I have arrived since then.

Two of the fundamental properties of matter are position and displacement (motion) and these two properties alone can combine to form geometry, therefore that geometry is a property of the configuration of matter.  It is to this particular geometry that I refer to when I discuss the motional geometry of matter that follows.

What I have found is that de Broglie waves, the isotropy of the speed of light, relativistic motion and the kinetic energy of particles are possible experimental evidence that the motion of matter, in general, is restricted to a 3-spherical geometry, as follows:

• De Broglie wave.  It is the equivalent wave (wavicle) traced by the trajectory of a point particle constrained to a geodesic of S3.
• Isotropy of the speed of light.  Is evidence of the positive circular curvature of the motional geometry of matter.  As a matter of fact the speed of light is a measure of the radius of its curvature.
• Relativistic motion.  It is a circular based constraint on motion.
• Kinetic energy.  Is rotational energy.

That is why I am eager to find more evidence for a universal 3-spherical geometry, such as the cosmological evidence leading science to what I consider a very ugly Big Bang.  I agree that the BB is a generally accepted concept, but as we all know, it has very ugly implications such as singularities and infinities that in my opinion are very unphysical.

I am very sure that it is possible to explain the redshift of distant light by means of spherical geometry, I just can’t prove that it would be the redshift that is observed and this is where I would again love some guidance from you if possible.  I have started an RG question post on that subject to which I have attached a link here.

If you are interested in my ideas on the motional geometry of matter, I have attached RG links to my latest monographs on the subject.

Regards, Bernardo.

https://www.researchgate.net/post/If_the_shape_of_the_Universe_is_a_3-sphere_can_that_particular_geometry_by_itself_explain_some_or_all_of_the_evidence_for_the_Big_Bang?_tpcectx=profile_questions

Research Matter-waves and Discrete-transitional Motion

Research The Isotropy of the Speed of Light and its Implications

Research The Motional Geometry of Matter

The question is incomplete. A detailed description of the experiment is required.