the underlying assumptions rig the debate

Can it? Why? What background do you have that gives you the confidence to say this? Let's start with something simple like a mixed state. What is a mixed state, in English? NO, the wavefunction DOES NOT evolve such that it appears it "know in advance" something. That is the whole point. The wave-function's evolution is goverened by QM and THERE IS NO POSSIBILITY WHATSOEVER that it can be affected by something in the future.It is the classically interpreted notion of the "single photon" that appears to "know in advance" and this is where the confusion lies.

Ok, so let's look at some descriptions of the process, and though I have read or plodded through papers by groups such as Chaio's and Zellinger's stuff and others, I think presenting less technical descriptions to describe the events that occur in these experiments is perfectly appropiate and can help others follow along. So here is material from a college professor and his course to his students.First, let me point out that your comment on the deterministic nature of the apparatus is deceptive if you are suggesting the polarization is causing the flip-flop so to speak of the interference patterns.Note to reader: the site has soem graphics not contained here that can help. http://grad.physics.sunysb.edu/~amarch/We can go back and forth all day long, but suffice to say, it's not that all these sources stating the exact same thing as far as occuring in these experiments are wrong, and somehow you are right, cavediver.There are different ways to explain what is observed, and you are welcome to explain them here, but the bottom line is the reason the misleading language of how do "photons" know what is going to happen is because they are describing a process where the reaction in others, to whether the potential to know something has occurred.

cavediver, you seem to have some confusion between the concept of theories and terms and an observed process. It's true that you need to learn some things, such as what is a photon or what polarization means, in order to know what the observations are in the experiments, but there is a process in these experiments of a photon being sent out through a medium or slit, etc, etc,....and that can be described in English.Now, the interpretation of what we observe may indeed require more depth, but at the same time, you seem to be the one constantly avoiding discussing the issue while hurling insults.Edited by randman, : No reason given.

Hadn't read this yet....so at least there is some substantive response. Good. As sidenote, does this mean you rule out transverse waves as possible since they do travel backwards in time if the theory is true?It seems that if you are correct and that it is such a hard and fast rule that this sort of thing is impossible, that the transverse wave theory should be viewed as some sort of joke, eh?Edited by randman, : No reason given.

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How does photon s know that we put the polarizer there?

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Because there is no "photon", only the extended wave-function. Nothing in these experiments is outside conventional deterministic qunatum mechanics. It just seems weird when it is brought from the mathematics into the real-world.

In the quantum eraser experiments, the polarization filters are set up and the interference pattern disappears (the idea being we could then obtain information about the path, right?).But when we scramble that with a third filter, the interference pattern reappars (the idea being it does so in response to not being able to be measured).What is your idea or explanation for this?

From our vantage point is the wave-function extended over segments of time? In other words, when we see a photon at different points of it's trajectory, are you saying that the wave-function occupies those different points simultaneously?Edited by randman, : No reason given.

No, I don't rule them out. In fact I referred to them earlier in this thread, where I pointed out that they actually weave a more fixed, absolute view of space-time, more akin to GR, than is usually considered within QM. I would say that this interpretation probably has implications for the hope that QM would somehow rescue free-will from an otherwise deterministic universe... as in, dashing that hope...

Will have to get back to you as the family is already late for church becasue of this

So you accept that it is reasonable to assert non-observed backwards in time waves, but that these waves cannot EVER affect the wave-function, being after all from the future and there is nothing in the future that can affect a wave funtion, as you stated so emphatically.And you don't see any inconsistencies with your statements here?Edited by randman, : No reason given.

If that sentence, the subtitle and the rest of my post didn't make it clear, the answer is yes. My point is that EVERYTHING is an assumption - some even argue Cogito ergo sum is a challengable assumption. Why? The assumption that time flows linearly has proven useful and practical. If you want to overthrow that, you need to do the work (not you specifically, of course). If someone in 1757 said 'Time is relative, not absolute', would you not think that that person had the burden of proof? Or would it be perfectly OK for him to say 'Prove me wrong?'Our 18th century scientist would be rightly ignored. It isn't just about challenging assumptions - even if the challenge turns out to be right. Its about doing to leg work and showing that time is relative etc.So the ball is in your court, in this regard.Even if the past did change due to events in the present, we'd never be able to tell. Its entirely unfalsifiable. It might be theoretically possible - but so is the brain in a jar scenario. How about you provide some evidence what we perceive is reality and not artifically induced stimuli. If you can't, I contest that your papers and ideas are all your perceptions of reality and we cannot be sure they are not artificial perceptions.Naturally, my idea is supported by evidence (our brain can be damaged and alter our perception of reality), but it is entirely unfalsifiable. So why bother with it as a real objection to anything? heh - so did I. That thread goes into entanglement in some hefty detail - you might find it interesting. Indeed, and my brainjar claim is not philosophical, but based on neurology. Not only that, but it is a more fundamental claim that lies at the heart of everything else that you have ever said (or thought you have said) - thus you make the non-brainjar assumption even in your non-linear time scenario.

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So you are saying that a present can occur which there was no determinate past, but that when the present occurs, the past is then determined.

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How is this not a demonstration that a present event can determine and thus have a causal effect on the past?

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My point is that the past is not materially affected. At the macroscopic scale nothing noticable has changed at all. But your argument requires a wholesale rewriting of the past at the macroscopic level. In short your assertions go way beyond what you are able to support, and it is entirely possible to reject your views without rejecting quantum entanglement.

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No. Not at all. The past as part of the whole is never completely fixed if there are present events that can determine, as you say, the past in any fashion at all.

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That is wrong, wrong wrong. There may be parts of the past that remain indeterminate but that does not entail that those parts of the past that have been determined could be changed.

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There is also the intrigueing notion of the effects of choice from more conscious observers, but then we are opening a big can of worms.

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If you are referring to the so-called "delayed choice" experiments, they offer no support for such an idea. They don't even try to measure the role of consciousness and there is no reason to suppose the results would be any different if the conscious choice were to be replaced by an unthinking mechanical choice.

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Suffice to say, you agree that the past is not static.

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That would be misleading. I do not agree that the macroscopic past can be changed through QM. You'd do much better appealing to GR. But even then you'd still have to deal with the arguments in my first post to this thread.

I find it somewhat ironic that you are refering to science in order to debunk science! Edited by RickJB, : No reason given.

This is a pretty clear misunderstanding of quantum theory. I won't go into detail as I see the discussion has moved on by 30 messages since I last posted.--Percy

The wave-function is really a 4d entity, and these waves are part of the wave-function. It is a consistent mathematical solution, which obeys causality. Simple as that... its not the interpretation that I use but it has some merits.