Possible Duplicate: Could the Heisenberg Uncertainty Principle turn out to be fa
ID: 1383292 • Letter: P
Question
Possible Duplicate:
Could the Heisenberg Uncertainty Principle turn out to be false?
Thought Experiment
Ponder, for a moment, if I had a cube with 10cm sides which I'll name The Box. By some unexplained means (future technology, magic, the work of deities, insert whatever you want), The Box had a special property: it would determine with absolutely zero uncertainty* the momentum of every particle inside of it (and only those inside of it). You can imagine it hooked to a computer with a listing of each particle and it's momentum, or whatever you like.
Edit: I've been informed that perhaps zero uncertainty is unattainable in the momentum, so if this is the case then perhaps simply "Known with enough certainty such that the combination of the momentum uncertainty with the size of the box yields ?m?x<?2, or in other words, the pair are known with more certainty than the Heisenberg's Uncertainty Principle says can be known."
What would this device be likely to cause in our universe, with our physical laws? Since by the Heisenberg's Uncertainty Principle (or the wavefunction commutation) their positions cannot be known, then it would seem to follow that I can no longer know they are in The Box, or indeed anywhere in the universe. But I know they are in The Box, because they are on the screen. Even if some small amount of uncertainty about The Box's location can be shown, because I have perfect certainty of the momentum, nothing about it's position can be known (by the HUP/WC) - so knowing anything about it is a violation.
Would this cause all particles to leave The Box once it was activated, leaving a perfect vacuum, devoid of even virtual particles (since once they popped into existence, I could determine their momentum and that they were inside The Box)?
If it caused a perfect vacuum inside of it, then it would seem that such a box would indeed not break HUP/WC at all - since I would still not have any knowledge of momentum and position of any particles. Could one argue that it is compatible with our laws of physics then, provided that activating it caused the expellation of every particle inside of it?
What would the existence of a region of true vacuum do to the surrounding matter, if anything at all?
Or would nothing out of the ordinary happen whatsoever, and it just turns out that the box 'beats' the HUP / defies the wavefunction commutation? Or perhaps, "forces classical behavior inside The Box"?
Would the confirmed existence of such a box force the reconsideration of QED Theory? As in "Well, that checks out, so I guess Quantum Theory wasn't a complete model of our universe"? Or would we just refine it, changing the details of the HUP/WC somewhat? (Stated another way: would we still have QED if HUP was proven false)
Other alternatives to consider? Details that I missed in formulating the thought experiment? Helpful suggestions?
Note: if you're not interested in considering the thought experiment, then don't. Wild conjectures will be fine, and the purpose of the question is to assist my understanding of the implications of the HUP/WC. "The Box couldn't exist" or "That can't happen" isn't helpful or relevant. I'm asking that consideration of it's existence and validity is already accepted (it's accurate and not just making things up), not asking for how to build one or why we haven't made it yet.
Explanation / Answer
momentum can be any real number, and most real numbers dont have a finite description. So already there is a (non-relevant) problem of how you can know the momentum with infinite precision. So lets say we try to measure with arbitrary precision the momentum of particle 1, then we know a?e<p1<a+e, for some value e, as we perform our measurements we can decrease e, however if you do so you you need more and more energy to probe your particle and lower e, and since any kind of box is finite, eventually you'll reach an energy where you cant know for certain that your particle is inside the box.