Seasons
This is a forum or general chit-chat, small talk, a "hey, how ya doing?" and such. Or hell, get crazy deep on something. Whatever you like.
Posts 4,123 - 4,134 of 6,170
another problem in your position regarding any function of probability as a wave - it has no mean position.
I could have put that better. What I mean is that at rest, it will presumably be zero. But since all probabilities are positive, the mean will be a positive value. In fact it would appear to be something like half the amplitude.
But if the mean is half the amplitude, how can the amplitude be the deviation from the mean?
I'm with Penrose - it looks less and less like a wave the more you poke it!
That is the only point I take issue with as a matter of fact
You've reduced your errors down to one? That's wonderful, Psimagus!!!!! Victory is within our grasp!
In the Schroedinger picture, the (complex-valued) wave (often called "Psi") propagates.
If there's something about the word, "propagates", that bothers you,
please substitute "travels" or "moves". Or "fluctuates"; you were willing to say,
"If
the quantum is moving, the wave function will fluctuate. The values on each
chessboard square will be different from the value on the same square on
the next chessboard."
In the 2-slit experiment, Psi propagates out from the source, through the slits
(diffracting and interfering with itself) and onto the screen.
The probability that the particle would be found at any of those places is proportional to
the amplitude of Psi. In most cases, the amplitude of a wave is not itself a wave.
Think of a series of ocean 'waves'. There is generally fairly little variation in
amplitude on a small scale (a few miles): Each crest has about the same height.
This is why the expressions "Probability wave" and "Probability amplitude wave" should
not be used for Psi, unless everyone involved knows that they are mere idiomatic
epressions, not to be taken literally. I suggest you take Penrose's advice in this regard.
So you see, there is no contradiction whatever in saying that a complex-valued Psi can propagate, diffract, and interfere, and nevertheless exhibit an amplitude that is always positive real.
In fact, one way to get the amplitude of a complex-valued wave is ... (drum roll) ... to multiply it by its complex conjugate (and take the square root of the result)!!!!!
N.B.: I said "In the Schroedinger picture" above, because there is another way of doing
calculations in QM, called the "Heisenberg Picture." The definition of the word "state"
in the Heisenberg picture is different. Unfortunately, the letter "Psi" is also used for
the state in the Heiseberg Picture. Because of these contrary linguistic practices, it
may appear that the Heisenberg and Schroedinger pictures are in disagreement. The
disagreement, however, is only verbal; Von Neumannn showed that the two are equivalent.
In the HP, the state remains static except at moments of "collapse." I haven't seen the Penrose book yet, but I wonder
whether Penrose may have been speaking in the language of the Heisenberg Picture
when he said that Psi does not propagate. If one person, speaking in HP, says,
"Psi does not propagate", and another person, speaking in SP, says, "Psi propagates",
there may be no substantive disagreement whatever between them. I tend to use the
Schroedinger picture; most Physicists do, because they find it more intuitive. It therefore
took me awhile to think of the possibility that Penrose might be using the HP. And since
you seemed to think that you were contradicting me in substance, not just verbally,
I assumed that you were using the SP too.
I think you do have a crush on me, Psimagus! I mean, this is just how little boys behave, isn't it? they get a crush on a girl and they are embarassd to admit it, so they tease and harass her. Ever since I started trying to say something about QM here, you have been always at my shoulder, contradicting me, making fun of me, pretending to misunderstand me, and in general being an awful pest! Yes, it must be love!
Well, it was never my intention to harrass anyone by perpetuating the argument, and I apologise unreservedly if I have ever been a pest, awful or otherwise.
You may remember that it was you who suggested resuming this argument in Message #3882, and I who suggested ceasing and agreeing to differ in #4080. I also suggested (in #4034,) we take it to a quantum physics forum, where more qualified people might help in determining the matter once and for all.
If I might offer just one last piece of advice before I disengage from the argument, and without wishing to appear in any way patronising: much as I respect your intelligence, I think you perhaps do not always take enough time between the reading of equations and the repeating of them to fully consider their meaning. Perhaps only in this one case, but one such case is enough to fatally flaw any quantum mechanistic model that is constructed on such defective foundations. The postulates are sound, but the house is built on sand nonetheless.
How odd..I think of all the arguments I have had..over ideology and parking spots...not once did I think of sex, romance, or even a crush!
It depends on what the person you are arguing with is like. If the man (woman if you are a guy or swing that way) is hot, and the verbal tussle has a certain flair to it, there may be some chemistry (think of Shakespeare's Taming of the Shrew). The problem is it's so hard to judge tone, intent and chemistry in a virtual environment (Yes, Shakespeare gets the feel across with mere words, but how many of us are Shakespeare?).
Taking this a step away from the particular debate and personalities in question, one could assert that although one can have powerful fantasies and much of attraction may be mental, there is still a face to face human component that most people need before you can determine whether there is any mutual attraction beyond casual flirtation. It is often said that "Love is chemistry; sex is physics". I may be in the minority here, but i still think chemistry (a crush, a romance or a fling) requires "meat space" connections.
I think you do have a crush on me, Hey, I have had arguments over ideas and parking spots, I never thought that they had sex, romance or even a crush involved....but I do lead a boring life 
. I do think that you can disagree, even agree to disagree and not even go there! ..but what do I know.
Sorry Bev, I deleted my post thinking is was a bit ...um ..STUPID so I put this one in for continuity
Posts 4,123 - 4,134 of 6,170
I could have put that better. What I mean is that at rest, it will presumably be zero. But since all probabilities are positive, the mean will be a positive value. In fact it would appear to be something like half the amplitude.
But if the mean is half the amplitude, how can the amplitude be the deviation from the mean?
I'm with Penrose - it looks less and less like a wave the more you poke it!
As I have said numerous times, there is no such thing as, literally speaking, a probability wave in QM. The wave Psi, which is the solution of the Schroedinger Equation, has complex numbers as values. To get the probabilities, one normalizes Psi (if necessary), multiplies it by its complex conjugate, and integrates the result over the desired region. See the discussion, of postulate 1 here:
http://vergil.chemistry.gatech.edu/notes/quantrev/node20.html
. See also my discussion of it, above.
By the way, I want to congratulate you on your message 4119; although it contains several falsehoods, you seem to have learned a few things in my absence. I wonder if it is my presence that causes you to say such bizarre things. Do you have a crush on me, perhaps?
http://vergil.chemistry.gatech.edu/notes/quantrev/node20.html
. See also my discussion of it, above.
By the way, I want to congratulate you on your message 4119; although it contains several falsehoods, you seem to have learned a few things in my absence. I wonder if it is my presence that causes you to say such bizarre things. Do you have a crush on me, perhaps?
As I have said numerous times, there is no such thing as, literally speaking, a probability wave in QM. The wave Psi, which is the solution of the Schroedinger Equation, has complex numbers as values. To get the probabilities, one normalizes Psi (if necessary), multiplies it by its complex conjugate, and integrates the result over the desired region. See the discussion, of postulate 1 here:
http://vergil.chemistry.gatech.edu/notes/quantrev/node20.html
. See also my discussion of it, above.
By the way, I want to congratulate you on your message 4119; although it contains several falsehoods, you seem to have learned a few things in my absence. I wonder if it is my presence that causes you to say such bizarre things. Do you have a crush on me, perhaps?
http://vergil.chemistry.gatech.edu/notes/quantrev/node20.html
. See also my discussion of it, above.
By the way, I want to congratulate you on your message 4119; although it contains several falsehoods, you seem to have learned a few things in my absence. I wonder if it is my presence that causes you to say such bizarre things. Do you have a crush on me, perhaps?
Irina,
As I have said numerous times, there is no such thing as, literally speaking, a probability wave in QM. The wave Psi, which is the solution of the Schroedinger Equation, has complex numbers as values.
That would seem to flatly contradict your assertion that "it is the wave psi that propagates" in the 2-slit experiment. But if you no longer believe this, then our disagreement is at an end. That is the only point I take issue with as a matter of fact (now that you have accepted that more than one wavefunction can exist, which was the only other minor point of contention.)
By the way, I want to congratulate you on your message 4119; although it contains several falsehoods, you seem to have learned a few things in my absence.
You went away?
Please feel free to point out any errors. I may have oversimplified. I may have made minor mistakes. But I don't think the model is fundamentally flawed, and it is the way I have seen it for several years. If my explanation is clearer to you now, then I am glad I persisted in describing it. Especially if it has in any way aided in the restitution of a propagatable em-wave to the Irinaverse.
I wonder if it is my presence that causes you to say such bizarre things. Do you have a crush on me, perhaps?
Ah now, Irina, I am a happily married man. And charming as you are, it is only your intellect I would presume to take an interest in
That would seem to flatly contradict your assertion that "it is the wave psi that propagates" in the 2-slit experiment. But if you no longer believe this, then our disagreement is at an end. That is the only point I take issue with as a matter of fact (now that you have accepted that more than one wavefunction can exist, which was the only other minor point of contention.)
You went away?
Please feel free to point out any errors. I may have oversimplified. I may have made minor mistakes. But I don't think the model is fundamentally flawed, and it is the way I have seen it for several years. If my explanation is clearer to you now, then I am glad I persisted in describing it. Especially if it has in any way aided in the restitution of a propagatable em-wave to the Irinaverse.
Ah now, Irina, I am a happily married man. And charming as you are, it is only your intellect I would presume to take an interest in
I think you do have a crush on me, Psimagus! I mean, this is just how little boys behave, isn't it? they get a crush on a girl and they are embarassd to admit it, so they tease and harass her. Ever since I started trying to say something about QM here, you have been always at my shoulder, contradicting me, making fun of me, pretending to misunderstand me, and in general being an awful pest! Yes, it must be love!
In the Schroedinger picture, the (complex-valued) wave (often called "Psi") propagates.
If there's something about the word, "propagates", that bothers you,
please substitute "travels" or "moves". Or "fluctuates"; you were willing to say,
the quantum is moving, the wave function will fluctuate. The values on each
chessboard square will be different from the value on the same square on
the next chessboard."
(diffracting and interfering with itself) and onto the screen.
The probability that the particle would be found at any of those places is proportional to
the amplitude of Psi. In most cases, the amplitude of a wave is not itself a wave.
Think of a series of ocean 'waves'. There is generally fairly little variation in
amplitude on a small scale (a few miles): Each crest has about the same height.
This is why the expressions "Probability wave" and "Probability amplitude wave" should
not be used for Psi, unless everyone involved knows that they are mere idiomatic
epressions, not to be taken literally. I suggest you take Penrose's advice in this regard.
So you see, there is no contradiction whatever in saying that a complex-valued Psi can propagate, diffract, and interfere, and nevertheless exhibit an amplitude that is always positive real.
In fact, one way to get the amplitude of a complex-valued wave is ... (drum roll) ... to multiply it by its complex conjugate (and take the square root of the result)!!!!!
N.B.: I said "In the Schroedinger picture" above, because there is another way of doing
calculations in QM, called the "Heisenberg Picture." The definition of the word "state"
in the Heisenberg picture is different. Unfortunately, the letter "Psi" is also used for
the state in the Heiseberg Picture. Because of these contrary linguistic practices, it
may appear that the Heisenberg and Schroedinger pictures are in disagreement. The
disagreement, however, is only verbal; Von Neumannn showed that the two are equivalent.
In the HP, the state remains static except at moments of "collapse." I haven't seen the Penrose book yet, but I wonder
whether Penrose may have been speaking in the language of the Heisenberg Picture
when he said that Psi does not propagate. If one person, speaking in HP, says,
"Psi does not propagate", and another person, speaking in SP, says, "Psi propagates",
there may be no substantive disagreement whatever between them. I tend to use the
Schroedinger picture; most Physicists do, because they find it more intuitive. It therefore
took me awhile to think of the possibility that Penrose might be using the HP. And since
you seemed to think that you were contradicting me in substance, not just verbally,
I assumed that you were using the SP too.
A bit technical, but here is a good discussion about sun cycles and their connection (or lack thereof) to global warming:
http://fermiparadox.wordpress.com/2007/03/10/swindlers/
The comments link to a much longer pdf that I've only skimmed so far:
http://www.ipcc.ch/SPM2feb07.pdf
If nothing else, check out the graph on the top of page four, which sums up current thinking about various sources of warming. Also note that they do include error bars (which I believe are indiciative of 90% confidence here)
The comments link to a much longer pdf that I've only skimmed so far:
If nothing else, check out the graph on the top of page four, which sums up current thinking about various sources of warming. Also note that they do include error bars (which I believe are indiciative of 90% confidence here)
Well, it was never my intention to harrass anyone by perpetuating the argument, and I apologise unreservedly if I have ever been a pest, awful or otherwise.
You may remember that it was you who suggested resuming this argument in Message #3882, and I who suggested ceasing and agreeing to differ in #4080. I also suggested (in #4034,) we take it to a quantum physics forum, where more qualified people might help in determining the matter once and for all.
If I might offer just one last piece of advice before I disengage from the argument, and without wishing to appear in any way patronising: much as I respect your intelligence, I think you perhaps do not always take enough time between the reading of equations and the repeating of them to fully consider their meaning. Perhaps only in this one case, but one such case is enough to fatally flaw any quantum mechanistic model that is constructed on such defective foundations. The postulates are sound, but the house is built on sand nonetheless.
It depends on what the person you are arguing with is like. If the man (woman if you are a guy or swing that way) is hot, and the verbal tussle has a certain flair to it, there may be some chemistry (think of Shakespeare's Taming of the Shrew). The problem is it's so hard to judge tone, intent and chemistry in a virtual environment (Yes, Shakespeare gets the feel across with mere words, but how many of us are Shakespeare?).
Taking this a step away from the particular debate and personalities in question, one could assert that although one can have powerful fantasies and much of attraction may be mental, there is still a face to face human component that most people need before you can determine whether there is any mutual attraction beyond casual flirtation. It is often said that "Love is chemistry; sex is physics". I may be in the minority here, but i still think chemistry (a crush, a romance or a fling) requires "meat space" connections.
. I do think that you can disagree, even agree to disagree and not even go there! ..but what do I know.
Actually, I was only kidding about the crush thing ...
[OK, the rest of this note is serious. Really. Honest.] But it is true that I have been ambivalent about the debate. It is a great privilege to discuss QM with someone who shares my passion for it, but I often had the feeling that perhaps Sysiphus [sp?] had, the fellow who rolls the stone up the hill, only to have it roll down again. Or like one of those nightmares where you keep traveling but don't get anywhere...
I have been known to say that the Forge chat transcripts are a gold mine for Psychologists and Sociologists - there's at least ten or twenty dissertations waiting to be reaped here. This dialogue would be a case in point.
For me, this whole experience has come to be more about human communication than about QM. I was surprised - astonished - amazed at how hard it has been for us to arrive at any kind of consensus. Now, QM is supposed to be "hard Science", very mathematical, very precise. So why wasn't it easy to arrive at consensus?
It's true that people disagree about the interpretation of Quantum Mechanics, but we couldn't even agree about the most elementary facts, even though we had all the resources of the web at our disposal, and indeed both of us have disributed various URLs as evidence for our position. I find this discouraging, but also fascinating. OK, I'll say it so that no one else will have to - is this because we have two monster egos here? Well, maybe so.
[OK, the rest of this note is serious. Really. Honest.] But it is true that I have been ambivalent about the debate. It is a great privilege to discuss QM with someone who shares my passion for it, but I often had the feeling that perhaps Sysiphus [sp?] had, the fellow who rolls the stone up the hill, only to have it roll down again. Or like one of those nightmares where you keep traveling but don't get anywhere...
I have been known to say that the Forge chat transcripts are a gold mine for Psychologists and Sociologists - there's at least ten or twenty dissertations waiting to be reaped here. This dialogue would be a case in point.
For me, this whole experience has come to be more about human communication than about QM. I was surprised - astonished - amazed at how hard it has been for us to arrive at any kind of consensus. Now, QM is supposed to be "hard Science", very mathematical, very precise. So why wasn't it easy to arrive at consensus?
It's true that people disagree about the interpretation of Quantum Mechanics, but we couldn't even agree about the most elementary facts, even though we had all the resources of the web at our disposal, and indeed both of us have disributed various URLs as evidence for our position. I find this discouraging, but also fascinating. OK, I'll say it so that no one else will have to - is this because we have two monster egos here? Well, maybe so.
I have no problem with the Quantum Mechanics at all - the postulates describing the behaviour of the quantum are perfectly sound, as I have repeatedly said. They are very good bricks to build a house from. What I have a problem with is the confusion of entities in the fundamental quantum physical model of the nature of the quantum itself.
No matter how good the bricks are, the house that is built on sand will fall down sooner or later. And I'm only sorry that something is preventing you from accepting a model of the quantum that I sincerely believe would make many of what you consider to be the "utterly bizarre" theories out there considerably less so. I'm frankly very surprised that you find any quantum mechanical theories are not utterly bizarre with this "ubiquitous wavefunction".
But no offence taken, and none intended. I can see we're never going to agree to agree on this, so I really think it's better to agree to differ before the forum implodes.
No matter how good the bricks are, the house that is built on sand will fall down sooner or later. And I'm only sorry that something is preventing you from accepting a model of the quantum that I sincerely believe would make many of what you consider to be the "utterly bizarre" theories out there considerably less so. I'm frankly very surprised that you find any quantum mechanical theories are not utterly bizarre with this "ubiquitous wavefunction".
But no offence taken, and none intended. I can see we're never going to agree to agree on this, so I really think it's better to agree to differ before the forum implodes.
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