Maxwell's equations and determinism

[vidmar]

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?

 

[Andrew Mason]

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.

AM

 

[Crosson]

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?

In free space, Maxwell's Equations reduce to a wave equation for E and a wave equation for H. The solutions are guranteed to be unique, and exist for all time. The equations are even linear, so will not display chaotic behavior (so that prediction is not just theoretically possible, but somewhere in the ballpark of actually possible). But if we include free charges the system becomes extremely nonlinear.

 

[Antiphon]

Yes, they are deterministic- but they may not be sufficient as in the case of
a chaotic system. It's no different than the 3-body celectial mechanics problem.

And I believe you do not need special relativity since ME are already Lorentz
invariant. You may in fact need GR if you want to solve problems near massive
bodies.

 

[Juan R.]

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?

Yes, Maxwell equations are deterministic, but determinism is only valid for the average of the physical ensemble.

If E_instant = <E> + E_fluctuation

Determinism works only for the average <E>. Molecular noise is not determinist. For example, fluctuations f in the electric field measured in a macroscopic solution of ions (near equilibrium) is indeterminist, only average behavior

<f> = 0

<f f'>= delta(t-t')

can be predicted.

 

[vidmar]

Thanks for the answers. I tend to like determinism :) 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.

 

[Crosson]

do Maxwell's allow for the formation of matter out of this form of energy

As far as I know, the only theories in which particles can be created from energy are relativistic Quantum Field theories.

 

[Juan R.]

Thanks for the answers. I tend to like determinism :)

Then you like an unphysical issue :-)

Determinism does not work.

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.

Maxwell equations, like the rest of classical physics, are for constant number of particles,.

 

[vidmar]

Then you like an unphysical issue :-)

Determinism does not work.

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.

 

[reilly]

The answer to your initial question is yes, but ... Don't forget that M's equations involve sources, which can have their own dynamics. Technically the combined source-field equations are, in classical circumstances, deterministic. All this means is that second order differential equations, partial included, are fully determined for all t by the system of equations together with initial conditions. (See most any text on E&M) Note that self-energy issues, put some of the determinism in doubt -- the self-energy problem has never been satisfactorily solved.

One could, I suppose, add a source in which the number of particles is a function of, say E*E + B*B. But now the set of equations is horribly non-linear, and all bets are off.

Purely free fields are trivially deterministic, as are particles with no forces involved..

Regards,
Reilly Atkinson

 

[Crosson]

Then you like an unphysical issue :-)

Determinism does not work.

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.

 

[Juan R.]

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.

The failure of determinism goes beyond QM.

moreover Bohm formulation is incomplete and non scientific, since claim unobserved things.

 

[Juan R.]

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.

The most simple reply "because world is not determinism."

Determinism is a phylosophical option cannot be shown from physics. But undeterminism can be proved. E.g. QM.

 

[Crosson]

moreover Bohm formulation is incomplete and non scientific, since claim unobserved things.

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]

moreover Bohm formulation is incomplete and non scientific, since claim unobserved things.

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).

But undeterminism can be proved. E.g. QM.

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.

 

[Juan R.]

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.

Determinism only works in simple systems. Like Einstein theory applied to one idealized body system, Newtonian mechanics applied to celestial bodies, etc. When Newton mechanics is applied to condensed matter does not work fine and is generalized by Langevin type equations. Almost all of statistical mechanics is not determinist, thermodynamics is not, chemical kinetics, of course is not, etc. At higher levels, biochemistry, ecology, medicine, sociology, dynamics of human populations, etc. determinism fails completely.

It is not true that Quantum mechanics can be rewritten in a deterministic form. In fact, nobody has newer developed any deterministic consistent formulation of quantum mechanics. The problem of some people is that does not understand probability and think that probabilities of QM are some kind of measure of ignorance of some fundamental underlying formulation, which is, by ad hoc definition in those theories, unobservable.

As said, determinism is a philosophical option with no solid link with pure physics because is not a testable scientific hypothesis. Moreover, there are further difficulties with idea of determinism regarding human matters (free well, ethic, etc.)

Einstein theory is deterministic just like approximation, when stochastic (random) components vanish.

That determinism does not work is not a philosophical issue, it is a fact of science. The problem of physics is that begin focusing in simple systems where determinism work at first approximation. There is no a culture of determinism on chemistry for example.

*****************************

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).

Kepler orbits are observed (Kepler theory does not say that orbits are unobservable items) and the theory tested by direct measure of position of planets which follows from Newton gravitation. I already said why Bohm mechanics is incomplete. Any theory to be taken seriously may be based in observed things. Bohm postulates the existence of things cannot be measured, even in principle.

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.

No QM alone, but scientific experiments prove (in a strict scientific sense) that world is not determinist. Do you know some single experimental proof of that world is determinist? Of course, the wave function is not a complete description of the state. That is already known. Wave functions work only for pure quantum states, it does not work for quantum mixtures. Another aspect ignored by Bohm...

 

[vidmar]

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]

This is the twentieth century dichotomy in physics: Physicist want their scientific models to help them "really know" what's happening, but they have all bought the party line which says "all that matters in physics are observables".

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

Do you know some single experimental proof of that world is determinist?

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.

 

[CJames]

http://eos.uom.gr/~hatzifot/orbits-trans.gif

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.

 

[Crosson]

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.

Think harder. The picture I showed you is a cartoon. This is important because you will not find a photograph of the solar system from that perspective. The cartoon is a theoretical model, it is impossible (in principle, considering optics) to actually observe the exact scene that that cartoon depicts. Yet the predictions of the model are correct, and we accept the existence of orbits as a fact even though no has ever observed them as depicted in that cartoon.

The point is that we can infer the existence of things that we don't see, if it makes our world view more conceptually pleasant.

 

[Juan R.]

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.

The problem is that for explaining experimental data one needs formulations with deterministic forces more random forces. Determinism is a phylosophical attitude and i, of course, respect if you like it, but is scientifically unproven. In fact, none even conceivable experiment can prove determinism. Of course, is a phylosophical option.

In classical physics, systems are not deterministic: e.g. thermodynamics or chemical kinetics.

Yes, experiments can prove that the world is undeterministic by measuring random forces, which cannot be reduced to deterministic forces. From a phylosphical view, it is true that nondeterminism is not proved but scientifically it is. You have a random copmponent that cannot be explained in determinisitc terms, that is science. Now you can phylosophically claim that that random component is really caused by an underlying deterministic theory. Yes, phylosophically it is possible. But and scientifically?

If you want your hypotesis to be scientific you may prove that can be verified (falsable) in experiments.

You may formulate the deterministic final EXACT theory, then derivate random components from it and show that coindice with experiments. This is by definition imposible because by definition the theory may be exact (which may be imposible), you may measure with infinite precision, which is imposible, the proposed state of all universe (even beyond observable universe!), which is imposible, and may compute the EXACT result, which is imposible (except by the use of a perfect computer more larger than universe itself), then and only then if experiment coincides with theory you could prove that universe is determinist.

But we compute with imperfect computers, measure with finite precision, develop inexact theories, and cannot know the state of the entire universe. In fact, there is further limitations even for measuring positions and momentum of 10²⁴particles in an ideal gas. Therefore experiments prove that F_total = F_determ + F_random

And that is all science can say.

You cannot apeal to hidden variables because if are hidden. How do you scientifically show that variables are there?

It is like the hyphotesis of "pink elephants" that i said.

Personally, I see not problem with the phylosophical interpretation of a world which is non determinist. That mean free will, and love, and ethics, etc.

 

[Juan R.]

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

I think that you are a bit confounded.

http://uts.cc.utexas.edu/~setreal/Pics/ny/empire%20state%20building.jpg

You are claiming basically that Empire tate does not exist because i cannot see it entire. I am sited at north i only can see a side, if i am at west i can see another side but like i cannot see all togheter it cannot exist. Moreover like i cannot see a guy sited in the floor 25 from the street but i can the guy if i am inside the Emipre, in the 25 (and then cannot see the Empire), them both Empire state and the guy both do not exist.



I cannot see the entire solar system once (in principle I believe that one could) but i can see parts of them at each time and then reconstruct the entire system in a graphical from. Like i can obtain a collection of photos of the Empire and reconstruct it with a graphical package.

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.

For classical mechanics

a = F_determ + F_random

Random components is related to Temperature and strengh "gamma" of interactions, inverse of mass, etc.

In Astronomy, "gamma" --> 0, and T --> 0, and (1/m) --> 0... and

a --> F_determ

But is only an approximation. For example, T is not zero in space, but is so small that effects are not measured in usual astronomical experiments.

The problem of physics is that began with Astronomy and the myth of determinism arised because in astronomy things appears to be deterministic. Chemistry began with condensed matter and newer claimed that world was deterministic. Chemistry always was based in uncertainlty, therein that was did arise like science 100 years after than physics.

 

[Nam_Sapper]

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.

Bohmian Mechanics is of course an excellent formal interpretation of QM theory. 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. The latest installment, the Transactional Interpretation of QM, is also an extension of Einstein's deterministic and logical program, only this time picking up from Feynman's projected agenda.

Thus:

Einstein --> Bohm --> Feynman --> Cramer --> Mead.

Offering the best and most scientifically cogent interpretation of QM yet conceived. Mead carried off Feynman's hope of formulating QED without using Maxwell's Equations at all! (and he succeeded where Feynman failed)
The final result is Collective Electrodynamics, a short but awesome feat.

 

[Juan R.]

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.

False, QM stablishs that classical determinism does not work. In fact, any attempt to introduce determinism on QM is based in hidden variables, doing clear that if pure determinism exists, it cannot be observed, and if cannot be observed then it cannot be proved, doing determinisitc interpretations a field of phylosophy or methaphysics.

In a more thecnical side, still nobody has shown like probabilities of QM arises from an underliyng -phylosophical- deterministic evolution.

Bohmian Mechanics is of course an excellent formal interpretation of QM theory.

False, this is the reason that is not followed by physicists, except by some guys with a distorted view of reality. Even Bohm claimed that quantum potential is "strange".

The best example of that Bohm mechanics is not complete or consistent is that there is dozens of different versions of it. E.g. Hilley version of Bohm (Broglie/Bohm) emphasizes that quantum potential is the key, whereas the Dürr School (named Bohmian mechanics) regards the guidance condition as the fundamental equation and avoids the quantum potential.

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.

False, chemistry (e.g. chemical kinetics) is not deterministic being causal. Statistical mechanics is causal being no determinisitc, Langevin equations are causal being no deterministic, etc.

You are confounding causality with determinism.

Bohm offered a posibility which was studied but is rather discredited today. There is not logical rationality on Bohm theory. In fact, is more "weird" that usual QM claiming for misterious effects that are hidden and cannot be observed (even in principle). The idea that Bohm theory is carrying out Einstein's hope is complete nonsense. Einstein claimed for a complete determinism based in observable reality. Einsten waited reduce QM to classical physics. Einstein said about Bohm mechanics

it was unnecessary superstructure

Bohm claim for a unobserved reality: a new mechanics that is not classical mechanics, is based in hidden variables (therefore is not physical) and obtain less results that from standard approaches.

 

[Crosson]

In fact, is more "weird" that usual QM claiming for misterious effects that are hidden and cannot be observed (even in principle).

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.

 

[inha]

You really really have to stretch the concept of wave function to call it a hidden variable.

 

[Juan R.]

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.

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.

Of course, Bohm theory is not more concrete than standard QM. This is the reason that is not standard :-)

In fact, it is so "weird" that only a "dozen of" people follows it.

But if you do not understand standard QM, how can you understand Bohm theory?

The trajectories of Bohm theory are not real trajectories like in classical mechanics, therefore the supposed "rationality" is lost.

Moreover, that trajectories are unobserved. Therefore, if existence is purely a philosophical isssssssssssssuuuuuuueeeeee.

That even ignoring that Bohm theory is less useful, consistent, and predictive that standard approach.

Even Einstein -who rejected QM and loved classical physics- rejected Bohm theory

too cheap

Einstein 1952

 

[Crosson]

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.

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.

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.

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, QM just assumes there are not.

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.

Of course, because Bohm's quantum theory of motion describes particles moving with well defined trajectories, 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.

Let me repeat myself: Bohm's theory does not involve anything which could be called a "hidden variable". 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).

 

[reilly]

There's a lot of really weird stuff in this thread. Planetary orbits? Well, just look in your newspaper for the times of "planet-rise" and "planet-set", which seem to correspond to reality. These are, of course based on the standard theory of planetary orbits, with, perhaps some perturbations -- the data can be found in the ephemeris. And, then there's NASAs various probes which seem to get to where they are going. Crosson, if you have a better theory, lay it on us. For planetary orbits, theory and observation agree nicely. What else do you want?

Bohm to the contrary, QM is the best game in town. Further, it's been around for long enough that many physicists have a very good understanding -- for example. lasers, magnetic resonance, optical pumping, and on and on. Bohm has not gotten very far in the physics community because his work, Bohm-Aronof (sp?) as an exception, has not led to any new physics. It's a kluge designed to alleviate philosophical discomfort, rather that confront any empirical situation. It certainly is not Occam friendly.

And remember, whether in Newtonian or Einsteinian form, theory gives no clue as to the why of gravitation; who knows the why of electromagnetic fields? There is not a physics theory around that is anything other than descriptive -- frankly, some folks claim that classical physics is somehow different in interpretive substance than today's physics. Nothing could be further from the truth. If you are pushing nostalgia for the illusory certainty of past theory, why not go back to the idea of prime mover?

Crosson -- of course we can measure wave functions, at least up to a phase. We're talking scattering experiments for example. QM will continue to be the best game in town until it fails to explain an experiment or phenomena that it should be able to explain. That's the way science works.

Regards,
Reilly Atkinson

 

[Crosson]

Crosson -- of course we can measure wave functions, at least up to a phase.

Actually what you measure are positions, energies, momenta. People use wavefunctions to calculate energies, and then measure energies, and the next thing you know they are saying they have measured a wavefunction. All I am saying is that the complex-valued wavefunction is a hidden variable that is used to predict things that we actually measure, where as Bohm's theory always speaks in terms of things we directly measure: postions, energies and statistical Hamilton-Jacobi functions. (How would a wavefunction be measured? With what sort of complex measuring device?)

My point about orbits was obviously a miss. I am not claiming that copernican/ptolemaic (Newtonian really) astronomy does not accurately predict the positions of celestial bodies. I was simply saying that the orbits we imagine the planets to move along cannot be directly observed.

Personally I don't give a crap about observation, but if someone attacks the causal (Bohmian) interpretation of QM on the grounds that quantum trajectories are inobservable (the "in principle" part comes from that unfounded assumption of QM that I brought up earlier), then I expect that person to think about which things we discuss in physics are truly observable: the truth is that many are not.

Occam says that one should not increase, beyond what is necessary, the number of entities required to explain anything. Bohm's theory does not "increase the number of entities", it simply talks about a particle and a wave associated with the particle (the wave is a generalized Hamilton's statistical function). QM talks about both these things, but in speaks of the particle in a totally inconsistent nonsensical way (as if it teleports around through places it has "no probability of being").

If the particle and its properties do not exist other then when they are measured, what sort of particle is that? Didn't someone accuse me of claiming the empire state building does not exist when we are not looking at it? How ironic that this is the world view of standard QM which I am against.

 

[Juan R.]

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.

Simply to say

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.

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.

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,

QM just assumes there are not.

"Just Assumes"

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.

QM would be wrong if there was a time operator

You have no idea of time is. Of course Bohm theory is unnecesary (even if were consistent) for obtain a time operator. Strictly a time superoperator.

Of course, because Bohm's quantum theory of motion describes particles moving with well defined trajectories,

Completely false, the trajectories of Bohm are not classical trajectories and are not well defined.

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.

I already cited a very recent experiment where QM offered the correct answer and Bohm theory, again, the wrong answer.

Let me repeat myself: Bohm's theory does not involve anything which could be called a "hidden variable".

Of course false. You do not understand nothing of Bohm theory.

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).

Marketing? Is the complex valued function a hidden variable?

But are you studied QM some day? do you know what is the |Phy> in QM? do you know what is a ray?

For you Bohm theory of hidden variables is physical and both QM and planets orbits are hidden variables theories.

 

[Crosson]

This is my last response to you Juan, because you are an internet troll. You responded to my points with various and that is not enough a discussion to be worth my time.

You seem hung up on the idea that I don't understand basic QM, and even after I try to move on beyond that disgusting obstacle to our discussion, you make a cocky remark like "simple to say" and repeat your groundless accusations. I feel totally disrespected by you, I don't feel that you have read or thought about what I have had to say at all. Here is one of your false characterizations of my point:

For you...orbits are hidden variables.

I laugh at this, because if you truly think that that is the point I am making by talking about orbits, then you have failed to understand basic philosophy of science. Given that, I find it hard to believe that you have actually thought about standard or Bohmian QM at all; it is more likely that you simply learned to apply the voodoo rules of standard QM and to spout the party line about Bohmian mechanics. Here is how I feel about you, troll:

 

[Juan R.]

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.

About planetary orbits you basically said that were unobserved. You waited that we said "oh yes they are unobserved, therefore, unobserved Bohm trajectories are also scientific ones". But, i and others already said on orbits, and fortunately people has studied Bohm theory and this is the reason that is rejected.

About "realism" of Bohm mechanics, it is interesting how you omit reference i cited where Bohm mechanics has been experimentally discredited. It is also interesting like you ignore the rest of my arguments and quotes, including Einstein rejection of it.

In short, Bohm mechanics is

artificial metaphysics

Pauli

 

[Locrian]

Hi Crosson. You posted way back on page one:

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.

Any comments on this?

 

[Crosson]

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.

Causal Determinism, as discussed by philosophers and myself, does not require there to be any method to determine the future universe state. For this reason, philosophers often avoid using the terms "predetermined" and "predestined", because these carry the connotation that somebody already knows the future U-state.

After the discovery of chaos in relatively simple nonlinear systems, it is generally agreed that humans will NEVER be able to predict the future U-state because our measurements only have finite precision, and we only have finite time to calculate. This does not rule out the idea that the universe is deterministic, as in Feynman's famous quote: "The universe integrates empirically", but it absolutely rules out our ability to make even short term weather predictions.

 

[reilly]

Actually what you measure are positions, energies, momenta. People use wavefunctions to calculate energies, and then measure energies, and the next thing you know they are saying they have measured a wavefunction.
>>>>>>>>>>>>>>>>>>
RA

Well, how else do you measure probabilities? (I'm aware of the convergence difficulties and other matters of mathematical rigor) When you have a coin toss, you measure which face of the coin is up. Then you count them. And, generally, you'll find, a 50-50 or close thereto, split. Of course, you want to make as many measurements as you can. As I'm sure you must know, physicists do a lot more with wave functions than calculate energy levels.

My thesis concerned electron-proton scattering, and I certainly used wavefunctions. When you do a scattering experiment you measure the probability that, say, an electron scattered from a proton, goes to a particular angular position. Sometimes you measure both electron and proton positions. But, in any event, you measure the modulus of the appropriate wave function. I don't expect you to believe me, but how about Bohm? He devotes over 70 pages to scattering theory in his classic book, Quantum Theory, and clearly demonstrates what I've just stated -- as do countless books and papers.


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.
C
All I am saying is that the complex-valued wavefunction is a hidden variable that is used to predict things that we actually measure, whereas Bohm's theory always speaks in terms of things we directly measure: positions, energies and statistical Hamilton-Jacobi functions. (How would a wavefunction be measured? With what sort of complex measuring device?)
>>>>>>>>>>>>>>>>>>>>>>>>>>.

RA
Generally speaking the wave function is exactly that, one of space and time and spin and... If, in fact the wave function is a "hidden variable", in what space is this true? (Just to be precise, one normally does not consider a wave function as a variable.)

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
C
My point about orbits was obviously a miss. I am not claiming that copernican/ptolemaic (Newtonian really) astronomy does not accurately predict the positions of celestial bodies. I was simply saying that the orbits we imagine the planets to move along cannot be directly observed.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>.
(RA) That's right for sure, certainly for complete orbits, or long sections thereof. It's not an issue of any consequence -- it well might be if our predictions of planetary motions were incorrect.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.
C
Personally I don't give a crap about observation, but if someone attacks the causal (Bohmian) interpretation of QM on the grounds that quantum trajectories are inobservable (the "in principle" part comes from that unfounded assumption of QM that I brought up earlier), then I expect that person to think about which things we discuss in physics are truly observable: the truth is that many are not.

>>>>>>>>>>>>>>>>>>>>>.
RA
The fact that you speak so disparagingly of observations says, with all due respect, you don't know nuthin' about physics. Physics has been based on observation for many centuries. Without observations physics would be the nothing more than pure speculation, with no way to discern truth, just a time-killer for restless minds. -- barring a return to the divine right of kings.

I was interested in Bohm's ideas when I was a student, albeit many years ago. My professors kindly suggested to me that. if I wanted to be a professional -- which I did -- it would be wise to learn "mainstream" physics first, and then, if I felt the urge, to return to Bohm's work. Further, I sensed that many of my Profs had great respect for Bohm, as a very bright, able and accomplished physicist. I gave my students similar advice with respect to Bohm and the whole area of alternative interpretations of QM. In short, the standard track in any profession is: pay your dues, get your union card, start you career with some strength. (Bohm certainly did) --true for docs, lawyers, jazz musicians and blues singers, academics, .. Don't fall on your sword until there's a medic around.

And, my criticism of Bohm's hidden variables is that it has not produced any new physics, unique to its precepts. I know that many physicist have a similar position. Further, as I remember, computations are more difficult with Bohm's approach. Here's a challenge: compute the Lamb Shift for hydrogen a la Bohm's approach.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.
C
Occam says that one should not increase, beyond what is necessary, the number of entities required to explain anything. Bohm's theory does not "increase the number of entities", it simply talks about a particle and a wave associated with the particle (the wave is a generalized Hamilton's statistical function).
>>>>>>>>>>>>>>>.
(RA)Strictly a matter of opinion.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>.
C
QM talks about both these things, but it speaks of the particle in a totally inconsistent nonsensical way (as if it teleports around through places it has "no probability of being". (RA-- How so?)

If the particle and its properties do not exist other then when they are measured, what sort of particle is that? Didn't someone accuse me of claiming the empire state building does not exist when we are not looking at it? How ironic that this is the world view of standard QM which I am against.

>>>>>>>>>>>>>>>>>>>>>>>>>>>

The QM you discuss, and the QM I've known and worked with for many years appear to be rather different. Particles exist only when observed? (David Hume could make a case for that position.) Nope. Most of us do not believe that, as amatter of pragmatism. You totally misstate the "world view of standard QM", and vastly overstate the importance of the arguments about interpretation. Day-to-day physics works with a pragmatic Born-Bohr interpretation, and most physicists are involved in day-to-day. It's pretty basic to assume the real objective world exists. And day-to-day physics makes the same assumption.

I never got back to Bohm because I found high energy theory much more interesting and challenging. (But, of course, I will admit a bias toward observation, which might disqualify my intellectual seriousness.) What in the world do you mean by teleportation?

Why does QM upset you so much? The fact that we can participate in this forum is totally based on QM -- as in semiconductors,. Have you actually taken a graduate level QM course?
Are you aware that with the use of wave packets, trajectories can be defined loosely? -- a staple of formal scattering theory.

If you wish to cling to your ideas about QM, then if you want to be taken seriously, you will have to cite chapter and verse, rather than handwaving and indignation, about what you consider to be the inadequacies of QM, and give strong support based on observations and or mathematics. But if you really don't give a crap about observations, then as I said above, you are not doing nor talking about physics.

Regards,
Reilly Atkinson

PS By the way, Locrian, your definition of determinism is exactly the one used in physics. Philosophy might well talk a different talk.

 

[Juan R.]

Hi Crosson. You posted way back on page one:



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.

Any comments on this?

Juan R. did extensive comments on why we cannot know that hypotetical future state in this thread, post ago.

 

[Juan R.]

Causal Determinism, as discussed by philosophers and myself, does not require there to be any method to determine the future universe state. For this reason, philosophers often avoid using the terms "predetermined" and "predestined", because these carry the connotation that somebody already knows the future U-state.

After the discovery of chaos in relatively simple nonlinear systems, it is generally agreed that humans will NEVER be able to predict the future U-state because our measurements only have finite precision, and we only have finite time to calculate. This does not rule out the idea that the universe is deterministic, as in Feynman's famous quote: "The universe integrates empirically", but it absolutely rules out our ability to make even short term weather predictions.

This is pure phylosophical speculation. You are asuming -phylosophically, of course- that universe is deterministic but you are not providing scientific evidence. Again your understanding of themes is -sorry to say this- superfitial. You are arguying just by the use of deterministic chaos. But what about nondeterministic chaos?

In nondeterministic chaos the initial state is perfectly stated and even if you know it exactly, and you compute with infinite precision, you cannot predict the future because Poincaré resonances break the unitary evolution and uncertainty arise. Of course, determinisitc chaos is valid in the limited regime when Poincaré resonances vanish, but is a approximation like the asumption T=0 in astronomy.

We could discuss about determinism from a phylosophical point of view but you appears confounded about the difference between phylosphy and science. There is no room for determinism on science except like approximated description when random forces vanish.

What about experimental proofs that Bohm theory is not correct? You are not replied to this still.

 

[Juan R.]

The QM you discuss, and the QM I've known and worked with for many years appear to be rather different.

Excellent reply!

I also arrived to the conclusion that QM studied by Crosson is very different of studied by rest of academia.

Also the Bohm theory studied by Crosson is different. All people, claim that Bohm theory is a theory of hidden variables and QM is not, but Crosson had claimed the contrary, which is, at least for me, rather atonishing.

Note: Crosson also claimed that planetary orbits are unobserved sugesting that Solar System model is an astronomical analogous of Bohm microtheory. It appears that now has rectified in this point.

 

[Crosson]

Do you people arguing against me feel that QM is true description of reality? Or do you view it as a black box for getting answers, as say a chemist does?

Don't start bringing up semiconductors, we all know way that QM earns its keep. The real question is whether or not QM describes the way the universe works on a fundamental level. We are not talking about the "day to day" in this thread, or what makes for easy calculations, we are talking about determinism, and determinism ultimately depends on the true metaphysical nature of reality.

It was Juan R.'s statement that determinism had been ruled out, that motivated me to start posting in this thread. Based on this statement, it seems that Juan has faith that QM is a description of reality, rather then being a statistical theory that represents our ignorance of the what is actually going on down there. Indeed, the QM which we have all studied includes the following postulate:

"The wavefunction provides the most complete description of the system that is, in principle, possible."

Here is a quote from Peter Holland, at the University of Western England:

"We emphasize the speculative character of the completeness assumption. It is not forced upon us by experimental facts and the more detailed theory of individual processes (Bohmian Theory) that it forbids is not excluded by the generally agreed upon formalism. A difficulty with it (CP) is that it takes for granted that the formalism is essentially closed and unambiguous."

I am not in love with Bohmian theory in particular, but I do believe that the completeness postulate is false, and that Bohm's theory is a step in the right direction towards moving beyond this obstacle.

The funny thing about the completeness postulate is that it is completely against the spirit of physics; it essentially tells all future generations that the problem is solved and is not up for discussion. The completeness postulate was developed out of the Copenhagen interpretation, and I see it as an arrogant, unnecessary, and almost certainly false assumption that has been kept alive only by a religion-like mob mentality of faith in the Copenhagen Interpretation.

If the completeness postulate is not true, then QM is entirely irrelevant to discussions about determinism. (I hope you see why).

 

[Juan R.]

Do you people arguing against me feel that QM is true description of reality? Or do you view it as a black box for getting answers, as say a chemist does?

Don't start bringing up semiconductors, we all know way that QM earns its keep. The real question is whether or not QM describes the way the universe works on a fundamental level. We are not talking about the "day to day" in this thread, or what makes for easy calculations, we are talking about determinism, and determinism ultimately depends on the true metaphysical nature of reality.

It was Juan R.'s statement that determinism had been ruled out, that motivated me to start posting in this thread. Based on this statement, it seems that Juan has faith that QM is a description of reality, rather then being a statistical theory that represents our ignorance of the what is actually going on down there. Indeed, the QM which we have all studied includes the following postulate:

"The wavefunction provides the most complete description of the system that is, in principle, possible."

Here is a quote from Peter Holland, at the University of Western England:

"We emphasize the speculative character of the completeness assumption. It is not forced upon us by experimental facts and the more detailed theory of individual processes (Bohmian Theory) that it forbids is not excluded by the generally agreed upon formalism. A difficulty with it (CP) is that it takes for granted that the formalism is essentially closed and unambiguous."

I am not in love with Bohmian theory in particular, but I do believe that the completeness postulate is false, and that Bohm's theory is a step in the right direction towards moving beyond this obstacle.

The funny thing about the completeness postulate is that it is completely against the spirit of physics; it essentially tells all future generations that the problem is solved and is not up for discussion. The completeness postulate was developed out of the Copenhagen interpretation, and I see it as an arrogant, unnecessary, and almost certainly false assumption that has been kept alive only by a religion-like mob mentality of faith in the Copenhagen Interpretation.

If the completeness postulate is not true, then QM is entirely irrelevant to discussions about determinism. (I hope you see why).

I respect philosophical opinions of people. I you want believe on determinism i see no problem, but you are doing an attempt to shown that physical world is deterministic, which, i already said, is impossible.

You incorrect statement begin with "is true description of reality?" You assumes what is reality and asumes what is true description. You assumes that world is deterministic and perfectly determined from positions of particles, but you are not showing that since you are beginning from that philosophical postulate. already explained becauses determinism is a phylosophical option but cannot be scientifically proven.

you cannot ask "The real question is whether or not QM describes the way the universe works on a fundamental level." If you do not know that mean fundamental level. QM says that fundamental level is QM says, and experiments prove this. Bohm theory claims an underlying deterministic structure that cannot be discovered/measured even in principle. This is reason that is called theory of hidden variables, but if those supposed variables are hidden and newer can be measured then Bohm theory is is in words of Pauli

artificial metaphysics.

we are talking about determinism, and determinism ultimately depends on the true metaphysical nature of reality.

But physics and science is about how world is in experiments/measurings, nor like the world can be imagined. I can imagine that quarks are composed of small pink elephants, but that is pure imagination, is not science.

It was Juan R.'s statement that determinism had been ruled out, that motivated me to start posting in this thread.

Exactly i said that i) determinism only was claimed by physics, newer was accepted in other complex sciences like chemistry or biology. ii) Determinism of Astronomy arises like approximation (already explain with equations) iii) nobody has proven that probabilities of QM are derived from a deterministic structure (in fact no one Bohm simphatizer has proved this still).

Based on this statement, it seems that Juan has faith that QM is a description of reality, rather then being a statistical theory that represents our ignorance of the what is actually going on down there.

No comment! I talked enough about this in this thread!

I newer said that QM was complete nor that wavefunction was a complete description of reality. In fact, it is well-known that |phy> is ONLY valid for pure quantum states. See also my words in the density matrix thread.

About the power of Bohm theory, even new versions of the theory are theoretically discredited and/or experimentally incorrect. I already said enough and add references on this.

In a recent "attack" (PHYSICS TODAY, March 1998) Bohmian believers said that new studies on QM like decoherence or the Gell-Mann/Hartle decoherent histories formalism were proofs of validity of Bohm theory. Of course, this is a nonsense and celebrated physicists Gell-Mann, Hartle, and others wrote public responses on that.

Extract from nobel laureate Gell-Mann and highly respected quantum theorist

Sheldon Goldstein's two-part article contains much valuable material. Unfortunately, his discussion of consistent histories is, in certain respects, misleading; at the very least, it is out of date.

Emphasis is mine.

Also an important physicist like S. Weinberg has replied

http://www.mathematik.uni-muenchen.de/~bohmmech/BohmHome/weingold.htm

Dear Professor Goldstein...

You are pretty persuasive about Bohmism. Is there a succinct (emphasis on succinct) clear statement of Bohm's theory that I can read?"

That is, fram from philosophies and asumptions about like Nature would be. Bohm theory explains all of QM (including relativistic processes) and explain things that QM cannot?

Reply is no.

 

[reilly]

Crosson -- I totally fail to understand your ad hominum bon-mots. The most arrogant person I've ever encountered, happened when I was a graduate student, was J. Robert Oppenheimer, who also was the most charismatic and charming man. His level of charisma was astonishing, of people in my lifetime only FDR and Churchill could compete. My experience was one lecture, and watching him at a faculty get togther. He was quite gracious in public, whether talking about national scientific policy, or the intracacies of QED. But, I gather, he could be devastingly pointed in private. I suspect there is a lesson there to be learned.

Between your scatalogical rejection of observation, and your assertion that there's a party line to be adhered to, and that, somehow, transistors, and I presume, superconductors, lasers, radioactive ispotopes and beams for cancer treatment -- two in my familiy have been treated that way -- and on and on, are really of no great consequence to you, I find it quite legitimate to question, as Juan R. has your knowledge of science and physics. I've had a copy the "Festschrift" for Bohm in 1987, Quantum Implications: Essays in Honour of David Bohm" for a few years, and have studied quite a bit of it. And, I note that a high level of civility abounds in the book.

That brings questions: has anyone actually observed the trajectories, say in the two slit experiment? Are they observable? What is the advantage of using highly nonlinear equations -- the HJ equation with quantum potential, and the continuity equation?

My view, and that of many physicists is that a state vector is defined by a complete set of variables -- true in classical physics, and in many engineering disciplines. Subject to future change? Of course. But, so far, this rather global approach has worked wonderfully. If you can poke an empirical (Oops, sorry about that reference to observation.) hole in the concept, let us hear it. Otherwise, are you willing to lecture to the entire scientific community about the "system approach" and statements about the inadequacy of such a utilitarian approach to state description, acepted as widely as a Visa or MasterCard credit card -- maybe even more so.

Party line? Hardly. Turns out that physicists are highly independent, just ask their employers. Most of us accept QM, imperfect as it is, troubling at the margins as it is, because we are convinced that it's the best game in town. Your idea and our idea of science and physics clearly differ. We are pragmatic, plumbers, quick and dirty back-of-the envelope folks with dirty hands and opportunistic minds. As scientists, our collective work over the centuries have brought enormous benefits of mankind -- my oldest son, a cancer survivor will, as an attorney, testify to that statement. We fly in airplanes, listen to the the radio, we can eat food that was harvested months ago, we are, unfortunately, very good at developing weapons, computing ballistic trajectories, we use electricity, use refrigerators, use natural gas, and ... You are, of course, free to reject such matters with whatever handwaving you wish. But, most of us will pay no attention to such rejection. I'm sure that you can figure out why.

Science is what scientists do. Physics is what physicists do. The plain fact is, that we have a long way to go to begin to say that we truly understand reality. But we do have an approach that has served us well over the centuries, and there is no reason to change horses at the moment.

And do remember, that physics is one of the most enduring and successful of human enterprises. If we turn out to be wrong, we admit it, and keep going toward what we perceive to be the truth. We have been guided by our own criteria for centuries; one of the few human activities that can so claim. The party line, if you will, is the process, which is grounded in empiricism and observation.

If A and B present you with their asserted complete and true theories of reality, how would you choose between them?

Regards,
Reilly Atkinson

 

[Crosson]

Between your scatalogical rejection of observation, and your assertion that there's a party line to be adhered to, and that, somehow, transistors, and I presume, superconductors, lasers, radioactive ispotopes and beams for cancer treatment -- two in my familiy have been treated that way -- and on and on, are really of no great consequence to you, I find it quite legitimate to question, as Juan R. has your knowledge of science and physics.

Of no great consequence? I am talking about determinism, which is the subject of this thread. Transistors are irrelevant to me in this discussion because they pertain to engineering, which is an application of physics, and is very far removed from the true metaphysical nature of reality. . Reilly, you strike me as much more of an engineer then a physicist. I consider physicists to be people like Einstein, who would never set foot in a laboratory.

As for you questioning my knowledge of science and physics, I think it is funny. The way you muddle engineering and physics, in a philosophical discussion where only the most fundamental physics is relevant, does not tend to make me take you questioning my credibility seriously.

 

[Juan R.]

A correction. The

"That is, fram from philosophies and asumptions about like Nature would be. Bohm theory explains all of QM (including relativistic processes) and explain things that QM cannot?"

is my interpretation of Weinberg question. It would appear outside of quote box. However, i think that I interpreted correctly Weinberg question.

 

[reilly]

Of no great consequence? I am talking about determinism, which is the subject of this thread. Transistors are irrelevant to me in this discussion because they pertain to engineering, which is an application of physics, and is very far removed from the true metaphysical nature of reality. . Reilly, you strike me as much more of an engineer then a physicist. I consider physicists to be people like Einstein, who would never set foot in a laboratory.

As for you questioning my knowledge of science and physics, I think it is funny. The way you muddle engineering and physics, in a philosophical discussion where only the most fundamental physics is relevant, does not tend to make me take you questioning my credibility seriously.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

You have totally mischaracterized Einstein. In fact, he was, among other things a rather good engineer and experimentalist. How did you ever get the idea that he never set foot in a laboratory?

He wrote a paper in 1923 with Hans Muhsam on an experiment they did for determining the permeability of filters. He and Leo Szilard applied for eight patents in Germany, six in Great Britain, one in the US, one in Switzerland, and one in Holland; all but two in Britain were awarded -- these mostly dealt with the design of a "noiseless household refrigerator." He holds a patent with Rudolf Goldschmidt on a then new type of hearing aide. He worked on a way (1907) to build a device to amplify small voltage differences, apparently in his own little laboratory.

If you want to understand the real rather than the mythical Einstein read the biography of Einstein by Pais. I've only quoted examples from Pais' book; I've heard of work on torpedo design, but I can't immediately find a reference.

By the way, Einstein's practical side was and I presume still is well known in the physics community. I learned my General Relativity from Prof. M. Schiffer, one of Einstein's mathematicians, as well as wonderful tidbits about Einstein's practical nature and other aspects as well. (The course became the well known, text by Adler, Bazin, and Schiffer. ) It's pretty clear that you really don't know much about Einstein, per your comment about his eschewing laboratories. The historical record proves you to be quite incorrect.

All I will say is that in my younger days, I was indeed a theoretical physicist, and considered as such by my peers and students -- why, some even congratulated me on my work and considered it to be physics.

To characterize Einstein as somehow beyond practical experiments is totally incorrect, and does damage to his early work on Brownian Motion and the Photoelectric Effect. Read Pais, and get it right.

Regards,
Reilly Atkinson

(Note: the inventors of the transistor won Nobels in physics. You are gong to challenge their awards as misguided?)

 

[Juan R.]

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

You have totally mischaracterized Einstein. In fact, he was, among other things a rather good engineer and experimentalist. How did you ever get the idea that he never set foot in a laboratory?

It is the myth of the theoretical physicist, who can discover world only via thinking without experiment (note this is also the claim of string theorists and after of more than 30 years still achieved exactly nothing even if they claim that computed BH entropy, and obtained graviton, etc. reality is very different).

Also is popular that Newton obtained gravitation laws from the falling of apple. But that is a myth, no real. Newton was a experimentalist (during 30 years!) and did experiments in densities of mass and with he learned here, after computed motion of some astros, etc.

 

[CJames]

Juan, I am suprised as to your opinion of string theory. I am a mere undergrad so bear with me. I am thinking of going into theoretical physics and wanted to study string theory. Is that a misguided attempt? I'm asking not because I think you're wrong but rather because I would like to know something about what I'm doing with my life.

As for determinism, I don't think the question at this point is so much whether or not the universe is deterministic, but more whether it is in principle possible to prove or disprove. Considering the heisenburg uncertainty principle, I just don't see how you could possibly demonstrate a particle behaving in a deterministic manner. That makes it unfalsifiable.

As for what is "really" happening, other than what we can measure it is all up to you. I prefer to think of "particles" as physical waves that contain 1 unit rather than as probability waves. But that's just an interpretation

 

[Juan R.]

Juan, I am suprised as to your opinion of string theory. I am a mere undergrad so bear with me. I am thinking of going into theoretical physics and wanted to study string theory. Is that a misguided attempt? I'm asking not because I think you're wrong but rather because I would like to know something about what I'm doing with my life.

you may got many sources of information and after take YOUR decision. If in some moment your initial decision turn wrong, then you may solve that. This is life

There is a thread about this in PF with many information: documents, quotes of specialists, beliefs, last string conference, etc.

https://www.physicsforums.com/showthread.php?t=89539