I don't have a problem personally.However,these specific questions about 'detectors on ;but not recording' and 'destroying hypothetical recordings' have been a very contentious issue on the board here in the past.A particular board member,Claudio,who is no longer here,was very relentless about pursuing the 'truth' about this whole thing.To the point where everyone involved seemed to be at their wit's end.Both parties believed they were correct and effective communication broke down with nothing being resolved.As a casual participant I became more curious and interested about looking into the claims of both sides as I had already been also very interested in the QM stuff.I also admit that I have a fear of being self deluded. 'We can connect any star in the sky' if you know what I mean....I like to search for what 'truth' can be known.

Claudio,cited information from physics forums (who's members were deriding Tom's Interpretation )and a quantum physicist who joined the board here named Chris Drost.They all stated that Tom and RRs were mistaken.The information was logical and seemed to be backed by evidence.Yet,at the same time,so did the interpretations used often here on the board too IMO.
( To me,the twin photon DCQE really does seem to depend on "available information" as we say.)

I know it's not my job to defend anyone else but feeling that both sides had valuable points,I discovered the 'Relational Interpretation/Super Copenhagen Interpretion' that seemed to mesh well with all of the information at hand (as best as I can tell) And as I posted,I believe I may have outlined a situation above in which both parties can still be 'right'. (By lengthening the path of the DS ) Not being anything close to a physicist ( I work as a medical 'professional') I feel pretty happy about this now. For me,as I understand,they are both right. I'm hoping any else who has taken interest in this past conflict will take a look at what I've said and either agree or disagree.

Like I said before,I'm not too attached to the outcome and I believe the model of reality here has great value no matter what.

As I said here in this thread as I made my first post: I was reading along for quite some time until I then decided to register.
Part of the reason was very trivially the fact that I could not use the boards internal search function - its just not there to not registered readers.

So: I also know about Claudio and the problems he had with the theory this board is about.
I also know the conversation with Chris Drost and that it - temporarily - seemed to have quite an impact.
But from it arose even more confidence than there was.
That seemed true for Tom as well as certainly for me and maybe others.

Me, I could never really grasp what it was that "upset" Claudio time and time again.
It is similar with you, as I said.
I just fail to see where you seem to have an issue.

But there seem to be issues with the alternative, too (the one you mentioned).
Similar as Ted has said, in another thread I believe, I will not go learn all about an alternative way to look at things just to discuss them when I personally have no issue other than curiosity maybe.
This is not to come across as arrogant. And I probably will look into the relational interpretation, just out of curiosity.
You mentioned it earlier and gave link to a youtube video, which I watched. I also commented on what I perceived from that.
(the main thing I perceived was: it's based on the unquestioned assumption of physical reality, but that might be incorrect)
Recalling that, I'm not encouraged, but will very probably do it nonetheless ;)

All the Best!

I am speculating that knowledge or proof of the particle nature or polarizer presence is not substantive

- what is substantive is knowledge of an FWAU

of which slit it went through at the moment of collapsing the screen measurement

by observation by said FWAU,

so that the computer knows which of the two light "shadow-negatives" to send it to

if knowledge or proof of the particle nature was substantive, then all such screen measures should have changed to the particle representation in this PMR, upon proof that light operated on a photon by photon basis

thus, which slit is not a proxy for particle-arity - which slit is the fundamental

which-slit collapses the uncertainty regarding the location of the particle

its like, the computer is eager to represent light or things in collapsed form, but failing a data point for where to start, provided by an observing FWAU, it remains "at ease", in the more wishy washy probabilistic wave form...until directed otherwise

(I am putting this down entirely to clarify my understanding and subject it to critique - not presuming that I am even understanding your logic)

_________________
Does this PMR make my butt look big?

Matrixwissen (Oliver), has created a video explaining the double slit in general and the MBT solution in particular - he does a particularly good job explaining the delayed quantum erasure experiment. The english version video can be found here on the MBT YouTube site:
http://www.youtube.com/user/twcjr44?fea ... wF303YZ26w
The original version can be found on Oliver's website ( http://www.matrixwissen.de/ ) in both German and English. Here is the English version:
http://www.matrixwissen.de/index.php?op ... 05&lang=en
You can read it in text or watch the video.

Tom

so lets see if I have this right

one aspect of the 1999 experiment is that it establishes the collapsed and un-collapsed state, simultaneously

the photon particle pathways through slit A (red line) and B (blue line)are subsequently divided into 2 possible sets of pairs, either A(1), A(2) or B(1), B(2)

A is the upper slit, B is the lower slit - this is just arbitrary labelling for the purpose of this posting

(1) refers to the up pathway, and (2) refers to the down pathway, when the photon pathway is split the first time after passing through a slit

A(2) is further split into A(2)(i) and A(2)(ii).

(i) refers to the reflected pathway, and (ii) refers to the passthrough pathway, when the photon is split the second time - this is arbitrary

B(2) is further split into B(2)(i) and B(2)(ii).

B(2)(ii) is further split to B(2)(ii)(a) [reflected] and B(2)(ii)(b) [passthrough]

A(2)(ii) is further split to A(2)(ii)(a) [reflected] and A(2)(ii)(b) [passthrough]

all of these splits are immaterial. As long as you have a pathway that has a definite A or B identifier, you and the system know the source slit.

at detector(0)- A(1) and B(1) are each directed to detector(0), reconstituting the uncertainty of which slit the photon came through, and the wave state is rendered (detected)

at detector(1)- A(2)(ii) and B(2)(ii)(a) are each directed to detector(1), reconstituting the uncertainty of which slit the photon came through, and the wave state is rendered (detected)

at detector(2)- A(2)(i) and B(2)(ii)(b) are each directed to detector(2), reconstituting the uncertainty of which slit the photon came through, and the wave state is rendered (detected)

at detector(3)- B(2)(i) only is directed at detector(3), conserving the certainty of which slit the photon came through, and the photon particle state is rendered (detected)

at detector(4)- A(2)(i) only is directed at detector(4), conserving the certainty of which slit the photon came through, and the photon particle state is rendered (detected)

_________________
Does this PMR make my butt look big?

I am wondering how you could make this experiment more accessible, or even dramatic to the layperson.

For example, after administering gravol, place three (a number sufficient to achieve sufficient certainty) physicists on a slowly rotating platform, comfortably sitting in chairs

within eyesight, the double slit experiment is taking place, photon by photon, with the slit source displayed on a screen, not recorded, visible to the scientists during some portion of the rotation, so that the slit source data (or registration of it being seen) is fed into the big computer through the conciousness of the physicists, on a toggling binary cycle.

50 feet from this is an observation platform, from which a gathering of FWAUs may view the rotation, may view the screen result (particle or wave pattern), but may not view the slit data.

What I think the science would predict, would be the screen result switching between particle state when the slit data is within view of the physicists, and wave state when the slit data is out of view of the scientists - and this would be a form of the experiment that pretty much anyone could understand - and it would be most dramatic to do it at Times Square or something.

You could also set it up so that anyone could sit on the slit observer platform or sit on the screen observation platform, as a permanent quantum challenge to the planet.

I guess it would be easier to just have them put on and take off blindfolds, and you would save on gravol expense.

I wonder how the "at home" quantum eraser protocol, using polarizers, could be adapted to be more accessible and theatrical to the layperson.

_________________
Does this PMR make my butt look big?

Note: Gravol is the name for a motion sickness medication marketed in Canada.

Ted

It seems to me that the schematic and the description does not accurately represent the experimental setup.

First comes the double-slit.
Directly behind is the barium borate crystal - there the two entangled "photons" are created from only one incident "photon" (the single one created by and coming from the laser, which hit the crystal through eighter slit).
Then, these entangled "photons" are sent on different ways using the first prism (which is a polarizing prism - and one of the two entangled photons is horizontally polarized, the other vertically, thus the prism separates their direction).
Only then comes the lens, the next prism and everything else.

To clarify where I see the misrepresentation in the otherwise excellent(!) description:
The first prism actually splits ALL entangled photons, not just 50% of them, as could be deduced by following the red and blue lines, which in the currently used schematic appear to go right past the prism half the time.

It does not make a difference in the end, but one could wonder, why exactly 50% of the photons would go right past the prism and how one could be sure it really did or did not go through it.

This prism is a key element - it is the first prism in the path, which separates the two entangled photons, no?
Or is this nitpicking, does not really matter, or is what I wrote just downright wrong?

See here, or is this not the same experiment?

Yes, that is the same experiment. communicate any graphics error to Matrixwessen, He is a poster here.

To all:
Well this is my last try on this.I'm not trying to be confrontational,my intention is to point out an inconsistency I think I see.If I'm wrong that's ok,just tell me why please. I honestly believe that the first chapter of that video could be in error.

Guys,please read this information about 'decoherence' which is part of the PMR rule set.

Here are some quotes from the article linked below:

" To find out how these processes can destroy the interference pattern and lead to classical behaviour, we gradually added gas to the chamber of our Talbot-Lau interferometer during the experiments with carbon-70 molecules (figure 3a). We found that the amount of contrast between the interference fringes fell exponentially as more gas was added, and that the fringes disappeared almost entirely when the pressure had reached just 10-6 mbar. This was in full quantitative agreement with a theoretical analysis of the scattering processes. Although a single collision with a gas molecule will not kick the massive fullerene out of the interferometer path, it is enough to destroy the interference pattern because it carries sufficient information to determine the path that the interfering molecule has taken. The exponential decay is thus directly related to the collision probability."

Notice that they didn't actually measure a single gas molecule's collision with the beam,but it seems that because they could in principle,the interference disappeared.They didn't have an ability to look ;or not look. The path information was part of the (virtual) environment at that point and was represented as such with the loss of an interference pattern.It didn't need to be put on a tape.The (virtual) environment and the detection screen act as the tape.


"We then looked at how a molecule's "internal temperature" affects interference. The concept of internal temperature is not relevant for atoms or electrons, but it is for molecules, which are complex objects. It describes the energy distribution of the many vibrational and rotational degrees of freedom. Hot objects, of course, emit thermal photons that are then absorbed by the environment, transferring momentum in the process. In other words, each photon can transfer information about the position of the emitting object that can, in principle, be measured. Indeed, when we increased the internal temperature of carbon-70 molecules to above 1000 K, the contrast between the interference fringes slowly disappeared"



"When the cavity was empty - so that no which-path information could be deposited - the Paris team saw high-contrast atomic interference fringes. But when a small coherent field, containing as few as nine photons on average, was added to the resonator, the fringes became less pronounced. This indicated that the interference had been destroyed due to the entanglement with the phase of the mesoscopic coherent photon field."

"Entanglement between a quantum particle and its environment is not the only way of destroying interference. Noise - due to our inability to control all the experimental conditions sufficiently well - can also be a problem. In particular, experimentalists will have to fight the fact that random fluctuations in the relative length difference between the two interferometer arms can tend to wash out the interference pattern. "

"What seems to be the key factor in the transition from quantum to classical behaviour is the exchange of information between the quantum system and the outside world. This transition only depends on whether the experimental set-up allows - or does not allow - such information about the quantum system to be revealed. In the case of interference experiments, all that matters is that "which path" information is, in principle, available to the outside world. Contrary to popular belief, it is irrelevant whether a person actually makes the effort to find out that information."

This is what experiments showed,not opinions. I do not think this all means that reality is objective and that the result is really 'out there' while you don't look.But ,I do understand it to mean that when you do look, you will see a history that is consistent with the rules of QM which include 'decoherence' with the (virtual) environment.If you did something during the experiment to allow you to learn certain properties ,even in principle, then there will not be an intereference pattern when you look.

It finally states this:
"The crucial point is to acknowledge that no quantum object is completely isolated; rather it is embedded in an environment consisting of gas particles, photons and the like. The environmental state gets easily "entangled" with the quantum object, which causes information about the whereabouts of the quantum object to be rapidly disseminated into the surroundings. The absence of quantum behaviour in the macroworld is a natural consequence of the fact that bigger and more complex objects are much harder to isolate. In other words, the quantum features of the environmental interaction and the resulting information transfer lead to the appearance of classicality in quantum objects."

I really think midix put it very concisely when he wrote: "Destroying the tool will not undo things done with it." Like I said before,double slit experiments don't just appear in the VR.The consciousness of a scientist-avatar plans them,puts them to together,and carries them out.

Wouldn't TBC know what the avatar did in the VR and wouldn't the consciousness of the avatar-scientist know that certain interactions consistently lead to certain outcomes in the VR?

Why should a segment of history in an experiment be erased because he/she didn't look at one step? After all the loss of interference doesn't mean there is an objective particle.Even if it's probability distribution is constrained by the 'history' of it's interaction with a slit detector,it is still none the less determined by probability....

If you know that you had slit detectors on and didn't scramble 'which path' info before detection,why would the outcome be inconsistent with this?Wouldn't a unit of consciousness know that the slit detectors were there and turned on because the experiment itself was planned in consciousness? Again I ask what's the difference between virtual 'macroscopic' (decohered) tapes from slit detectors and virtual 'macroscopic' (decohered) photo graphic plates ? Why is a backwall not able to reveal determined information but a tape is?




http://physicsworld.com/cws/article/print/21590

The things done to reduce the interference pattern all changed the probability distribution representing the particle from a rather peaked up distribution to a very flat broad one. The probability of a particle going through any slit slowly was reduced to zero by adding uncertainty to its probable posistion. The result being that the diffraction pattern goes away as the probability of a particle ever getting near the slit also goes away. No news there. If one stands in front of the photon gun, or puts a wooden box over the slits, the pattern also goes away.

"Contrary to popular belief, it is irrelevant whether a person actually makes the effort to find out that information."

This is absolutely true. What is relevant is that the information exists and is available in PMR -- it matters not if someone "makes the effort to find out that information" as long as someone could find out that information.

Thanks for jumping in Tom,
Sorry for dragging out this whole thing again,but as I followed it before I found that your view point on whether or not "information is available" made good sense.But at the same time we have the evidence from 'decoherence' experiments ,like I quoted above, which seem to show that when information is available in principle 'within' the virtual environment,that is enough to destroy interference. This really seems to run counter to the first chapter about the DS experiment in the video posted above.

So,in regard to the DS experiment: The cases of 'detectors on but not recording' and 'detectors on, but the recording is destroyed before you look' would seem to still show a destruction of interference in my limited understanding.This is because the 'particles' (even the wave behavior still exposes 'localized' grains of silver on a screen!?!) would have reached the final detector while the slit detectors were in operation.The information should be available there in the virtual environment already at the detection screen (when you look).So an interference pattern would fly in the face of this history which would be present in the mind of the experimenter....

Maybe it could be as the video says if the path were to be lengthened between the slits and the 'backwall' ? (Though I'm not sure ) See what I mean? So you see, I'm not challenging your interpretation ( I don't think I'm some expert believe me here) but only a particular hypothetical senario which I think doesn't fit with it and could be in error.

(Edited for spelling and clarity)

This is demonstrably not so in the first case, the second is covered by the delayed choice quantum eraser.
The DCQE actually has two results simultaneously, both "real":
1.) no interference if we do know which way
and
2.) interference if we can't know which way - because we deliberately saw to it that the information that could have been available was not anymore.

I'm not referring to the DCQE with twin photons.

There is none (without interaction of the observer) with single photons ... (AFAIK)
And still, that would leave us with:

Could you clarify again what DS experiment and video you are referring to?
I'd really like to understand the question ...