What of the Wavefunction?

[Ronald Hyde]

The wave-function doesn't represent a concrete thing in Nature, it's a mathematical device used to calculate certain things about the Hydrogen atom, such as the energy levels, transition rates, etc..

They can be calculated in other ways, e.g. Heisenberg matrices, or Feynmans path integral method. So when the wave-function 'collapses' it is of no significance whatever, because the system has changed in a way that requires a new wave-function to describe it.

 

The Electron doesn't hide in a 'probability cloud' around the Proton, when it's bound to the Proton, they both cease to exist as single entities and a new entity is formed, the Hydrogen atom, which has excitations which can be deduced using the wave-function, among other methods. If you use the 'probability cloud' model to perform calculations you will get errors.

[juanrga]

The wave-function doesn't represent a concrete thing in Nature, it's a mathematical device used to calculate certain things about the Hydrogen atom, such as the energy levels, transition rates, etc..

They can be calculated in other ways, e.g. Heisenberg matrices, or Feynmans path integral method. So when the wave-function 'collapses' it is of no significance whatever, because the system has changed in a way that requires a new wave-function to describe it.

 

A wave-function describes the state of some quantum systems. As its name indicates, it is a function not a "thing". Heisenberg matrices and Feynman path integral method can be derived from wave-function theory, because matrix and path integral are two alternative formulations of the same theory.

 

The Electron doesn't hide in a 'probability cloud' around the Proton, when it's bound to the Proton, they both cease to exist as single entities and a new entity is formed, the Hydrogen atom, which has excitations which can be deduced using the wave-function, among other methods. If you use the 'probability cloud' model to perform calculations you will get errors.

 

Electron and proton do not cease to exist in a Hydrogen atom and each can be detected.

 

Nobody would confound the wave-function with the 'probability cloud'. It depends on what calculations you are making that you use one or another.

[Ronald Hyde]

A wave-function describes the state of some quantum systems. As its name indicates, it is a function not a "thing". Heisenberg matrices and Feynman path integral method can be derived from wave-function theory, because matrix and path integral are two alternative formulations of the same theory.

 

 

 

Electron and proton do not cease to exist in a Hydrogen atom and each can be detected.

 

Nobody would confound the wave-function with the 'probability cloud'. It depends on what calculations you are making that you use one or another.

You'd be surprised at how many people regard the wavefunction as a 'thing', including far too many theorists. Just read all the nonsensical posts about

the collapse of the wave function, and it's supposed philosophical importance.

 

By what methods of measurements can you separately determine the properties of the electron and proton in a bound hydrogen atom, without unbinding it?

Can you for instance tell us the separate positions of them? If you can't, then your statement that they separately exist is unproven.

[derek w]

The wave-function doesn't represent a concrete thing in Nature, it's a mathematical device used to calculate certain things about the Hydrogen atom, such as the energy levels, transition rates, etc..

 

 

A radio receiver tunes into different wave lengths.I am not sure that I understand what you mean when you say" the wave function doesn't represent a concrete thing in nature".

[Ronald Hyde]

 

A radio receiver tunes into different wave lengths.I am not sure that I understand what you mean when you say" the wave function doesn't represent a concrete thing in nature".

This is a very good question. It represents the probability that you will receive photons, and the fact that that reception is synchronized with the voltage variation of the antenna. It was James Clerk Maxwell who discovered that the wave equation fit into the theory of electromagnetism, and at the time that theory was purely classical, no one had any idea that light in all its forms was quantized. Now we know better than that, we know that the 'wave' is really just a calculational device associated with the discrete photons.

[juanrga]

By what methods of measurements can you separately determine the properties of the electron and proton in a bound hydrogen atom, without unbinding it?

 

There is lots of techniques. This is one recent tracing the motion of an electron in an atom

 

http://newscenter.lb...ectrons-moving/

 

Can you for instance tell us the separate positions of them? If you can't, then your statement that they separately exist is unproven.

 

Who said you than one electron and one proton in an atom have separate positions? Quantum particles are not tiny billiard balls.

 

The wave-function doesn't represent a concrete thing in Nature, it's a mathematical device used to calculate certain things about the Hydrogen atom, such as the energy levels, transition rates, etc..

A radio receiver tunes into different wave lengths.I am not sure that I understand what you mean when you say" the wave function doesn't represent a concrete thing in nature".

 

A radio receiver receives electromagnetic waves. Electromagnetic waves are physical systems; waves are 'things' in the OP language.

 

Wavefunctions are functions; a mathematical function is not a physical system; it is not a 'thing' in the OP language.

Edited August 3, 2012 by juanrga

[Ronald Hyde]

There is lots of techniques. This is one recent tracing the motion of an electron in an atom

 

http://newscenter.lb...ectrons-moving/

 

Reply: Read that description very carefully.

 

Who said you than one electron and one proton in an atom have separate positions? Quantum particles are not tiny billiard balls.

 

Reply: That is exactly the point that I'm making, you can't depend on pictures at this level of explanation.

 

A radio receiver receives electromagnetic waves. Electromagnetic waves are 'things', are physical systems.

 

Wavefunctions are functions; a mathematical function is not a 'thing'.

 

Reply: Electromagnetic waves are functions too. Like every wavefunction. The fact that they are classical waves doesn't make them more or less real.

[juanrga]

Reply: Read that description very carefully.

 

And your point is?

 

Reply: That is exactly the point that I'm making, you can't depend on pictures at this level of explanation.

 

Your original point was that electron and proton cease to exist in an atom but this is not true: QM does not "depend on pictures".

 

Reply: Electromagnetic waves are functions too. Like every wavefunction. The fact that they are classical waves doesn't make them more or less real.

 

No. Electromagnetic waves are physical systems. They have energy momentum and other physical properties and thus are real.

 

Quantum wavefunctions are functions and therefore are not real.

Edited August 3, 2012 by juanrga

[Ronald Hyde]

And your point is?

 

 

 

Your original point was that electron and proton cease to exist in an atom but this is not true: QM does not "depend on pictures".

 

 

 

No. Electromagnetic waves are physical systems. They have energy momentum and other physical properties and thus are real.

 

Quantum wavefunctions are functions and therefore are not real.

 

This is a comment you made on a very recent post:

 

The collapse is not instantaneous. Moreover you are assuming that the system was not prepared in an eigenstate of the observable, in whose case there is not collapse.

 

You seem to believe that all wavefunctions are 'real'.

 

Quote: QM does not "depend on pictures". Answer, but people do, so they treat the wavefunction as reality and not a mathematical device. Only the results we calculate using the wavefunction are real, the transition rates, etc.

[juanrga]

Quantum wavefunctions are functions and therefore are not real.

 

This is a comment you made on a very recent post:

 

The collapse is not instantaneous. Moreover you are assuming that the system was not prepared in an eigenstate of the observable, in whose case there is not collapse.

 

You seem to believe that all wavefunctions are 'real'.

 

I am pretty sure that my above quote "wavefunctions are functions and therefore are not real" says the contrary to what you pretend.

 

Quote: QM does not "depend on pictures". Answer, but people do, so they treat the wavefunction as reality and not a mathematical device. Only the results we calculate using the wavefunction are real, the transition rates, etc.

 

Any textbook on QM that I have makes it clear that wavefunctions are mathematical functions, not physical 'things'. Only some people who has not studied QM or does not understand it claims otherwise.

[Ronald Hyde]

 

I am pretty sure that my above quote "wavefunctions are functions and therefore are not real" says the contrary to what you pretend.

 

Reply: It's what YOU said in a post on this topic, your exact words.

 

The collapse is not instantaneous. Moreover you are assuming that the system was not prepared in an eigenstate of the observable, in whose case there is not collapse.

http://www.scienceforums.net/topic/68101-my-particularly-troublesome-version-of-the-epr-paradox/

 

Any textbook on QM that I have makes it clear that wavefunctions are mathematical functions, not physical 'things'. Only some people who has not studied QM or does not understand it claims otherwise.

I'm not worried much by what the textbooks say, I'm worried by the fact that people keep making posts about the 'collapse of the wavefunction', Schrodingers Cat, and other silly and misleading ideas.

[juanrga]

I am pretty sure that my above quote "wavefunctions are functions and therefore are not real" says the contrary to what you pretend.

 

Reply: It's what YOU said in a post on this topic, your exact words.

 

The collapse is not instantaneous. Moreover you are assuming that the system was not prepared in an eigenstate of the observable, in whose case there is not collapse.

http://www.sciencefo...he-epr-paradox/

 

What I said in this thread is exactly what you quote above: "wavefunctions are functions and therefore are not real". And the words that you are quoting from another thread do not say the contrary, evidently. What part of wavefunctions are not real you do not still understand?

 

Any textbook on QM that I have makes it clear that wavefunctions are mathematical functions, not physical 'things'. Only some people who has not studied QM or does not understand it claims otherwise.

 

I'm not worried much by what the textbooks say, I'm worried by the fact that people keep making posts about the 'collapse of the wavefunction', Schrodingers Cat, and other silly and misleading ideas.

 

If you open a textbook on QM you will find the postulate about wavefunction collapse. It must be a silly idea for people who has never studied QM or cannot understand it.

 

P.S: Since you are so worried about other people posts, could you devote five minutes to learn to reply other's posters without adding your words inside the quotes of others? Thanks

Edited August 3, 2012 by juanrga

[derek w]

This is a very good question. It represents the probability that you will receive photons, and the fact that that reception is synchronized with the voltage variation of the antenna. It was James Clerk Maxwell who discovered that the wave equation fit into the theory of electromagnetism, and at the time that theory was purely classical, no one had any idea that light in all its forms was quantized. Now we know better than that, we know that the 'wave' is really just a calculational device associated with the discrete photons.

 

 

 

So am I to take it that wavelength is governed by the time between cycles of the highest probability to lowest probability and back to highest probability?

[studiot]

Yet another thread with no apparent point or question.

 

 

Rule 5.......or post only to incite a hostile argument.

Rule8.........This is a discussion forum, not your personal lecture hall. Discuss points

 

 

The above extract from the rules (reproduced more fully below) outline my objections to this type of post very clearly.

 

As Juanrrga said

 

What is your point?

 

 

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[Ronald Hyde]

 

What is your point?

 

We're all discussing the physical significance of the concept of the wavefunction.

 

And you have ( for whatever reason ) revived the topic so we can continue it.

[Phi for All]

I'm not worried much by what the textbooks say, I'm worried by the fact that people keep making posts about the 'collapse of the wavefunction', Schrodingers Cat, and other silly and misleading ideas.

Can you give some examples of the kind of posts that prompted your anxiety?

[Ronald Hyde]

Can you give some examples of the kind of posts that prompted your anxiety?

 

Here's two examples:

 

 

http://www.scienceforums.net/topic/63628-wave-function-collapse-takes-some-time/page__p__654800__hl__collapse__fromsearch__1#entry654800

 

http://www.scienceforums.net/topic/65712-measurement-immediately-after-wave-function-collapse/page__p__671373__hl__collapse__fromsearch__1#entry671373

 

But they're really all over the web. There's hardly a forum you can go to that someone isn't discussing or hasn't discussed 'collapse of the wavefunction' or the

related 'Schrodingers cat problem'.

 

The wave-function doesn't represent a concrete thing in Nature, it's a mathematical device used to calculate certain things about the Hydrogen atom, such as the energy levels, transition rates, etc..

A radio receiver tunes into different wave lengths.I am not sure that I understand what you mean when you say" the wave function doesn't represent a concrete thing in nature".

 

Actually that's an excellent picture to draw from. The radio transmitter antenna continually creates the wavefunction, and the receiver antenna continually 'collapses' part of it.

 

The collapsed part represents photons that have produced currents and moved changes in the antenna, which have in turn induced changing voltages in the receiver input

circuits, which are amplified and detected to convert them to audio frequency signals, then amplified more to go to the headphones.

[juanrga]

I'm not worried much by what the textbooks say, I'm worried by the fact that people keep making posts about the 'collapse of the wavefunction', Schrodingers Cat, and other silly and misleading ideas.

 

Can you give some examples of the kind of posts that prompted your anxiety?

 

Here's two examples:

 

http://www.sciencefo...__1#entry654800

 

http://www.sciencefo...__1#entry671373

 

But they're really all over the web. There's hardly a forum you can go to that someone isn't discussing or hasn't discussed 'collapse of the wavefunction' or the

related 'Schrodingers cat problem'.

 

The collapse of wavefunctions is one of the postulates of QM [*] and was introduced by Von-Neumann. Moreover, as it is said in one of your above links there are dynamical models of the collapse discussed in advanced literature.

 

Yours is a very strange point of view. At the one hand you claim that you do not worry by what that textbooks say. At the other way you worry a lot of, when material in textbooks is discussed on the web. Why?

 

[*] E.g. see postulate III in Shankar. See also the further discussion about postulate III in the section "The Collapse of the State Vector".

Edited August 11, 2012 by juanrga

[derek w]

I have a question,a point I am not sure of regarding the radio antenna,are electrons being knocked out of atoms in the same way as the photo-electric effect?

I didn't think radio waves had enough energy/frequency to do this?

[Ronald Hyde]

I have a question,a point I am not sure of regarding the radio antenna,are electrons being knocked out of atoms in the same way as the photo-electric effect?

I didn't think radio waves had enough energy/frequency to do this?

 

This is a very good question to ask, and it shows a lot of insight on your part to ask it. No, the electrons are in the 'conduction band' of the metal of the antenna,

so they can take on a nearly continuous spectrum of momentum and energy states. When a time varying voltage ( potential ) is applied to the antenna terminals

the electrons make transitions between those states. During some of those transitions they can emit photons of the frequency ( energy ) of the voltage variation.

Because there are so many photons of such low energy ( frequency ) we can safely represent them as a continuous wave satisfying Maxwells wave equations.

 

This radio antenna antenna analogy turns out to be a very good way to represent important aspects of the notion of a wavefunction.

 

The collapse of wavefunctions is one of the postulates of QM [*] and was introduced by Von-Neumann. Moreover, as it is said in one of your above links there are dynamical models of the collapse discussed in advanced literature.

 

Yours is a very strange point of view. At the one hand you claim that you do not worry by what that textbooks say. At the other way you worry a lot of, when material in textbooks is discussed on the web. Why?

 

[*] E.g. see postulate III in Shankar. See also the further discussion about postulate III in the section "The Collapse of the State Vector".

 

This post is very worthy of reply. Your statement that mine is a strange point of view is entirely correct. You see, I view the world as being entirely

mathematical in its form, I do not entertain a 'dynamical' view of the world, and I haven't since I was a teenager reading about the behavior of an

electron in a cathode ray tube. I concluded then and there that all we knew about the electron were things that could be expressed mathematically

and the notion of the electron was only to be understood in such a context.

 

So to me physics is entirely about building mathematical representations of Nature, the electron is one such, the wavefunction is another. But we have

to understand the significance of each representation, and place it in its proper context.

 

So I'll study more about the 'collapse of the wavefunction', but from what I've seen so far it supports my own view that it represents the best

information that we have about a system, and how that information evolves with time through the Hamiltonian and Lagrangian representations,

but is not to be taken too literally.

 

BTW, I learned something really important from you, and it applies to the subject here. You said on another post that the Ammonia molecule time

varying representations were 'physical', and that has a strange implication in itself. It implies that any system whatever must be the superposition

of at least two base states. The sole exception to that in all of Nature would be the Higgs particle which is a true 'one state system'. But maybe

that should be discussed in another post.

[juanrga]

The collapse of wavefunctions is one of the postulates of QM [*] and was introduced by Von-Neumann. Moreover, as it is said in one of your above links there are dynamical models of the collapse discussed in advanced literature.

 

Yours is a very strange point of view. At the one hand you claim that you do not worry by what that textbooks say. At the other way you worry a lot of, when material in textbooks is discussed on the web. Why?

 

[*] E.g. see postulate III in Shankar. See also the further discussion about postulate III in the section "The Collapse of the State Vector".

 

This post is very worthy of reply. Your statement that mine is a strange point of view is entirely correct. You see, I view the world as being entirely

mathematical in its form, I do not entertain a 'dynamical' view of the world, and I haven't since I was a teenager reading about the behavior of an

electron in a cathode ray tube. I concluded then and there that all we knew about the electron were things that could be expressed mathematically

and the notion of the electron was only to be understood in such a context.

 

So to me physics is entirely about building mathematical representations of Nature, the electron is one such, the wavefunction is another. But we have

to understand the significance of each representation, and place it in its proper context.

 

So I'll study more about the 'collapse of the wavefunction', but from what I've seen so far it supports my own view that it represents the best

information that we have about a system, and how that information evolves with time through the Hamiltonian and Lagrangian representations,

but is not to be taken too literally.

 

My post remarks your strange point of view about textbooks and websites and made a specific question to you, which you ignored.

 

My post was not related about your point of view about Nature... in any case, let me emphasize that physics is not a synonym for theoretical physics neither for mathematical physics.

 

BTW, I learned something really important from you, and it applies to the subject here. You said on another post that the Ammonia molecule time

varying representations were 'physical', and that has a strange implication in itself. It implies that any system whatever must be the superposition

of at least two base states. The sole exception to that in all of Nature would be the Higgs particle which is a true 'one state system'. But maybe

that should be discussed in another post.

 

I said something different. There is nothing as an "Ammonia molecule time varying representations". Molecules are not static objects but translate, rotate, vibrate, etc. One of the vibration modes of Ammonia gives umbrella like inversion. Each mode is not a representation of the molecule but there are two different molecules as correspond to two different minima in PES (each minimum is separated of the other by a potential barrier as was said to you). I never said that this ordinary molecular process "has a strange implication in itself". Inversion of Ammonia molecule has nothing to do with a superposition of "two base states" (I already explained to you the difference between a molecular process and the concept of resonance in benzene, which is not a process).

[Ronald Hyde]

My post remarks your strange point of view about textbooks and websites and made a specific question to you, which you ignored.

 

My post was not related about your point of view about Nature... in any case, let me emphasize that physics is not a synonym for theoretical physics neither for mathematical physics.

 

I said something different. There is nothing as an "Ammonia molecule time varying representations". Molecules are not static objects but translate, rotate, vibrate, etc. One of the vibration modes of Ammonia gives umbrella like inversion. Each mode is not a representation of the molecule but there are two different molecules as correspond to two different minima in PES (each minimum is separated of the other by a potential barrier as was said to you). I never said that this ordinary molecular process "has a strange implication in itself". Inversion of Ammonia molecule has nothing to do with a superposition of "two base states" (I already explained to you the difference between a molecular process and the concept of resonance in benzene, which is not a process).

 

Obviously we have different points of view. You seem to want to convert me to yours, after all yours is 'right' and any other is wrong. Sounds more like religion to me.

 

I understand about the Ammonia molecule. I understand all those things that you did or did not say. I understand what your friend said

about molecular configurations too, which is also relevant.

 

All of Nature is a process, from our space-time point of view. Everything that is a part of Nature is a process running within the larger process. People, benzene

molecules, stars, galaxies, you name it. This is the view that will eventually prevail. Think of the notion of process that is used in computer science, that is a

better analogy than most.

 

Nature is a mathematical-logical contruct. All the laws of Nature that have ever really worked are mathematical laws. There are no wheels and gears, no little

balls circling around other little balls, there are only mathematical representations, the less we try to interpret them as little 'things' the better off we are.

 

That's my reply to whatever question you asked.

[juanrga]

Obviously we have different points of view. You seem to want to convert me to yours, after all yours is 'right' and any other is wrong. Sounds more like religion to me.

 

What I said about the ammonia molecula is well-known. I do not know why you mix scientific knowledge with religion, but it is still more strange when one notices that you have been accused by other poster, in another thread, of preaching us.

 

I understand about the Ammonia molecule. I understand all those things that you did or did not say. I understand what your friend said

about molecular configurations too, which is also relevant.

 

All of Nature is a process, from our space-time point of view. Everything that is a part of Nature is a process running within the larger process. People, benzene molecules, stars, galaxies, you name it. This is the view that will eventually prevail. Think of the notion of process that is used in computer science, that is a better analogy than most.

 

It is not true that all of nature is a process. For instance Benzene resonance is not a process (as explained to you), a stationary state is not a process, etcetera. Also I do not know what you mean by "our space-time point of view". Wavefunctions are not defined in spacetime for example.

 

The notion of process used in computer science is not fundamental and do not represent what we know about nature. In fact the old idea that nature is a kind of computer does not hold up on close inspection

 

http://www.nybooks.com/articles/archives/2002/oct/24/is-the-universe-a-computer/?pagination=false

 

Nature is a mathematical-logical contruct. All the laws of Nature that have ever really worked are mathematical laws. There are no wheels and gears, no little balls circling around other little balls, there are only mathematical representations, the less we try to interpret them as little 'things' the better off we are.

 

We differentiate between sciences of Nature such as physics, chemistry, biology... and disciplines such as mathematics and logic. Feynman has a delightful discussion of the difference between optics (a branch of physics) and maths in his famous lectures.

[derek w]

This is a very good question to ask, and it shows a lot of insight on your part to ask it. No, the electrons are in the 'conduction band' of the metal of the antenna,

so they can take on a nearly continuous spectrum of momentum and energy states. When a time varying voltage ( potential ) is applied to the antenna terminals

the electrons make transitions between those states. During some of those transitions they can emit photons of the frequency ( energy ) of the voltage variation.

Because there are so many photons of such low energy ( frequency ) we can safely represent them as a continuous wave satisfying Maxwells wave equations.

 

 

 

Thanks Ronald,I have been reading up on points you made e.g:- "conduction band".

 

So I have learnt that varying voltage applied to the antenna's (conduction band),produces a varying short range EMF & a long range EMF.

I take it that the long range EMF consist's of photons of the require frequency?

Edited August 15, 2012 by derek w

[studiot]

So I have learnt that varying voltage applied to the antenna's (conduction band),produces a varying short range EMF & a long range EMF.

I take it that the long range EMF consist's of photons of the require frequency?

 

Photons and EMF are very different things.

 

Further the word range does not associate well with the concept of EMF.