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I’ve been wondering about this question for some time. Is the uncertainty in QM due to simply being unable to measure with certainty? Or is the actual nature of the subatomic world uncertain?
This is certainly a valid question. So consider this. I'm sure you have seen (or maybe even done) the diffraction experiment, where light passes through a single thin slit, and you get the nice diffraction pattern on a screen. In fact, notice how the diffraction patterns get wider and wider as you make the slit narrower. Now, would you consider the observation of the diffraction pattern as being due to our inability to measure with certainty, or would you consider this to be an intrinsic property of the "light-slit" system? I vote for the latter, because the accuracy of my measurements does nothing to affect the nature of the diffraction.Vast said:I’ve been wondering about this question for some time. Is the uncertainty in QM due to simply being unable to measure with certainty? Or is the actual nature of the subatomic world uncertain?
This is indeed a important question and one in which I have been struggling for sometime as well.Vast said:I’ve been wondering about this question for some time. Is the uncertainty in QM due to simply being unable to measure with certainty? Or is the actual nature of the subatomic world uncertain?
Photons exhibit the uncertainty too. It is not just that you do something that to affect the particle and that causes a physical change. For example: in EPR experiments, the 2 particles obey the uncertainty relations. If it were a question of the observation changing the physical situation, why is the other particle affected? Answer: the uncertainty is real and fundamental.Matrixman13 said:I thought that the uncertainty principle comes about because when we try to measure the position of a particle, some kind of information has to be sent back and forth. This is usually done with particles like photons. When we do this, the velocity of the particle is then impossible to find with accuracy because we just hit it with a photon, thus changing its velocity. Please tell me anything questionable about what i've said.
Yes I’ve read about the slit experiment many times, that is that light can be either a particle or a wave, depending on whether one slit is open or two?ZapperZ said:This is certainly a valid question. So consider this. I'm sure you have seen (or maybe even done) the diffraction experiment, where light passes through a single thin slit, and you get the nice diffraction pattern on a screen. In fact, notice how the diffraction patterns get wider and wider as you make the slit narrower. Now, would you consider the observation of the diffraction pattern as being due to our inability to measure with certainty, or would you consider this to be an intrinsic property of the "light-slit" system? I vote for the latter, because the accuracy of my measurements does nothing to affect the nature of the diffraction.
The phenomena of the diffraction pattern from a single-slit is, believe it or not, a DIRECT manifestation of the uncertainty principle.
Zz.
I can’t quite put my finger on it but probabilistic determinations seem like it makes some sort of sense…sol2 said:This is indeed a important question and one in which I have been struggling for sometime as well.
Knowing full the question of momentum and position, and the difficulties involved here, two things became apparent to me. That as fuzzy as it may appear, uncertainty can be given structure in the form of orbitals?
http://superstringtheory.com/forum/stringboard/messages25/52.html [Broken] and looking back to bell curve, things seem realistic to me if we can count on BEC graphed situations, in concert with the Bell curve.
I would like to know if this thinking is wrong, as it has been the basis of my moves to the fifth dimension recognition of Kaluza and Klein ( the joining of electromagnetism to gravity ).
http://www.grandunifiedtheory.org.il/pics/book/09p11.gif
These concepts are in line with wave theory, which, like all natural theories (for example, Darwin’s), pulls together many observations and experiments. Kaluza and Klein’s fifth dimension matches the properties of a magnetic loop
http://www.grandunifiedtheory.org.il/book/universeP.htm#top
What kind of Energy does it take to confine a particle?
No, what I described has nothing to do with "wave particle" thingy. Note that I was describing diffraction from a SINGLE SLIT, not a 2-slit or multi-slit experiment. So there isn't any ambiguity of which slit a photon passed through.Vast said:Yes I’ve read about the slit experiment many times, that is that light can be either a particle or a wave, depending on whether one slit is open or two?
It does seem to show the fundamental property of nature being rather unpredictable.
Wow...are you guys are selling the standard Copenhagen interpretation today or what? Copenhagen would have us believe that not only is the theory complete, but that there is nothing else to know. It makes it all very convenient since then, as you say, the uncertainty is an intrinsic quality of nature and so 'determinism' can be buried in a deep hole as a poor-man's approximation of reality. Then we get to label things like 'free will' as meta-physical (because it certainly doesn't feel very 'causal') and believe it is because quantum mechanics obviously allows that sort of thing.somy said:I agree with chen. In fact it is the nature of the particles that make it imposible to measure some special quantities.
Cartuz -cartuz said:I think that this Quantum Mechanical principle has wrong interpretation. It is one of the Quantum-Mechanical axioms which is known as the Uncertain Complementation Principle by Bohr-Heisenberg. This Principle is consisting the philosophy basis of the absence the values of a coordinate and momentum of the microobjects at the same time before measurement. I think we can changing it by the well-known General Uncertain Inequalities as Quantum-Statistical Principle. The General Uncertain Inequalities been the form Δ(x)Δ(p)≥(h/2) in the Classical Statistical Physics where Δ(x), Δ(p) means the variance (dispersion) of measurement for the quantities x, p rather that uncertainly of its position. Than this theory we can name as Quantum Statistic but not Quantum Mechanic.
Of course it's incomplete -- it is in conflict with general relativity. However, you're erecting a lot of strawman arguments here. We can prove that there cannot be hidden variables. We can show (via logic) that any hidden variable theory will produce phenomena that we do not observe in this universe. Since we don't observe those phenomena, the universe cannot be described by any hidden variable theory.nickdanger said:Warren -
I don't say quantum mechanics is wrong...only partially right. It is incomplete. And don't quote me proofs that there are no hidden variables, we can't prove that anymore than we can prove that we have the theory of everything.
Science does not lie in wait of new ideas to modify successful theories -- it lies in wait of new experimental evidence. So far, all the evidence we have is in favor of QM's correctness. As we learn better how to use astrophysical systems for experimentation -- or use advances in technology to build more powerful apparatus, we will undoubtedly find the loose ends of QM.I look at it this way. Every theory is incomplete, we just don't know where or we would fix it. We await the theorist that will give us the new idea (think variable) that we missed and that's not just unification, it will be simplification.
Who cares what Einstein said? He never lived to see the theory fully developed! How is this a useful argument?Einstein said he didn't believe that QM was the 'real thing' yet.
The fact that it's difficult to visualize four dimensional spaces doesn't mean the conclusions of a theory that uses them are not valid. That's just another strawman argument. In fact, there are many ways to visualize quantum-mechanical systems via wavefunction evolution.And as I said, 'Copenhagen' concluded the opposite and moreover that there is nothing more to know. But we have a similar mess in special relativity. Einstein suggested 4 dimensional space-time and that we are at the point where we should stop trying to 'physically' imagine it and simply accept the mathematics...that's exactly what QM finally concludes: We have gotten so much from it, so don't question its validity.
Come on now -- neither theory has 'don't question it' as a postulate -- you're lying -- and you're just grasping at very small straws to say so. What do you think all the world's physicists do for a living?!So look at what we have. Two theories, QM and special relativity that are not reconciled and yet both of them have as their authors last postulate, 'don't question it'.
A good theory is one that predicts the outcomes of experiments. That is the one and only arbiter of a theory's success. Arguments about how you don't happen to like the theory are totally irrelevent. As it happens, anti-matter is well-understood, and QED is the most successful scientific theory ever created.Further, both theories have similar arguments in their defense: The correctness of their mathematical predictions when their theoretical basis is doesn't look so complete. You can't tell a technician on a synchrotron that special relativity is wrong, the math works everytime. Yet no one thinks when applied to cosmology that it is working theoretically. The same is true of QM, the predictions of the next particle is always correct. Yet anti-matter and QED are a mess. It's starting to look like correct predictions of 'easily' measureable, observable events doesn't correlate to a complete theory.
Next time, take your ill-founded attacks to the Theory Development forum.Well anyway, I'm giving you rhetoric when I can't give you any new idea...sorry about that.