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vidmar
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Are Maxwell's equations deterministic in the sense that e.g. if given free space with H and E defined for any point at time t0, then Maxwell's equations are sufficient to determine H and E for any t>t0?
Maxwell's equations alone are not sufficient to determine H and E for any observer at any time. You would have to apply special and general relativity.vidmar said:Are Maxwell's equations deterministic in the sense that e.g. if given free space with H and E defined for any point at time t0, then Maxwell's equations are sufficient to determine H and E for any t>t0?
Are Maxwell's equations deterministic in the sense that e.g. if given free space with H and E defined for any point at time t0, then Maxwell's equations are sufficient to determine H and E for any t>t0?
vidmar said:Are Maxwell's equations deterministic in the sense that e.g. if given free space with H and E defined for any point at time t0, then Maxwell's equations are sufficient to determine H and E for any t>t0?
do Maxwell's allow for the formation of matter out of this form of energy
vidmar said:Thanks for the answers. I tend to like determinism :)
vidmar said:I have another question, namely: gieven ab initio free space with E and H do Maxwell's allow for the formation of matter out of this form of energy (energy of the electromagnetic waves). Arguablly Einstein says E=mc^2, so they probably should. I know I'm probbaly asking questions in a way one with a more detailed knowledge of the theories would not but I'd be happy of any comments on them anyway.
Juan R. said:Then you like an unphysical issue :-)
Determinism does not work.
Then you like an unphysical issue :-)
Determinism does not work.
Crosson said:If you think that Determinism is invalidated by Quantum Mechanics, then you should read about Bohmian Mechanics.
Even besides the existence of the purely deterministic Bohmian interpretation of quantum mechanics, you should remember that no one suspects that the ill understood field of quantum mechanics is a description of true reality.
vidmar said:Why wouldn't determinism work. As far as I know Newton as well as Einstein are both deterministic. The only physical theory which is not is Quantum theory and I read (heard, I'm no longer sure) somewhere that even this one can be put on a deterministic footing just that then it doesn't sound that natural or something along does lines.
moreover Bohm formulation is incomplete and non scientific, since claim unobserved things.
moreover Bohm formulation is incomplete and non scientific, since claim unobserved things.
But undeterminism can be proved. E.g. QM.
vidmar said:Why wouldn't determinism work. As far as I know Newton as well as Einstein are both deterministic. The only physical theory which is not is Quantum theory and I read (heard, I'm no longer sure) somewhere that even this one can be put on a deterministic footing just that then it doesn't sound that natural or something along does lines.
Crosson said:No one ever observed a keplarian orbit either (they can't be directly observed from the earth), and this doesn't stop Kepler's theory of orbits from being a scientific theory.
How is Bohmian mechanics incomplete? Bohmian mechanics, like any theory, postulates the existence of theoretical entities (things that cannot be observed, but can be infered to explain observations).
Crosson said:The predictive power of QM doesn't prove that the world is indeterminate. Determinism says that given the current universe state, there is one and only one future universe-state. Knowing the initial wave function does not allow us calculate one and only one definite universe state, but perhaps the wave function is not a complete description of the state i.e. Hidden Variable theories.
Do you know some single experimental proof of that world is determinist?
I'm lost. The motion of the planets is indeed observable, in principle and in reality, and has been for a great deal of time.
I'm lost. The motion of the planets is indeed observable, in principle and in reality, and has been for a great deal of time.
vidmar said:OK I might as well add some of my own thoughts.
First of all, when I say I like determinism, it does not mean that I don't find theories, which are based on probabilities and are said to be undeterministic, interesting and useful if not beautiful. I just mean that I would prefer a theory at least in principle to allow for only one evolution of an observed system (even if the underlying technical difficulties don't enable us to have closed formed solutions - as for example in the three body problem of Newton - there the movement is determined (except for singularities) even though we can't have closed formed solutions as in the two body case). QM on the other hand is inherently undterministic (as far as I know) in the sense that gievn a system, its future development is not determined.
I also don't think that scientific experiments (can) prove (even if only in the limited strict scientific sense) that the world is undeterministic. What they show is that on a certain level of precision of physical measurments we have theories, which equipt us with tools necessary for the calculations of certin probabilities, that agree with the observed data within the error of measurment. But that doesn't mean that the world need be inherently undeterministic, let alone that we cannot have a deterministic theory, which would describe it. This may easily be seen with the introduction of hidden variables (which in my view don't make the theory incomplete). The succesfullness of a theory in physics may be measured only by its ability to predict the results of measurments and not by a formalism one chooses to have for it. The latter is more a matter of taste (as long as it does not entail that the theory would become less predicitve or make it harder to produce results) as it is a consequence of the world around us.
Crosson said:I dare you to look at the following picture of a theoretical model that could NEVER be observed, even in principle, but can only ever be infered INDIRECTLY from routine observations. This model is accepted as a practical fact today:
http://eos.uom.gr/~hatzifot/orbits-trans.gif
Crosson said:Why don't you take a look at the rest of the universe? For thousands of years western astronomers held the doctrine that the heavens were immutable, unchanging. The combined astronomical observations of all the humans who ever lived before the 15th century, considering that Astronomy was as important a skill in those days as driving a car is today, tend to support determinism.
Nam_Sapper said:QM doesn't disprove determinism at least for inanimate objects.
It only proves it is incapable of determining specific causes and making non-statistical predictions for itself.
Nam_Sapper said:Bohmian Mechanics is of course an excellent formal interpretation of QM theory.
Nam_Sapper said:Science is after all based upon causality, not witchcraft, and Bohm succeeded in offering a logically rational interpretation of QM effects, carrying out Einstein's hope.
it was unnecessary superstructure
In fact, is more "weird" that usual QM claiming for misterious effects that are hidden and cannot be observed (even in principle).
Crosson said:How ironic it is that standard QM makes use of "hidden variables" .When is the last time anyone measured a wave function? Wave functions are inobservable in principle and so it is they which are the true hidden variables.
Bohm's theory is much more concrete then standard QM, since it speaks of particles as having trajectories.
Einstein 1952too cheap
I see that you have reached the lowest common denominator, smearing me as someone who does not even understand the physics we are discussing. I assure you that I have a deep understanding of quantum mechanics. Unlike you, I have textbooks on Bohmian theory in addition to my textbooks on standard QM, so I am interested in the content of the theory rather then as labeling it with the term "hidden variables" in some kind of marketing attempt to brainwash young physicist.I see that you have a very distorted understanding that QM is. I see no need for contining this discussion before you learn QM from a textbook. After we will can continue the discussion.
Crosson -- of course we can measure wave functions, at least up to a phase.
Crosson said:I see that you have reached the lowest common denominator, smearing me as someone who does not even understand the physics we are discussing. I assure you that I have a deep understanding of quantum mechanics. Unlike you, I have textbooks on Bohmian theory in addition to my textbooks on standard QM, so I am interested in the content of the theory rather then as labeling it with the term "hidden variables" in some kind of marketing attempt to brainwash young physicist.
Crosson said:How ironic it is that standard QM makes use of "hidden variables" .When is the last time anyone measured a wave function? Wave functions are inobservable in principle and so it is they which are the true hidden variables.
Bohm's theory is much more concrete then standard QM, since it speaks of particles as having trajectories.
Crosson said:If you were to read a text on Bohm's theory, you will see that nothing about the trajectories makes them "unobservable in principle", that's totally bogus propaghanda. The only thing which indicates that the trajectories are hidden is one of the traditional postulates of QM: that the wavefunction is the most complete possible description of the system.
Crosson said:There is no reason for this, it is postulated. It is just an assumption, and doesn't go anywhere towards proving that Bohmian trajectories are unobservable,
Crosson said:QM just assumes there are not.
Crosson said:Lets get even more specific. Another postulate of QM is this voodoo: All observations correspond to self-adjoint operators, and the measured quantities correspond to that operator's spectrum of eigenvalues.
The problem with this is that it is impossible to construct a time operator in standard QM. In the 1950s Pauli proved that the above postulate is what imposes this limitation.
Crosson said:Of course, because Bohm's quantum theory of motion describes particles moving with well defined trajectories,
Crosson said:it is relatively straight foward to calculate how much time it takes for various interesting events to occur. It is hoped that one day experimental precision will extend to very short time scales that will allow us to test predictions of Bohm's theory that do not exist in standard QM.
Crosson said:Let me repeat myself: Bohm's theory does not involve anything which could be called a "hidden variable".
Crosson said:This is a marketing term used by many physicist who do not want to admit that the complex-valued wave function is what is truly hidden from observation. (What we observe are postions, momenta, energy levels and hopefully one day time scales, we certainly don't measure complex-valued wave functions).
For you...orbits are hidden variables.
Crosson said:How ironic it is that standard QM makes use of "hidden variables" .When is the last time anyone measured a wave function? Wave functions are inobservable in principle and so it is they which are the true hidden variables.
Bohm's theory is much more concrete then standard QM, since it speaks of particles as having trajectories.
artificial metaphysics
Crosson said:The predictive power of QM doesn't prove that the world is indeterminate. Determinism says that given the current universe state, there is one and only one future universe-state.
I had always thought determinism stated that given the current universe state, there is only one future universe-state and it can be found. By found, I mean that with some method - maybe even utilizing tools we can only imagine - the future universe-state can be known.