What makes an electron orbit?

[granpa]

I get the impression that you didnt download and read the pdf that I linked to.

[questionposter]

I get the impression that you didnt download and read the pdf that I linked to.

 

There was one was about the video, which wasn't very specific, and then there's a link where someone didn't correctly interpret data. There's numerous experiments that verify that measuring devices if completely measuring an electron will make the interference pattern impossible. Instead what is more likely is that the semi-conductors were able to pick up some information but not collapse the electron's wave function completely which is why there would still be an interference pattern. It depends on the method of semi-conductors, and the pdf didn't seem to state what information the person actually obtained by using the semi-conductors. Info on spin state? more precise momentum? Exact position? What?

As picky as it seems, those details are very important.

 

Also, he's substitution an electron for an electro-magnetic wave in his/her calculations, otherwise known as a photon, which is in many respects in dfferent than an electron, which may also account for large variations, because electrons are not described the same way as photons even within the same mechanics.

Edited May 4, 2012 by questionposter

[juanrga]

Alluded, yes but stated, never.

 

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

 

The definition of (elementary) particle was implicitly stated in #131 using a quote from Weinberg's talk.

 

I already used the term "elementary" in #93. The electron is an elementary particle the proton is a composite particle, both are particles.

[studiot]

Quote

 

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:

 

 

Thank you for your answer however I am unable to spot a clear and unambigouus current definition of a particle, elementary or otherwise in post#131.

 

I have quoted the part I think you are referring to but coloured the words which worry me. As I read this text it clearly states a historic definition and a refutation of this definition, but does not provide a current definiton.

Edited May 4, 2012 by studiot

[juanrga]

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.

 

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!

 

I replied to you in #95, stating that I did not understand your question. You never care to re-phrase or explain it. I do not still understand what do you mean by "a formal definition of charge". I only can guess that you mean "electric charge" and not "color charge" but little more...

 

You may believe that "there are many holes" in the statements done by me, by Weinberg in his talk, or in the statements found in the CERN website, but reality must be rather different.

 

Albert Messiah's QM is a dated textbook. QM is based in a set of postulates (see e.g. Cohen textbook or Weinberg textbook cited before), none of which is a "principle of complementarity". The rest of your quotation (specially the bold part) was already answered before in #56, using a quotation from an editor of the Wikipedia. I reproduce the quote from him:

 

Early quantum physicists are forced to use classical concepts such as "newtonian particle" and "Fresnel wave" to describe quantum objects in contradictory manner because they had no other concepts. [...] duality is only of historical interest. [...]

 

Sources, speaking on the "duality", either obsolete or are popular, educational, or philosophical literature. Serious contemporary theoretical sources don't mention about duality, they use more effective approaches, almost all based on PI. There is a good analogy with the notion of so-called "relativistic mass", which served its in the interpretation of relativistic effects in terms of Newtonian physics, but in the modern 4-dimensional formulation only creates a confusion

Finally, about Ryder, your own words were:

Now looking through Ryder's book on QFT I don't see any mention at all of wave like particles and the discussion is limited to particles, period.

 

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.

 

Already in #5 I emphasized that different theories give different meaning to different terms and that one would not mix concepts:

 

The concepts of electron in Maxwell-Lorentz theory, Bohr theory, Lewis theory, quantum mechanical theory, Dirac theory, quantum electrodynamics theory are different. For instance, an electron in Dirac theory has a property named spin, an electron in in Maxwell-Lorentz theory do not have spin. An electron in Bohr theory belong to a given atom, and electron in Lewis theory can belong to two atoms at once, etcetera.

 

The change was done because problems with the previous concepts were found in the lab and better concepts and theories were developed. The problem does not seem to be one of semantics, but twofold. At the one hand, some of people believes that outdated concepts/theories/books have the same status than modern ones. At the other hand, some people do not read my posts. One folk has recently stated that I never used the word "elementary" before, when I did... and more than one time.

 

If you believe that particle physicists claims such as "the electron is a particle" "Everything around us is made of matter particles" are not universal or need correction, please indicate us some amount of matter which is no made of the known particles in the table given before.

 

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.

 

As stated before, particle physicists have given precise definitions of what is and what is not a particle (either composite or elementary). Weinberg in his talk writes about what is a particle. Myself have given the properties that define specific particles (mass, charge, spin...) and given a table with all known particles plus some hypothetical.

 

I also stated that the definition of particle is found in textbooks. I cite a pair of relevant textbooks, including Weinberg one. In this book we can find a definition of quantum particle

 

http://books.google....ducible&f=false

 

I also give a Adv. Chem. Phys. article explaining how quantum mechanics has to be generalized for dealing with unstable particles...

 

Regarding your allusion to arrogance. The only arrogance that I can find here becomes from posters who believe that a Nobel laureate as S. Weinberg or a worldwide expert center as CERN are wrong when claim that an electron is a particle and that everything is made of particles. The 'argument' given by this posters is a vague allusion to the well-known interference experiments. I find arrogant that those posters pretend that Weinberg-CERN are wrong because do not know what is an interference experiment!

 

Thank you for your answer however I am unable to spot a clear and unambigouus current definition of a particle, elementary or otherwise in post#131.

 

I give it again now. And add a textbook link

Edited May 4, 2012 by juanrga

[imatfaal]

!

Moderator Note

Everyone - Please criticise only the arguments and not the attitude nor the person - ie no more talk of arrogance.

Juanrga - Your last link doesn't work for me. Could you perhaps put your own definition on the boards to satisfy the other posters?

[questionposter]

The definition of (elementary) particle was implicitly stated in #131 using a quote from Weinberg's talk.

 

I already used the term "elementary" in #93. The electron is an elementary particle the proton is a composite particle, both are particles.

 

So one scientist happens to describe a particle as something that kind of supports your argument. Big deal.

Also, your link doesn't really work for me either.

[studiot]

Surely the only definition of importance is the one employed by a poster making a point, rather than some hearsay definition from another source outside SF and this thread.

 

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

 

function of particle coordinates.

 

I am particularly chary of a source which makes this sort of statement.

 

A functional is a particular term for a mapping from a vector space of functions to the space of real numbers. How does any definition of a wave fit this?

 

 

 

[juanrga]

!

Moderator Note

Everyone - Please criticise only the arguments and not the attitude nor the person - ie no more talk of arrogance.

 

Juanrga - Your last link doesn't work for me. Could you perhaps put your own definition on the boards to satisfy the other posters?

 

First a remark: I am not giving my own definition of particle. I am alluding to the standard definition of particle used in a branch of science named particle physics.

 

It is this standard definition which Weinberg alludes to, when he emphasizes that "the electron is a particle" and when writes "The quantum theory of particles like electrons". When Weinberg writes in his talk that he starts with "Wigner's definition", he means Wigner definition of particle. It is this standard definition of particle which leads to Weinberg to say in his talk that the "old dualism" is "safely dead and will never return". This is the standard definition of particle used by guys at CERN when write, in their own website, that electrons are particles and that:

 

The theories and discoveries of thousands of physicists over the past century have resulted in a remarkable insight into the fundamental structure of matter: everything in the Universe is found to be made from twelve basic building blocks called fundamental particles

 

Evidently, CERN guys do not mention old myths as "dualism", "matter waves", and all that outdated and nonsensical stuff.

 

I have given a table of elementary particles in #114. Composite particles are made of elementary particles. For instance a proton is made of 2 quark-up plus 1 quark-down.

 

About the link, I just click in the link in the above post and it works for me, opening a new tab in my FF browser with the next webpage from Google Books:

Edited May 4, 2012 by juanrga

[Xittenn]

Finally, about Ryder, your own words were:

 

My interpretation of what juanrga was saying is that although wave functions have--at a more rudimentary level--explained some of the phenomena associated with quantum mechanics, more modern approaches have been developed that make better sense of the available information, like with QFT. Now looking through Ryder's book on QFT I don't see any mention at all of wave like particles and the discussion is limited to particles, period. The book does not however offer an explanation for this.

 

I found this on Wiki. I do however find it incredulous that anyone would offer Wiki as an argument for or against any point made in the context at present--especially against someone who has obviously spent some time considering more viable literature. How about offering up a more formal citation michel123456? I would like to point out that the wiki article I just submitted has zero citations to support its statements, which doesn't make it wrong, it just makes it weak.

 

----------------------------------------------------

 

I am finding more in Ryder's book on waves at closer look, maybe I'll find something relevant.

 

---------------------------------------------------

 

2.2 Klein-Gordon Equation

 

"The interpretation of the Klein-Gordon equation as a single particle equation, with a wave function [math] \phi [/math], therefore also has to be abandoned." - Ryder

 

the explanation is deeply mathematical and requires a chapter of discussion . . .

 

 

 

At first glance, and looking through the index, it had appeared that way. The first chapter starts on particles but then essentially takes a short route equivalent to Messiah's point. The elaboration is brief being about one chapter long contained in two chapters. I missed it at first because I had previously read some of the first chapter earlier, and when I went back I looked through the index and then went backwards through the book. I had come to a too quick conclusion, but I had addressed the fact within a five minute period of time--sometimes I type in a more live fashion, I'm sorry. Messiah develops the very same idea over many chapters, in great detail, and I don't see this text as outdated, and it happens to be well recommended by a great many scientist.

 

As for charge, I will go ahead and link the 'formal definition' in Wiki just to give you an idea of what I was thinking about:

Formal definition

 

More abstractly, a charge is any generator of a continuous symmetry of the physical system under study. When a physical system has a symmetry of some sort, Noether's theorem implies the existence of a conserved current. The thing that "flows" in the current is the "charge", the charge is the generator of the (local) symmetry group. This charge is sometimes called the Noether charge.

 

Thus, for example, the electric charge is the generator of the U(1) symmetry of electromagnetism. The conserved current is the electric current.

 

In the case of local, dynamical symmetries, associated with every charge is a gauge field; when quantized, the gauge field becomes a gauge boson. The charges of the theory "radiate" the gauge field. Thus, for example, the gauge field of electromagnetism is the electromagnetic field; and the gauge boson is the photon.

 

Sometimes, the word "charge" is used as a synonym for "generator" in referring to the generator of the symmetry. More precisely, when the symmetry group is a Lie group, then the charges are understood to correspond to the root system of the Lie group; the discreteness of the root system accounting for the quantization of the charge.

 

I bolded what I think is the relevant part to this conversation!

 

On a side note I neg rep'ed Granpa because he quotes his link, but it completely looks like they are his own opinions even though they are a quote . . . I don't think everyone caught that! Sorry if I was being critical, I just thought it should be more easily recognized as a quote and not Granpas writings. Someone has obviously corrected my reaction to post #147.

 

Evidently, CERN guys do not mention old myths as "dualism", "matter waves", and all that outdated and nonsensical stuff.

 

 

I do see where the literature very clearly states that 'Dualism' or 'Duality' or 'Wave-Particle Duality' from the historical view is incorrect. I think Messiah made statements that attempted to address this and is what I posted earlier. I do not however see anything that explicitly supports your statements that electrons are particles and not waves. I've seen literature that more explicitly states that electrons are waves except in certain experimental conditions where one would treat them exclusively as particles and not wave particles. I also believe that the deeper abstraction supports this view and not the one that you are trying to condition.

[swansont]

First a remark: I am not giving my own definition of particle. I am alluding to the standard definition of particle used in a branch of science named particle physics.

 

I'll say it again: Particle physics does not represent all of physics. You can't argue for something being generally true based on a specific example. Universal affirmatives can only be partially converted

[juanrga]

As for charge, I will go ahead and link the 'formal definition' in Wiki just to give you an idea of what I was thinking about:

 

I have no comments on that "formal definition".

 

Evidently, CERN guys do not mention old myths as "dualism", "matter waves", and all that outdated and nonsensical stuff.

 

I do see where the literature very clearly states that 'Dualism' or 'Duality' or 'Wave-Particle Duality' from the historical view is incorrect. I think Messiah made statements that attempted to address this and is what I posted earlier. I do not however see anything that explicitly supports your statements that electrons are particles and not waves. I've seen literature that more explicitly states that electrons are waves except in certain experimental conditions where one would treat them exclusively as particles and not wave particles. I also believe that the deeper abstraction supports this view and not the one that you are trying to condition.

 

Therefore, you saying me that when you go to the CERN glossary and read stuff as

 

Lepton

 

A class of elementary particle that includes the electron.

 

Particles

 

There are two groups of elementary particles, quarks and leptons. The quarks are up and down, charm and strange, top and bottom. The leptons are electron and electron neutrino, muon and muon neutrino, tau and tau neutrino....

 

You "do not however see anything that explicitly supports your statements that electrons are particles and not waves."

 

It seems evident that further discussion must be useless. No?

[studiot]

It seems evident that further discussion must be useless. No

 

Discussion is only useless with those who won't listen.

 

You made an all embracing sweeping statement

 

"Electrons are particles"

 

Now, I have a different understanding of the word 'particle' from yourself.

Furthermore I claim grandfather rights on my definition of the subject since my definition goes back at least as far as Newton's corpuscles.

 

However I have been prepared to listen and I now thank you for helping me update my view of the current state of particle physics.

 

Having followed the discussion I do not see that you have proved your point. In fact you have failed to respond when I observed that your hero is lax with mathematical terminology.

 

Your thesis is that we should take on trust the above statement apparantly because someone says so rather than on account of proof.

 

Like all physics 'an electron' is a model.

 

Models are useful when their response to a property of interest is the same or indistinguishable from the actuality.

 

A particle is a model. In my view a particle is an entity where the entire property or properties of interest can be considered to act or be concentrated at one point. A particle need not be small that depends upon the nature of the system under consideration.

[questionposter]

A pool of water can have ripples. Does that mean water is a wave but not water? Water can be waving and have wave-like properties, just like a particle can.

Edited May 4, 2012 by questionposter

[juanrga]

I'll say it again: Particle physics does not represent all of physics.

 

I think that I do not need to argue about something that I have not said. In fact, I cited a paper that introduces a generalization of the concept of particle used in particle physics.

Edited May 5, 2012 by juanrga

[qsa]

Surely the only definition of importance is the one employed by a poster making a point, rather than some hearsay definition from another source outside SF and this thread.

 

 

 

I am particularly chary of a source which makes this sort of statement.

 

A functional is a particular term for a mapping from a vector space of functions to the space of real numbers. How does any definition of a wave fit this?

 

 

 

 

 

http://en.wikipedia....nger_functional

 

http://physics.stack...-wavefunctional

 

http://en.wikipedia....article_duality

 

http://physics.stackexchange.com/questions/8179/how-can-a-point-particle-have-properties

 

 

 

 

http://en.wikipedia....:Point_particle

Edited May 4, 2012 by qsa

[juanrga]

Discussion is only useless with those who won't listen.

 

You made an all embracing sweeping statement

 

"Electrons are particles"

 

I do not wait to convince to people who cannot be convinced, but at least it would be fair if the "you made" is changed to "thousands of scientists, including you, made".

 

Already in #162 (i.e. the post just before the your) you can find quotes and link from CERN website stating that the electron is a particle.

Edited May 4, 2012 by juanrga

[studiot]

'Vector' is obviously not the only word where physicists, mathematicians and others use the same word for different definitions.

 

 

Edit

Thank you qsa for those references.

 

They appear to identify a wavefunctional with a definite integral or definite difference between a zero state and some specific state - and which is a real number and consistent with the maths definition.

 

Can someone identify the units of this real number since electrons apparantly these?

Edited May 5, 2012 by studiot

[juanrga]

A pool of water can have ripples. Does that mean water is a wave but not water? Water can be waving and have wave-like properties, just like a particle can.

 

After saying that an electron is a wave (a plain wrong statement), are you trying to say now that water is also a wave?

[swansont]

I think that I do not need to argue about something that I have not said. In fact, I cited a paper that introduces a generalization of the concept of particle used in particle physics.

 

emphasis added.

 

Kinda proves my point.

[juanrga]

I think that I do not need to argue about something that I have not said. In fact, I cited a paper that introduces a generalization of the concept of particle used in particle physics.

 

emphasis added.

 

Kinda proves my point.

 

Maybe I would have added that the generalization in that paper allows for a precise characterization of unstable particles, but it reduces to the particle physics definition for stable particles as the electron.

 

http://en.wikipedia....:Point_particle

 

Some relevant extracts from that link:

 

As of 2000, all X-ray scattering experiments have shown that electrons behave as point-like particles with no spatial extent (ref: H. Haken; Hans Christoph Wolf (2000). The physics of atoms and quanta: introduction to experiments and theory (6th ed.). Springer. p. 70. ISBN 3540672745. ).

 

My first understanding of the point particle came from reading the "God Particle:" by Lederman. On page 141 and 142 he discusses electron and refers to it as a point particle.

 

This can be observed in scattering experiments – a major topic we ought to have a better article on (cf [2] as an outline); also in high-precision tests of the electron's dimensionless magnetic moment (g-factor), which are in close agreement with the predictions of QED for a point particle;

 

And the corresponding article

 

http://en.wikipedia..../Point_particle

 

also contains relevant statements, which I reproduce next:

 

There is nevertheless a distinction between elementary particles such as electrons or quarks, which have no internal structure, versus composite particles such as protons, which do have internal structure: A proton is made of three quarks.

 

In quantum mechanics, there is a distinction between an elementary particle (also called "point particle") and a composite particle. An elementary particle, such as an electron, quark, or photon, is a particle with no internal structure, whereas a composite particle, such as a proton or neutron, has an internal structure (see figure).

 

For example, see atomic orbital: The electron is an elementary particle, but its quantum states form three-dimensional patterns

 

Nevertheless, there is good reason that an elementary particle is often called a point particle. Even if an elementary particle has a delocalized wavepacket, the wavepacket is in fact a quantum superposition of quantum states wherein the particle is exactly localized. This is not true for a composite particle, which can never be represented as a superposition of exactly-localized quantum states. It is in this sense that physicists can discuss the intrinsic "size" of a particle: The size of its internal structure, not the size of its wavepacket. The "size" of an elementary particle, in this sense, is exactly zero. For example, for the electron, experimental evidence shows that the size of an electron is less than 10^-18 m.^[6] This is consistent with the expected value of exactly zero. (This should not be confused with the classical electron radius, which, despite the name, is unrelated to the actual size of an electron.)

Edited May 5, 2012 by juanrga

[qsa]

@juanrga

 

I have given these references to show the nature of the debate. You can emphasize the arquements that support your point of view, that is fine. But my point is that there are two points of view, hence there is no final conclusion, if there was, you would have not seen those references.

 

But you also have the habit of taking a counter arquement and making it your own, I am a bit baffled as to the reason. For example (I don't have the energy to list all),

 

"

 

For example, see atomic orbital: The electron is an elementary particle, but its quantum states form three-dimensional patterns"

 

 

This arquement says that the electron is NOT considered as a point particle, but smeared in a probabalistic cloud in a relatively big volume.

 

http://www.physicsfo...ad.php?t=144746

 

notice the thread was locked. Since some hardcore mainstream would consider the question UNSCIENTIFIC, i.e. it is a philosophical musing. How many viewpoints do you like to see.

Edited May 5, 2012 by qsa

[questionposter]

After saying that an electron is a wave (a plain wrong statement), are you trying to say now that water is also a wave?

 

I think you need to read my posts more carefully. Besides, my very original post was that electrons wave, not that they are waves. Actually I didn't even state it waves, I just stated it has probability fields, then I stated it waves, and then to explain why it waves I said i has wave-particle duality which isn't exactly disproved.

Edited May 5, 2012 by questionposter

[qsa]

@juanrga

Also this from a well known physicist, notice the last pragraph!!

Exactly what I quoted but interpreted in a very strange way by you.

 

http://www.mat.univi...complementarity

-----------------------------------------------Why are fields more fundamental than particles?-----------------------------------------------

 

 

 

In quantum field theory, the field aspect and the particle aspect are complementary to each other (in a precise sense related to what is called ''second quantization''). Experimentally, depending on the experimental situation, we ''see'' one or the other. Now one can understand the particle concept as a limit of the field concept, namely as the approximation of geometric optics, where particle rays approximately follow definite paths. But there seems to be no way to regard the field concept as a limit of the particle concept. Moreover, a pure particle view cannot even formally capture all aspects of the fields. Dynamical symmetry breaking, for example, is an intrinsic field phenomenon. Finally, even in atomic physics and quantum chemistry, electrons are usually delocalized - a feature naturally explained in terms of fields but very counterintuitive in terms of particles.

 

For all these reasons, the field aspect must be considered to be more fundamental.On p.2 of his essay, What is Quantum Field Theory, and What Did We Think It Is? http://arxiv.org/pdf/hep-th/9702027v1,

 

Weinberg writes: ''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 May 5, 2012 by qsa

[juanrga]

@juanrga

 

I have given these references to show the nature of the debate. You can emphasize the arquements that support your point of view, that is fine. But my point is that there are two points of view, hence there is no final conclusion, if there was, you would have not seen those references.

 

But you also have the habit of taking a counter arquement and making it your own, I am a bit baffled as to the reason. For example (I don't have the energy to list all),

 

"

 

For example, see atomic orbital: The electron is an elementary particle, but its quantum states form three-dimensional patterns"

 

 

This arquement says that the electron is NOT considered as a point particle, but smeared in a probabalistic cloud in a relatively big volume.

 

http://www.physicsfo...ad.php?t=144746

 

notice the thread was locked. Since some hardcore mainstream would consider the question UNSCIENTIFIC, i.e. it is a philosophical musing. How many viewpoints do you like to see.

 

The part that you repeat above says "the electron is an elementary particle" and this exactly what I have said. No contradiction here.

 

The informal poll that you quote is not particle versus wave, but particle versus field. A field is an infinite collection of particles and, by definition, is unobservable. Particles are observed each day.

 

I think you need to read my posts more carefully. Besides, my very original post was that electrons wave, not that they are waves.

 

From your post #19

I was thinking because electrons are waves, they physically exist, and according to the math that describes it, they have physical oscillation.

 

 

@juanrga

Also this from a well known physicist, notice the last pragraph!!

Exactly what I quoted but interpreted in a very strange way by you.

 

http://www.mat.univi...complementarity

-----------------------------------------------Why are fields more fundamental than particles?-----------------------------------------------

 

 

 

In quantum field theory, the field aspect and the particle aspect are complementary to each other (in a precise sense related to what is called ''second quantization''). Experimentally, depending on the experimental situation, we ''see'' one or the other. Now one can understand the particle concept as a limit of the field concept, namely as the approximation of geometric optics, where particle rays approximately follow definite paths. But there seems to be no way to regard the field concept as a limit of the particle concept. Moreover, a pure particle view cannot even formally capture all aspects of the fields. Dynamical symmetry breaking, for example, is an intrinsic field phenomenon. Finally, even in atomic physics and quantum chemistry, electrons are usually delocalized - a feature naturally explained in terms of fields but very counterintuitive in terms of particles.

 

For all these reasons, the field aspect must be considered to be more fundamental.On p.2 of his essay, What is Quantum Field Theory, and What Did We Think It Is? http://arxiv.org/pdf/hep-th/9702027v1,

 

Weinberg writes: ''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.''

 

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 historical 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, 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:

 

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.

 

Third, Weinberg confirms my point that an electron is a particle and he does in several parts of his talk:

 

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

 

Neumaier is not right regarding the fundamental nature of fields. Being a mathematician Neumaier also omits to say that fields are not observable, unlike particles. Yes, I read the last paragraph. However, in another part Neumaier contradicts to himself and agrees with me on that both photons and electrons are particles.

 

http://www.mat.univi...faq/topics/free

 

In Nature, there are - strictly speaking - no free particles, only interacting ones. This holds both for photons and for other more tangible particles like electrons.

 

Apart from the several textbooks cited, the CERN website, the Weinberg talk, Neumaier FAQ, and myself explaining that the electron is a particle, you can find the same in lot of encyclopedias, academic websites, and online general dictionaries

 

http://scienceworld....s/Electron.html

The electron, denoted is a fundamental particle

 

http://physics.about.../g/electron.htm

An electron is a fundamental particle, which means it cannot be broken into smaller particles. [...] The electron is a fermion, which means it has a half-integer spin. Electrons are members of the lepton family of particles.

 

http://hyperphysics..../lepton.html#c2

As one of the leptons, the electron is viewed as one of the fundamental particles.

 

http://hyperphysics....s/spinc.html#c2

Fermions are particles which have half-integer spin and therefore are constrained by the Pauli exclusion principle. Particles with integer spin are called bosons. Fermions include electrons, protons, neutrons.

 

http://www.merriam-w...ionary/electron

Definition of ELECTRON: an elementary particle

 

http://www.thefreedi...ry.com/electron

A stable subatomic particle in the lepton family [...] a stable elementary particle present in all atoms, [...] A stable elementary particle in the lepton family

 

http://dictionary.re...browse/electron

Also called negatron. Physics, Chemistry . an elementary particle that is a fundamental constituent of matter

 

http://www.pbs.org/w...nt/part-nf.html

The electron is a negatively charged particle that surrounds the nucleus of an atom.

 

http://public.web.ce...ossary-en.php#L

Lepton. A class of elementary particle that includes the electron.

 

http://www.pas.roche...le_physics.html

Leptons are the six particles at the bottom of the periodic table. The bottom row shows the electron, the muon, and the tau particles. You are probably familiar with the electron

 

http://www.britannic...ectron-muon-tau

Probably the most-familiar subatomic particle is the electron, the component of atoms that makes interatomic bonding and chemical reactions—and hence life—possible. The electron was also the first particle to be discovered.

 

http://hepwww.rl.ac....l/glossary.html

Electron: A negatively charged particle (lepton) making up the outer shell ofthe atom.

 

http://burro.cwru.ed...rticlephys.html

There are the electron, muon, and tau particles

 

http://www-sldnt.sla...ndard_model.htm

Chemistry can be understood in the physics of 3 particles (proton, neutron and electron)

 

See also the newspaper presentation My favourite particle: the electron

Edited May 5, 2012 by juanrga