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After reading Art Hobson's article titled, "There are no particles, there are only fields" published in The American Journal of Physics in 2013, I'm wondering what other experts think of his main thesis: The double slit experiment, in all her variations, can be completely explained through relativistic quantum physics (quantum field theory) and that the alleged particle/wave "weirdness" is only weird because people don't realize that our best physical models of the universe model that universe as composed of fields ("particles" are excitations of that field).

I get how it can explain everything in the double-slit experiment except the following- how can fields explain why, when you watch which slit the "particle" goes through, does the interference pattern disappear?

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    $\begingroup$ I am not sure what exactly you are asking for. The article you don't link (it's here) is quite superficial and does not actually resolve anything technical. E.g., it expands in position eigenstates and claims to be doing QFT. That doesn't work, QFT has no naive position operator. "There are no particles, only fields" is, well, kind of correct, but it is not evident to see how that is supposed to explain the double slit. If you want to see a real QFT treatment of the double slit, look for instance here. $\endgroup$ – ACuriousMind Feb 8 '16 at 15:00
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    $\begingroup$ A lot of physicists agree, in private, with that article. More or less. But cannot publishe because---it isn't really anything definite and physical out of that mantra that differs from the opposite point of view. The complte opposite point of view was Feynmans's: he wanted to eliminate wave--particle duality by eliminating the waves. He, in effect, said, there are no waves (they are only a mathematical device), there are only particles. Perhaps I will write this up as an answer $\endgroup$ – joseph f. johnson Feb 8 '16 at 15:26
  • $\begingroup$ @ACuriousMind: The article isn't trying to resolve anything technical, it is trying to get physicist away from teaching nonsense about particles to the kids. Mott has told us in 1929 how particles arise in experiments and his insight has been ignored for close to a century now. Irrespective of that, he was correct and it's time that we stop teaching an 80 year old nonsense about there being two faces of quantum mechanical systems. There is only one face and that's quantized fields. That one can reduce non-interacting fields and the hydrogen atom to a single particle approximation are flukes. $\endgroup$ – CuriousOne Feb 8 '16 at 16:16
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    $\begingroup$ Manuscripts that don't have, as ultimate payload, something "technical", are hard to publish becuase it is hard to decide if they are worthwhile, make some kind of advance, etc. Even if correct! Feynman wanted to eliminate waves, he said this explicity, in the context of QM. I'll find the reference somewhere...either the LEctures on Physics or the Feynman--Hibbs book or something. He explicitly said the whole Bohr balancing act between wave--particle duality was unnecessary. Particles exist, waves are merely mathematical devices for computing transition amplitudes, according to him. $\endgroup$ – joseph f. johnson Feb 8 '16 at 16:24
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    $\begingroup$ @josephf.johnson Would you happen to be referring to a derivative of this video? youtube.com/watch?v=_7OEzyEfzgg (Feynman on Wave Particle Duality (QED Lecture in New Zealand). Quite the coincidence that I found this just yesterday and it gets brought up. $\endgroup$ – Striker Feb 8 '16 at 18:59
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how can fields explain why, when you watch which slit the "particle" goes through, does the interference pattern disappear?

a) Quantum field theory is a different mathematical tool and gives the same calculations as with simple first quantization calculations except it is just extremely more efficient in setting up solutions for complicated boundary conditions, and with the Feynman diagrams for calculating higher orders in perturbative expansion solutions. There exist no contradictions between first and second quantization, because the second quantization uses as a ground state function the psi solution of the boundary condition problem of the first quantization, and the field of operators acting on these ground states give the probability of an electron/muon/photon...( excitation of the field of electron/muon/photon...)to exist at that (x,y,z,t).

b) whether in first or second quantization framework , setting up detectors to define "which way " the particle went through, changes the boundary conditions of the problem. This recent experiment may help you understand .

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    $\begingroup$ QFT isn't deriving "the same calculations". QFT is a manifest theory of fields, which happens to be the correct theory for relativistic physics and multi-particle scenarios. QFT has absolutely nothing to do with "setting up" Feynman diagrams, unless you also believe that 19th century orbital perturbation theory is the "more efficient way" of setting up general Newtonian physics problems. $\endgroup$ – CuriousOne Feb 8 '16 at 16:13
  • $\begingroup$ @We will not agree on this. QFT is useful for calculations and it is only calculations giving checkable numbers that are relevant to physics. All the rest is mathematics. I am just pointing out the continuity between first (relativistic) and second quantization. There is no discrepancy. $\endgroup$ – anna v Feb 8 '16 at 16:43
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    $\begingroup$ QFT is no more or less "about calculations" than electrodynamics or thermodynamics are. It's a specific theoretical framework that can describe specific physical systems using a specific ontology of observable phenomena. There is no mathematics in physics. Mathematics deals with the proofs of non-trivial statements about infinite sets that are subject to axiomatic restrictions. That may be your hobby or second career, and it would be rewarding as either, but you have never, ever done that in your function as a physicist. $\endgroup$ – CuriousOne Feb 8 '16 at 16:48
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    $\begingroup$ @CuriousOne All physics theories use mathematics to fit experimental observations. The mathematics are not the physics, is all I am saying. The observations are. To assign reality, in the sense of : "fields exist even if there is nothing there", to what is a mathematical frame is a matter of metaphysics. $\endgroup$ – anna v Feb 8 '16 at 16:53
  • $\begingroup$ Physics uses the language of mathematics and it takes oversimplified results to talk sloppily about finite sets of measurements using mathematical statements that only make sense for infinite sets. It's perfectly OK to do that because it works (for the most part, until you hit non-trivial numerics where you learn the hard way how little you actually know about calculus and differential equations). What a theory is is defined by its ontology. Quantum field theory is defined by quantum fields just as thermodynamics is defined by homogeneous systems arbitrarily close to thermal equilibrium. $\endgroup$ – CuriousOne Feb 8 '16 at 17:00
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I can't comment on Hobson; I haven't read it. But I can comment on the ideas that you posted.

This is not an easy subject to unravel. Without looking too hard you'll find seemingly endless discussions. In my opinion, it boils down to what you mean by the words "particle". If your picture of a particle is a little bit of "something" that has an independent existence and moves through space in straight lines and bounces off of things, then you have a lot of trouble explaining things.

If by "particle" you mean a metaphor for an excitation of a field, something that is beyond our abilities to understand intuitively based on everyday experience, then you are in better shape.

It's certainly true that Young's experiment is easier to understand if we imagine a space-filling field which can be excited by one quantum here, and that quantum can be destroyed there. When destroyed, energy and momentum is transferred, as in a collision. With this picture, statements like "the particle goes through both slits" makes a little more sense. The field exists in both slits. One doesn't have to carry a nonsensical picture of a tiny blob of "something" being two places at once.

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    $\begingroup$ "One doesn't have to carry a nonsensical picture of a tiny blob of "something" being two places at once." only if one confuses the probability of being at either slit with real existence . Even in the creation and annihilation frame, it is the probabilities that are generated . quantum mechanics is about probabilities. $\endgroup$ – anna v Feb 8 '16 at 15:39
  • $\begingroup$ This is actually quite easy to unravel because "particle" has an extremely well defined meaning in classical physics: it's the approximation that an extended body (that's the only bodies that exist in classical physics) can be described by their center of mass coordinates alone. Nobody has ever redefined this in quantum physics, neither should one try because it doesn't work. $\endgroup$ – CuriousOne Feb 8 '16 at 16:10
  • $\begingroup$ @CuriousOne Well, that's what I was getting at. The word "particle" conjures up the classical picture, and that classical picture doesn't work. People coming upon this for the first time (perhaps the OP) doesn't know that, and tries to make the classical picture work. $\endgroup$ – garyp Feb 8 '16 at 19:00
  • $\begingroup$ @annav So you doubt the physical reality of the field. To you, it's just a mathematical tool, and we shouldn't bother trying to associate a physical interpretation. Maybe (see the discussion of Feynman diagrams), I don't know. But we humans like to "understand" in some sense. Perhaps we can't in QM. I try to create a picture for myself that makes sense and doesn't step on the theory too badly. Someone else might have a different picture that also "works". Particles as tiny blobs doesn't work. $\endgroup$ – garyp Feb 8 '16 at 19:15
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    $\begingroup$ @garyp paticle in the quantum mechanical regime has a different definition, it is a quantum mechanical entity. After all the standard model has a table of point particles with masses and spins that enter into the lagrangian for the calculations. Operator fields are very useful, but having sat through a nuclear physics course (back in 1962) with creation and annihilation operators for nuclear states, I always see them as an ingenious mathematical tool. $\endgroup$ – anna v Feb 8 '16 at 19:24
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Disturbtions of a field and particles

From the appearance of a wavelike intensity distribution behind slits Young concluded of a wave behavior of the light. Today we know, that such patterns occur also behind single edges, and this even with one by one flying photons or electrons. The last fact (single DEE and single particles) seems to imply more than the other experiments that we have to do with a disturbtion of a field from materialistic and/or energetic units (electric field and electron, EM field and photon). How to call units if not particles? They are particles and the emission as well as the absorption happens in quanta.

Interaction of particles and edges

It is without doubt that the edge of an obstacle divide incoming particles into reflected or absorbed particles and going away uninfluenced particles. Is there something between. Yes, it is. In the border area between "absorbed/reflected" and "going away" there is an area there particles could get deflected to some angles. From this follows that there is an interaction between the flying particles and the obstacle. How we call such an interaction? A field.

Quantized field and particle

If one move a charged surface close to an other surface the electric field of the charged surface induces a charge separation in the other surface. In edges and than more in sharp edges the induced electric field is stronger than in plane surfaces. The same phenomenon one can describe for magnetic fields.

What if suppose that the flying electron with its electric field as well as the photon with it's varying electric and magnetic fields are responsible for the induction of fields in the edge of an obstacle? Than the intensity distribution on an observer screen is the scaled image of the quantized field between the particles and the surface electrons of the edge(s).

The proof for such a point of view is

  • does it contradicts any observation, phenomenon or physical law and
  • makes it the exprlanation of phenomenons easier
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After reading Art Hobson's article titled, "There are no particles, there are only fields" published in The American Journal of Physics in 2013, I'm wondering what other experts think of his main thesis

I think there's some merit in it, but there's plenty wrong with it too. See his paper on the arXiv where you can read this: the Schroedinger field is a space-filling physical field whose value at any spatial point is the probability amplitude for an interaction to occur at that point. A physical field is a probability field? I don't think so. And whilst I like each electron extends over both slits, I don't like the field for an electron is the electron. OK the electron isn't some point particle. It has a standing-wave standing-field nature, such that the electron's field is what it is. But it's still a particle. Saying it's not, and that it's an excitation of the electron field, doesn't help much I'm afraid.

The double slit experiment, in all her variations, can be completely explained through relativistic quantum physics (quantum field theory) and that the alleged particle/wave "weirdness" is only weird because

I don't think it's weird at all. The electron or photon goes through both slits, but when you detect it at one slit something akin to an optical Fourier transform occurs. It becomes pointlike, so it goes through that slit only. Then when you detect it at the screen something akin to an optical Fourier transform occurs. It becomes pointlike, so you see a dot on the screen.

people don't realize that our best physical models of the universe model that universe as composed of fields ("particles" are excitations of that field).

I like this in his conclusion: In the 2-slit experiment, for example, the quantized field for each electron or photon comes simultaneously through both slits, spreads over the entire interference pattern, and collapses non-locally, upon interacting with the screen, into a small (but still spread out) region of the detecting screen. But I don't like this: the electron-positron field fills all space. Because I share Einstein's view that a field is a state of space. Space can't have two different states at one location. And we can convert photons into electrons and positrons and vice versa. The different fields can't be fundamental. They must be different aspects or configurations of the thing that is.

I get how it can explain everything in the double-slit experiment except the following- how can fields explain why, when you watch which slit the "particle" goes through, does the interference pattern disappear?

Like I was saying, something akin to an optical Fourier transform occurs. See Steve Lehar's web page for the optical Fourier transform performed by a lens.

enter image description here

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protected by Qmechanic Sep 15 '16 at 14:07

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