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Posted (edited)

That's because a photon isn't a single wave function, it's two

 

This is as saying an apple is not an cat because is two.

Edited by juanrga
Posted (edited)

No apologize is needed, because both quantum mechanics and experimental evidence support the idea of that a quantum particle is not a wave but... a particle.

 

 

 

here Steven Weinberg ( not introductory level) takes the opposite view. In my opinion it is a matter of opinion.

 

 

http://arxiv.org/pdf...h/9702027v1.pdf

 

quote from page 2

 

 

"In its mature form, the idea of quantum

 

field theory is that quantum fields are the basic ingredients of the universe,

 

and particles are just bundles of energy and momentum of the fields. In

 

a relativistic theory the wave function is a functional of these fields, not a

 

function of particle coordinates. Quantum field theory hence led to a more

 

unified view of nature than the old dualistic interpretation in terms of both

 

fields and particles."

 

 

 

Edited by qsa
Posted (edited)

here Steven Weinberg ( not introductory level) takes the opposite view. In my opinion it is a matter of opinion.

 

 

http://arxiv.org/pdf...h/9702027v1.pdf

 

quote from page 2

 

 

"In its mature form, the idea of quantum

 

field theory is that quantum fields are the basic ingredients of the universe,

 

and particles are just bundles of energy and momentum of the fields. In

 

a relativistic theory the wave function is a functional of these fields, not a

 

function of particle coordinates. Quantum field theory hence led to a more

 

unified view of nature than the old dualistic interpretation in terms of both

 

fields and particles."

 

 

 

 

I guess 1997 isn't terribly out of date, there were particle colliers at that time and even string theory and multiple-worlds theory.

Edited by questionposter
Posted

The only reason Shroedinger's wave mechanics formulation became dominant in the late 20s over Heisenberg's matrix formulation and Dirac's 'algebraic' formulation is that it was more familiar to the physics community and in a way closer to classical thinking.

 

The modern quantum field formulation has associated particles with it, but wave-particle duality is a misnomer. The case may be that it is neither particle or wave, it is just our mathematical model which is limited.

Posted (edited)

No apologize is needed, because both quantum mechanics and experimental evidence support the idea of that a quantum particle is not a wave but... a particle.

 

here Steven Weinberg ( not introductory level) takes the opposite view. In my opinion it is a matter of opinion.

 

 

http://arxiv.org/pdf...h/9702027v1.pdf

 

quote from page 2

 

 

"In its mature form, the idea of quantum

 

field theory is that quantum fields are the basic ingredients of the universe,

 

and particles are just bundles of energy and momentum of the fields. In

 

a relativistic theory the wave function is a functional of these fields, not a

 

function of particle coordinates. Quantum field theory hence led to a more

 

unified view of nature than the old dualistic interpretation in terms of both

 

fields and particles."

 

At contrary, Weinberg and me share a common view (although we differ in some details).

 

First, the part that you quoted is in the context of a historical description of how the subject was born. By "In its mature form" Weinberg refers to the work done about the 30s. The whole quote, including context, is:

 

In fact, it was quite soon after the Born–Heisenberg–Jordan paper of 1926 that the idea came along that in fact one could use quantum field theory for everything, not just for electromagnetism. This was the work of many theorists during the period 1928–1934, including Jordan, Wigner, Heisenberg, Pauli, Weisskopf, Furry, and Oppenheimer. Although this is often talked about as second quantization, I would like to urge that this description should be banned from physics, because a quantum field is not a quantized wave function. Certainly the Maxwell field is not the wave function of the photon, and for reasons that Dirac himself pointed out, the Klein–Gordon fields that we use for pions and Higgs bosons could not be the wave functions of the bosons. In its mature form, the idea of quantum field theory is that quantum fields are the basic ingredients of the universe, and particles are just bundles of energy and momentum of the fields. In a relativistic theory the wave function is a functional of these fields, not a function of particle coordinates. Quantum field theory hence led to a more unified view of nature than the old dualistic interpretation in terms of both fields and particles.

 

Second, in no part of that whole talk he says that a particle was a wave. At contrary, he writes stuff as:

 

The quantum theory of particles like electrons was being developed at the same time, and made relativistic by Dirac in 1928–1930.

 

the electron is a particle

 

and

 

I would like to urge that this description should be banned from physics, because a quantum field is not a quantized wave function

 

Third, as I said here photons are particles and the matter-wave duality is an outdated concept. Again Weinberg confirms this:

 

the old dualism that treated photons in an entirely different way from electrons is I think safely dead and will never return

 

Fourth, as explained above the quote that you reproduce is an old vision about quantum field theory and particles. Precisely Weinberg, writes after the part that you quoted (note that he starts writing in past sense):

 

The other thing I liked about quantum field theory during this period of tremendous optimism was that it offered a clear answer to the ancient question of what we mean by an elementary particle: it is simply a particle whose field appears in the Lagrangian. It doesn't matter if it's stable, unstable, heavy, light — if its field appears in the Lagrangian then it's elementary, otherwise it's composite.

 

Now my point of view has changed. [...] Let me run through this argument very rapidly. The first point is to start with Wigner's definition of physical multi-particle states as representations of the inhomogeneous Lorentz group.

 

Where the bold emphasis is from mine. Effectively, Weinberg starts from the unambiguous definition of particle. He then goes with the development and introduces the concept of fields after equation (3) for the interaction Hamiltonian. Technically he introduces fields as a way to satisfy certain requirements for the interaction between particles. The fields are not fundamental ingredients of nature but a technical help to write down a physically admissible S-matrix.

 

There exists theories whose interactions cannot be written using fields and those theories only use particles. That is why today quantum field theory is not believed to be a fundamental theory:

 

Now, all of these caveats really work only against the idea that the final theory of nature is a quantum field theory. [...] This leads us to the idea of effective field theories.
Edited by juanrga
Posted (edited)

The only reason Shroedinger's wave mechanics formulation became dominant in the late 20s over Heisenberg's matrix formulation and Dirac's 'algebraic' formulation is that it was more familiar to the physics community and in a way closer to classical thinking.

 

The modern quantum field formulation has associated particles with it, but wave-particle duality is a misnomer. The case may be that it is neither particle or wave, it is just our mathematical model which is limited.

 

It is true that isn't not completely a particle or a wave, which I already said, but wave-like properties can still describe many aspects of fermions and account for experimental results, especially neutrino oscillation and the double slit experiment as well as how photons localize and delocalize according to energy.

 

At contrary, Weinberg and me share a common view (although we differ in some details).

 

First, the part that you quoted is in the context of a historical description of how the subject was born. By "In its mature form" Weinberg refers to the work done about the 30s. The whole quote, including context, is:

 

 

 

Second, in no part of that whole talk he says that a particle was a wave. At contrary, he writes stuff as:

 

 

 

 

 

and

 

 

 

Third, as I said here photons are particles and the matter-wave duality is an outdated concept. Again Weinberg confirms this:

 

 

 

Fourth, as explained above the quote that you reproduce is an old vision about quantum field theory and particles. Precisely Weinberg, writes after the part that you quoted (note that he starts writing in past sense):

 

 

 

Where the bold emphasis is from mine. Effectively, Weinberg starts from the unambiguous definition of particle. He then goes with the development and introduces the concept of fields after equation (3) for the interaction Hamiltonian. Technically he introduces fields as a way to satisfy certain requirements for the interaction between particles. The fields are not fundamental ingredients of nature but a technical help to write down a physically admissible S-matrix.

 

There exists theories whose interactions cannot be written using fields and those theories only use particles. That is why today quantum field theory is not believed to be a fundamental theory:

 

 

 

I don't think you get it STILL. A particle doesn't include a limited field of view that limits an electron to being a little sphere or bundle, wave mechanics can be easily used to describe many aspects of a particle, but just can't completely account for a particle like EVERY variation of quantum mechanics.

And once again, bolding the word "particle" doesn't make your argument scientific law.

In the past perhaps Schrodinger tried to completely account for fermoins 100% by using quantum wave mechanics, which didn't work, and I had already said MULTIPLE TIMES that I'm fine with particles not being able to be 100% described by wave mechanics. Furthermore it's hypocritical of you to say that an electron is a particle considering the very quantum mechanics you are trying to uphold, quantum field theory, tries to represent fermoins like electrons as "fields" to look at how forces interact, which is one of the reasons why it's called quantum "field" theory. Not only that, but oscillation of fields is used in quantum field theory.

The word "particle" is often a vague term that means different things in different contexts.

Edited by questionposter
Posted

A particle doesn't include a limited field of view that limits an electron to being a little sphere or bundle

 

When Weinberg states that "the electron is a particle" he is not saying, not even insinuating, that was a "little sphere". :rolleyes:

 

In fact, Weinberg gives the definition of particle in his talk, but you missed that part as well...

Posted (edited)

Actually you need to be pretty careful what you mean by a particle or a wave.

 

I would be interested in protagonists' definitions.

Edited by studiot
Posted (edited)

I guess 1997 isn't terribly out of date, there were particle colliers at that time and even string theory and multiple-worlds theory.

 

THat article says that the description of a "field" for everything should be banned, not a wave.

 

 

"the idea came along that in fact one could use quantum field

theory for everything"

 

then a couple lines down

 

"I would like to urge that this

description should be banned from physics, because a quantum field is not

a quantized wave function"

 

It almost sounds like he is saying we shouldn't say things are fields because they don't consider wave-like properties.

 

Your defending quantum field theory yet the person you support doesn't seem to like it, it just goes to show my point that there are multiple ways to interpret what electrons and protons are, and all those views have their owns strengths and weaknesses. I just particularly like wave mechanics because it gives a better visual for "why" things actually are the way they are, and in many cases quantum wave mechanics can achieve similar results to other theories, at least experimental results, which is what really matters.

Edited by questionposter
Posted

@juanrga,

 

Weinberg is certainly not saying what you interpret what he is saying, IMHO. I will leave it to the interested reader to come to his own conclusion.

Posted

@juanrga,

 

Weinberg is certainly not saying what you interpret what he is saying, IMHO. I will leave it to the interested reader to come to his own conclusion.

 

No interpretation issue is here. Someone else said in this thread "the electron is a wave". I said that his claim is nonsense, because the electron is a particle and Weinberg in the same talk that you cite writes

The electron is a particle

 

Case closed.

Posted

No interpretation issue is here. Someone else said in this thread "the electron is a wave". I said that his claim is nonsense, because the electron is a particle and Weinberg in the same talk that you cite writes

 

 

Case closed.

 

Well a dictionary this to say about what a particle is, which is true in multiple interpretations of quantum mechanics.

Posted
Well a dictionary this to say about what a particle is, which is true in multiple interpretations of quantum mechanics.

 

So what do you (both) mean by a particle?

In other words by what characteristics might an imaprtial observer determine if an exhibit conformed to the definition?

 

And a wave too?

Posted (edited)

Well a dictionary this to say about what a particle is, which is true in multiple interpretations of quantum mechanics.

 

When Weinberg writes in his talk

The electron is a particle

 

and when the CERN folks write in their website

Everything around us is made of matter particles

 

They are not using ambiguous and imprecise words from a non-scientific online dictionary as you do. They are using the precise definition of elementary particle used in fundamental physics. A precise definition to which I alluded several times before in this thread but that seems that 'nobody' knows here :rolleyes:

Edited by juanrga
Posted (edited)
A precise definition to which I alluded several times

 

Alluded, yes but stated, never.

 

In particular I don't think you used the word 'elementary' to qualify the word particle before.

Edited by studiot
Posted

When Weinberg writes in his talk

 

 

and when the CERN folks write in their website

[/b]

 

They are not using ambiguous and imprecise words from a non-scientific online dictionary as you do. They are using the precise definition of elementary particle used in fundamental physics, one precise definition which I alluded several times before in this thread :rolleyes:

 

 

I had asked you to give a formal definition of charge, the fact that you didn't tells me that you are ignoring much of the story. Repeating yourself over and over again is not an argument, and there are many holes that you have not accounted for. If you can't account for the holes then you can't expect anyone to accept what you are saying as hard fact.

 

 

 

If one adopts the principle of complementarity, the wave-corpuscle duality ceases to be paradoxical; the wave aspect and the corpuscular aspect are two complementary aspects which are exhibited only in mutually exclusive experimental arrangements. Any attempt to reveal one of the two aspects requires a modification of the experimental set-up which destroys any possibility of observing the other aspect.

 

 

 

I'm pretty sure you are observing half of this statement, but not the other. I don't see Ryder making contradicting statements in this respect!

Posted

They are not using ambiguous and imprecise words from a non-scientific online dictionary as you do. They are using the precise definition of elementary particle used in fundamental physics. A precise definition to which I alluded several times before in this thread but that seems that 'nobody' knows here :rolleyes:

 

Argument by semantics is part of the problem, though, isn't it? You claim there are particles and no waves, but also admit that what CERN means by a particle is not what most people mean by particle, i.e. a "little sphere". Which is the whole point of discussing a wave-particle duality — it's precisely because we have these common interpretations that the physics is explained in this way. Admitting that physicists have redefined what particle means isn't particularly helpful to your argument. I could say that an electron is doo-doo, it's just I've redefined what doo-doo means for this case. Not really very helpful. Too Humpty-Dumpty-ish.

 

I think it's also a mistake to take what some high-energy physicists say and assume it represents all of physics. High energy particles have large momenta. That has certain implications using h/p.

Posted

There is also the issue of 'elementary'.

 

I had always understood the word to mean indivisible (in this application into smaller/more fundamental particles)

 

Does an electron meet this requirement?

Posted

juangra, I think it's high time you cough up, and state explicitly (rather than alluding to) what you mean by a non-classical particle. It is a very interesting debate, so I've done some asking around and, albeit wave functions are limited, and more modern treatments do not use them, I've been told the jury is still out, into how particles can be interpreted. IOW it is very abstract, and to palm off an interpretation as nonsense, just because a few text books use the word particle is a bit silly, no ?

 

Also, dropping the arrogance will do you some favours. You're making me suspicious.

Posted (edited)

Argument by semantics is part of the problem, though, isn't it? You claim there are particles and no waves, but also admit that what CERN means by a particle is not what most people mean by particle, i.e. a "little sphere". Which is the whole point of discussing a wave-particle duality — it's precisely because we have these common interpretations that the physics is explained in this way. Admitting that physicists have redefined what particle means isn't particularly helpful to your argument. I could say that an electron is doo-doo, it's just I've redefined what doo-doo means for this case. Not really very helpful. Too Humpty-Dumpty-ish.

 

I think it's also a mistake to take what some high-energy physicists say and assume it represents all of physics. High energy particles have large momenta. That has certain implications using h/p.

 

Having high energy does make them more localized, but it doesn't destroy their properties in the process.

 

When Weinberg writes in his talk

 

 

and when the CERN folks write in their website

[/b]

 

They are not using ambiguous and imprecise words from a non-scientific online dictionary as you do. They are using the precise definition of elementary particle used in fundamental physics. A precise definition to which I alluded several times before in this thread but that seems that 'nobody' knows here :rolleyes:

 

The problem with your arguments is that saying something is a "particle" doesn't mean it can't have wave-like properties.

 

Furthermore, do you think it's particle-like for an electron to occupy multiple positions simultaneously? Because it's not only quantum wave mechancis that predicts that, and you certainty couldn't intuitively infer that from the word "particle".

Edited by questionposter
Posted (edited)

http://www.sciencedaily.com/releases/2008/02/080222095358.htm

 

080222095358.jpg

 

http://arxiv.org/abs/1002.3880

 

the electron conducts itself not as re-radiated by the edge wave and not as a "probability amplitude wave". It behaves as deterministic non-local micro-object with a spatial density distribution. From the experimental observations of the angles of preferred scattering we may infer that this density

distribution has the shape of concentric shells of different hardness, the interval between the shells being of the order of de Broglie length

 

 

conclusions:

 

In the series of experiments above described I disproved the generally accepted since 1930s opinion that it is allegedly impossible without destroying interference pattern to observe the place, say, a slit, where the electron passed.

 

using the semiconductor sensors xed in the slit's edges enabled me to observe electron's fly not destroying the interference pattern.

 

 

Semiconductor sensors perceptible to nearby electron were so efficient that appeared to be capable to determine not only the slit where the electron passed through but even the proximity of the track to the left or right edge of each aperture.

 

When encountering an obstacle the electron does not bend around it, as EMWS do, but bounce o it as is appropriate to classical elastic macro-objects.

 

In the scattering pattern of electrons the left side peaks is formed by the ricochet from the right edge of the slit, and the right side peak is formed due to ricochet of electrons from the left edge of the slit, no interference of the electron's flows taking place

Edited by granpa
Posted (edited)

http://www.scienceda...80222095358.htm

 

080222095358.jpg

 

http://arxiv.org/abs/1002.3880

 

the electron conducts itself not as re-radiated by the edge wave and not as a "probability amplitude wave". It behaves as deterministic non-local micro-object with a spatial density distribution. From the experimental observations of the angles of preferred scattering we may infer that this density

distribution has the shape of concentric shells of different hardness, the interval between the shells being of the order of de Broglie length

 

 

conclusions:

 

 

 

using the semiconductor sensors xed in the slit's edges enabled me to observe electron's fly not destroying the interference pattern.

Those semi-conductors don't measure the particle, they merely alter the trajectory in a way that you can predict a possible outcome, and particles certainly aren't deterministic because you can't predict where they will actually be measured. That video/pictures is actually millions of separate measurements.

 

Semiconductor sensors perceptible to nearby electron were so efficient that appeared to be capable to determine not only the slit where the electron passed through but even the proximity of the track to the left or right edge of each aperture.

I'm a little worried about your semi-conductors, because there's the uncertainty principal which as not shown to be wrong which makes your statement wrong. It states the position and momentum cannot be known simultaneously.

 

When encountering an obstacle the electron does not bend around it, as EMWS do, but bounce o it as is appropriate to classical elastic macro-objects.

They may appear to bounce depending in their momentum. If your shooting an electron with a very high momentum, it will appear to be localized to a much much smaller area that seems like a solid particle than if you shot it at a low momentum that would make it more delocalized. And this is also why particles at CERN and in other particle colliders are generally more like precise spheres. They still can follow wave mechanics, but those wave mechanics jsut don't encompass a large area because of the uncertainty principal.

 

In the scattering pattern of electrons the left side peaks is formed by the ricochet from the right edge of the slit, and the right side peak is formed due to ricochet of electrons from the left edge of the slit, no interference of the electron's flows taking place

 

Your ricochet explanation doesn't make sense because scientists have already tried shooting small solid spheres through a double slit and they do not make that pattern. And then again, the uncertainty principal, which isn't wave mechanics, Heisenberg developed it separately from Schrodinger.

 

You can observe which slit an electron goes through, but if you constantly measure all the electrons in the experiment, you will NOT see the double slit pattern. This is scientifically proven.

Edited by questionposter
Posted
Your ricochet explanation doesn't make sense because scientists have already tried shooting small solid spheres through a double slit and they do not make that pattern. And then again, the uncertainty principal, which isn't wave mechanics, Heisenberg developed it separately from Schrodinger.

 

I wouldnt expect them to.

Posted (edited)

I wouldnt expect them to.

 

Then you shouldn't expect a measured electron to either, because a measured electron collapses down to a finite point.

 

It is possible to use semi-conductors, but if they don't directly measure the electron, they merely alter it's probability, which would explain why you could get "some" information about the electron but still have it be somewhat delocalized and form a different interference pattern.

Edited by questionposter
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