I'm really looking for input (I suspect this may be a short thread) from the knowledgeable folks trolling the forum. Yes, bring me the brain. You know, like Alphamumeric, Prometheus, rpenner and the rest of the conspiracy clique. The question is:http://www.sciforums.com/showpost.php?p=2630643&postcount=77 What explanation accounts best for the apparent results of these experiments? Personally, I side with the Copenhagen interpretation, however, it's perfectly possible that I've completely misunderstood the fundamentals. If I'm wrong, I need to know about it. If AlexG is wrong, he has to buy me a years subscription to Penthouse.
I think this statement of yours is the crux of the disagreement: You say that the indeterminancy arises from limits of measurement. I say it's a fundamental aspect of the quantum world. "The conspiracy clique". You mean they all got together and conspired to earn advanced degrees in physics?
I don't understand. AlexG, you referenced Greene's book and listed the pages to look under... A couple of the pages are not available in the preview. However, from what I've read, he's saying the same thing that I am. Only he's taking more time to do it. I referenced in another thread that we still have the Uncertainty Principle. The more accurately we measure the wave as a wave, we lose accuracy on measuring it as a particle. The more accurately we measure it as a particle, we completely lose accuracy of measuring the wave. We cannot measure the Wave AND the particle at the Same Time.\ Since the light or electron exhibits particle/wave duality and we cannot measure one without sacrificing the accuracy of the other... The issue seems to be one of measurement, not one of the electron deciding for itself, one where the electron determines its path or one in which the electron is mysteriously attracted to a detector. It doesn't violate locality. http://en.wikipedia.org/wiki/Decoherence#Mechanisms http://en.wikipedia.org/wiki/Decoherence#In_interpretations_of_quantum_mechanics
But in this case, that of the slit experiment and it's variations, what we are measuring is neither position nor momentum. It's determining which path to the detector a given photon (or electron) takes. Heisenbergs principle does not come into play here. What we note is whether an interference pattern is created by the wavicle, or not. If an interference pattern is produced by a single photon, it means that when the photon passes through the slits, it is in a wave form and interferring with itself. If there is no interference pattern it's because the photon acted like a particle, and not a spread out, self interferring wave form. Now if we put a path detector in front of one of the slits, and turn it on, there is no interference pattern. We know definitively that the photon went through one slit or the other, but not both. Turn the detector off, so we do not know the path information, and the interference pattern is present. So we could say that knowing it's path (not it's position or momentum, we don't carr about that) forces the photon to choose to be a particle. But the same thing happens if we place the detector past the slits, after the choice of wave or particle took place. Knowing the path information after the photon passes through the slit seems to retroactively cause a choice of wave or particle.
Question: You have a Screen set up that is able to show an interference pattern in the experiment. You run the experiment and sure enough, there is the pattern. Now, without removing the screen, you place a detector as well. The detector notes the hit-- is there an interference pattern on the screen?
The detector notes the hits? or the detecor notes which slit the photon came through. If the detector tells us which slit the photon came through, there will be no interference pattern on the screen. Turn the detector off, and the interference pattern reemerges. That's enough for me tonight, I've got to get some sleep.
Bad wording on my part? You knew what I had meant... Ok, sleepyhead. Thanks for taking the time to explain.
The double slit experiments has nothing to do with the uncertainty principle, Neverfly. The uncertainty principle talks about inherent limitations to the accuracy of simultaneous measurements of position and momentum (or any pair of conjugate variables). It says that there is a threshold to accuracy beyond which even the very best of instrumentation cannot cross. It doesn't matter which interpretation of quantum mechanics one ascribes to which one ascribes. They all have this basic limit in common. The limitation arises from nature itself rather than the our failure to make better instruments. Note also that it applies to simultaneous measurements of conjugate variables. The uncertainty principle has been (badly) usurped by those outside of the realm of physics who (erroneously) think the uncertainty principle means that attempting to measure something interferes with the measurement. That might be true, but that is not what the uncertainty principle is about. The double slit experiment is measuring neither position nor momentum. The purpose of the double slit experiment and its follow-ons is to determine whether light acts like a particle or a wave and to identify some of the truly bizarre circumstances that make that behavior flip from one mode to another.
