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johanfprins
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Post by johanfprins »

happyjack27 wrote: please don't insult me. i don't know all of the experiments. there are a lot. i do know that a photodetector behind a photomultiplier under very low light produces discrete "clicks" as it were.
So it means that different entities with energy an momentum are being recorded: Why are they undefined "particles" and not localized waves?
i also know they've experimentally measured the fine structure constant, i believe by the time it takes an electron to travel a certain distance across a voltage gradient? not sure of the setup there, but the implication is that perturbation theory is correct here, and perturbation theory implies particle-like interactions.
Perturbation theory assumes waves; so how can it imply undefined "particles"?
also they've verified the pauli exclusion principle and entanglement.
Two waves with opposite magnetic fields will obviously be able to share the same space, while two waves with parallel magnetic fields will repel: Where do undefined "particles" come into the picture?
many things predicted by QED. in fact, EVERYTHING predicted by QED from my understanding.
A theory which is built on subtracting infinity from infinity to get the electron's mass is obviously fudged to get the answer you want: This cannot be real physics.
also, oh, and here's a big one: the tracks in a bubble-chamber! in modern day we use solid-state analogs.
This means that there is an entity with a center-of-mass; why call it "a particle" if you cannot define what a 'particle" is
by their curvature you can tell their charge-to-mass ratio * velocity, via the lorentz force. what happens is as they pass by other particles they impart energy to them, and then it is that energy that you see... well i suppose you can read more about how the original versions worked
. So why is it "a particle". A localized wave with a center-of-mass will do the same.
so there are a few examples.
now the question is how do you construct a mathematical apparatus that correctly predicts all these outcomes, using as few assumptions as possible? obviously it's going to involve spatial fields w/moving singularities, because that's, well, what we're seeing. e.g. a photograph ("spatial field") w/a black line on it ("singularity"). and this line is a "track" through time, i.e. the "singularity" moves through time. so you see this is a very direct consequence. we're adding nothing here.
None of your examples cannot be explained by a wave which moves slower than the speed of light and thus has mass energy and a center-of-mass.

I am afraid you just want to use the term "particle" for behavior which can just as well be modeled in terms of a wave. Why make this distinction if you cannot even define what a "particle" is?

johanfprins
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Post by johanfprins »

KitemanSA wrote:One of my favorite lines from the movie "Master and Commander" was where the "hero" said "name a shrub after me. Something prickly and hard to irradicate". I do hereby name that shrub the HappyJohan! :D :D :D
Yes I am a prickly pear, I sting from the outside when people want to abuse me, but am very sweet on the inside with people who are not treating me as if I am an idiot who does not know his subject.

happyjack27
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Post by happyjack27 »

johanfprins wrote:
happyjack27 wrote: please don't insult me. i don't know all of the experiments. there are a lot. i do know that a photodetector behind a photomultiplier under very low light produces discrete "clicks" as it were.
So it means that different entities with energy an momentum are being recorded: Why are they undefined "particles" and not localized waves?
i also know they've experimentally measured the fine structure constant, i believe by the time it takes an electron to travel a certain distance across a voltage gradient? not sure of the setup there, but the implication is that perturbation theory is correct here, and perturbation theory implies particle-like interactions.
Perturbation theory assumes waves; so how can it imply undefined "particles"?
also they've verified the pauli exclusion principle and entanglement.
Two waves with opposite magnetic fields will obviously be able to share the same space, while two waves with parallel magnetic fields will repel: Where do undefined "particles" come into the picture?
many things predicted by QED. in fact, EVERYTHING predicted by QED from my understanding.
A theory which is built on subtracting infinity from infinity to get the electron's mass is obviously fudged to get the answer you want: This cannot be real physics.
also, oh, and here's a big one: the tracks in a bubble-chamber! in modern day we use solid-state analogs.
This means that there is an entity with a center-of-mass; why call it "a particle" if you cannot define what a 'particle" is
by their curvature you can tell their charge-to-mass ratio * velocity, via the lorentz force. what happens is as they pass by other particles they impart energy to them, and then it is that energy that you see... well i suppose you can read more about how the original versions worked
. So why is it "a particle". A localized wave with a center-of-mass will do the same.
so there are a few examples.
now the question is how do you construct a mathematical apparatus that correctly predicts all these outcomes, using as few assumptions as possible? obviously it's going to involve spatial fields w/moving singularities, because that's, well, what we're seeing. e.g. a photograph ("spatial field") w/a black line on it ("singularity"). and this line is a "track" through time, i.e. the "singularity" moves through time. so you see this is a very direct consequence. we're adding nothing here.
None of your examples cannot be explained by a wave which moves slower than the speed of light and thus has mass energy and a center-of-mass.

I am afraid you just want to use the term "particle" for behavior which can just as well be modeled in terms of a wave. Why make this distinction if you cannot even define what a "particle" is?
more precisely a superposition of waves. yes, one can of course do a fourier transform on the position density function. i never meant to imply that you couldn't.

why does that frighten you? i could turn that logic on its head thusly: "why call it a wave when you cannot even define what a "wave" is?" the answer in both cases is the same: it's simply a matter of convenience. that's what language is for. and i've already defined a "particle" many times over. maybe if you were more precise in what to you constitutes a "definition", i could fit those criteria. but if you mean to offer impossible criteria than i don't see the use anymore than i see the meaningfullness of saying "it can't be defined". why? because you defined "definition" that way! it seems pretty senseless to me. in any case we both seem to agree about its properties so i dont see the point of all this fuss about semantics.

Grurgle-the-Grey
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Post by Grurgle-the-Grey »

Ok, let's get to work here.
A candidate model for SC must pass all know lab results with a reasonable explanation, qualitatively at least, until the calculations can be done to make it quantitative.
Prof. Leggett told me that he hadn't heard of Josephson coupling over 10nm in vacuo, though he didn't cite the paper that presumably did that.
In scanning tunnelling microscopes the point typical works at ~ .5nm and has a barrier potential equivalent to the work-function of the lattice.
To increase the tunnelling range 20X requires the barrier potential for the coupling entity to be 1/400 that of normal electrons. This effectively means that any entity with 1/400 th the normal barrier potential would be thermally and photo-emitting like crazy.
Field effects for the geometry of the point may give a factor in here, but not two orders of magnitude?

johanfprins
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Post by johanfprins »

happyjack27 wrote: more precisely a superposition of waves. yes, one can of course do a fourier transform on the position density function. i never meant to imply that you couldn't.
A superposition of which waves? A wave is determined by its boundary conditions and changes when its boundary conditions change.
why does that frighten you?
Nothing frightens me.
i could turn that logic on its head thusly: "why call it a wave when you cannot even define what a "wave" is?"
A wave is a field (region) in space having a distributed energy, so that the total energy of the wave is the sum total of its distributed intensity. So I can define what a wave is!
the answer in both cases is the same:
Not so!
it's simply a matter of convenience. that's what language is for. and i've already defined a "particle" many times over.
Where have you done so? Has a "particle" got a distributed energy in space? If so, it is a wave not an undefined entity which you call "a particle"
maybe if you were more precise in what to you constitutes a "definition", i could fit those criteria.
OK let us try again to get you to be more precise! Does a "particle" have volume and what constitutes this volume?
I have now asked yoou again but if you mean to offer impossible criteria than i don't see the use anymore than i see the meaningfullness of saying "it can't be defined". why? because you defined "definition" that way! it seems pretty senseless to me. in any case we both seem to agree about its properties so i dont see the point of all this fuss about semantics.
You say that it must be "a particle", which you cannot define, to have those properties; while I say that a localized wave, which I can define, has the properties without having to call it "a particle".

johanfprins
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Post by johanfprins »

Grurgle-the-Grey wrote:Ok, let's get to work here.
A candidate model for SC must pass all know lab results with a reasonable explanation, qualitatively at least, until the calculations can be done to make it quantitative.
I agree, but sometimes some of the measurements cannot be done. In my case I can generate a superconductor which deteriorates below its critical temperature which I estimate is about 600 Celsius. I can thus not measure the voltage drop or magnetic change at the critical temperature.
Prof. Leggett told me that he hadn't heard of Josephson coupling over 10nm in vacuo, though he didn't cite the paper that presumably did that.
Neither have I until you mentioned it. The distance must be less than for an insulator; and in the latter cases I have only read of layers within the angstrom range. It will be surprising if Josephson tunneling can cover a larger distance through a vacuum.

Again I must point out that one should first know for which material it is claimed and what the geometrical conditions are under which this result has been measured.

Grurgle-the-Grey
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Post by Grurgle-the-Grey »

Ok, so one of the best SCs is Niobium Tc about 12K, so I guess that requires a cryostat, ie. a vacuum, so any papers on Josephson coupling with Nb should give us data??
But generally we want to find the largest known J coupling in vacuo??
Neither of us have academic access so help would be appreciated.

Betruger
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Post by Betruger »

If I still live on campus this semester, I could help, provided clear references to look for. I don't have access to all journals, and this isn't my field at all, but I'd be glad to give you whatever I found.

I'll know whether I move off campus or not in a week or so.

johanfprins
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Post by johanfprins »

Betruger wrote:If I still live on campus this semester, I could help, provided clear references to look for. I don't have access to all journals, and this isn't my field at all, but I'd be glad to give you whatever I found.

I'll know whether I move off campus or not in a week or so.
This is an extremely kind offer. I do not even know for what to look. Maybe Grurgle-The-Gray can contact you?

happyjack27
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Post by happyjack27 »

johanfprins wrote:
happyjack27 wrote: more precisely a superposition of waves. yes, one can of course do a fourier transform on the position density function. i never meant to imply that you couldn't.
A superposition of which waves? A wave is determined by its boundary conditions and changes when its boundary conditions change.
not neccessarily. a wave is a function expressed in the fourier domain.
A(s) = a1 * cos(s) + a2 * cos(2*s) + ...

to describe how it responds to changes you'd have to write down a time-evolution equation. and that's altogether different from talking about its spatial distribution, i.e. what "it" is. (as opposed to what is _not_ "it").
[/quote]
why does that frighten you?
Nothing frightens me.
you said "I am afraid you just want to use the term "particle" for behavior which can just as well be modeled in terms of a wave. " so clearly that frightens you, by your own admission.
i could turn that logic on its head thusly: "why call it a wave when you cannot even define what a "wave" is?"
A wave is a field (region) in space having a distributed energy, so that the total energy of the wave is the sum total of its distributed intensity. So I can define what a wave is!
but that's what a particle is!
the answer in both cases is the same:
Not so!
"not so" doesn't do anything for me.
it's simply a matter of convenience. that's what language is for. and i've already defined a "particle" many times over.
Where have you done so? Has a "particle" got a distributed energy in space? If so, it is a wave not an undefined entity which you call "a particle"
numerous times in above posts. maybe i'll repeat myself once again for you later. i'm kinda getting tired of it. yes, it does. no, that does not follow. (and if as you say it's undefined, then one can't very well say what it is and is not! that would be a definition!)
maybe if you were more precise in what to you constitutes a "definition", i could fit those criteria.
OK let us try again to get you to be more precise! Does a "particle" have volume and what constitutes this volume?
that's not what i meant by defining your definition. you are making your own definition of particle and asking if it fits. i'm supposed to be making _my_ definition and seeing if the _definition_ fits the definition of definition.
but ill humor you: no, it does not neccesarily have volume. it could be a point particle (i.e. its volume could be infinitesimal.*) what "constitutes" it - perhaps a poor choice of word there 'cause now you're on philosophically shaky ground. how do you measure it experimentally might be a better way to phrase that. in that case there are probably multiple ways to do so. elastic collisions, at what point forces that vary with distance become singular, etc. but the one i'm most familiar with is the work done by einstien, where he reasoned from the brownian motion of particles. also i know that we've measered the radius of a prtoon to be something of the order of 1E-18 meters. that makes its volume someing like (pi/3)*1E-18^3 cubic meters. and that's probably going to be the more accurate number so 'cause we don't _really_ know if it's spherical, so the radius is more of an average radius.
[/quote]
I have now asked yoou again but if you mean to offer impossible criteria than i don't see the use anymore than i see the meaningfullness of saying "it can't be defined". why? because you defined "definition" that way! it seems pretty senseless to me. in any case we both seem to agree about its properties so i dont see the point of all this fuss about semantics.
You say that it must be "a particle", which you cannot define, to have those properties; while I say that a localized wave, which I can define, has the properties without having to call it "a particle".
again you're talking semantics. it is a trivial matter to define <b>anything</b>, be it a particle, a wave, or a fdhdkvnvouernv, which is a word that i obviously just made up. so to say that one can define one hypothetical entity and not another is a bit absurd. the process is the same regardless of the name of the thing. you haven't answered my question about how does it really tell us anything more about the physics; how is it really useful.


*but that doesn't mean it doesn't have area or length. e.g. a square has finite area but zero volume. cause ofcourse it's 2-d instead of 3-d. point being it might still have a "measure" analogous to volume, but in a lower-dimensional space. but that's a tangent unto itself.

johanfprins
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Post by johanfprins »

happyjack27 wrote: not neccessarily. a wave is a function expressed in the fourier domain.
a1 * cos(t) + a2 * cos(2* t) + ...
Not necessarily Fourier. In the case of quantum mechanics there are many other "function spaces" which are applicable depending on the boundary conditions as determined by the so-called "potential-energy" function in Schroedinger's equation. It is the boundary conditions that determine the wave; the fact that a wave can be built up from function spaces which have functions which are not themselves allowed solutions of the boundary conditions does not mean that the latter basis waves have any physical meaning.
to describe how it responds to changes you'd have to write down a time-evolution equation. and that's altogether different from talking about its spatial distribution, i.e. what "it" is. (as opposed to what is _not_ "it").
Why a time evolution operator? If you know what the boundary conditions are before they change and what they are after they have changed, you can derive what the original wave and the outcome after the boundary conditions have changed without using a "time-evolution" operator. In fact a measurement is an abrupt change in boundary conditions which do not require a "time evolution" operator at all. I suspect that the time-evolution operator is most probably not real physics.
"I am afraid you just want to use the term "particle" for behavior which can just as well be modeled in terms of a wave. " so clearly that frightens you, by your own admission.
Clever answer; but you know I did not imply any real fear.
but that's what a particle is!
If that is what a "particle" is why do you distinguish between "particles" and "waves" as if they are different entities?
but ill humor you: no, it does not neccesarily have volume. it could be a point particle.
A "point" is a mathematical abstraction. just like the term singularity. There are no such entities in nature.
in that case there are probably multiple ways to do so. elastic collisions, at what point forces that vary with distance become singular, etc. but the one i'm most familiar with is the work done by einstien, where he reasoned from the brownian motion of particles. also i know that we've measered the radius of a prtoon to be something of the order of 1E-18 meters. that makes its volume someing like (pi/3)*1E-18^3 cubic meters. and that's probably going to be the more accurate number so 'cause we don't _really_ know if it's spherical, so the radius is more of an average radius.
None of these experiments define a "particle". They can all be explained in terms of energy fields with distributed energy. Thus there is nop need for a concept like "a particle" which you, by the way, have not yet been able to define.
again you're talking semantics.
No you are the master when it comes to semantics.
it is a trivial matter to define <b>anything</b>, be it a particle, a wave, or a fdhdkvnvouernv, which is a word that i obviously just made up. so to say that one can define one hypothetical entity and not another is a bit absurd.
A wave is not a hypothetical entity like the concept of "a particle". So if you are able to define :anything: even your made up word as a "particle", then you are admitting that the concept of "a particle" has no meaning.
you haven't answered my question about how does it really tell us anything more about the physics; how is it really useful.
:oops: It removes metaphysics from the interpretation of physics. It removes the need for Bohr's nonsensical Principle of Complementarity; which is obviously physics nonsense: Can a particle, as you seem to know what is is, act like a wave? You seem to say no. But can a wave act like a particle as you think that a particle behaves: Yes it can and since we have the same entity acting in a way which you call "a particle" and acting as a wave by diffracting, then there is no reason to make a distinction between the two: Unless you have a specific definition for "a "particle" which mandates that a distinction must be made: But you have not yet given me such a definition. So there are no particles: Only waves!

happyjack27
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Post by happyjack27 »

johanfprins wrote: Let us rather leave this alone: You are clearly not able to argue logic!
i never responded to this. clearly it was inappropriate. but just to allay any concerns you may have: i am a proffessional computer programmer. and my spatial reasoning skills have been officially tested multiple times via standard i.q. tests (w/an officail test administrator, etc.), the gatt test, etc. they consistently put my spatial reasoning skills in the 99.99th percentile. i scored top of my school on the AHSME with the first qualifying score for the AIME in over a decade. i could go on. i don't mean to tout my own horn here, but the point is the weight of emiprical evidence does not support your assertion. and if i were you, i'd be careful not to underestimate my ability there.

happyjack27
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Post by happyjack27 »

johanfprins wrote:
happyjack27 wrote: not neccessarily. a wave is a function expressed in the fourier domain.
a1 * cos(t) + a2 * cos(2* t) + ...
Not necessarily Fourier. In the case of quantum mechanics there are many other "function spaces" which are applicable depending on the boundary conditions as determined by the so-called "potential-energy" function in Schroedinger's equation. It is the boundary conditions that determine the wave; the fact that a wave can be built up from function spaces which have functions which are not themselves allowed solutions of the boundary conditions does not mean that the latter basis waves have any physical meaning.
of course there are other transforms. the term "wave" is generally associated with the fourier transform. if you meant to refer to a different orthogonal system, i presumed you'd likewise use a different word. but it is no matter. the point is the function is a density function that describes what is and is not the thing, and one can choose any orthogonal basis to represent that. (though some might result in singularities and what not where others don't, depending on the nature of the function)
to describe how it responds to changes you'd have to write down a time-evolution equation. and that's altogether different from talking about its spatial distribution, i.e. what "it" is. (as opposed to what is _not_ "it").
Why a time evolution operator? If you know what the boundary conditions are before they change and what they are after they have changed, you can derive what the original wave and the outcome after the boundary conditions have changed without using a "time-evolution" operator. In fact a measurement is an abrupt change in boundary conditions which do not require a "time evolution" operator at all. I suspect that the time-evolution operator is most probably not real physics.
my subtle philosophical differences with some of that aside, you miss my point. my point is that to describe the time evolution is to introduce some function (discrete, continuous, what have you) that somehow takes time as one of its argument. and this is an altogether different thing than an atemporal expression of the state in a given basis. and it applies to "wave"s as much as it does to "particle"s. it is irrespective of the basis you choose to represent the state.
"I am afraid you just want to use the term "particle" for behavior which can just as well be modeled in terms of a wave. " so clearly that frightens you, by your own admission.
Clever answer; but you know I did not imply any real fear.
yes, of course i know that. "concern" more properly. that is besides the point. what "concerns" you; why does it "bother" you; how do you think it might be problematic; etc.
but that's what a particle is!
If that is what a "particle" is why do you distinguish between "particles" and "waves" as if they are different entities?
i don't. they are two different pictures of the same thing. the question is what is the most useful picture for the particular problem. as far as an intuitive visual understanding, the particle picture is the one that most clearly and simply describes the known properties, IMHO.

now i ask the same question to you.
but ill humor you: no, it does not neccesarily have volume. it could be a point particle.
A "point" is a mathematical abstraction. just like the term singularity. There are no such entities in nature.
i'll give you that a point is a mathematical abstraction. but in the same sense so is a 3-dimensional space, and so is a wave. as regards whether there are such entities in nature, however, and esp. when it comes to "singularities", i beg to differ. the event horizon of a black hole? the fusion of two nuclei? beta decay? phase transition from a solid to liquid or liquid to gas (nucleation)? lasers? the extinction of a species? the first stage of morphogenesis of an embryo? the emission of a photon by an electron? the resulting light spectrum produced in spectroscopy? the list is endless...
in that case there are probably multiple ways to do so. elastic collisions, at what point forces that vary with distance become singular, etc. but the one i'm most familiar with is the work done by einstien, where he reasoned from the brownian motion of particles. also i know that we've measered the radius of a prtoon to be something of the order of 1E-18 meters. that makes its volume someing like (pi/3)*1E-18^3 cubic meters. and that's probably going to be the more accurate number so 'cause we don't _really_ know if it's spherical, so the radius is more of an average radius.
None of these experiments define a "particle". They can all be explained in terms of energy fields with distributed energy. Thus there is nop need for a concept like "a particle" which you, by the way, have not yet been able to define.
ARGGGHH!!! you didn't ask me to define a particle! you asked me to discuss volume as it relates to physical observables on fine scales! and that is precisely what i did! and repeating a thing does not make it true!
again you're talking semantics.
No you are the master when it comes to semantics.
please. again this "i know you are but what am i." stuff doesn't do anything for me.
it is a trivial matter to define <b>anything</b>, be it a particle, a wave, or a fdhdkvnvouernv, which is a word that i obviously just made up. so to say that one can define one hypothetical entity and not another is a bit absurd.
A wave is not a hypothetical entity like the concept of "a particle". So if you are able to define :anything: even your made up word as a "particle", then you are admitting that the concept of "a particle" has no meaning.
no. that's like saying no words in any language have any meaning! if that were the case then i fail to see the point of any of this discussion!
Last edited by happyjack27 on Fri Jan 07, 2011 5:10 pm, edited 4 times in total.

happyjack27
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Post by happyjack27 »

johanfprins wrote:
you haven't answered my question about how does it really tell us anything more about the physics; how is it really useful.
:oops: It removes metaphysics from the interpretation of physics. It removes the need for Bohr's nonsensical Principle of Complementarity; which is obviously physics nonsense: Can a particle, as you seem to know what is is, act like a wave? You seem to say no. But can a wave act like a particle as you think that a particle behaves: Yes it can and since we have the same entity acting in a way which you call "a particle" and acting as a wave by diffracting, then there is no reason to make a distinction between the two: Unless you have a specific definition for "a "particle" which mandates that a distinction must be made: But you have not yet given me such a definition. So there are no particles: Only waves!
i think i get you. so you are saying that the particle description can't explain all of the physically observable properties, but the wave description can, thus the particle description fails, leaving only the wave description?

on this i beg to differ.

re: "Can a particle, as you seem to know what is is, act like a wave? You seem to say no. " i say yes, actually, a particle can act like a wave. rather an unknown distribution of indistinguishable particles amidst a distribution of forces, who individually can't know of anything except their very and i mean _very_ immediate environment in the aggregate resembles a wave equation just like the individual components of a string vibrate harmoniously without knowing anything about anything besides their immediate neighbors by way of the wave equation and just like the classical approximation of "least action" (which is informationally impossible because there's no way for a particle to know the shortest path in advance unless the distance between any two points in space is always zero) follows as a limit case of the feymann path integral (which _is_ informationally possible without a "null space" as it were).

happyjack27
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Post by happyjack27 »

i was reading up on particle detection mechanisms and found this: http://www.wimp.com/cloudchamber/ pretty frickin' cool, IMO.

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