JustGeoff said:
Pragmatist,
I am not going to respond to each and every part of your post because much of it can be skipped and replaced with :
Some scientists within the field are arguing that reverse causality does happen, and until that argument is resolved, I am not going to accept your judgement on its outcome. Some physicists agree with my claim (reverse causality is possible). Some don't, and you are one of them. What else is there to argue about? It is arguing for the sake of it.
Esoteric discussions about the difference between "possible" and "not impossible" seem to be little more than a pointless argument in the face of the above paragraph. It's not going to be resolved, is it?
Yes, it's easy to just ignore all the arguments which have been shown to be fallacy and reiterate the original position like it never happened! I'm not trying to be difficult there but it is a pattern in your discussions that you ought to be aware of. I don't care WHY you do it, but you may find it personally profitable to take a time out and think carefully yourself about why you do it.
Your claim that reverse causality is possible IS refuted. We don't know that it IS possible. We have established that it is truly unknown and that in reality all we can honestly say is that there is a possibility that it is possible (NOT that it is possible per se) - and that is ONLY at the microscopic quantum level, that tells us NOTHING about any putative MACROSCOPIC case. Like I said before, to assert what you do involves a fallacy.
JustGeoff said:
I didn't say that. I said you didn't like his metaphysical position, because you don't seem to like metaphysics. That doesn't mean you "don't like him."
With all due respect, you DID say that. But I will accept that you may not have MEANT that.
And once again you are trying to extrapolate beyond the data. You have no evidence that I don't like his metaphysics. I said I disliked discussing metaphysics in general which implies nothing about my likes or dislikes ABOUT metaphysics. In this particular case I don't like him confusing his metaphysics with his SCIENCE. I haven't examined his metaphysics in sufficient detail to draw any conclusion about it, other than it's not scientific.
JustGeoff said:
Actually, it was implied in your argument. You defined "observer" as a physical human being.
No I didn't. I REFUSED to "define" an observer, remember? I told you that I didn't see any need for a "definition" of an observer, and when you asked me what I thought an observer WAS, I gave you a description of a possible observer. A description is NOT a definition.
I thought I made it quite clear that I wasn't playing philosophical games, if I didn't make that clear enough I apologise.
JustGeoff said:
Then this discussion isn't likely to go anywhere. It has reached a point it cannot currently pass.
Then WTF are we arguing about? 
*I* am arguing about your specific claims that QM supports your other claims,and about "laws of science" etc. What you think YOU are arguing about is anybody's guess!
All the rest of your assertions about my "definition" of an observer are irrelevant because it never happened.
I had a quick look back through the whole thread to see if I could resolve any outstanding problems and I realised that you may not have understood what I originally said about Schrodinger's Cat and that seems to be influencing your thinking. Let me try to explain again and make it clearer.
Schrodinger proposed the "cat experiment" to highlight an absurdity. The proposed interpretation of quantum mechanics at that time was that an UNKNOWN quantum state could be considered to be an equal mixture of opposing probabilities.
The wavefunction gives us probabilities of events up to the point of collapse. Therefore BEFORE the moment of collapse one can legitimately say that both opposing probabilities are POSSIBLE - AS FAR AS WE KNOW. The wavefunction collapses when an observation is made. An "observation" is a really bad and confusing term because it does NOT imply any person or consciousness or anything else. ALL it means is that there is some INTERACTION at the quantum level. In practical terms it means that a photon bounces off the object in question, or an electron is deflected in it's path near the object. There is no "intelligence" involved in the process, it is a simple, physical process, not involving people or cats or anything else.
The moment something interacts with the system, the state of the system changes. For example, the path of an electron changes if we bounce another electron off of it. The bouncing of the electron is an "observation". So all "observation" actually means at the end of the day is a "change in the state of the system" (literally a change in the state vector in QM terms). But the wavefunction is a description of the state vector! So what that means in practise is that the moment there is some physical interaction between the object and some other object, that the old wavefunction is invalid and a new one is needed to reflect the changed circumstances. At the moment of interaction however, some of the unknowns in the OLD wave function have become knowns. So what we mean when we say a wavefunction "collapsed" is that some of the old unknowns were resolved and the wavefunction subsequently became invalid because the situation changed as a result of the interaction.
Now, in case that is not crystal clear, let me use an analogy. Let us imagine a town. And that town has exactly 100 streets. One of the streets is called Main Street, and at some point there is a crossroads between that street and another called Cross Street. We are outside the town, looking down on it from an aircraft, but there is low, heavy cloud so we can't actually SEE the town or the streets clearly. We watch the roads leading into town and we see a bus entering the town, and also a particular car. But as they enter the town they disappear under the cloud cover. So all we know is that the town has 100 streets, and that SOMEWHERE in that town there is a bus and a car. So we now construct a wavefunction. That wavefunction tells us that there is a 1% probability that the bus is on any given street, and that there is also a 1% probability that the car is on any given street. The fact that there is a 1% probability that the bus is on ANY given street does not imply for one moment that the bus is somehow spread out smeared over all 100 streets! However, if we tried to visually plot a GRAPH of the wavefunction, that is EXACTLY what it would appear like. But we know that a mathematical description is NOT the same as a physical reality (the map is NOT the territory). We have no way of knowing anything further about the situation until suddenly we hear a traffic report on the aircraft radio. The report announces that at 9:59 am precisely the bus which was travelling down Main Street, collided with the car which was crossing the junction with Cross Street. THAT is an observation. The collision establishes that at precisely 9:59 am, that the car and the bus were BOTH at the junction of Cross and Main (otherwise they wouldn't have collided). Therefore we know that at 9:59 am precisely, the probability that the bus was anywhere OTHER than Main Street is ZERO. And the probability that the car was anywhere OTHER than Cross Street is also ZERO. And it doesn't matter who observed the crash or when or how. The observer may have been a person standing on the corner of Cross and Main. But it may equally have been recorded by an unmanned security camera on a nearby building. We can reasonably conclude that the crash was not CAUSED or significantly influenced by the expectations of any observer.
There is a bigger issue with the above. The wavefunction, the guess that the bus had a 1% chance of being on ANY street (same for the car) IMMEDIATELY prior to the crash is no longer valid, it has collapsed because the probabilities were changed by the collision. BUT we also know that SOME of the old probabilities were NEVER reasonable POSSIBILITIES at all. For example, in the last second of time just before the collision, the wavefunction told us that there was a 1% chance that the bus was on ANY street. But that was a mathematical GUESS, not an actual situation. In reality there was NO possibility whatsoever that it was on ANY street OTHER than Main Street at that moment in time. But we didn't know that until we heard about the crash. So some of the other POSSIBILITIES that appeared in the old wavefunction, were NEVER ever possibilities at all! If they weren't even POSSIBILITIES then they were never PROBABILITIES (other than zero).
Therefore when we said there was a 1% probability that the bus was on ANY street in the last second before the crash, we were lying. Or at least uninformed. But we had no way of knowing that PRIOR to the moment of collision. And therefore the statement that there was even a POSSIBILITY that the bus was on any street OTHER than Main just before the crash is ALSO a fallacy! It was not even a possibility, but in the absence of information, there was a possibility that it was a possibility! We have hit the same fallacy as the "reverse-causality is possible" one.
Schrodinger realised this. It disturbed him. So he told the other QM physicists, "Look guys, when you talk about probabilities and stuff, you are really only talking about mathematical possibilities of possibilities, don't confuse that with reality". But it seems they didn't understand him, so he proposed the cat experiment to show how obviously absurd it was to talk about there being "equal probabilities" for unobserved events. The "equal probabilities" is ONLY A GUESS. Nothing more than that.
So in the cat experiment, the idea that the cat is either alive or dead is ONLY A GUESS. It HAS to be one or the other, but until we actually LOOK into the box we don't know WHICH of the two possible guesses is correct. There is an equal MATHEMATICAL PROBABILITY that the cat is alive with the cat being dead. But that does NOT mean that the cat is BOTH alive and dead at the same time! THAT idea only comes about if we confuse our mathematical "map" with the actual "territory" of the experiment.
The big problem with Schrodinger's cat is that instead of giving everyone a wake up call and return to sanity it prompted the darned philosophers to elaborate on the idea of the cat being BOTH dead and alive at the same time. It was truly ironic that Schrodinger's absurdity, designed to put an end to ridiculous misinterpretation and meaningless speculation, led to a new kind of even WORSE misinterpretation and speculation! Schrodinger was FURIOUS about it! This is what prompted him to make his many outspoken comments about the absurdity of the rampant philosophizing that had taken over QM.
It was Schrodinger himself who pointed out that the wavefunction was NOT collapsed when someone looked into the box. It was almost certainly collapsed some time prior to that because there would be many quantum interactions within the box all the time. Any one of these would constitute an "observation" that would collapse the wavefunction. But he also made the mistake of allowing himself to be drawn into philosophizing about WHEN this could possibly happen (i.e. was it when the radioactive decay occured in the trigger, or was it when a cosmic ray passed through the box etc.). Again, it's meaningless speculation because we DON'T KNOW.
Consciousness NEVER entered into the cat equation. However, many years later, another person, Wigner suggested a modification to the cat experiment in order to "resolve the paradox" (what paradox???). His idea was to replace the cat with a conscious human and instead of a poison vial he would have a light. So the same situation would cause the light to possibly go on in the box. The experiment was called "Wigner's Friend".
Wigner however made the confusion worse. He speculated that on an extrapolation of the wavefunction there was an equal probability that there were TWO conscious humans in the box, one in the dark and one in the light at the same time. And by some wierd philosophical logic he came up with a multiplicity of conscious humans in the box at the same time, all equally smeared out in the space within the box! But even HE could see that was absolutely absurd. So he came up with a conclusion. He concluded that because it DOESN'T happen, that must mean that CONSCIOUSNESS itself somehow prevents the multiple person wavefunction from ever coming into existence. The logical corollary of that being that CONSCIOUSNESS itself must collapse the wavefunction BEFORE the splitting into multiple conscious observers occurs!
Now, for my own personal opinion. I don't care how good a philosopher Wigner was. That idea is the biggest load of horse puckey I have ever heard! It is patently ridiculous! The ONLY way you can reach such an insane conclusion is if you confuse a mathematical expression ABOUT a possible reality with the reality itself.
THAT is the essence of the problem with QM and Schrodinger's cat. There are some people who believe there is some paradox inherent in Schrodinger's experiment because they believe that somehow the mathematical description of a system is somehow more real than the reality itself. And there are others like me, who think the whole thing is totally absurd and that scientists should not be playing at being philosophers (and especially vice versa). Paradoxes arise when someone confuses their abstractions with the object abstracted, or extrapolates beyond the available data. They are resolvable simply by recognising the difference between an object and an abstraction of an object and not trying to equate the two. In other words, the map is NOT the territory.
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