Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: McQueen on 09/11/2007 22:30:17

Title: Causality
Post by: McQueen on 09/11/2007 22:30:17
What is causality ? It can be defined by the example used by the British Philosopher David Hume: A boy picks up a stone and throws it towards a window, the window breaks. So causality is a sequence of events resulting in another event.

It has become almost axiomatic to smile condescendingly when anyone speaks of a ‘Mechanical Universe’.  We have been programmed to instinctively react like ‘Mr. Bean’, when we hear the term a ‘clockwork universe’ to express our condescension by rolling our eyes and grimacing, without really paying much attention to what we are doing.

Yet the world is very much a ‘mechanical’ or ‘physical’ place. Everything from childbirth, to the functioning of the heart and lungs, everything including the genesis of both living and non-living things is intensely mechanical in nature. Even to say that  it is all causal does not quite describe the manner in which things are put together like a jig-saw puzzle, and this phenomena extends to the furthest reaches of the Universe many billions of light years away.

It is amazing that in the face of all this evidence to the contrary, Quantum Mechanics, when faced with a few unexplained phenomena, decided that the sub-atomic world did not follow causality. One result of this is that Physicists tend to live in a magical Harry Potter kind of world, where the normal rules do not apply. In this sub-atomic world things can be in two places at the same time, an object can start of at one location undergo disembodiment and suddenly appear at another location or an object can be two things at one and the same time, events in short that never take place in the macroscopic world.

What evidence did QM have in support of this view-point of a non-causal sub-atomic world. It could be perfectly understandable, if for instance the electron orbited the nucleus at near relativistic speeds but it doesn’t.  Such a viewpoint would also be explained if the photon from time to time  traveled faster than light, it never does. So where is the justification for the hypotheses.

It is possible to predict the exact number at which a ball in a roulette wheel will stop and to do so before the wheel stops turning. This is possible provided the speed of the ball, it’s angle of trajectory, its spin and weight are known beforehand, together with information as to the height and slope of the partitions between the numbers, the depth of the partitions, the size of the wheel etc., all of this information is fed into a computer where probability theory is used to calculate with a 99.4% accuracy where the ball will finally end up when the wheel stops turning. Twenty years ago this would have seemed an impossible feat, and it is precisely this kind of initiative on the part of man to explore possibilities that QM attempts to extinguish, this is what irritated Einstein.

What does QM have to offer as an alternative. QM often boasts of its probability functions that they are the most mathematically logical perfect solution to the problem in hand. Yet if this same probability function were applied to the roulette wheel problem it would never work. Why? Because it has nothing to work with, neither the speed, trajectory, size of the ball or anything else. What can mathematics based on such data hope to achieve?
Title: Causality
Post by: JP on 09/11/2007 22:59:18
Fortunately, quantum mechanics has the virtue of being correct, and having a correct theory is more important than having a well-behaved one.
Title: Causality
Post by: McQueen on 09/11/2007 23:10:25
Fortunately, quantum mechanics has the virtue of being correct, and having a correct theory is more important than having a well-behaved one.
Thank God you have turned up. I must have looked like Don Quixote to quite a few people here!
Title: Causality
Post by: Soul Surfer on 10/11/2007 07:55:39
Some of the behaviour of particles does not look quite so peculiar if you consider a many dimensional universe because things a long way apart in our familiar space dimensions may be very close in other dimensions.  also the wave like nature can have similar long range properties interference peaks  can be a very long way apart if the waves are coherent and closely related.

Another fact is the phase of the quantum waves is always hidden.

To return to your recent complelmetarity question  The duality is there it is the method of measurement that tends to define the choice of wave or particle models.

I agree quantum mechanics is weird and non intuitive but it becomes more understandable if you start making classical physical measurements close to the quantum limits with for example an atomic force microscope.

This allows us to "see" the shapes of individual atoms and move them around by moving a probe with a single atom at its tip over a surface and measuring and controlling the force between the probe tip and the material.

At this level everything is vibrating violently almost at the point of falling apart.  Go any further and it is clear that the vibrations will be so great that vague probabilities will be the only thing that it is possible to measure.
Title: Causality
Post by: McQueen on 10/11/2007 14:44:01
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Some of the behaviour of particles does not look quite so peculiar if you consider a many dimensional universe because things a long way apart in our familiar space dimensions may be very close in other dimensions.  also the wave like nature can have similar long range properties interference peaks  can be a very long way apart if the waves are coherent and closely related.

Talking of many dimensions, Schrodinger’s wave equation needs 265 dimensions to describe an atom of uranium. Even supposing one is willing to permit a certain amount of lee-way, isn’t this over the top?

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Another fact is the phase of the quantum waves is always hidden.

If one can have hidden quantum waves or ‘matter waves’ why not an aether ? After all the whole question of causality does imply some sort of underlying fabric allowing the phenomenon of causality to exist.  This question is not adequately addressed. I mean think of the situation where faster than light phenomenon is allowed to take place. A person could theoretically be anywhere or in multiple places at the same time. The very existence of matter would be questionable. Yet that kind of chaos does not exist, everything is ordered. Why?

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This allows us to "see" the shapes of individual atoms and move them around by moving a probe with a single atom at its tip over a surface and measuring and controlling the force between the probe tip and the material.

Recent experiments with femto second lasers have allowed scientists to predict where in its orbit, or at least in which half, an electron will be? Note not an atom but an electron. Not that this disproves Heisenberg’s Uncertainty Principle, common sense tells us that would still be valid to some extent or another.

On the whole, while certain theories propounded by Quantum mechanics are undoubtedly of great value, other theories have been hurriedly put into place and never revised, or they have been forced to comply with the facts by the use of dubious methods, this is a far from satisfactory situation.
Title: Causality
Post by: lyner on 10/11/2007 16:38:41
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Schrodinger’s wave equation needs  265 dimensions  to describe an atom of uranium
Don't you mean '256 parameters'? i.e. quantum numbers
Title: Causality
Post by: lightarrow on 10/11/2007 17:57:57
What is causality ? It can be defined by the example used by the British Philosopher David Hume: A boy picks up a stone and throws it towards a window, the window breaks. So causality is a sequence of events resulting in another event.

It has become almost axiomatic to smile condescendingly when anyone speaks of a ‘Mechanical Universe’.  We have been programmed to instinctively react like ‘Mr. Bean’, when we hear the term a ‘clockwork universe’ to express our condescension by rolling our eyes and grimacing, without really paying much attention to what we are doing.

Yet the world is very much a ‘mechanical’ or ‘physical’ place. Everything from childbirth, to the functioning of the heart and lungs, everything including the genesis of both living and non-living things is intensely mechanical in nature. Even to say that  it is all causal does not quite describe the manner in which things are put together like a jig-saw puzzle, and this phenomena extends to the furthest reaches of the Universe many billions of light years away.

It is amazing that in the face of all this evidence to the contrary, Quantum Mechanics, when faced with a few unexplained phenomena, decided that the sub-atomic world did not follow causality. One result of this is that Physicists tend to live in a magical Harry Potter kind of world, where the normal rules do not apply. In this sub-atomic world things can be in two places at the same time, an object can start of at one location undergo disembodiment and suddenly appear at another location or an object can be two things at one and the same time, events in short that never take place in the macroscopic world.

What evidence did QM have in support of this view-point of a non-causal sub-atomic world. It could be perfectly understandable, if for instance the electron orbited the nucleus at near relativistic speeds but it doesn’t.  Such a viewpoint would also be explained if the photon from time to time  traveled faster than light, it never does. So where is the justification for the hypotheses.

It is possible to predict the exact number at which a ball in a roulette wheel will stop and to do so before the wheel stops turning. This is possible provided the speed of the ball, it’s angle of trajectory, its spin and weight are known beforehand, together with information as to the height and slope of the partitions between the numbers, the depth of the partitions, the size of the wheel etc., all of this information is fed into a computer where probability theory is used to calculate with a 99.4% accuracy where the ball will finally end up when the wheel stops turning. Twenty years ago this would have seemed an impossible feat, and it is precisely this kind of initiative on the part of man to explore possibilities that QM attempts to extinguish, this is what irritated Einstein.

What does QM have to offer as an alternative. QM often boasts of its probability functions that they are the most mathematically logical perfect solution to the problem in hand. Yet if this same probability function were applied to the roulette wheel problem it would never work. Why? Because it has nothing to work with, neither the speed, trajectory, size of the ball or anything else. What can mathematics based on such data hope to achieve?

I don't know exactly if you mean that you don't understand QM or if you think it's wrong or what. I certainly cannot say I understand it well; however I have started to think about the possibility that classical physics it's not the "right" way of thinking, it's the "wrong" one.

Imagine an alien civilization who is studying us humans from a "collective" point of view: they will perceive thousands of people all together, moving in strange ways and they will duduce rules about this collective behaviours.

We could say that kind of study is a nonsense, that we should study and understand every single person's behaviour and psychology; but they would reply that their way of thinking, which they call "classical mechanics of people" has precise, definite rules, while a single individual's psychology is "smeared", "indefinite"; "for example", they can say, " human's behaviour depends on the person who interact with it, even in the exact same circumstances; so how can you ascribe intrinsic and objective properties to that single human?" "Instead, collective behaviours are more predictable and more objective".

With classical physics is the same: you observe rules that, actually, comes as *result* of many interacting wavefunctions of single microscopic objects. The same concepts of "position" and "velocity" arises as result of such overlapping of wavefunctions. Our mistake, when we study QM, is that we want to see "position" "velocity" and other classical concepts in things that don't have; the same as if we see from above the shape "C" formed by a group of people and then we go looking for a similar "C" shape in the single persons!
Title: Causality
Post by: McQueen on 11/11/2007 02:21:52
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Our mistake, when we study QM, is that we want to see "position" "velocity" and other classical concepts in things that don't have; the same as if we see from above the shape "C" formed by a group of people and then we go looking for a similar "C" shape in the single persons!

All of that would not matter in the least, if you can't see something statistics are fine. All I'm saying is that a thing should be logically consistent, facts should not be bent to suit ones purpose. Absurd statements on the efficiency of one's system should not be made, when one after all one is dealing with statistics in the broadest sense. Where there are one or two explanations for a phenomena, one explanation should not be advocated as being the only soluti0on. Things like that.

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Don't you mean '256 parameters'? i.e. quantum numbers

No not parameters but dimensions, in fact I got it wrong. An atom with two electrons would exist in six mathematical dimensions and an atom with four electron would exist in twelve mathematical dimensions, so that obvioulsy an atom of Uranium would have many more mathematical dimensions than I had originally stated.
Title: Causality
Post by: Soul Surfer on 11/11/2007 10:10:57
Mcqueen you are making the mistake of confusing mathematical dimensions in a problem and true physical dimensions.  It is easy for the number of mathematical dimensions in a problem to approach infinity they are used initially in analysis to allw many degrees of freedom which are eventually constrained as the model develops.  Consider tracking all the atoms in a box full of gas or analysing a long coded message where initially all observations of every particle or sample must be considered as independent "dimensions" in the problem.

True physical dimensions are much more circumscribed and mostly the province of string theorists.  It is relatively easy to understand and visualise  the four dimensions of space time but higher numbers and the sort of calabi yau spaces the string theorists talk about is almost impossible.  even then these "dimensions" may turn out to be composite properties of space time for example a vortex axis (think of vortexes produced by things moving around underwater visualised by having a few small particles around) is very like a string posessing ends and a tension. 

One of the main things that I do not like about string theory is the arbitrariness of the strings.  I agre wholeheartedly that one needs to depart from point particles into structure but would far prefer to see models based on a space time vortex structure,  Some of the theoreticians working on spin networks may be much nearer a physical reality.
Title: Causality
Post by: McQueen on 11/11/2007 13:17:45
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Mcqueen you are making the mistake of confusing mathematical dimensions in a problem and true physical dimensions.  It is easy for the number of mathematical dimensions in a problem to approach infinity they are used initially in analysis to allw many degrees of freedom which are eventually constrained as the model develops.  Consider tracking all the atoms in a box full of gas or analysing a long coded message where initially all observations of every particle or sample must be considered as independent "dimensions" in the problem.

Soul Surfer, don’t you see that this is just semantics, even Schrodinger felt the same,  it was Max Born, the German physicist who rescued him by postulating that what he was referring to were probability waves .  Yet, for heavens sake, hear what I have to say! If a photon was the synthesis of a particle and a wave(this exists in our world) . There would be no need for any of this. How can you have an absolute theory, when more plausible theories exist????

Title: Causality
Post by: lightarrow on 11/11/2007 18:05:53
Yet, for heavens sake, hear what I have to say! If a photon was the synthesis of a particle and a wave(this exists in our world) . There would be no need for any of this. How can you have an absolute theory, when more plausible theories exist????
Ok, and what establishes how the photon must behave (wave or particle) in different settings?
Title: Causality
Post by: Soul Surfer on 11/11/2007 21:12:43
The fact that particles like electrons, protons and even macroscopic assemblies of atoms have a wave like nature in the quantum domain is visible in the observation of their interference and diffraction patterns.  these are just not features of a particle nature.  in the case of massive particles the wavelength observed is a function of the momentum of the particle.  ie the product of the mass and the velocity.  the slower the particle is moving the longer the wave.  this is one of the features that allows electron microscopes ti have a far better resolution than optical microscopes and defines the spatial resolution of high energy colliders like the one at CERN.
Title: Causality
Post by: McQueen on 11/11/2007 21:25:47
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this is one of the features that allows electron microscopes ti have a far better resolution than optical microscopes and defines the spatial resolution of high energy colliders like the one at CERN.

The explanation conveniently overlooks the fact that the elctron is much smaller than light waves!
Title: Causality
Post by: McQueen on 11/11/2007 21:29:11
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Mcqueen you are making the mistake of confusing mathematical dimensions in a problem and true physical dimensions.  It is easy for the number of mathematical dimensions in a problem to approach infinity they are used initially in analysis to allw many degrees of freedom which are eventually constrained as the model develops.

This seems to me more or less a question of semantics. What is a dimension, apparently yes it is a parameter, my apologies. However, it is a little more complicated than you make out, take the co-ordinates on a map, latitude and longitude, so you have a two dimensional model. Next add  a third dimension namely height and you have a three dimensional model add time and you have a four dimensional model. What, I want to know, does a two hundred and fifty-six dimension model look like ?

OK I’ll tell youi what I like and don’t like in Quantum Mechanics:

1)   I believe in the QM model of the atom, as a central nucleus consisting of protons and neutrons with  electrons circling this nucleus.
2)   I believe in the manner in which the protons and neutrons are held together in the nucleus by exchange of muons etc.,
3)   What I don’t believe in is the structure of the photon.
4)   And the wave particle duality of light and matter.

I think that this is what has made QM so bloated and so incomprehensible, everything that is esoteric, archaic and hard to explain or comprehend in QM stems from wave particle duality.
Title: Causality
Post by: McQueen on 11/11/2007 21:34:14
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Ok, and what establishes how the photon must behave (wave or particle) in different settings?
That's the whole point, it doesn't matter, it is a synthesis
of a particle and a wave. It behaves naturally according to the circumstances, either as a particle or a wave.  Note that this model explains how an electron with dimensions of 10^^-13 can emit and absorb photons that are so much largere than themselves. There is no magic or wave particle duality about it!
Title: Causality
Post by: Soul Surfer on 11/11/2007 21:51:11
How do YOU then define the "size" of an electron?

and how do you propose to measure this size?
Title: Causality
Post by: lyner on 12/11/2007 10:54:47
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Note that this model explains how an electron with dimensions of 10^^-13 can emit  and  absorb photons that are so much largere than themselves.
Since when did an object need to be as big as the wave, in order to absorb some energy?
My ears are 60 cms across and I can  hear sound waves from a 50 Hz source - wavelength  6m! I know a half wave dipole is well matched to free space but a ferrite rod antenna can match to 1500m waves quite easily. 'Size' is not relevant.
And, in any case, no one says the electron emits or absorbs photons. It is the system which includes the electron that involves photon exchange. If an electron is not interacting with something else, there are no photons.
Go away and come up with a bit more complete theory before you present your ideas  - you seem to be a bit confused and very selective about which bits of the standard model you like and which you don't.
Title: Causality
Post by: lightarrow on 12/11/2007 13:01:42
OK I’ll tell youi what I like and don’t like in Quantum Mechanics:

1)   I believe in the QM model of the atom, as a central nucleus consisting of protons and neutrons with  electrons circling this nucleus.
First of all, thank you to have expressed your ideas clearly.

When you say "with  electrons circling this nucleus" you mean "electrons as pointy particles going around the nucleus classically"? If this is your idea, I have to advise you it is obsolete from more than a century. At high school they teach us that's not possible since charges emits EM radiation when they accelerate, so the electrons should lose energy in a tiny fraction of a second and fall in the nucleus. But this doesn't happen in the reality.

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2)   I believe in the manner in which the protons and neutrons are held together in the nucleus by exchange of muons etc.,
Probably you meant "mesons"; muons are electron-like particles, about 200 times more massive.

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3)   What I don’t believe in is the structure of the photon.
No one knows how is a photon, if it has a structure or not.

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4)   And the wave particle duality of light and matter.
To be nitpicking, you should say "dualism", not "duality"; the last term is a mathematical concept, completely different (used, for example, between vectorial spaces).

Anyway, the fact is that you can think of a photon as wave and particle together, as in some interpretations (see Bohmian mechanics that I mentioned some posts ago), but these theories don't simply say "the photon is both wave and particle" and that's all, they have to describe in detail how the thing works; in particular, as I told you, how the photon decides to behave as wave or as particle depending on the experimental setting.
Title: Causality
Post by: lightarrow on 12/11/2007 13:07:58
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Ok, and what establishes how the photon must behave (wave or particle) in different settings?
That's the whole point, it doesn't matter, it is a synthesis
of a particle and a wave. It behaves naturally according to the circumstances, either as a particle or a wave.  Note that this model explains how an electron with dimensions of 10^^-13 can emit and absorb photons that are so much largere than themselves. There is no magic or wave particle duality about it!
1. "It behaves naturally according to the circumstances" doesn't explain anything. I could reply: "a photon is a blue angel with golden wings and behaves as it have to do, according to circumstances". Prove me that I'm wrong. Physics is something else.
2. Which is a photon dimension? No one knows (maybe it doesn't even have one!)
Title: Causality
Post by: McQueen on 12/11/2007 13:38:05
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How do YOU then define the "size" of an electron?

and how do you propose to measure this size?
It ought to be smaller than the size of an atom the Bohr radius is given as 0.5 x10^^8 cms, so the generally acceoted value of the electron raidus as 10^^-13cms must be near enough.
Title: Causality
Post by: McQueen on 12/11/2007 13:40:32
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1. "It behaves naturally according to the circumstances" doesn't explain anything. I could reply: "a photon is a blue angel with golden wings and behaves as it have to do, according to circumstances". Prove me that I'm wrong. Physics is something else.

Surely this is closer to the QM description of a photon as being both a particle (in the classical sense) and a wave (in the classical sense) but never possesses both properties simultaneously. Compared to this my explanation of a photon as a synthesis of a particle and a wvae makes much more sense.
Title: Causality
Post by: lightarrow on 12/11/2007 19:48:32
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How do YOU then define the "size" of an electron?
and how do you propose to measure this size?
It ought to be smaller than the size of an atom the Bohr radius is given as 0.5 x10^^8 cms, so the generally acceoted value of the electron raidus as 10^^-13cms must be near enough.
Why "it ought to be smaller than the size of an atom"? Can you prove it's not as big as the atom itself, *in the atom*?
"The generally acceoted value of the electron raidus as 10^^-13cms". At which energy? The greater the energy, the smaller the electron...
Measure its dimension when it's free and has a speed of 1m/s.
Title: Causality
Post by: Soul Surfer on 12/11/2007 21:56:36
Agreed light arrow. that was precisely what I was getting at the slower an electron is moving the bigger it gets.
Title: Causality
Post by: McQueen on 21/11/2007 23:01:02
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Agreed light arrow. that was precisely what I was getting at the slower an electron is moving the bigger it gets.


With all due respect to Soul surfer and Light arrow this is utter BS. ( pardon the strong language!) Nowhere , either within the atom or outside it, is an electron traveling at relativistic speeds, or anywhere near relativistic speed (speed of light) so its size cannot possibly change according to its speed as you claim. An electron the size of an atom indeed!!!
Title: Causality
Post by: lightarrow on 22/11/2007 08:31:08
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Agreed light arrow. that was precisely what I was getting at the slower an electron is moving the bigger it gets.


With all due respect to Soul surfer and Light arrow this is utter BS. ( pardon the strong language!) Nowhere , either within the atom or outside it, is an electron traveling at relativistic speeds, or anywhere near relativistic speed (speed of light) so its size cannot possibly change according to its speed as you claim. An electron the size of an atom indeed!!!

Where do they do experiments with electrons and other particles? In accelerators! Do you think electrons go slowly there?  [;)]

However, if you think that I intended "relativistic contraction", you're wrong.
How do you establish a nucleu's dimension, for example? Certainly not taking a caliber and putting it inside! [:)] You shoot it with high energy particles and see how they are scattered. Simple example: a proton against another proton, they both go at 0.9c, one against the other, will bounce back at a certain minimum distance between them; but if you shoot them one against the other faster, they approach more, so this minimum distance of interaction reduces, if you increase the particle's energies.
Title: Causality
Post by: Batroost on 22/11/2007 19:35:00
Electrons have no measured size.

You are confusing the DeBroglie wavelength with physical size; see http://en.wikipedia.org/wiki/De_Broglie_hypothesis (http://en.wikipedia.org/wiki/De_Broglie_hypothesis). The low momentum of thermal electrons is what gives rise to the small DeBroglie wavelength and hence the high resolution of electron-microscopes.

The physical dimensions of the electron have never beem measured; even clasical physics arrives at a size <3 x 10-15m. But they could be genuine 'points'..?!?


Title: Causality
Post by: lightarrow on 22/11/2007 20:12:52
Electrons have no measured size.

You are confusing the DeBroglie wavelength with physical size; see http://en.wikipedia.org/wiki/De_Broglie_hypothesis (http://en.wikipedia.org/wiki/De_Broglie_hypothesis). The low momentum of thermal electrons is what gives rise to the small DeBroglie wavelength and hence the high resolution of electron-microscopes.

The physical dimensions of the electron have never beem measured; even clasical physics arrives at a size <3 x 10-15m. But they could be genuine 'points'..?!?



Sorry, I didn't understand to who you have answered.
Title: Causality
Post by: Batroost on 22/11/2007 20:28:47
Sorry,

Re-reading the posts I think you've already covered this.

But, don't you find the idea of an electron as a 'point-like' particle quite appealing (regardless of the wave-like behaviour you can also measure)?



Title: Causality
Post by: Soul Surfer on 23/11/2007 11:28:38
McQueen You have seemed to have forgotten that the wave particle duality applies to ALL materials both microscopic and macroscopic. In the quantum world an electron can be a wave as much as a photon is a particle.  They display interference and diffraction fringes in experiments based on their wavelength and like a photon their notional "size" is a function of their wavelength.  Now the wavelength of an electron or any other body with mass is dependant on the amount of energy/momentum that it has over the rest mass that it possesses ie it depends on its velocity.  This has absolutely nothing to do with relatavistic contraction. IE the slower an electron is travelling the bigger it is.

An interesting aside if you look at the electron orbiting a proton in a hydrogen atom in a classical context and take its wavelength based on the momentum that it has and the classical orbit that you would expect it to be you will find that the orbitals that it takes up quantum mechanically coincide with total numbers of wavelengths of the electron in the classical context.  This acts as a bridge between classical and quantum physics.
Title: Causality
Post by: Soul Surfer on 23/11/2007 11:40:06
There were several posts while I was writing my previous reply.  I agree that no minimum size has yet been measured for an electron.  By "size" I mean the area within which the electron is likely to be located by quantum mechanical uncertanty and the lower the energy of the electron the more "fuzzy" it is and the greater is the volume in which you are likely to find it by probing with another particle.  This effect can be measured experimentally.
Title: Causality
Post by: lightarrow on 23/11/2007 20:13:50
Sorry,

Re-reading the posts I think you've already covered this.

But, don't you find the idea of an electron as a 'point-like' particle quite appealing (regardless of the wave-like behaviour you can also measure)?

But, even regardless of the wave-like behaviour, there is a very known, ancient problem about a point-like electron: its energy should be infinite!
It's a charge, and the potential energy of a charge is proportional to q/r. Send r to zero and...
Title: Causality
Post by: McQueen on 23/11/2007 22:38:02
It is all very well to talk about ‘matter’ waves but no-one can say what they are. De Broglie himself described them as ‘waves that correspond to matter.’ But no-one has till today managed to find out what these matter waves are, what is sure is that nothing is ‘waving ‘.
Title: Causality
Post by: lyner on 23/11/2007 22:47:02
McQueen, did you ever have any formal education in Physics or have you started all your ideas from scratch?
You should wait until you have had time to establish a bit more depth (i.e. serious mathematical treatment) of your ideas if you want people to take them seriously. Your model will have to be consistent with measured observations, to date.

Electron diffraction experiments are good enough to show that particles behave as waves, are they not? Have you got a better explanation?
Title: Causality
Post by: McQueen on 24/11/2007 18:28:03
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Electron diffraction experiments are good enough to show that particles behave as waves, are they not? Have you got a better explanation?

The same experiments can be shown to prove that particles behave as particles ! First I would like to say something about the double speak that has been going on in this thread.
What would you say to me if I told you that the Union Jack was Red, White and Blue in one conversation and then later on during the same conversation insisted that it was Green, Yellow and Purple! Obviously I would have been told to shut up and put a sock in it, because as you can all see for yourselves, the Union Jack is in fact Red, White and Blue.

Each of you who has posted their opinions on ‘matter’ waves in this thread have been guilty of exactly the same kind of misleading statement. By referring to ‘matter’ waves as something real as in “…..as the matter waves get smaller the object gets larger” etc.,  you are treating as something real, ergo ‘matter’ waves an abstraction that has no basis in reality at all. Yet, this is not due to ignorance, each of you is aware of the facts.

Let me refresh your memory. Louis De Broglie won the Nobel Prize in 1924 for his ‘discovery of ‘matter’ waves. The ‘discovery’ of matter waves seemed to support wave particle duality. Schrodinger decided to build a new model of the atom based on De Broglie’s hypotheses. Originally his idea was that ‘matter’ waves were real and he decided to base his model of the electron within the atom as a series of standing waves. Unfortunately, he soon found out, that it was practically impossible to implement. The German physicist Born, then put forward the theory that’matter’ waves did not refer to anything real but that they were waves of probability.

My point is that you are taking an abstraction and treating it as if it were solid fact. Is that entirely ethical?  It is almost like selective amnesia………
Title: Causality
Post by: Soul Surfer on 24/11/2007 19:59:35
You are very wrong McQueen matter waves associated with electrons are clearly visible and observable and definitely not a figment of an imagination you may not like the fact that our universe is built out of a web of probability rather than some sort of solid rock but it is.
Title: Causality
Post by: lyner on 25/11/2007 00:13:21
Anyone who wants  a 'good understanding' of Physics would NEVER try to say what something 'really is'. All you can say about particles is that they can be seen to behave as if they are waves. That is readily demonstrated. It is a fruitful way of looking at things because it allows you to predict certain behaviours  but that is all.
Is that point worth arguing about?

Note: The de Broglie wavelength is not concerned with size - it relates momentum to wavelength.
The 'slower an object is moving, the longer its wavelength. Or, to pass the McQueen objection, we would say it behaves, under a number of circumstances, that way.
Title: Causality
Post by: McQueen on 25/11/2007 00:50:55
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You are very wrong McQueen matter waves associated with electrons are clearly visible and observable and definitely not a figment of an imagination you may not like the fact that our universe is built out of a web of probability rather than some sort of solid rock but it is.
Schrodinger's model of the atom is founded on the proposition that 'matter' waves are not real, they have nothing to do with reality, they are probability waves. You can either say 'matter' waves are real or you can say that they are not real and that they are in fact probability waves. You can't have it both ways. Believe me in the real world you can't have it both ways! Further more you state that matter waves are clearly visible and detectable because they exhibit diffraction. Remember that waves, actual waves in the sea, undergo diffraction. All that is needed for diffraction to be manifested is for the hole the waves, or particles of waves  are passing through, are relatively larger, more than half the dialmeter,  than the hole they are passing through.
Title: Causality
Post by: McQueen on 25/11/2007 00:55:58
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Anyone who wants  a 'good understanding' of Physics would NEVER try to say what something 'really is'. All you can say about particles is that they can be seen to behave as if they are waves. That is readily demonstrated. It is a fruitful way of looking at things because it allows you to predict certain behaviours  but that is all.
Is that point worth arguing about?
Then why do you say, and all of you in this thread have said it. That 'matter' waves are real. If you had said the probability of the of an electron becoming larger increases slighlty when it is in its rest state,  it would have been more acceptable, more truthful and to the point. The reason that you didn't put it like that is because it doesn't sound very convincing!
Title: Causality
Post by: lightarrow on 25/11/2007 16:01:29
Then why do you say, and all of you in this thread have said it. That 'matter' waves are real.
We are telling you that photons, electrons, ecc. behaves as particles and as waves.
I don't understand where is your problem.
Title: Causality
Post by: another_someone on 25/11/2007 16:57:48
It is all very well to talk about ‘matter’ waves but no-one can say what they are. De Broglie himself described them as ‘waves that correspond to matter.’ But no-one has till today managed to find out what these matter waves are, what is sure is that nothing is ‘waving ‘.

I think the more fundamental problem is that nobody has defined what 'matter' is, so the argument about whether it is or is not a wave is rather moot.

All we know about matter is that it has momentum, it carries (although not all matter carries all of these) attributes such as charge and spin, and various other forces.

We can measure the forces, and we can measure how the focal point of those forces move through space (and from that, we can attribute characteristics like mass and momentum, etc.).  Beyond that, we cannot say what, or where, matter is.
Title: Causality
Post by: lyner on 26/11/2007 10:36:54
We have all heard the story of the five blind men who came upon an elephant. Each one found a different part of the animal and described it in his own terms. Each was all right in his own way but failed to get the bigger picture. Between them, they could have had a better understanding.
Why must people be so insistent on a single description of something so multifaceted as matter?