Are All Fundamental Particles Truly Pointlike?

[Sean Torrebadel]

So what is the quantum mechanical solution that explains interference caused by one electron at a time/ two slit experiment? In one respect this thread is adamant that an electron is a point particle. In the next it evokes wave/particle duality to explain that electrons are spread out. Are you saying that an electron is a point particle that goes through both slits simultaneously and therein interferes with itself? I know one thing. The electron hits the photographic plate in a single ping. I would argue that it is more reasonable to state that an electron is a point particle whose nature extends into the surrounding space. But then we don't want to talk about aethers do we?

 

[ZapperZ]

So what is the quantum mechanical solution that explains interference caused by one electron at a time/ two slit experiment?

Read T. Marcella, Eur. J. Phys. v.23, p.615 (2002).

In one respect this thread is adamant that an electron is a point particle. In the next it evokes wave/particle duality to explain that electrons are spread out. Are you saying that an electron is a point particle that goes through both slits simultaneously and therein interferes with itself? I know one thing. The electron hits the photographic plate in a single ping. I would argue that it is more reasonable to state that an electron is a point particle whose nature extends into the surrounding space. But then we don't want to talk about aethers do we?

At what point do we actually OPEN A BOOK and look at what QM actually HAS said?

Does Feynman path integral ring a bell? What about "superposition of paths"? Would you also be surprised that I can actually get the same interference pattern when I have supercurrent going through two branches of paths in a superconducting circuit? It has nothing to do with the size of it. It has everything to do with the superposition principle. In the case of the double slit, it is the superposition of paths that each electron can take. This is what causes the interference. I can get the same thing with a glob of coherent electrons (supercurrent), or something as big as buckyballs! It doesn't matter! As long as these are quantum particles and I set up the experiment in such a way that I have no way to tell how which way they go, then I have set up a superposition of states and I get interference results! You have been distracted so much towards the electrons that you forgot (or maybe you didn't know) the principle involved in producing such effects!

I think this thread has ran its course and I don't see anything of benefit anymore in this discourse, especially when things that are available to be learned from are being ignored. Nothing that I've said here is news to anyone who has opened a standard QM text. It gets very tiring to keep having to backtrack and cover basic QM just simply to get rid of the misinformation or outright mistakes being made. Maybe someone else want to continue with this, but I think I'm done here. I don't see the point of having to repeat things that are available right out of a standard textbook.

Zz.

 

[Sean Torrebadel]

Perhaps you misunderstood me. One electron, one, shot at a time-say one a day. Over a period of time, say 200 days, an interference pattern is observed on the exposure.

Yes quantum mechanics can explain the path that each electron has followed. It does a wonderful job.

But explain why the electron chose that path when it was alone. What did it interfere with? When it was alone?

 

[Sean Torrebadel]

Does the electron know that another electron is coming behind it, in say an hour... Does it know that one came before it? What is this spontaneous interference? Just because there are two paths to choose, one through either slit, and just because there is an equation in quantum mechanics that can account for interference as a whole, does not mean that there is an explanation as to why interference occurs when

one electron a day travels through either of two slits...

Otherwise, everything around us would interfere with everything. In the subatomic realm, everything would interfere with everything.

 

[Sean Torrebadel]

Perhaps we should just say that quantum physics describes the path taken, mathematically- and admit that there is no easy explanation for this phenomenon. Zap

 

[Phred101.2]

Does the electron know that another electron is coming behind it, in say an hour... Does it know that one came before it? What is this spontaneous interference? Just because there are two paths to choose, one through either slit, and just because there is an equation in quantum mechanics that can account for interference as a whole, does not mean that there is an explanation as to why interference occurs when

one electron a day travels through either of two slits...

How can an "electron" know anything? Unless you mean it "communicates" by sending and receiving photons (to other electrons)? How does an electron "choose" to emit or absorb a photon? Why do you think these things have to "explain" something? Or what it "means" or "does not mean" to them? What, after all is an "explanation" except something humans "produce" (in their heads)?

 

[Sean Torrebadel]

How can an "electron" know anything? Unless you mean it "communicates" by sending and receiving photons (to other electrons)? How does an electron "choose" to emit or absorb a photon? Why do you think these things have to "explain" something? Or what it "means" or "does not mean" to them? What, after all is an "explanation" except something humans "produce" (in their heads)?

This is exactly the point. Do not infer that i am saying that this is the case.

The question is how ---one electron-- can interfere with its own path. If there is only one slit there is no interference. If there is two slits there is interference --even if only one isolated electron passes through the experiment, say, every hour. This does not mean that I do not understand the phenomenon of interference when there is a stream of particles. I understand the Uncertainty principle, and that the shrodinger has a definition for the electron's motion. I know that the paths which have been taken are consistent with interference.

What I want to know is how, an electron, if it is a point particle, and even if its smeared over some infinite space- how it interferes with itself?

For without an explanation to this, then my more philosophical rambling above remains valid.

 

[Hurkyl]

The question is how ---one electron-- can interfere with its own path.

Exactly in the way QM describes!

 

[Hurkyl]

Perhaps we should just say that quantum physics describes the path taken, mathematically- and admit that there is no easy explanation for this phenomenon. Zap

What other possible meaning could you give to the word "explanation"?

 

[malawi_glenn]

So what is the quantum mechanical solution that explains interference caused by one electron at a time/ two slit experiment? In one respect this thread is adamant that an electron is a point particle. In the next it evokes wave/particle duality to explain that electrons are spread out. Are you saying that an electron is a point particle that goes through both slits simultaneously and therein interferes with itself? I know one thing. The electron hits the photographic plate in a single ping. I would argue that it is more reasonable to state that an electron is a point particle whose nature extends into the surrounding space. But then we don't want to talk about aethers do we?

And when you examine which slit the electron passes, the interference pattern disappear. First you may read and study what contemporary physics is doing, at the real level... No one who has studied QFT at university level an has passed are devoted to aehter theories, as least not i know anyone.

 

[malawi_glenn]

Perhaps you misunderstood me. One electron, one, shot at a time-say one a day. Over a period of time, say 200 days, an interference pattern is observed on the exposure.

Yes quantum mechanics can explain the path that each electron has followed. It does a wonderful job.

But explain why the electron chose that path when it was alone. What did it interfere with? When it was alone?

And it also says that a measurement causes the wave function to collapse into an eigenstate to the opeator.. If you have no device that is looking for which path an electron takes, you get no diffraction pattern. Its all about the superposition of eigenstates that Zapper wrote, and there is NO way to say which eigensstate the electron was before measurment.

 

[Sean Torrebadel]

And it also says that a measurement causes the wave function to collapse into an eigenstate to the opeator.. If you have no device that is looking for which path an electron takes, you get no diffraction pattern. Its all about the superposition of eigenstates that Zapper wrote, and there is NO way to say which eigensstate the electron was before measurment.

I don't see how throwing Heisenberg at me is an answer the question? I know that any measurement or attempt to observe the electrons path will affect the path. What I am asking is how an electron interferes with itself? The path that a single electron takes is the same as those taken by streams of electrons. It is an interfering pattern. I think that this goes beyond the math.

I've been looking through the archives. Over and over again the concept of one electron/ two slit phenomenon is somehow misconstrewed as being a stream. Everytime this topic comes up the same references are made to the Uncertainty principle, the shrodinger equation, the QM texts, that the math explains the electrons behaviour. There is no doubt about these truths.

The question is how a single point particle or even a single cloud of charge (whatever its boundary), at a frequency or scintillation count that guarantees that only one electron is moving towards the two slits at a time, so that with the highest degree of probability a single electron is making its way through the slits, with enough time between electrons, that it can be considered entirely alone. Then and only then how does the electron intefere with itself and thereby follow the interference paths that quantum mechanics has so well defined?

The only explanation that I can make is the one that I have given. ( above) That particles may be construed as a point as an origin of some process that connects them to the surrounding space. That this connection needs to be both simultaneously connected with the surrounding space to effect change within that space, and then discontiuous with that space in order for it to have its own inertia. This argument allows for the electron to exist both as a point wherein the volume may be a minimum and it may also extend the nature of the electron to the fields that surround it. An electron would therefore be defined by both its center and the process and the physical consequences of that process that extend into the surrounding space.

In conclusion, an electron may pass through one slit as a particle and an origin of some force. The effect that it has upon the surronding field may extend to the second slit, become discontinous from the source, radiate through and to the other side, and in a secondary reflection or resonance of the electrons inherent nature, cause the electron to follow a path of interference...

This at least is an attempt to answer the question. Yes it is more philosophically minded. But at least it is an attempt to answer the question.

I thank you for your patience. Your time and your insight. I shall now withdraw from this discussion because it is clear that the answer to my question is either beyond QM or as Hericlitus would say... I have been told but fail to listen, to comprehend.etc If that is the case then I am sorry. I really like what you guys are doing here. Keep up the good work.

Sean Torrebadell

 

[Phred101.2]

That particles may be construed as a point as an origin of some process that connects them to the surrounding space. ...An electron would therefore be defined by both its center and the process and the physical consequences of that process that extend into the surrounding space.

In conclusion, an electron may pass through one slit as a particle and an origin of some force. ...the surronding field may extend to the second slit, become discontinous from the source, radiate through and to the other side, and in a secondary reflection or resonance of the electrons inherent nature, cause the electron to follow a path of interference...

Isn't this your attempt at some explanation? Because you are sticking to your definition: "a point particle with zero dimensions", and claiming that it is: "defined by its center and the process", and then concluding something from what is, after all your definition, which you appear to have read somewhere and are trying to adapt to your logic about what must be 'happening'.
But a quantised 'particle' is not definable this way (as a point-like tiny sphere), except in a mathematical sense.
You really should read more about the quantum world and what is known about these things...

 

[Fra]

I didn't follow this thread. I just jumped in here with some personal associations fwiw.

What I am asking is how an electron interferes with itself? The path that a single electron takes is the same as those taken by streams of electrons. It is an interfering pattern. I think that this goes beyond the math.

I think I see your point and I agree it's a relevant reflection but the nature of the reflection makes it overlap also to philosophy which makes it harder to get a grip on, but often the interesting questions are the slippery ones :) It may be tempting to reject the reflection due to it's slippery nature, but making it less slippery probably takes some work and you've got to start somewhere.

I think that sometimes considering a general case first is easier, as one doesn't need to get distracted by details relevant to the special case only.

What would self-interaction mean in general? The notion seems to suggest that there are some internal changes that does not depend on the non-self. To answer that one first ask what the definition and distinction between the self and the non-self is?

IMO, that distinction is not clear mainly because the self usually have a history of interaction with the environment(=the non-self; the remainder of the self). So trying to draw a line somewhere, and so to speak try to define the self while cutting the relation to the environment is arbitrary at best, because I think often a structure is defined in terms of it's relations to it's environment. This is why I think it's so difficult to make a decomposition and expect that to be consistent and unambigous. The self tend to have the "support" for it's very stability and thus "sense", in the environment, this is why I think the decomposition is only practical in cases where we can understand the stability of the structure in a the more general environment we have a hard time to decouple from even if we wanted to.

My personal abstracted view of self interaction is built upon the concept of the process of revising your opinion upon arrival of new information. A sort of internal equilibration and adjusment that is ongoing. This is why I consider particles rather as steady state configurations, that are (for reasons I don't know, but are trying to answer) are effectively stable. Clearly the selection of stable particles and their state is environment dependent. Then the next interesting question I ponder is when you consider the interaction of several selves, there is clearly also an evolution of the environment itself due to mutual adaption. So the other question is what kind of stable environments we may expect from different initial configurations. I think would relate to spacetimes and vaccuums.

I personally think that answering these philosophical questions takes us to analyse these most fundamental entities.

If you don't want to do this, and just accepts the effective foundations as "effective empirical hard facts", then these question remains philosophical and progress must be sought elsewhere. But I have no problems to at least to my best to question what I normally use as reference.

The only explanation that I can make is the one that I have given. ( above) That particles may be construed as a point as an origin of some process that connects them to the surrounding space. That this connection needs to be both simultaneously connected with the surrounding space to effect change within that space, and then discontiuous with that space in order for it to have its own inertia. This argument allows for the electron to exist both as a point wherein the volume may be a minimum and it may also extend the nature of the electron to the fields that surround it. An electron would therefore be defined by both its center and the process and the physical consequences of that process that extend into the surrounding space.

It seems this at least leans a little bit towards by thinking, but words tend to be ambigous, but you're not alone to consider these questions. I do it to. I accept that sometimes there is no way around dealing with the slippery stuff. But I try to find a balance between rambling about it with others and try to make real progress. I am currently trying to work out a satisfacory mathematical formalism that is to my satisfaction in a direction that I think am convinced will be a powerful tool in extending knowledge.

/Fredrik

 

[Phred101.2]

Hey Fredrik. How's your insight into the goings on at SFN? (it's Fred).
Looks like there are more than a few people struggling with quantum concepts. It's a tough one because these things simply refuse to behave like little billiards for us, but they can be treated as pointlike particles to analyse their behaviour in some sense. Then if they are treated like waves you can analyse their behaviour from a different 'perspective' (and both views 'work').
If you actually do any experiments with electrons you get a better insight into their mysterious structure (wavelength and 'size'), and what the Planck constant is. It doesn't look like they are doing anything 'special' (in the experiments), but they behave "strangely" all the time.

 

[Fra]

Hello Fred! I am usually selective in reading like most people I guess, due to time constraints. I'm not "following" all the discussions there nor here. My main purposes for participating is two, the first one is the exchanged ideas that is relevant to what I'm doing and to perhaps learn from othre peoples ideas and knowledge. So for me, these forums are all about ideas.

The other point, is when I bump into discussion where I think I can provide useful ideas or encouragement. Not everyone on these forums are experts, but even the non-experts but even experts used to be non-experts. And in particular when it comes to the QM issues, I have a feeling most people who studied physics has gone through some phases. It's completely natural to question the new concepts in the light of what you've learned in the past. I went though this process myself. But at this state I'm not as aroused by debating it as I perhaps was, I usually comment only if I think I can feed somebody elses process.

Is there a particular thread you refer to over there?

/Fredrik

 

[malawi_glenn]

Where did i throw HUP at you?

Now two discussions arose, 1. electron as point particle; 2. double slit experiment of electron beam.

When you measure the particle properties of the electron, it is a point particle. When you measure its wave properties, you get something else. This is what QM is all about; superposition of states, operators, particle-wave duality and so on. Get used to it. If you never had taken QM classes before, start with that

I don't see how throwing Heisenberg at me is an answer the question? I know that any measurement or attempt to observe the electrons path will affect the path. What I am asking is how an electron interferes with itself? The path that a single electron takes is the same as those taken by streams of electrons. It is an interfering pattern. I think that this goes beyond the math.

I've been looking through the archives. Over and over again the concept of one electron/ two slit phenomenon is somehow misconstrewed as being a stream. Everytime this topic comes up the same references are made to the Uncertainty principle, the shrodinger equation, the QM texts, that the math explains the electrons behaviour. There is no doubt about these truths.

The question is how a single point particle or even a single cloud of charge (whatever its boundary), at a frequency or scintillation count that guarantees that only one electron is moving towards the two slits at a time, so that with the highest degree of probability a single electron is making its way through the slits, with enough time between electrons, that it can be considered entirely alone. Then and only then how does the electron intefere with itself and thereby follow the interference paths that quantum mechanics has so well defined?

The only explanation that I can make is the one that I have given. ( above) That particles may be construed as a point as an origin of some process that connects them to the surrounding space. That this connection needs to be both simultaneously connected with the surrounding space to effect change within that space, and then discontiuous with that space in order for it to have its own inertia. This argument allows for the electron to exist both as a point wherein the volume may be a minimum and it may also extend the nature of the electron to the fields that surround it. An electron would therefore be defined by both its center and the process and the physical consequences of that process that extend into the surrounding space.

In conclusion, an electron may pass through one slit as a particle and an origin of some force. The effect that it has upon the surronding field may extend to the second slit, become discontinous from the source, radiate through and to the other side, and in a secondary reflection or resonance of the electrons inherent nature, cause the electron to follow a path of interference...

This at least is an attempt to answer the question. Yes it is more philosophically minded. But at least it is an attempt to answer the question.

I thank you for your patience. Your time and your insight. I shall now withdraw from this discussion because it is clear that the answer to my question is either beyond QM or as Hericlitus would say... I have been told but fail to listen, to comprehend.etc If that is the case then I am sorry. I really like what you guys are doing here. Keep up the good work.

Sean Torrebadell

 

[Hurkyl]

Then and only then how does the electron intefere with itself and thereby follow the interference paths that quantum mechanics has so well defined?

The only explanation that I can make is the one that I have given.

There's another, obvious one: "the math".

I said it humorously, but I meant it seriously: how can we expect any other type of explanation make sense? It seems to me that you are making an implicit assumption that there are "greater principles" to which all quantum phenomena can be reduced, and furthermore that you already understand those greater principles. But upon what grounds can such an assumption be made? Without justification, such an assumption is not reasonable: it's simply arrogant.


It's unreasonable to think you can learn quantum mechanics without learning quantum mechanics. Even if you don't want to spend the time to get a physics degree, you can still come to understand some of the simpler aspects... but only if you're willing to learn it as quantum mechanics.

 

[Phred101.2]

malawi_glen:
You seem to be presuming something here though. Is it that you believe QM must somehow be 'wrong', or some kind of self-sustaining delusion that, since it isn't intuitive to our 'classical' brains, means there is something 'wrong' with the view? I think a guy called Descartes has looked at this one already.
We can only try to explain the phenomena, and, being stuck inside "non-quantum' brains makes this tricky. But it's hard to argue with a semiconductor industry, lasers, PET scanners, and quantum dots...

 

[malawi_glenn]

Phred101.2

Descartes lived in the 16th century or something like that..

My standpoint is that Qm is correct and are trying to explain the unbelivers that altough QM contradicts or dayly life experience, it is the way nature seem to work.

So please read this thread again before accusing me for not believe in QM!

 

[Phred101.2]

Whoops -misdirected post, yes I see that you seem to be a true believer: please redirect to a Philosophy student...