What is the relationship between scale and rate of change in quantum mechanics?

[Tiberius]

Originally posted by M. Gaspar
Ah, here we are...

As you see, you were not talking about quantum experiments here. You were talking about "New Age" books that promote how "consciousness plays a role in determining reality."

Yep - that's exactly what I was talking about. And?

I would use a different word than "determining". I would say "creating". And I would not say "consciousness", I would say "intention" (which is an aspect of consciousness).

Ok.

Hence, my response was to my personal "interpretation" of what you were facetiously saying to Fliption(?) -- that is, "Intention plays a role in creating reality." -- in which case I suggested that instead of burning the books, simply look to your life experiences to see if there is "evidence" that your intentions have "created" your "experience" (the word I would substitute for "reality").

What do you mean? Do you mean things like, I "intend" to take out the trash, so then I do, so then the trash is outside? Or I intend to get a job - then I have a job? If that's all you mean then "duh". If you mean something more, please explain.

...Meanwhile, although I feel like a little dog yapping to get the attention of a pack of BIG DOGS ... I at least do not have to apologize for being "off topic". You, yourself, imported my notions about consciousness when you started this thread ...which gives me license to yap in from time to time.

OH! So that's what's going on. Here I am responding to other's posts and seeing you interjecting as though I was talking to you (which is ok by the way - just confusing). And I was thinking, "What is this guy talking about - does he know me?" So you think I've imported your notions about consciousness when I started this thread?? As I said, when I started this thread I didn't know you or your ideas from adam. This thread was started because the misinterpretations of "observation" in QM is a very common mistake and I simply had the idea to correct it here. In fact, even now I had to look up to remind myself of your screenname - "Gasper" - got it. Sorry for not noticing you before. It's hard to keep everyone and their particular viewpoints straight. Honestly, I guess I don't remember because I respond to particular statements and ideas - not people. Who you are isn't as important to me as what you're saying in any given thread. So, I often respond without even taking note of who the user is.

 

[M. Gaspar]

Originally posted by Tiberius
What do you mean? Do you mean things like, I "intend" to take out the trash, so then I do, so then the trash is outside? Or I intend to get a job - then I have a job? If that's all you mean then "duh". If you mean something more, please explain.

Not exactly. And while I'm willing to lay down a few lines on the subject, I'm wondering whether this is the thread? Apparently, staying "on topic" is important to the mentors ...and I can understand why.

So you think I've imported your notions about consciousness when I started this thread??

My mistake...facilitated, no doubt, by the appearance of your first post immediately after I asked a question about the phantom QM "observer" on another thread.

Honestly, I guess I don't remember because I respond to particular statements and ideas - not people. Who you are isn't as important to me as what you're saying in any given thread. So, I often respond without even taking note of who the user is.

Alrighty, then. Henceforth I will realize that -- at least on these threads -- you are primarily responding to ideas.

 

[Mentat]

Originally posted by Fliption
I'm not sure I can because I don't understand what your question is. The point of that experiment was that idler photons were be "blocked" and this was causing the "signal" photons to collapse. Even though the two were on entirely different paths. The Signal photons had previously shown an interference pattern. Once the idler photons were blocked the signal photons collapsed. The difference is that now we can calculate which path the signal photons took.

No, the difference is that you blocked the idler photons. These photons were quantum-bound, and what you do to one, immediately affects the other. Surely you know of the EPR experiment, wherein an electron's spin is changed instantaneously because of it's being quantum-bound to another electron, which was being "observed" directly by the experimenters (at least I think that's what happened). However, this "quantum entanglement" is really just a product of the fact that they are not individual particles, but greater probabilities of the wave-function of one electron (or so it was explained to me).

My point is that you cannot literally (in the sense of an individual particle - which doesn't really exist in QM) split a massless particle into two massless particles, but you can split the probability wave of a particle (in the case of your experiment, a photon) in which case, whatever you do to one of the "halves" will instantaneously affect the other "half" (since they are both really the same "particle").

 

[Fliption]

Originally posted by Mentat
No, the difference is that you blocked the idler photons. These photons were quantum-bound, and what you do to one, immediately affects the other. Surely you know of the EPR experiment, wherein an electron's spin is changed instantaneously because of it's being quantum-bound to another electron, which was being "observed" directly by the experimenters (at least I think that's what happened). However, this "quantum entanglement" is really just a product of the fact that they are not individual particles, but greater probabilities of the wave-function of one electron (or so it was explained to me).

My point is that you cannot literally (in the sense of an individual particle - which doesn't really exist in QM) split a massless particle into two massless particles, but you can split the probability wave of a particle (in the case of your experiment, a photon) in which case, whatever you do to one of the "halves" will instantaneously affect the other "half" (since they are both really the same "particle").

OK you're getting closer but you still aren't getting the full picture. As I've said, obviously the signal photons have been impacted in some way which has caused them to collapse. I understand this completely. But if you read through these experiments you can see that just "blocking the idler photons" is not what causes the collapse. The experiment can be set up such that blocking the idler photons doesn't collapse the signal photons at all. The only difference between the 2 would be that in one case, blocking the idler photons enables you to calculate information about the signal photons. As I said previously, the collapse of the wave function is not 100% correlated with blocking anything. It is 100% correlated with changing the experiment so that you can achieve "knowledge". Thus it is the changes in environmental conditions that create potential for knowledge that collpase wave functions.

When the scientists say they are not interfering with the particle I think they mean that they can hold the interference constant and get a different result. The only thing that changes in the conditions to create this different result is the potential for knowledge; not an additional interference.

 

[Mentat]

Originally posted by Fliption
OK you're getting closer but you still aren't getting the full picture. As I've said, obviously the signal photons have been impacted in some way which has caused them to collapse. I understand this completely. But if you read through these experiments you can see that just "blocking the idler photons" is not what causes the collapse. The experiment can be set up such that blocking the idler photons doesn't collapse the signal photons at all. The only difference between the 2 would be that in one case, blocking the idler photons enables you to calculate information about the signal photons. As I said previously, the collapse of the wave function is not 100% correlated with blocking anything. It is 100% correlated with changing the experiment so that you can achieve "knowledge". Thus it is the changes in environmental conditions that create potential for knowledge that collpase wave functions.

When the scientists say they are not interfering with the particle I think they mean that they can hold the interference constant and get a different result. The only thing that changes in the conditions to create this different result is the potential for knowledge; not an additional interference.

Do you mean to imply that they can interfere with the idler photons, in such a way as to make them unable to "gain knowledge" of the state of the other photons, and yet somehow they "know" that they haven't collapsed the wave-function of the other photons?

 

[Fliption]

Originally posted by Mentat
Do you mean to imply that they can interfere with the idler photons, in such a way as to make them unable to "gain knowledge" of the state of the other photons, and yet somehow they "know" that they haven't collapsed the wave-function of the other photons?

Yes. I'm not sure I understand where the beef is on this knowing that the wave function didn't collapse. When the wave function doesn't collapse, an interference pattern emerges. Seems simple. Am I missing something?

 

[Mentat]

Originally posted by Fliption
Yes. I'm not sure I understand where the beef is on this knowing that the wave function didn't collapse. When the wave function doesn't collapse, an interference pattern emerges. Seems simple. Am I missing something?

I'm sorry, restate that please (didn't quite get what you mean, and don't want to respond without understanding).

 

[Fliption]

Originally posted by Mentat
I'm sorry, restate that please (didn't quite get what you mean, and don't want to respond without understanding).

Sorry. I was making an assumption that perhaps I shouldn't have. Let's start over. Please rephrase your question. I'm not sure I understoood it.

This question...

Do you mean to imply that they can interfere with the idler photons, in such a way as to make them unable to "gain knowledge" of the state of the other photons, and yet somehow they "know" that they haven't collapsed the wave-function of the other photons?

 

[Mentat]

Originally posted by Fliption
Sorry. I was making an assumption that perhaps I shouldn't have. Let's start over. Please rephrase your question. I'm not sure I understoood it.

This question...

Do you mean to imply that they can interfere with the idler photons, in such a way as to make them unable to "gain knowledge" of the state of the other photons, and yet somehow they "know" that they haven't collapsed the wave-function of the other photons?

Hmm...I guess I was asking if they were saying that they interfered with the idler photons, but didn't collapse the wave-function - in the first experiment. This is what you seemed to imply.

 

[Fliption]

Originally posted by Mentat
Hmm...I guess I was asking if they were saying that they interfered with the idler photons, but didn't collapse the wave-function - in the first experiment. This is what you seemed to imply.

No I don't think so. The very first thing they would do is probably not interfere with the idler photons and show that the wave function did not collapse. Then they measure the idler photons and show that the signal photons wave function collapses. The next step is what I was talking about. Where the measurement is made on the idler photons and then subsequently the information "erased". When this is done the signal photons show an interference pattern again. I will have to re-read to see how or whether this exact step was done in this experiment. But if you read through the article you will see it littered with experiments that go this next step. You may recall the "eraser" experiments? These experiments do exactly this. They interfere and determine the path of the photons moving through the 2 slits(I like this word ) thus causing the wave function to collapse. The photons choose a path. Then the experiment places an eraser of this information on the opposite side of the slits. The photons have to decide whether to collpase or not before it gets to the eraser. Once this information is erased the interference pattern returns. So the question in this particular experiment would be "How does the photon know that the information will be erased on the opposite side of the slits?" I don't ask this question looking for a profound answer. I ask it so that you can see what the point of the experiment is.

Anything else could have been placed in the path of the photons besides the eraser and the wave function would have remained collapsed. It requires more than just something blocking it or other particles to bump into. If that was all it took then it's a wonder we ever see an interference pattern. These experiments continually appear to show that not only are photons nowhere in particular but they are also nowhen in particular! The only thing that makes the photon choose a place and a time is when the conditions allow for information. Once the information is gone, the photon returns back to lala land.

What does all this mean? Who knows? But it's certainly not the billiard ball "common sense"(his words not mine) world that Tiberius painted in his original post on this thread.

 

[Mentat]

Originally posted by Fliption
No I don't think so. The very first thing they would do is probably not interfere with the idler photons and show that the wave function did not collapse.

How can you possibly "show" that the wave-function didn't collapse? This is impossible, even according to their hypothesis (which postulates that their being able to "know" whether the wave-function had collapsed or not would cause it to collapse).

Then they measure the idler photons and show that the signal photons wave function collapses. The next step is what I was talking about. Where the measurement is made on the idler photons and then subsequently the information "erased". When this is done the signal photons show an interference pattern again. I will have to re-read to see how or whether this exact step was done in this experiment. But if you read through the article you will see it littered with experiments that go this next step. You may recall the "eraser" experiments? These experiments do exactly this. They interfere and determine the path of the photons moving through the 2 slits(I like this word ) thus causing the wave function to collapse. The photons choose a path. Then the experiment places an eraser of this information on the opposite side of the slits. The photons have to decide whether to collpase or not before it gets to the eraser. Once this information is erased the interference pattern returns. So the question in this particular experiment would be "How does the photon know that the information will be erased on the opposite side of the slits?" I don't ask this question looking for a profound answer. I ask it so that you can see what the point of the experiment is.

But the photon can't "know" anything! Isn't that obvious? Honestly! Please choose different terminology, because a hypothesis that require conscious photons is doomed to failure.

Anyway, I don't understand what "erasing" means. What does it mean to "erase the information", in this experiment?

Anything else could have been placed in the path of the photons besides the eraser and the wave function would have remained collapsed. It requires more than just something blocking it or other particles to bump into. If that was all it took then it's a wonder we ever see an interference pattern. These experiments continually appear to show that not only are photons nowhere in particular but they are also nowhen in particular! The only thing that makes the photon choose a place and a time is when the conditions allow for information. Once the information is gone, the photon returns back to lala land.

Whatever, but the information had nothing to do with it (AFAIU), since information doesn't even exist at the subatomic level. But, I will withhold further comment, until you explain what an "eraser" is.

 

[Fliption]

Originally posted by Mentat
How can you possibly "show" that the wave-function didn't collapse? This is impossible, even according to their hypothesis (which postulates that their being able to "know" whether the wave-function had collapsed or not would cause it to collapse).

Yeah this is where I thought you were originally going several posts back. I do not understand this point at all. You know that the wave function does not collapse because you can observe the interference pattern. This is exactly the point. The photon wave function does not collapse just because it has hit a screen. It takes more than just a physical disturbance. The screen will show an interence pattern demonstrating that the wave function DID NOT collapse. This is just the basics of QM. You can go no further if you don't understand this.

But the photon can't "know" anything! Isn't that obvious? Honestly! Please choose different terminology, because a hypothesis that require conscious photons is doomed to failure.

Hmm you're a bit sensitive. This is just a figure of speech. Scientists wax poetic all the time in this manner. So you'll excuse me if I don't spend an extra 15 minutes trying to find words that will appease. I kinda expected this reaction which is why I said I don't ask this question to provoke a profound answer. I am merely asking the question this way so that you can understand the goal of the experiment. Whether consciousness is involved is totally irrelevant to this point anyway.

And let me also suggest that once you understand this stuff NOTHING is obvious. This is really the whole point of my entry into this thread. This "clarification" has oversimplfied QM to the point that it's just wrong. If you disagree then you will have to say why. Saying it is obvious will not work.

Anyway, I don't understand what "erasing" means. What does it mean to "erase the information", in this experiment?

This is clearly spelled out in the experiments.

Whatever, but the information had nothing to do with it (AFAIU), since information doesn't even exist at the subatomic level. But, I will withhold further comment, until you explain what an "eraser" is. [/B]

Then you are not disagreeing with me. You are disagreeing with every QM experiment that's been done. All I can say is that you need to be much more thorough at reading about this stuff. Spend some time with it objectively. Leave your pre-conceptions about what is "obvious" behind. If you don't know what the concept of an eraser is then you don't understand enough about the experiments to make the statements you're making.

I say go try to understand it and then let's talk about what it means. It is much more efficient for me to provide links to information and then we discuss it. The details of the experiments speak for themselves. You have to understand that much before we can talk about what it means and what it doesn't mean.

 

[Mentat]

Originally posted by Fliption
Yeah this is where I thought you were originally going several posts back. I do not understand this point at all. You know that the wave function does not collapse because you can observe the interference pattern. This is exactly the point. The photon wave function does not collapse just because it has hit a screen. It takes more than just a physical disturbance. The screen will show an interence pattern demonstrating that the wave function DID NOT collapse. This is just the basics of QM. You can go no further if you don't understand this.

No, I understand this just fine, but doesn't it contradict their own assumption (that their "knowledge" of the state of the wave-function causes it to collapse)?

Hmm you're a bit sensitive. This is just a figure of speech. Scientists wax poetic all the time in this manner. So you'll excuse me if I don't spend an extra 15 minutes trying to find words that will appease. I kinda expected this reaction which is why I said I don't ask this question to provoke a profound answer. I am merely asking the question this way so that you can understand the goal of the experiment. Whether consciousness is involved is totally irrelevant to this point anyway.

No it's not, since you are implying that the photon changes "when threatened" by the possibility of being "known". This is an example of foresight, and it takes consciousness to have foresight. Please note: this is not a semantic argument, you can try to use other words if you want, but it won't change the fact that they are implying a photon's having "knowledge".

And let me also suggest that once you understand this stuff NOTHING is obvious. This is really the whole point of my entry into this thread. This "clarification" has oversimplfied QM to the point that it's just wrong. If you disagree then you will have to say why. Saying it is obvious will not work.

Well, I understand that we shouldn't oversimplify QM, and that it is really inconceivable, but I still don't see where Tiberius got anything wrong.

Okay, I will say why I disagree that Tiberius is wrong: The actual textbooks on QM agree with him. That's basically it, though I also happen to know a bit about consciousness and knowledge now - that they are macroscopic phenomena and couldn't possibly have an affect on the subatomic realm (where the brain is composed of exactly the same things as a rock).

This is clearly spelled out in the experiments.

When will people understand that I get one hour on the internet, to do everything that I have to do (mainly PFs, but I am also involved in trying to find some therapies for my friends dying wife (she has breast cancer that is in metastasis )). Please, if you cannot explain what an "eraser" is, just say so. If you can, then do it. I don't have time to refer to the links. Sorry.

Then you are not disagreeing with me. You are disagreeing with every QM experiment that's been done.

In what way?! Information is a product of the workings of computers (be the organic or otherwise). But all of these computing devices (including the brain) are composed of subatomic particles. Therefore, how is a photon to distinguish an electron that happens to belong to a brain, from one that happens to belong to a piece of seaweed?

Also, take the experiment that we are discussing, for example: They said that they had "split the photons", when you obviously cannot split a massless particle into smaller pieces - thus, what it means to "split the particle" is to split it's probability, so that it is most probably in those two different directions. If you have not understood this (quantum entanglement) by now, then it is you who needs to do more study (and layman texts are probably not the best place - no offense).

All I can say is that you need to be much more thorough at reading about this stuff.

I will continue to read about "this stuff", but I won't rely on layman texts to do so, since they can only ever be partially accurate, and are usually reliant on analogy. Think of how much havoc the Schrodinger's Cat analogy caused. Instead of viewing QM as a theory of particles - which is what it is - they viewed it as a theory where cats are only alive when we're looking at them (an interpretation that was certainly not Schrodinger's goal).

Spend some time with it objectively. Leave your pre-conceptions about what is "obvious" behind. If you don't know what the concept of an eraser is then you don't understand enough about the experiments to make the statements you're making.

Well then could you please enlighten me, as to what an eraser is? I don't like when people make statement such as the above (quoted), they sound like they are dodging (or, rather, avoiding giving me an explanation since they themselves don't understand it). I'm not saying that that's what you are doing, but "do more research" comments (without some kind of explanation) are usually dodges.

 

[Fliption]

Originally posted by Mentat
No, I understand this just fine, but doesn't it contradict their own assumption (that their "knowledge" of the state of the wave-function causes it to collapse)?

I am still not following. Please be more specific about what you're question is here. I see no contradiction. If it is there, then tell me what it is exactly.

No it's not, since you are implying that the photon changes "when threatened" by the possibility of being "known". This is an example of foresight, and it takes consciousness to have foresight. Please note: this is not a semantic argument, you can try to use other words if you want, but it won't change the fact that they are implying a photon's having "knowledge".

Ahhh. Now I see where the problem is. You cannot respond to the experiments. You just don't intuitively like what you "think" they imply based on what I'm saying. Well they don't imply any of that necessarily. I have made a few statements several pages back about what I think the implications could be. But that's a discussion that belongs in this philosophy forum if we can ever get people past the classical physics dogma.

Well, I understand that we shouldn't oversimplify QM, and that it is really inconceivable, but I still don't see where Tiberius got anything wrong.

Because he believes what you believe. Thats the bottom line apparently. I have shown you text where what Tiberius is saying is just wrong, but you won't read it or refuse to understand it. What else can I do? If I tell you what it says you'll just do what you're doing now. You'll just tell me it's laymans text and ignore it. If the text is wrong then point specifically to the reason why. Picking at my choice of words as I oblige your time constraints is not convincing.

Okay, I will say why I disagree that Tiberius is wrong: The actual textbooks on QM agree with him. That's basically it, though I also happen to know a bit about consciousness and knowledge now - that they are macroscopic phenomena and couldn't possibly have an affect on the subatomic realm (where the brain is composed of exactly the same things as a rock).

Consciousness need not have anything to do with it. These assumptions are getting in your way of understanding, I think.

When will people understand that I get one hour on the internet, to do everything that I have to do (mainly PFs, but I am also involved in trying to find some therapies for my friends dying wife (she has breast cancer that is in metastasis )). Please, if you cannot explain what an "eraser" is, just say so. If you can, then do it. I don't have time to refer to the links. Sorry.

I can explain what an eraser is. I assure you I would not be saying that Tiberius is inaccurate if I couldn't.

In what way?! Information is a product of the workings of computers (be the organic or otherwise). But all of these computing devices (including the brain) are composed of subatomic particles. Therefore, how is a photon to distinguish an electron that happens to belong to a brain, from one that happens to belong to a piece of seaweed?

Here are more presumptions about what you "think" the experiments imply. Let go of these bias' and just read. Photons are not proved or implied to be conscious in any way by anything that I have linked. I think that you are assuming that these experiments imply some sort of conscious connection and you have the opinion that this couldn't possibly be true so you are just closed off to what the experiments are saying. Free your mind! Forget the conscous stuff and approach with an attitude of inquisition.

Also, take the experiment that we are discussing, for example: They said that they had "split the photons", when you obviously cannot split a massless particle into smaller pieces - thus, what it means to "split the particle" is to split it's probability, so that it is most probably in those two different directions. If you have not understood this (quantum entanglement) by now, then it is you who needs to do more study (and layman texts are probably not the best place - no offense).

And I bet you think the photon is really there too? You think the probability for it's position is just because we can't know where it is right? Not because it isn't really "someplace"? Is this what you think? I may just ask you to explain Qm as you see it. That might help quite a bit. But if it is nothing but an extension of classical physics at the sub atomic level, then I'm likely to say it's wrong.

I will continue to read about "this stuff", but I won't rely on layman texts to do so, since they can only ever be partially accurate, and are usually reliant on analogy. Think of how much havoc the Schrodinger's Cat analogy caused. Instead of viewing QM as a theory of particles - which is what it is - they viewed it as a theory where cats are only alive when we're looking at them (an interpretation that was certainly not Schrodinger's goal).

You haven't even read it so how can you consider it to be laymans text? And if you have read it you have not responded to it specifically. All you've done is respond that what I'm telling you contradicts what you think, therefore it must be wrong.

And if it is laymans text then why ask me what it means?

Well then could you please enlighten me, as to what an eraser is? I don't like when people make statement such as the above (quoted), they sound like they are dodging (or, rather, avoiding giving me an explanation since they themselves don't understand it). I'm not saying that that's what you are doing, but "do more research" comments (without some kind of explanation) are usually dodges. [/B]

Gulp. Dodging? Heh. I have done nothing but lay out my argument for you. I have provided text for you to pick apart. How could I be dodging? If you want to understand the experiments, including the eraser, then go read the text provided. I can sympathize with time contraints but I don't think you're time prorities ought to be the basis for my consideration as a dodger.

Now I could explain to you what the eraser is but the honest to god truth is that I don't think it would matter as far as your opinion is concerned. I suspect we have some semantic problems here anyway because I still cannot understand the question at the top of this thread that you asked. This seems like a basic understand of QM. We can't progress at all until we get that straight. Why don't you just explain what you think QM is? How abbout explaining the 2 slit experiment and explain what's happening as you go?

 

[Ivan Seeking]

Well I need to read the entire thread but the discussion is all too familiar: Fliption is right. Sorry Mentat, but I have seen this problem before. The empiricists point of view is still alive, but you are struggling to breath under the weight of the evidence.

I recently made a survey of this issue of measurement and deeper interpretations. The fact is, the greatest minds in science are all over the board. Here is an excerpt from a letter written to a friend. Bare in mind that sub catagories of each subject are also found.

@A: Murray Gell-Mann

@Q: Niels Bohr brainwashed a whole generation of physicists into
believing that the problem [of the interpretation of quantum mechanics] had been solved fifty years ago.

@R: Acceptance speech Noble Prize (1976)



It seems that tempers haven't calmed much in 50 years. Consider Heisenberg's comment on the subject from 1927:

"I remember that it ended with my breaking out in tears because I just couldn't stand this pressure from Bohr"

Here is the thing that most surprises me: The arguments about what causes the collapse of a quantum wave function - the definition of "measurement" - are still all over the board. Of course, Bohr's decedents still hold that it doesn't matter. All that matters are the numbers. This is fine for empiricists, but what will the theoreticians do? Really though, this seems to ignore the requirement for a complete theory. Penrose and friends argue that gravity acts to force Schrödinger's equations non-linear causing the collapse. Gell-Mann and friends contend that collapse occurs when a quantum system interacts with another system having many degrees of freedom - "decoherence" . The Many Worlds people, which I guess still includes Wheeler [I forget where Whitten comes down on all of this] still contend that the entire universe splits into two with every observation. The requirement that a consciousness be observing - one core problem with Schrödinger's Cat - is still widely argued. This all gets into Von Neumann's discussions about what happens if I measure using an instrument that measures another instrument, measuring instruments etc. Which measurement actually causes the collapse? Then, the brain gets into the act as an instrument. This then gets into ideas that consciousness is a quantum phenomenon, and that the observer's consciousness gets "entangled" with the experiment... Boy, if you want to send a Bohrian into orbit try that one on him!

But here is my favorite:

It seems the Quantum Cosmologists have their own funny ideas. They don't think we can collapse wave functions by observing things, rather, they argue that when I look at a gauge, I leap into a superposition of eigenstates! Gee, I never felt a thing!

Finally, I also saw a recent article in Scientific American, I think, where collapse is argued to be a relative phenomenon. It's a wave for you and a particle for me...all in the same universe? YIKES!

 

[Mentat]

Originally posted by Fliption
I am still not following. Please be more specific about what you're question is here. I see no contradiction. If it is there, then tell me what it is exactly.

Ok (now I've read some more of the site, though I still don't have time to read all of it). It was my understanding that they are assuming they can know that the wave-function didn't collapse, and yet not collapse it by their knowledge of it's state, and yet their premise is that the collapse of the wave-function is a result of their knowledge of it's state.

Ahhh. Now I see where the problem is. You cannot respond to the experiments. You just don't intuitively like what you "think" they imply based on what I'm saying. Well they don't imply any of that necessarily. I have made a few statements several pages back about what I think the implications could be. But that's a discussion that belongs in this philosophy forum if we can ever get people past the classical physics dogma.

No, my problem is that they use such terms as the "threat" of being detected and the "knowledge" of being observed.

I'm sorry, I must go now. I will finish my response as soon as I can get back on-line.

 

[Fliption]

Originally posted by Mentat
Ok (now I've read some more of the site, though I still don't have time to read all of it). It was my understanding that they are assuming they can know that the wave-function didn't collapse, and yet not collapse it by their knowledge of it's state, and yet their premise is that the collapse of the wave-function is a result of their knowledge of it's state.

Ahh ok I see what you're saying. Let me see if I can clarify. They aren't saying that the wave function of a photon will collapse when they know the state of the wave function itself. The knowledge that they are speaking of is not knowledge of the state of the wave function. Whether the wave function is present or collapses can easily be determined. That isn't the issue.

The knowledge that they are speaking of is the path of the photon itself. This is what cannot be known without collapsing the wave function. And when ever the information pointing to the path of the photon has been erased, the wave function will re-appear!

I decided earlier that I would try to post a step by step of an experiment. This way you can point to a segment that bothers you. Hopefully at the end, it will be clear what the experiments have shown. I don't have time right now. Will try to do this later.

No, my problem is that they use such terms as the "threat" of being detected and the "knowledge" of being observed.

The words they use are simply the easiest to use without a lot of explanation. I assume they figure most people can tell from scientific context what they are saying.

 

[Mentat]

Originally posted by Fliption
Because he believes what you believe. Thats the bottom line apparently. I have shown you text where what Tiberius is saying is just wrong, but you won't read it or refuse to understand it. What else can I do? If I tell you what it says you'll just do what you're doing now. You'll just tell me it's laymans text and ignore it. If the text is wrong then point specifically to the reason why. Picking at my choice of words as I oblige your time constraints is not convincing.

Alright, maybe my problem with the experiment is that I don't completely understand it. It seems like they are trying to prove that just the "threat" - or possibility - of our gaining knolwedge of it's path makes it's wave-function collapse. It appears that they believe they can deduce this from the fact that they interrupted the idler photon but not the signal photon, thus making themselves able to know the path of the signal photon, without interfering with it, and yet the wave-function still collapsed. (Please correct me if I'm wrong about any of this, of if I missed something.)

The thing is that this experiment is just like the EPR experiment, and that has long been settled (or so I thought) by saying that the two electrons (or, in the case of your experiment, photons) are quantum-bound to each other (since they are really just greater probabilities of the same particle), and so whatever you do to one affects the other.

Consciousness need not have anything to do with it. These assumptions are getting in your way of understanding, I think.

Well, consciousness is required for the photon to detect our gaining knowledge, or the possibility of our gaining knowledge. But I can drop that point for now, if you want.

I can explain what an eraser is. I assure you I would not be saying that Tiberius is inaccurate if I couldn't.

Then do it.

Here are more presumptions about what you "think" the experiments imply. Let go of these bias' and just read. Photons are not proved or implied to be conscious in any way by anything that I have linked. I think that you are assuming that these experiments imply some sort of conscious connection and you have the opinion that this couldn't possibly be true so you are just closed off to what the experiments are saying. Free your mind! Forget the conscous stuff and approach with an attitude of inquisition.

Alright, I can forget the "conscious stuff", if you can explain to me how a photon can "know" or "suspect" or even "assume" without being conscious. After all, it must "know", "suspect", or "assume" that we can gain knowledge of it, in order to "decide" (another conscious process) to collapse it's wave-function.

And I bet you think the photon is really there too? You think the probability for it's position is just because we can't know where it is right?

NO! Completely the opposite. In fact, I thought that hints of this kind of classical reasoning were at the heart of your reasoning. But I guess we both misjudged each other there.

You haven't even read it so how can you consider it to be laymans text? And if you have read it you have not responded to it specifically. All you've done is respond that what I'm telling you contradicts what you think, therefore it must be wrong.

That's not what I was intending to imply, and I apologize if it came out in such an arrogant fashion. However, I have now read most of the text, and have replied (above) to what I think a couple of flaws are.

Also, please remember that "layman's text" is not degrading in any sense; and it certainly doesn't mean that they don't cover any serious or complicated issues. It only means that they leave out the details (usually mathematics), and instead try to interpret them into common language. I believe I gave the example before of Schrodinger's Cat illustration. In that analogy, Schrodinger was explaining the common occurances of the subatomic world, in terms of some macroscopic being, which most people could relate to easily. However, this may mislead people into thinking that it is our watching of our pet cat that causes it's very existence, which is not really true.

 

[Mentat]

Originally posted by Ivan Seeking
Well I need to read the entire thread but the discussion is all too familiar: Fliption is right. Sorry Mentat, but I have seen this problem before. The empiricists point of view is still alive, but you are struggling to breath under the weight of the evidence.

I recently made a survey of this issue of measurement and deeper interpretations. The fact is, the greatest minds in science are all over the board. Here is an excerpt from a letter written to a friend. Bare in mind that sub catagories of each subject are also found.

@A: Murray Gell-Mann

@Q: Niels Bohr brainwashed a whole generation of physicists into
believing that the problem [of the interpretation of quantum mechanics] had been solved fifty years ago.

@R: Acceptance speech Noble Prize (1976)



It seems that tempers haven't calmed much in 50 years. Consider Heisenberg's comment on the subject from 1927:

"I remember that it ended with my breaking out in tears because I just couldn't stand this pressure from Bohr"

Here is the thing that most surprises me: The arguments about what causes the collapse of a quantum wave function - the definition of "measurement" - are still all over the board. Of course, Bohr's decedents still hold that it doesn't matter. All that matters are the numbers. This is fine for empiricists, but what will the theoreticians do? Really though, this seems to ignore the requirement for a complete theory. Penrose and friends argue that gravity acts to force Schrödinger's equations non-linear causing the collapse. Gell-Mann and friends contend that collapse occurs when a quantum system interacts with another system having many degrees of freedom - "decoherence" . The Many Worlds people, which I guess still includes Wheeler [I forget where Whitten comes down on all of this] still contend that the entire universe splits into two with every observation. The requirement that a consciousness be observing - one core problem with Schrödinger's Cat - is still widely argued. This all gets into Von Neumann's discussions about what happens if I measure using an instrument that measures another instrument, measuring instruments etc. Which measurement actually causes the collapse? Then, the brain gets into the act as an instrument. This then gets into ideas that consciousness is a quantum phenomenon, and that the observer's consciousness gets "entangled" with the experiment... Boy, if you want to send a Bohrian into orbit try that one on him!

This just proves that there is still contraversy on the subject, and I never said that there wasn't. However, for those that say that consciousness has something to do with it, all I can say is that they need a better understanding of the workings of the brain. Consciousness is one of those workings of the brain, and so it is obviously not distinguishable at the subatomic level (it would be like postulating that "color" has some affect on sub-atomic phenomena).

But here is my favorite:

It seems the Quantum Cosmologists have their own funny ideas. They don't think we can collapse wave functions by observing things, rather, they argue that when I look at a gauge, I leap into a superposition of eigenstates! Gee, I never felt a thing!

Finally, I also saw a recent article in Scientific American, I think, where collapse is argued to be a relative phenomenon. It's a wave for you and a particle for me...all in the same universe? YIKES!

I don't like when people appeal to common sense, while trying to understand QM. QM is counter-intuitive and cannot be understood in terms of common sense (which is why good layman texts are so hard to find).

 

[Ivan Seeking]

Originally posted by Mentat
This just proves that there is still contraversy on the subject, and I never said that there wasn't. However, for those that say that consciousness has something to do with it, all I can say is that they need a better understanding of the workings of the brain. Consciousness is one of those workings of the brain, and so it is obviously not distinguishable at the subatomic level (it would be like postulating that "color" has some affect on sub-atomic phenomena).

In the end thought must be enabled through QM processes. I don't necessarily agree with this point of view, but that the mind could somehow entangle with an experiment is seen worthy of pursuit by some very brilliant people. Also, the original post by Tiberius and many of the comments that follow would indicate that this is not justifiably controversial. My post was intended to show otherwise. The core of this argument about consciousness is over 70 years old. Are you arguing that you have figured it out? You don't seem willing to learn before drawing conclusions. It does appear as if your mind is set to one interpretation in spite of evidence to the contrary. Oh what an entangled web we weave when first we measure to perceive.

I don't like when people appeal to common sense, while trying to understand QM. QM is counter-intuitive and cannot be understood in terms of common sense (which is why good layman texts are so hard to find).

Was I appealing to common sense, or was this just a general comment?

 

[Fliption]

Originally posted by Ivan Seeking
I recently made a survey of this issue of measurement and deeper interpretations. The fact is, the greatest minds in science are all over the board.

I have to agree with all this. From all that I've read there does seem to be a lot of differences among scientists on this very topic. This is the very reason I responded to this thread. I don't have the answers on QM but I am pretty sure that Tiberius doesn't either. Which is exactly the point. This issue has not been resolved. If what Tiberius is saying is true then I see no reason at all why these scientists are wasting there time doing these experiments because they are geared toward answering the question "what causes the wave function to collapse?" Why bother if the answer is so obvious?

 

[Ivan Seeking]

Originally posted by Fliption
I have to agree with all this. From all that I've read there does seem to be a lot of differences among scientists on this very topic. This is the very reason I responded to this thread. I don't have the answers on QM but I am pretty sure that Tiberius doesn't either. Which is exactly the point. This issue has not been resolved. If what Tiberius is saying is true then I see no reason at all why these scientists are wasting there time doing these experiments because they are geared toward answering the question "what causes the wave function to collapse?" Why bother if the answer is so obvious?

IMHO, one reason this happens is the unfortunate habit that physicists have of stating their position as if it is the only one. I was literally taught not to waste time by informing everyone that an assertion is just my opinion. To be exact, the phrase was "everyone already knows that". This was a part of the prepared lecture. Unfortunately, when the typical student reads about the theory and philosophy of a particular school of thought, that this material is not gospel truth is not always obvious. I was lead in circle for years because of this. I have encountered a fair number of physicists who will deny the credibility of theories about which they know very little. Someone taught them that Bohr was right and there it ended.

 

[Fliption]

Originally posted by Mentat
Alright, maybe my problem with the experiment is that I don't completely understand it. It seems like they are trying to prove that just the "threat" - or possibility - of our gaining knolwedge of it's path makes it's wave-function collapse. It appears that they believe they can deduce this from the fact that they interrupted the idler photon but not the signal photon, thus making themselves able to know the path of the signal photon, without interfering with it, and yet the wave-function still collapsed. (Please correct me if I'm wrong about any of this, of if I missed something.)

Yes I'd say you just about got that one. But let me say that I still think you are putting too much emphasis on the words like "threat" or possibility of knowledge and you're assuming that the implications has to do with consciousness, therefore this is wrong. The first thing we must do, is understand the experiment. Then we can decide what it means and what it doesn't mean. Once you understand the experiment you will no longer have to guess what they mean when they use certain words. You will know what they mean.

So let's just start with an example similar to the one you stated above since you seem to have it. Now I'm going to butcher the experiments a bit. I want to get to the main points without going into detail on exactly how a mirror was positioned ect. I will try to stick to the relevant points and simplify this a bit.

1) A beam of light has been split into two. Mirrors are used to point these 2 beams back together and converge them at another splitter forming a diamond shape. The second splitter sends two beams to 2 photon detectors;One detector for each beam.

Without going any further, with just step 1, we know that the photons arrival data into the detectors will show an interference pattern. This means that we cannot know which path a photon chose to go. It's path between the 2 splitters( a diamond shape) is a complete mystery. It seemingly has gone down both paths.

2) Now you place a device into the path of one of the split beams that changes the polarization of the photons.

This is simply a way to "tag" these photons and differentiate them from the photons going down the other path. Polarization of photons is binary so there are only 2 options. So now we have 2 paths of photons with different polarity converging at the 2nd splitter. Now the interference pattern in the light detectors is gone.

At this point you(Mentat) would say the wave function collapses because we have simply interacted with it. And these scientists are saying that it collapses because we can now determine which slit the photons traveled. Because now whenever either detector tells us that it has received a tagged photon, we know which path the photon has traveled. So either interpretation could be correct at this point.

3) Now you place a polarization filter in front of both detectors that only allows photons of one polarity through.

Now with this addition we have inserted another physical interaction with the photons. We have filtered out one polarity type. So that means that the detectors will now receive no distinguishing information about the photons. This is very much the same situation we started with. And now the interference pattern has re-appeared.

It is this 3rd step that isn't explained by what you are saying. This is the "eraser" part since the distinguishing information that we had has now been erased by the filter.

I have heard you say that our interaction with the photons is what collapses the wave function, but I have not heard you say that another interaction uncollapses it! The correlation seems to be with the abilty for the path to be known; not interactions or disruptions.

The thing is that this experiment is just like the EPR experiment, and that has long been settled (or so I thought) by saying that the two electrons (or, in the case of your experiment, photons) are quantum-bound to each other (since they are really just greater probabilities of the same particle), and so whatever you do to one affects the other.

True but this leaves out step 3 above.

Well, consciousness is required for the photon to detect our gaining knowledge, or the possibility of our gaining knowledge. But I can drop that point for now, if you want.

Alright, I can forget the "conscious stuff", if you can explain to me how a photon can "know" or "suspect" or even "assume" without being conscious. After all, it must "know", "suspect", or "assume" that we can gain knowledge of it, in order to "decide" (another conscious process) to collapse it's wave-function.

Does the universe understand Calculus? It seems to because it obeys it perfectly. I'll let you simmer on that one a while. This discussion really is where we ought to be in this forum.

 

[Ivan Seeking]

I have read quite a bit of this thread but it is very long. Please forgive if this has been discussed. From what I gather this issue of the eraser is problematic. Another example that may be helpful is that of a certain diffraction experiment that I read about. Some kind of special material I think was used, I'm not sure what this was, but the properties were such that for every photon that enters, two emerge with half the frequency of the source and at different angles. From this, in principle we have a one to one mapping between photon pairs a, and a'. We now take one of each pair and send them down separate paths, A, and A'; into the required mirrors and such, through a diffraction grating, and finally onto a target.

If I make no measurement, we see the classic diffraction pattern on targets A, and A'. If we measure the position of particle a in path A, we can infer the position for the corresponding particle a' in A'. Thus, if I measure for position in path A, since now I can infer knowledge of position for a’, in A', the diffraction pattern is destroyed in both A, and A'.

 

[Fliption]

Originally posted by Ivan Seeking
If I make no measurement, we see the classic diffraction pattern on targets A, and A'. If we measure the position of particle a in path A, we can infer the position for the corresponding particle a' in A'. Thus, if I measure for position in path A, since now I can infer knowledge of position for a’, in A', the diffraction pattern is destroyed in both A, and A'.

Yes, actually that's the same experiment as the eraser experiment. The eraser is just an additional step on that same setup. The device that you mentioned is called a down-converter in the article. It does just as you said. It splits a photon into 2 lower frenquency photons and sends them down different paths.

 

[Mentat]

Originally posted by Ivan Seeking
In the end thought must be enabled through QM processes. I don't necessarily agree with this point of view, but that the mind could somehow entangle with an experiment is seen worthy of pursuit by some very brilliant people. Also, the original post by Tiberius and many of the comments that follow would indicate that this is not justifiably controversial. My post was intended to show otherwise. The core of this argument about consciousness is over 70 years old. Are you arguing that you have figured it out? You don't seem willing to learn before drawing conclusions. It does appear as if your mind is set to one interpretation in spite of evidence to the contrary. Oh what an entangled web we weave when first we measure to perceive.

My current view of consciousness is not of my own origin; I've done my research. Cartesian Theater models of the Universe don't make sense, and very few respectable Neuroscientists or Psychologists would argue otherwise. Daniel Dennett's "Multipe Drafts" model works for me for now, until proven false, or until something better arrives.

Was I appealing to common sense, or was this just a general comment?

Well, you probably weren't, but some of the things your quote were:

It seems the Quantum Cosmologists have their own funny ideas. They don't think we can collapse wave functions by observing things, rather, they argue that when I look at a gauge, I leap into a superposition of eigenstates! Gee, I never felt a thing!

Finally, I also saw a recent article in Scientific American, I think, where collapse is argued to be a relative phenomenon. It's a wave for you and a particle for me...all in the same universe? YIKES!

 

[Mentat]

Originally posted by Fliption
Yes I'd say you just about got that one. But let me say that I still think you are putting too much emphasis on the words like "threat" or possibility of knowledge and you're assuming that the implications has to do with consciousness, therefore this is wrong.

Well, they did, after all use those very words, and it appears to fit with their hypothesis, since their "knowledge" would have to change the photon (and it doesn't appear that this could be the case, unless the photon, at some point, posessed knowledge of our knowledge).

The first thing we must do, is understand the experiment. Then we can decide what it means and what it doesn't mean. Once you understand the experiment you will no longer have to guess what they mean when they use certain words. You will know what they mean.

Alrighty then.

So let's just start with an example similar to the one you stated above since you seem to have it. Now I'm going to butcher the experiments a bit. I want to get to the main points without going into detail on exactly how a mirror was positioned ect. I will try to stick to the relevant points and simplify this a bit.

1) A beam of light has been split into two. Mirrors are used to point these 2 beams back together and converge them at another splitter forming a diamond shape. The second splitter sends two beams to 2 photon detectors;One detector for each beam.

Without going any further, with just step 1, we know that the photons arrival data into the detectors will show an interference pattern. This means that we cannot know which path a photon chose to go. It's path between the 2 splitters( a diamond shape) is a complete mystery. It seemingly has gone down both paths.

2) Now you place a device into the path of one of the split beams that changes the polarization of the photons.

This is simply a way to "tag" these photons and differentiate them from the photons going down the other path. Polarization of photons is binary so there are only 2 options. So now we have 2 paths of photons with different polarity converging at the 2nd splitter. Now the interference pattern in the light detectors is gone.

At this point you(Mentat) would say the wave function collapses because we have simply interacted with it. And these scientists are saying that it collapses because we can now determine which slit the photons traveled. Because now whenever either detector tells us that it has received a tagged photon, we know which path the photon has traveled. So either interpretation could be correct at this point.

3) Now you place a polarization filter in front of both detectors that only allows photons of one polarity through.

Now with this addition we have inserted another physical interaction with the photons. We have filtered out one polarity type. So that means that the detectors will now receive no distinguishing information about the photons. This is very much the same situation we started with. And now the interference pattern has re-appeared.

It is this 3rd step that isn't explained by what you are saying. This is the "eraser" part since the distinguishing information that we had has now been erased by the filter.

I have heard you say that our interaction with the photons is what collapses the wave function, but I have not heard you say that another interaction uncollapses it! The correlation seems to be with the abilty for the path to be known; not interactions or disruptions.

But they didn't make all of these different changes on the same beem of light (did they?), and so it needn't be collapsed an then uncollapsed.

As far as that third step goes, I'd say that you've not taken into account the quantum effect on the very polarization of the photon. After all, you have not "split" some ball-shaped (yet massless) particle, but have just split it's probability - so that it is greatly probable that it is in one of those two positions, but it is not completely "true", since nothing is in the Quantum Mechanical world.

I apologize, I must get off-line now. I will complete my response tomorrow. I would much appreciate it if you didn't respond to my post until it is complete, but that is up to you.

 

[Ivan Seeking]

Originally posted by Mentat
My current view of consciousness is not of my own origin; I've done my research. Cartesian Theater models of the Universe don't make sense, and very few respectable Neuroscientists or Psychologists would argue otherwise. Daniel Dennett's "Multipe Drafts" model works for me for now, until proven false, or until something better arrives.

Perhaps I misunderstood your intent. It seemed that you were asserting that your opinion is the consensus among scientists; that this is not only your view but also the proper view. If you are arguing why you prefer one model over another, then this is something else entirely. In this case you are wrong but not misguided.

Well, you probably weren't, but some of the things your quote were:

Ah. I was being flippant. Being from a personal letter to a friend, the tone was a little different than a regular post. I was just joking a bit.

 

[Jagger2003]

quote:
--------------------------------------------------------------------------------
Originally posted by M. Gaspar
Name three (implications)...pls.

--------------------------------------------------------------------------------



Well, I can't name implications. I can only tell you that there are implications to explore. In my post to Tiberous I narrowed down the scope of those implications to be either 1) Conscious beings define knowledge and therefore define the criteria which collapse the wave function or 2) Conscious beings simply discover the rules and equations that produce knowledge. At the moment number 2 seems to make the most sense. Conscious beings obtain knowledge through the use of mathematical and logical equations. Universal physics can also be modeled by these same rules. It probably isn't coincidence.

Fascinating thread. IMO, the implications are revolutionary. Assuming knowledge is non-material, what we are seeing is a possible non-material component of cause and effect.

quote:
--------------------------------------------------------------------------------
Originally posted by Mentat
My current view of consciousness is not of my own origin; I've done my research. Cartesian Theater models of the Universe don't make sense, and very few respectable Neuroscientists or Psychologists would argue otherwise. Daniel Dennett's "Multipe Drafts" model works for me for now, until proven false, or until something better arrives.
--------------------------------------------------------------------------------



Perhaps I misunderstood your intent. It seemed that you were asserting that your opinion is the consensus among scientists; that this is not only your view but also the proper view. If you are arguing why you prefer one model over another, then this is something else entirely. In this case you are wrong but not misguided.

Ivan is correct. Science isn't even close to proving an origin of the consciousness.

 

[Mentat]

Originally posted by Ivan Seeking
Perhaps I misunderstood your intent. It seemed that you were asserting that your opinion is the consensus among scientists; that this is not only your view but also the proper view. If you are arguing why you prefer one model over another, then this is something else entirely. In this case you are wrong but not misguided.

Why am I wrong?

 

[Mentat]

Originally posted by Jagger2003
Ivan is correct. Science isn't even close to proving an origin of the consciousness.

I direct you to Consciousness Explained by Daniel Clement Dennett.

 

[Ivan Seeking]

Originally posted by Mentat
Why am I wrong?

Because this is my opinion.

As soon as I have reviewed all of the related information I will jump in. This thread is so long I didn't even spot the source article the first time.

One thing that I am trying to determine is whether or not these photon pairs from the down-converter are considered entangled until measured.

 

[Mentat]

Originally posted by Fliption
True but this leaves out step 3 above.

No it doesn't, since when you block a certain polarization from taking one of the paths, you have changed the quantum-bound photon.

Does the universe understand Calculus? It seems to because it obeys it perfectly. I'll let you simmer on that one a while. This discussion really is where we ought to be in this forum.

Know, I don't think the Universe understands anything, as a whole. I think that mathematics is just a form of logic, which is the way that the Universe works - but not the way it had to work.

 

[Ivan Seeking]

Originally posted by Mentat
I direct you to Consciousness Explained by Daniel Clement Dennett.

One book is hardly a consensus. I am quite sure that no notices have gone out to the journals announcing that the mystery of consciousness is solved.

I can show evidence that consciousness continues even if no EEG can be measured. Would this scenario be explained by Clement's thesis?

 

[Mentat]

Originally posted by Ivan Seeking
Because this is my opinion.

As soon as I have reviewed all of the related information I will jump in. This thread is so long I didn't even spot the source article the first time.

One thing that I am trying to determine is whether or not these photon pairs from the down-converter are considered entangled until measured.

All quantum pairs, produced by such "splitting" experiments, are considered entangled. That should be rather obvious, since (as I've been pointing out repeatedly) you cannot literally split some massless particle in half, you can only split it's probability wave, so that it greatly probable that it is one of the two places.