Just because I am willing to step away from the physics and enter into a philosophical or theological discussion does not mean I am willing to confuse the science with the philosophy or the theology.
Yet you are willing to assert your theology as definitive in this discussion?
Well, let's just stick to the science side then.
The Wheeler's delayed choice experiment simply means that it is the detection method which determines the result.
Well, that's a pretty big thing in and of itself, and certainly Wheeler thought so and took it so far to advance the observer/participancy principle of which he makes the following remarks.
Stronger than the anthropic principle is what I might call the participatory principle. According to it we could not even imagine a universe that did not somewhere and for some stretch of time contain observers because the very building materials of the universe are these acts of observer-participancy. You wouldn't have the stuff out of which to build the universe otherwise. This participatory principle takes for its foundation the absolutely central point of the quantum:
No elementary phenomenon is a phenomenon until it is an observed (or registered) phenomenon.
Cosmic Search Vol. 1, No. 4 - FORUM: John A. Wheeler
Also, on his thought experiment.
The astronomers choice of how to observe photons from the quasar here in the present apparently determines whether each photon took both paths or just one path around the gravitational lens-billions of years ago. As they approached the galactic beam splitter the photons must have had something like a premonition telling them how to behave in order to satisfy a choice to be made by unborn beings on a still nonexistent planet.
The fallacy giving rise to such speculations,Wheeler explains, is the assumption that a photon had some physical form before the astronomer observed it. Either it was a wave or a particle; either it went both ways around the quasar or only one way. Actually Wheeler says quantum phenomena are neither waves nor particles but are intrinsically undefined until the moment they are measured. In a sense the British philosopher Bishop Berkeley was right when he asserted two centuries ago that "to be is to be perceived."
http://www.fortunecity.com/emachines/e11/86/qphil.html
Apparently, you disagree with Wheeler and think the particle does have some physical form before observation/measurement, and that's fine, but don't act like I am ignorant or just don't understand the experiments or what is being said here. It's explicitly clear what Wheeler and Mandel think. Let's look at Mandel's opinion on the matter.
Now comes the odd part. The signal photons and the idler photons, once emitted by the down-converters, never again cross paths; they proceed to their respective detectors independently of each other. Nevertheless, simply by blocking the path of one set of idler photons, the researchers destroy the interference pattern of the signal photons. What has changed?
The answer is that the observer's potential knowledge has changed. He can now determine which route the signal photons took to their detector by comparing their arrival times with those of the remaining, unblocked idlers. The original photon can no longer go both ways at the beam splitter, like a wave, but must either bounce off or pass through like a particle.
The comparison of arrival times need not actually be performed to destroy the interference pattern. The mere "threat" of obtaining information about which way the photon travelled, Mandel explains, forces it to travel only one route. "The quantum state reflects not only what we know about the system but what is in principle knowable," Mandel says.
http://www.fortunecity.com/emachines/e11/86/qphil.html
Maybe Mandel is wrong, but he is not some ignorant buffoon, and my parroting these guys doesn't make me one either.
It absurd to think that the detection method changes what happens at the two slits anyway.
Why is it absurd? The whole experiment measures whether the particle travels in a wave-like pattern or a particle-like pattern through the slits, right? If detecting the photon, after the photon has passed through the slits or around the quaser in the thought experiment, causes the photon to take one route or another, or travel one form or another, then how you can say the detection event doesn't affect what the photon does at the 2 slits? It certainly does. Wheeler sort of gets around causality to a degree by saying the photon really didn't exist in a physical form until it was detected, but regardless, a later detection event determines a prior path.
It is not the threat, of determining the route which the photon has taken, which changes the result.
So you say. Mandel says:
The mere "threat" of obtaining information about which way the photon travelled, Mandel explains, forces it to travel only one route. "The quantum state reflects not only what we know about the system but what is in principle knowable," Mandel says.
Why does he say this and disagree with you? I think it's important to grasp that. The whole idea of the delayed-choice experiments was to try to determine if it was the act of measurement in a physical sense that caused the collapse of the wave function or something else. The delayed-choice is the idea that the choice to "disturb" the wave function was after the wave function had passed a certain point, and so determining what it did in it's prior projectory dismisses the mechanical explanation you are advancing. At least that's what these guys, like Wheeler, thinks they are doing.
One is that measurement requires direct physical intervention. Physicists often explain the uncertainty principle in this way:in measuring the position of a quantum entity, one inevitably blocks it off its course, losing information about its direction and about its phase, the relative position of its crests and troughs.
Most experiments do in fact involve intrusive measurements. For example, blocking one path or the other or moving detectors close to the slits obviously disturbs the photons passage in the two-slit experiment as does placing a detector along one route of the delayed-choice experiment. But an experiment done last year by Mandel's team at the University of Rochester shows that a photon can be forced to switch from wavelike to particlelike behaviour by something much more subtle than direct intervention.
You remarked:
Physicists implicitly know that this is the case, but that does not prevent them from exploiting the apparent paradox to make their work seem more interesting
If you are correct, then I guess Wheeler and men like Zellinger and Mandel are either senile old men or absolutely insane to suggest something like observer participancy, eh? You mention:
In the Mandel experiment it is blocking the path to the idler detector which changes the results.
But one set of photons' path is not blocked and so is not physically interfered with in any manner, right?
Now comes the odd part. The signal photons and the idler photons, once emitted by the down-converters, never again cross paths; they proceed to their respective detectors independently of each other. Nevertheless, simply by blocking the path of one set of idler photons, the researchers destroy the interference pattern of the signal photons. What has changed?
The answer is that the observer's potential knowledge has changed. He can now determine which route the signal photons took to their detector by comparing their arrival times with those of the remaining, unblocked idlers. The original photon can no longer go both ways at the beam splitter, like a wave, but must either bounce off or pass through like a particle.
So clearly the path of one set of photons is not affected mechanically, and yet it collapses too. Mandel thinks the issue is the mere threat of knowing which way the photon went. That may be true, but I have also wondered why entanglement wouldn't explain the collapse, assuming the other set of photons were entangled with the group that collapses without physical interference, but either way, what is occuring is remarkably different than the way you are describing it.
Your stance and the stance sometimes of others is that this is nothing really remarkable at all. It's not that different than heating up water into steam or some such. You mechanically disturb the wave function and it changes, but that's the very issue these experiments and others sought to settle. Is it physical disturbance that changes the wave function from that point on, or can the collapse occur even without direct physical disturbance, and the answer is yes, it does occur without that.
I am open to hearing your side, but acting like the ideas gleaned from Wheeler and others about what these experiments and QM shows is mere ignorance on my part is wrong. There is something pretty strange going in with QM.
Now, admittedly there is a lot of controversy, but there is no reason to act like where I am coming from on this is outside the mainstream or not under consideration of quantum physicists, at least in terms of the science. We ought to be able to have a good discussion, but it seems you are bent on just saying, well, you're wrong, and that doesn't go very far....?
Edited by randman, : No reason given.
Edited by randman, : No reason given.
Edited by randman, : No reason given.
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