Layman asks about Quantum "interaction"

[Peter Mole]

I don't believe you can learn or understand QM purely by getting the right words in the right order. Ultimately, the ability to use the correct words precisely comes from an understanding of the subject; and not vice versa.

For the record, I've been reading your posts PeroK but not always responding as it's quite clear PeterDonis has become pretty attached to me at this point and I worry about making him jealous.

Just to show how right you are, I'm not even sure what's meant by Quantum Mechanics. At best I'd say I'm trying to understand some of the fascinating ideas or concepts that it's raised for people like me who aren't even qualified to called laymen on the topic. I've yet to be convinced "the subject" is synonymous with the math. I do promise I'll let you know when/if you convince me... not of the validity of the math, but of the requirement that I understand it by my own self instead of through folks like you. I already, in good faith, accept the validity of the math even if I don't understand it.

 

[PeterDonis]

Seems like we could have come up with something a little less wordy

I thought the less wordy term we had agreed on for this was "collapse".

In this case, the change in the quantum wave function specific to times when rule 7 is applied means you've readjusted the equation to account for seeing a double bar pattern instead of an interference pattern.

No. It means I've changed the wave function I'm using to describe the electron based on my knowledge of which which-way detector registered. I then use that changed wave function to predict a different distribution of probabilities for where a dot on the detector screen will appear for that electron. (Note that this distribution is not a double bar pattern--it is just one of the two "bars", because I am making use of the information about which which-way detector registered. I only get a double bar pattern if I make use of the information that one of the two which-way detectors has fired, but I refuse to make use of the information about which one it was.)

I'm actually surprised by your answer, or rather your decision not to answer.

I didn't make a decision not to answer. I told you I had already answered and you were just wasting our time by belaboring the point. Continuing to belabor the point even further does not help.

What might help would be, if you insist on talking about invisible purple gods, for you to explain what you think the difference is between "physical interactions" and "invisible purple gods" that makes you so persistent about asking me whether the basic rules of QM allow interpretations based on the former but not the latter. Why do you even care what the answer is? I suspect that if you actually took some time to think about that question, it would answer itself and you would be able to stop belaboring the point.

have you considered that that article might well be an inventory of your pre-conceived notions about the ignorant and naive reader who comes to these forums?

I never used the words "ignorant" and "naive" in the article or in that discussion thread. So if those words are coming from anywhere, they're coming from you, not me.

 

[Peter Mole]

to PeterDonis,

I thought the less wordy term we had agreed on for this was "collapse".

I thought so too, but in post #58 you corrected me and so I changed it to try to appease you by phrasing it exactly as I thought you wanted it phrased. Scroll up and see #60 where I was clearly just trying to be accommodating to you.

Specifically, I changed it to "the change in the quantum wave function specific to times when rule 7 is applied", because "where rule 7 is applied in the experiment" wasn't precise enough for you.

ME: For the double slit experiment firing electrons and using the which-way detectors, rule 7 is applied when the detectors detect the electron. This is the first collapse.

YOU: Yes. More precisely, rule 7 is applied in order to correctly predict probabilities for where a dot will show up on the detector screen for that electron, given the knowledge of which which-way detector registered.

ME: I believe I understand what you mean. In this case, the change in the quantum wave function specific to times when rule 7 is applied means you've readjusted the equation to account for seeing a double bar pattern instead of an interference pattern.

YOU: No. It means I've changed the wave function I'm using to describe the electron based on my knowledge of which which-way detector registered.

That's exactly what I meant. The QWF was initially setup for the electron leaving the firing mechanism, but then at the point where the detector detected the electron it was necessary to apply rule 7 which meant you changed the wave function equation which I stated as you readjusted the equation.

I then use that changed wave function to predict a different distribution of probabilities for where a dot on the detector screen will appear for that electron.

Again, that's exactly what I meant. We've been over this. I've been trying to say it back to you to show I've understood, and I dare to say that anyone reading this would see this is all I'm doing.

(Note that this distribution is not a double bar pattern--it is just one of the two "bars", because I am making use of the information about which which-way detector registered. I only get a double bar pattern if I make use of the information that one of the two which-way detectors has fired, but I refuse to make use of the information about which one it was.)

Right, speaking only in terms of the math without describing what "really happened," the QWF for the single electron that got detected by the detector went on to form one of the dots on the back screen that would make up one of the bars of the double bar result. But the reason you readjusted the equation for the electron that was detected by the which way detector was because you were accounting for seeing the double bar pattern instead of the interference pattern. Seeing the results of the experiment told you were to go back an apply rule 7. This is what you taught me.

I'm sorry and a little dumbfounded you found it so confusing, but what you are describing is exactly what I meant.

I'm actually surprised by your answer, or rather your decision not to answer.

I didn't make a decision not to answer.

? Okay, but not only did you refuse to answer it the first time, you are doing it again NOW. Is it possible you really are hedging on this? As I've said more than a couple times I don't have any agenda with how the change in the quantum wave function specific to times when rule 7 is applied is interpreted.

I told you I had already answered and you were just wasting our time by belaboring the point. Continuing to belabor the point even further does not help.

But as I explained I wasn't just belaboring the point. I had a very specific reason for asking the question which you either ignore or just didn't understand. Again, just scroll up and read it. You've now have two opportunities to simply type the two letter word "no" and yet you refuse to do it or explain why you refuse to do it. Who's wasting who's time now? I find your behavior truly puzzling.

What might help would be, if you insist on talking about invisible purple gods, for you to explain what you think the difference is between "physical interactions" and "invisible purple gods" that makes you so persistent about asking me whether the basic rules of QM allow interpretations based on the former but not the latter.

This is bizarre.

1) You've spend DAYS telling me specifically not to wade into interpretations and just to focus on the groundwork and stick with the "rules".

2) Furthermore, I did explain exactly what I thought the difference was between "physical interactions" and "invisible purple gods" with regards to the quantum wave function math and that difference was nothing.. zero... because you've been hammering it into me for days that we can't draw conclusions about "what really happens" or what "exists" based on the math.

Here's what I said exactly about it in #60 after you refused to answer the first time...

For days, over and over again, you've been trying to hammer into me that I can't draw conclusions about "existence" or "what's really happening" based on the math. Over and over you have set a firewall against using the math to wade into discussions about interpretations. And here I finally come around to accept this and when I ask you a question to solidify the point, you hedge. Either that, or I'm just misunderstanding you again.

I suspect that if you actually took some time to think about that question, it would answer itself and you would be able to stop belaboring the point.

I DID THINK ABOUT IT AND I ALREADY TOLD YOU I FULLY EXPECTED THE ANSWER TO BE "NO". Scroll up and read the part you just deleted before answering me.

Is this for real? Are you pranking me right now?

Peter! What's going on with you? Clearly I must have offended you. You're acting needlessly contrarian and argumentative. Is this about what I wrote to PedroK about you? I only meant that as light joking with no animosity whatsoever. I'm truly sorry if I offended you.

have you considered that that article might well be an inventory of your pre-conceived notions about the ignorant and naive reader who comes to these forums?

I never used the words "ignorant" and "naive" in the article or in that discussion thread. So if those words are coming from anywhere, they're coming from you, not me.

I never at all meant to suggest you did. And yes, those words were from me. The words ignorant and naive were words I was using to describe myself coming here trying to talk with people who were and are much wiser on the topic of quantum physics than I am. I feel no shame whatsoever in being ignorant or naive nor would I put shame on anyone else for being so. Regarding the article, clearly, I must have hurt your feelings by suggesting that you consider your own pre-conceived notions about what readers here are saying and, given the tone and attitude your displaying towards me here, it should be clear to anyone reading this that I had a point. I mean, WOW!

As I have said to you already, I really have been enjoying this conversation with you. I mean, I've easily got 6-8 hours into this thread just because I've been so thoughtful in how I've replied while struggling with some of your insights.

I truly don't understand what just happened.

Would you agree it might be best you should take a break from this thread and I'll ask someone else my questions?

 

[almarino dtd]

hate to jump in, but please include the experiment a few years ago where detectors were placed where there should be no recordings if interference and, shore enough, no detections.

 

[PeterDonis]

please include the experiment a few years ago where detectors were placed where there should be no recordings if interference and, shore enough, no detections.

No, please don't. Let's please keep this thread focused only on the experiment described in the OP. If you want to ask questions about a different experiment, please start a separate thread, and please give a specific reference that describes the experiment you want to ask about.

 

[PeterDonis]

I've been trying to say it back to you to show I've understood

Then you're apparently doing a bad job of that, since every time you think you're just saying back what I said, what you say looks to me like you're saying something different.

If we could use math in this discussion, it would be a lot easier to avoid such problems.

Is this for real? Are you pranking me right now?

No.

Clearly I must have offended you.

No, you haven't. I am only trying to help you understand QM better; I have no personal feelings or personal issues involved in this discussion at all. If I am unable to help you, that will be unfortunate, but it won't be any problem for me; I'll just bow out and let someone else try, if anyone else wants to.

I truly don't understand what just happened.

What is happening is that you are repeatedly becoming distracted by irrelevancies. They don't seem to be irrelevancies to you, but they are, and I, who know a lot more about QM than you do, as you have admitted, can easily see that they are irrelevancies. So I am trying to stop you from being distracted by them. Evidently I am not doing a good job of that, but I am doing my best.

(One of the irrelevancies you are being distracted by is worrying about whether you have offended me. Another is worrying about whether I am pranking you.)

The other thing that I think is happening is that, as I have commented several times now, you are persistently refusing to even consider using what has been proven by long experience to be the best tool for the job of understanding QM, or indeed any physical theory: math. And you are repeatedly seeing the drastic limitations that you are imposing on yourself by doing that: we can't even communicate simple ideas because the ordinary language words we are using mean different things to the two of us. When I use them, I am referring to particular specific concepts that are best expressed in math; but you won't look at the math, so I can't just point at a specific piece of math and tell you that this is what I mean by ordinary language expression X. And when you use ordinary language terms, you have nothing to refer them to, because you don't know the math, so they end up not actually meaning anything useful, even though it seems to you that they do.

 

[PeterDonis]

I did explain exactly what I thought the difference was between "physical interactions" and "invisible purple gods" with regards to the quantum wave function math and that difference was nothing.. zero... because you've been hammering it into me for days that we can't draw conclusions about "what really happens" or what "exists" based on the math.

Saying that we can't draw conclusions about "what really happens" or what "exists" based on the math is very different from saying that there is no difference at all between "physical interactions" and "invisible purple gods". Obviously there is, and you know it as well as I do. It's what I said in post #54:

In terms of QM interpretations, these two are certainly not equally valid, because "physical interaction" at least gestures in the direction of something we know about--it leads to questions like "what interaction? Is it electromagnetic? Strong interaction? Weak interaction? Gravity?" and so on--whereas talk about invisible purple gods does not.

Also, note that when we start asking questions like "which interaction?", we open up possibilities for experimental tests, in which we can potentially expand the scope of the basic rules, by finding out more things that force us to apply Rule 7. So asking such questions can be viewed as exploring experimental possibilities, not just as pure interpretation. It becomes more like pure interpretation when "interactions" are postulated under conditions where we have no way of testing whether they are there.

You even picked up on this:

Ya ya. I'm looking forward to getting into that at some point.

But instead of actually getting into it--by, say, asking a further question about it--you kept on about invisible purple gods. This is an example of what I meant in my previous post when I said you are repeatedly getting distracted by irrelevancies.

 

[PeterDonis]

Would you agree it might be best you should take a break from this thread and I'll ask someone else my questions?

Anyone else is already free to respond to your posts.

 

[Morbert]

Can wave collapse occur simply by gaining "information" about the particle without physical interaction?

What interpretation are you operating under? Under some interpretations, collapse is a physical process that can never happen. Under others, collapse is a spontaneous physical process. Under others, collapse is something that happens in the scientist's notebook when she learns new information. Under others, collapse is something that happens in a scientist's notebook when she is constructing logics to characterise the system. etc etc

 

[almarino dtd]

the double slit example i gave was on target, but if you wish to ignore, so be ir.

 

[PeterDonis]

the double slit example i gave was on target

I have no way of evaluating this unless you give a specific reference. If the configuration you are describing is exactly the same as one of the two cases described in the OP of this thread, then giving such a reference in this thread would be fine, and indeed would help with the discussion; but if it is exactly the same, I'm confused as to why you would be asking us to "include" it in the discussion, since it's already included. Your asking "please include" is why I assumed that you were talking about some other experiment, not the same as what was described in the OP.

 

[Lord Jestocost]

Can wave collapse occur simply by gaining "information" about the particle without physical interaction?

Here a quote from: “Quantum measurements and new concepts for experiments with trapped ions” by Christof Wunderlich and Christoph Balzer, Advances In Atomic, Molecular, and Optical Physics, Volume 49, 2003, Pages 293-372 (https://arxiv.org/abs/quant-ph/0305129)

"So far, in the discussion of measurements on quantum systems we have not explicitly considered the case of negative result measurements (for a recent review see (Whitaker 2000).) We will restrict the following discussion to quantum mechanical two-state systems for clarity. In some experimental situations (real or gedanken) the apparatus coupled to the quantum probe and quantum system, may respond (for example by a “click” or the deflection of a pointer) indicating one state of the measured system, or not respond at all indicating the other. Such measurements where the experimental result is the absence of a physical event rather than the occurrence of an event have been described, for instance, in (Renninger 1960, Dicke 1981). A negative-result measurement or observation leads to a collapse of the wave function without local physical interaction involved between measurement apparatus and observed quantum system. This will be discussed in more detail in the following paragraphs. In particular, the meaning of the concept “local physical interaction” is looked at in this context."

See also: “Renninger negative-result experiment”
https://en.wikipedia.org/wiki/Renninger_negative-result_experiment

 

[EPR]

If that's how I came off I certainly didn't mean to be.

Then why did you ask if a physical intraction was necessary for wave function collapse?

The whole setup through which you phrase your questions in this thread is misguided as there are no particles as such. Even if this situation is more confusing, at least it's not misguiding and you'd be somewhere from where real progress can be made. Not in a deadend.

 

[member 656954]

Wow, this is like watching one of those tennis slugfests where the ball is kept in play for far longer than you expect the players have stamina for!

@PeterDonis, you deserve kudos for patience and grit

@Peter Mole, I feel that you're in one of those traveler situations where you don't speak the language but feel that if you talk English slowly enough and loud enough surely they'll eventually understand you. They won't

The point has been made that to understand things in the country of QM, you need to learn the language...and that's math. Anything else is vague, open to (mis)interpretation, and likely to lead to the wrong conclusions.

I share your desire to desire to comprehend QM at more than the pop sci level, and have been following this thread with interest, but having read many PF discussions in the QM forums, it's obvious that without the math I'll only ever get a glance at the landscape and one that is often more confusing than enlightening.

So my question is, aside from the reference book Peter noted early on in this thread (which I can't now find to note the name of), are there other suggested places to start for those with no prior knowledge?

 

[StevieTNZ]

So my question is, aside from the reference book Peter noted early on in this thread (which I can't now find to note the name of), are there other suggested places to start for those with no prior knowledge?

You may like Jonathan Allday's book - https://www.bookdepository.com/Quantum-Reality-Jonathan-Allday/9781584887034 (that contains a lot of basic maths)

This book - https://www.bookdepository.com/Sneaking-a-Look-at-God-s-Cards/9780691130378

And https://www.bookdepository.com/Quantum-Mechanics-Theoretical-Minimum-Leonard-Susskind/9780141977812

 

[PeterDonis]

the reference book Peter noted early on in this thread (which I can't now find to note the name of)

Did you mean this?

If you really want to learn how all this works, you need to learn it from a QM textbook. I would recommend Ballentine myself

 

[member 656954]

Thanks, @PeterDonis, I did mean Ballentine