Is Quantum Mechanics First Principles Enough?

[sciencenoob]

I honestly do not believe quantum mechanics (QM) is first principles enough, in the philosophical sense. QM deals with probabilites and unstrapped the desire (or at least is currently incapable as of now) of aiming to describe the particle behavior and motion of small particles and systems and their interactions. Rather it tries to justify its current inabilities to understand actual particle dynamics because the excuse is that statistical means as an 'best alternative' is actually sufficient.

 

However, physics in general, philosophically can only do so much as to describe natures laws because physics is surposed to define the most fundamental and the idea of 'facts' is much harder, if ever possible to achieve in physics, than in other subjects in which concrete proofs and 'facts' may be achievable. But in physics the idea of first principles is the use of the most fundamental laws to describe nature's responses, and QM fails to do this because it fails on being able to describe particle dynamics in which to correlate the QM current findings (e.g. probability desnity of particles), etc.

 

Wt do you think.

[BhavinB]

QM postulates are derived from many many experiments. The experiments dictate a statistical nature...not that its an 'excuse'.

[Klaynos]

I honestly do not believe

 

In addition to BhavinB's comments, I'd just like to say that science doesn't care what you believe, the theory says it is that way, as annoying as that may be...

[sciencenoob]

I am not saying what I believe is significant.

 

What I am saying is that QM is insufficient to describe the actual dynamics of the small particles, etc. The idea of first principles should be, the idea of the most fundamental description of nature, yes no matter how abstract. But using probability to describe the system isnt good enough, hence not 'first principles enouigh' because it fails to describe or explain the manifestation and phenomenas we observe, that is to explain the probability density observed as explained by QM.

 

So future theories can certainly go further and more fundamental than what QM is currently capable of accomplishing, hence QM cant be the most fundamental description of nature.

[Quartile]

http://en.wikipedia.org/wiki/Hidden_variables

 

i too am "convinced that god does not play dice"

[sciencenoob]

Well I have always known that einstein was famous in his attemps to discredit QM because he feels that its not deterministic enough, but its not because of einstein why people should also believe that science can be more fundamental than QM.

 

It really should be quite obvious for people to simply accept the fact that a certain theory, whether or not they have huge invested interests in it or not (such as careers, self study dedication, etc) to understand that QM simply isn't complete in the philosophical sense. That is, statisitcs really isnt fundamental (or first principles) enough, because it fails to describe the actual manifestation and dynamics and interactions of the system itself. Of course that is not to say QM is useless because I am a strong supporter of QM for its actual usefulness and for what we can do, but at the same time I understand the limitations of QM as a fundamental theory and its incompleteness that a lot of people simply will not accept.

 

For example, we can very well make a probability density function of a relatively hard standardized test (e.g. public exams, iq tests etc) and then be able to achieve somewhat of a normal distribution. We can then infer from this information the average test score of the population which we can then go on to say that the population is on average '____ this' smart, etc (within limitations); this works similarly to the concepts of QM. But thats not good enough in the philosophical sense of being a fundmanetal first principles description. What we will really need, is to explain perhaps the experiences of every individual taking the test, their brain network structure, how they think, etc etc, and put this in some sort of complicated matrix solution or simulation, to then obtain from this, the final observation we get from the statistics, and to even go as far as to predict what certain indibviduals in the population is capable of achieving, from the modelling alone. That will be the approach from first principles.

 

Hence like einstein I believe in the deterministic nature of theories to be more fundamental, but unlike einstein I respect QM for its usefullness.

[fredrik]

But using probability to describe the system isnt good enough, hence not 'first principles enouigh' because it fails to describe or explain the manifestation and phenomenas we observe, that is to explain the probability density observed as explained by QM.

 

So future theories can certainly go further and more fundamental than what QM is currently capable of accomplishing, hence QM cant be the most fundamental description of nature.

 

I'm not sure I caught your point, but I have no illusions that QM is perfect.

 

But your arguments against it make we wonder. If your objection is that to "only" predict the probability for a specific prediction, rather than the exact prediction is a sign of failure then I think you are missing a point that part of the truly foundational things, IS the concept of information and knowledge, and in my thinking at least the core of the business is that fact that we obviously do not know everything. That's reality. The problem of any living thing in reality is how to make progress and survive, while beeing immersed in things we don't know and understand.

 

What can we do about it? It seems we can analyse what the do know, and try to extrapolate our understanding to areas where we have limited explicit experience. Given a set of initial conditions and prior assumptions, induced from our past experience, we formulate a prediction.

 

At the simplest level, one can think that we don't know, so any guess is as good as any, and we let the feedback discriminate.

 

At the next level one may see that we got alot of faulty predictions, so our attention is turned to the logic of making predictions. By definition there is no way of KNOWING. There is not mathematical formula that can create information we don't have. The only thing we can do is to perhaps have mathematical formulas that help us, efficiently produce predictions of the unknown, from what we know that allows us to progress. The success is in the survival, of organisms or theories.

 

My issues with QM is that it I am not sure it takes these issues into FULL account. The whole idea that we can assign an objective, exact value of the probability itself, is disturbing and is not quite self-consistent IMO. Self-consistency, suggest something more. But this is more advanced objections that IMO has little to do with the issue of uncertainy principles, and the counterintuitive things that I think anyone encounters when trying to understand QM, coming from classical mechanics.

 

If I missed your point I apologise.

 

/Fredrik

[BenTheMan]

I've always seen quantum mechanics as more of a paradigm for understanding physics which we wouldn't have otherwise understood. One could argue that classical mechanics wasn't fully understood untill Newton taught us how to attack the problem analytically---quantum mechanics may be the same sort of ill-guided attempt at understanding the world that people practiced before Newton.

 

All of this probability stuff may be just a way for us to deal with the measurements we make in the lab.

 

Either way it doesn't matter. We'll probably never be able to do any better. QM gives the right answer, so what difference does it make if it makes any sense? Unless we can find an experiment to preform which disproves QM, then we are stuck with Hilbert spaces, wavefunctions, and uncertainty principles. Humans live in a world that is deterministic, and electrons live in a world ruled by probabilities. When we try to understand electrons, things don't make sense because we evolved in a world that is deterministic. So, in the words of Feynman, ``Shut up and calculate.''

[fredrik]

All of this probability stuff may be just a way for us to deal with the measurements we make in the lab.

 

Either way it doesn't matter. We'll probably never be able to do any better. QM gives the right answer, so what difference does it make if it makes any sense? Unless we can find an experiment to preform which disproves QM, then we are stuck with Hilbert spaces, wavefunctions, and uncertainty principles. Humans live in a world that is deterministic, and electrons live in a world ruled by probabilities. When we try to understand electrons, things don't make sense because we evolved in a world that is deterministic. So, in the words of Feynman, ``Shut up and calculate.''

 

I definitely expect us to do better. In my thinking "Shut up and calculate" is more like an engineering attitude, using scientific results as a tool only, with no intention whatsoever of extending the application of, or refining the tools themselves. But I have a little hard to see how science would progress as well if going beyond the "shut up an calculate" philosophy was discouraged. "shut up an calculate" is the business of computers, I don't quite compare myself with a computer. Even the simplest computer outperforms me on number crunching, but we beat them on thinking outside the box.

 

But

QM gives the right answer, so what difference does it make if it makes any sense?

is a relevant question.

 

I think the difference is in the bigger dynamic context of evolution of theories and understanding. If we expect to learn no more, the difference would only be that we may find a simpler (less resource consuming) representation of our theory. In the context of progress and improvement, this compactification is I think an essential step. It's like when we sleep at night, our brain reorganizes new information. Not because it makes much of a difference at an instant, but it may prepare us for upcoming progress.

 

/Fredrik

[BenTheMan]

Hmm.

 

I don't know how much physics you know, so excuse the vernacular.

 

All we can ever measure is the effective theory. An example would be the standard model---if we only find a single higgs at the LHC and nothing else, then that's it. The natural scale for new physics is too high for us to ever hope to measure---we will know that there is some more fundamental structure, but we'll never be able to test it. And any attempts to describe our universe beyond what we can actually test is not phsyics at all.

 

The same can be said for quantum mechanics. You'll never be able to remove the physical act of measuring from QM. This means you'll ALWAYS be stuck with the uncertainty principle, which pretty much dictates how we see QM.

 

So you can do philosophy, I'll do physics:) We should be in the business of measuring things. If we aren't, then we might as well talk about many universes and landscapes and such. Untill you come up with an experiment which shows some fault with QM, then the question of ``Is QM "first principles" enough'' isn't a question about phsyics at all.

[fredrik]

Hmm.

 

I don't know how much physics you know, so excuse the vernacular.

 

All we can ever measure is the effective theory. An example would be the standard model---if we only find a single higgs at the LHC and nothing else, then that's it. The natural scale for new physics is too high for us to ever hope to measure---we will know that there is some more fundamental structure, but we'll never be able to test it. And any attempts to describe our universe beyond what we can actually test is not phsyics at all.

 

The same can be said for quantum mechanics. You'll never be able to remove the physical act of measuring from QM. This means you'll ALWAYS be stuck with the uncertainty principle, which pretty much dictates how we see QM.

 

So you can do philosophy, I'll do physics:) We should be in the business of measuring things. If we aren't, then we might as well talk about many universes and landscapes and such. Untill you come up with an experiment which shows some fault with QM, then the question of ``Is QM "first principles" enough'' isn't a question about phsyics at all.

 

Ben, from your response I think you misunderstood me.

 

I am one of those ho definitely argue for measurements. I would even suggest that standard formalisms doesn't take this to full consistency. There are alot of idealisations. Did you ever observe a probability space? I haven't. But have we observed something that looks close enough to a probability space? Yes. The notion of probability space and how that is *deduced* is not trivial to me at least.

 

I was not refering to the classic objections that stems from the resistance of reevaluating the ideals of determinism and realism. This is another part of the discussion. Perhaps that was what the original poster meant though, I don't know. This is not an issue for me. The uncertainy principle we have to live with no doubt. But there are other issues.

 

The logic in the current theories is not clean enough IMO. Of course, if you choose to not observe this, and observed only the correlation between numbers produced from numbers and the numbers produced from our measurement apparatouses, then you are home as long as they agree. But if you choose to observed also the evolution of the theory itself, it somehow doesn't reach the same standards.

 

I don't suggest that QM or the standard model is off chart. I am just thinking that we are not yet completely understanding the logic of it. In particularly since the unification is not yet completed. I think this is partley related to our insufficient understanding on the QM foundations, and i don't exclude the possibility that there may come tweaks to it.

 

I don't think I do philosophy only, I try to do reality.

 

/Fredrik

[BenTheMan]

Of course, if you choose to not observe this, and observed only the correlation between numbers produced from numbers and the numbers produced from our measurement apparatouses, then you are home as long as they agree. But if you choose to observed also the evolution of the theory itself, it somehow doesn't reach the same standards.

 

I guess that this gets to the heart of the matter---like I said, all we ever measure is an effective theory. As physicists, we cannot talk about what is ``true'' and what is ``right''. We can never know these things. All we can ever talk about is ``agree with experiments''. QM predicts experimental results, which is all we can ever hope for. Because our knowledge of the subatomic world rests with results of experiments, then we can never do any better than QM, UNLESS you can show me an experiment in which QM fails.

 

Also, I don't know what things like this mean :

 

The logic in the current theories is not clean enough IMO.

 

In QM, all one does is use the uncertainty principle, promote classical observables to hermitian operators, and everything else follows. The thing that is really fundamental to QM is the uncertainty principle, and it seems to me that unless you get rid of that, then you are stuck with QM.

 

Finally,

 

Did you ever observe a probability space? I haven't. But have we observed something that looks close enough to a probability space? Yes. The notion of probability space and how that is *deduced* is not trivial to me at least.

 

Tell me what you mean by this. I think that you're wrong, but I want to know what you mean by ``probability space'' before I say so

[foodchain]

Not to but it but sense you guys seem to know what you are talking about maybe you could help with a curveball I cant seem to hit.

 

On the quantum level there is a relationship to the rest of the visible or known universe right? As if carbon and oxygen for instance have quantum effects going on, but they have natural and predictable behavior, as in carbon for instance wont instantly decide it cant bond with oxygen after the fact.

 

So what I would like to know is simply how stable is a quantum system? From all the verbs tossed out from QM that I vaguely understand it sounds as if the universe should just randomly turn into a microwave with a slice of pizza in it, or basically just not be able to persist in time in any regular form?

 

Am I off truly on my understanding of things?

[iNow]

Not to but it but sense you guys seem to know what you are talking about maybe you could help with a curveball I cant seem to hit.

 

On the quantum level there is a relationship to the rest of the visible or known universe right? As if carbon and oxygen for instance have quantum effects going on, but they have natural and predictable behavior, as in carbon for instance wont instantly decide it cant bond with oxygen after the fact.

 

So what I would like to know is simply how stable is a quantum system? From all the verbs tossed out from QM that I vaguely understand it sounds as if the universe should just randomly turn into a microwave with a slice of pizza in it, or basically just not be able to persist in time in any regular form?

 

Am I off truly on my understanding of things?

This is a big post, foodchain, and warrants it's own thread. Might I be so bold as to suggest that you start a thread on your own for this? Perhaps a title of "Quantum Systems and Material Consistency - I need help on the basics."

 

 

 

Collapsing wave functions in an entangled way...

[fredrik]

I guess that this gets to the heart of the matter---like I said, all we ever measure is an effective theory. As physicists, we cannot talk about what is ``true'' and what is ``right''. We can never know these things. All we can ever talk about is ``agree with experiments''. QM predicts experimental results, which is all we can ever hope for.

 

Yes, but "agree with experiments" is not entirely trivial statement, because there is a feedback, from our understanding in designing new experiments and devices, beeing constrained to the same rules as everything else. So I think this should be seen in a larger context where our understanding, and our theories evolve... in this context there is another thing beyond falsification, which is effiency or fitness of methodology. One can be correct and right, and yet inefficient.

 

So the effiency of inference in making good predictions is part of the fitness.

 

One observations of mine that that QM fails to predict is the real life relation between the fundamental forces. I can't ignore this observation.

 

So I wouldn't say is flat our wrong, but my personal thinking is that the methodology leading to it, can be severly improved, which in turn will have some spinoff benefits.

 

In QM, all one does is use the uncertainty principle, promote classical observables to hermitian operators, and everything else follows. The thing that is really fundamental to QM is the uncertainty principle, and it seems to me that unless you get rid of that, then you are stuck with QM.

 

My main issue with QM is not the uncertainy principle. It's for example the idealisation of objective probabilities, and slight issues of unitarity and the nature of spacetime. Maybe one can think that - this isn't QM - this is about gravity etc.. but there is only one world. It's bound to be related - this is a basic universal observation.

 

I

Tell me what you mean by this. I think that you're wrong, but I want to know what you mean by ``probability space'' before I say so

 

A probabiliy space is a mathematical object. It's a sample space, event space and a measure constrained to the axioms of probability.

 

The problems resides in that it's logically hard, or impossible to impose an exact bound on our own ignorance. We can do it by hand, trial and error as per some scientific method, or one can try to formalize the scientific method itself, and implement this into the theories themselves so that can evolve on their own, without ad hoc input.

 

The match with reality is just postulated. I think this can be done better. I want the probability space itself to be elevated as an, to principle, observable, dynamic structure. This should I think be founded, at the level of QM axioms.

 

The benefit, that remains for me to proove of course, is that is that this will increase the fitness of the methodology dramatically, and it will resolve some of my issues mentioned.

 

I didn't mean to explain any of this now. It's too early. I just add my personal opinion to the record that there are more issues with QM than the old "classical mechancs, determinsm/realism" issues. Even if you get over that, there are still issues to be resolved in the future. That's what I think, and is working towards.

 

I see things at two levels.

 

Theories as ouput of a scientific methology. My attention is at the latter, and then you can try to device a theory of the theories that can be attributed a sort of fitness if you think of a theory as an organism cruising through the unkonwn. In that perspective, QM has alot to wish - at least IMHO.

 

/Fredrik

[sciencenoob]

To put it simply, I am a believer that the universe is deterministic. I believe that a particle has a trajectory path similar to the classical newtonian sort of way (i.e. it is continuous in spacetime). You may be able to describe things using statistics (what QM is doing) and it perhaps suffices for engineering applications, but it does not exclude from the real possibility that particles travel real deterministic paths, and hence if that were to be the case then QM simply cannot be fundamental enough. If it is true (but I dont see how one were to go about proving), the principle that particles travel discontinuously (i.e. it can exist in one point then all of a sudden decompose in spacetime and instantly spawn in another and different spacetime), then QM may then be argued to be as fundamental as it can get (perhaps, because then you may still be able to predict/document the dynamics of its movements).

 

I dont care for the uncertainty principle that underlies QM, because that principle is simply a construct developed for the need to explain what is observed experimentally and at a theoretical level. However the uncertainly principle relates strictly applicable to QM only, the mechanism of which is perhaps explainable with more fundamental understanding.

[swansont]

To put it simply, I am a believer that the universe is deterministic.

 

Impressing beliefs or ideology onto science run counter to how the process works.

 

One can take such an idea and test it to see if it's right, of course, replacing belief with hypothesis. Unfortunately the evidence from such experiments does not agree with you. An electron goes through both slits, and there are no hidden variables. Science requires that you reformulate your hypothesis.

[BenTheMan]

noob---

 

You are extrapolating your classical intuition FAR beyond its regime of applicability. This is not science. Even your first scentence, ``I am a believer...'' evidences this. In science there is no belief, only what can be tested and proven.

[geoguy]

In addition to BhavinB's comments, I'd just like to say that science doesn't care what you believe, the theory says it is that way, as annoying as that may be...

 

Excellent.

[sciencenoob]

Hold on a second, you are obviously the science bunch that read science textbooks, learn the modern interpretation of it (repeat: _intepretation_) without any real knowledge of the actual evolution of the theory, and perhaps the interpretation as seen through the eyes of the founders of such theory (even though they themselves may not be right, or have complete view of the theory's potential, etc).

 

There is such thing as: 'principle', through which logical, scientific and mathematical relationships that is physics, can be successfully applied. Lets look at the numerous numerous examples.

 

Einstein wanted to reinforce the principle of special/general relativity because he 'believed' it was true in life, that was the foundation of his theory on it. It agreed with experiments hence its now good.

 

Wolfgang Pauli hypothesized the existance of the neutrino because of his 'belief' that the energy is surposed to be conserved. Energy conservation is a principle, a good willed belief. The neutrino was discovered later.

 

ETC ETC

 

So, it is no suprize that there are those in the scientific comunity (Einstein being one also!) that believes the world is deterministic and that particles infact do travel continuous, real paths. It is only because of QM's current inabilities, that such actual particle dynamics are not theorized. It doesnt make this 'belief' wrong. Maybe you just dont like the word belief and get all technical on me, and maybe i could have used a better term like the statement of a principle, etc - but like it or not ill stick to the word belief because ultimately that is what it is, it is when you can build a theory on this belief and that it agrees with experiments that it becomes science. Lets wake up a little.

[Klaynos]

Wolfgang Pauli hypothesized the existance of the neutrino because of his 'belief' that the energy is surposed to be conserved. Energy conservation is a principle, a good willed belief. The neutrino was discovered later.

 

Surely it was not a belief but the missing energy and momentum in the equations and experiments so there had to be some other particle to preserve the conservation laws...

[sciencenoob]

Surely it was not a belief but the missing energy and momentum in the equations and experiments so there had to be some other particle to preserve the conservation laws...

 

Yet this proves you dont understand what I am saying or what is going on here. Do you not understand that the conservation of energy is a PRINCIPLE. We call it a law because it is so strongly substantiated in all forms of life that we can call it a law, but ultimately its a principle. Something that is the very basic foundation, perhaps abstractly controlled by natures wierd ways (which physics will never be able to __explain__ and shall never aim to anyways). But it is no doubt that if for example, conservation laws were not to be conserved then certain theories may certainly break down.

 

I hope you do realize that Pauli looked at the problem of the missing energy, then he went on to apply a principle here to reinforce his postulate of what is the 'neutrino' now, that energy has to be conserved in life (this is a belief also!!! a good belief, yes but a belief! a principle!).

 

Its like how the lorentz transformation is so wierd and abstract. How do you explain or understand it? Well you dont. Its a mathematical relationship, used and made and designed such that you will have the theoretical establishment of the principle of special relativity to ensure that the speed of light is (on the whole of course strictly speaking) the maximum.

[Klaynos]

It's not really a belife as a consequence of several theorems....

 

http://en.wikipedia.org/wiki/Conservation_of_energy#Modern_physics

 

It's actually quite easy to understand lorentz transformations if you derive them from considering light paths etc... Of course you have to start with the law that the speed of light is constant.

 

But then again that comes from maxwells equations....

 

So your next point would be what?

[BenTheMan]

Hold on a second, you are obviously the science bunch that read science textbooks, learn the modern interpretation of it (repeat: _intepretation_) without any real knowledge of the actual evolution of the theory, and perhaps the interpretation as seen through the eyes of the founders of such theory (even though they themselves may not be right, or have complete view of the theory's potential, etc).

 

Are you speaking as someone who has studied science seriously?

[foodchain]

So, it is no suprize that there are those in the scientific comunity (Einstein being one also!) that believes the world is deterministic and that particles infact do travel continuous, real paths. It is only because of QM's current inabilities, that such actual particle dynamics are not theorized. It doesnt make this 'belief' wrong. Maybe you just dont like the word belief and get all technical on me, and maybe i could have used a better term like the statement of a principle, etc - but like it or not ill stick to the word belief because ultimately that is what it is, it is when you can build a theory on this belief and that it agrees with experiments that it becomes science. Lets wake up a little.

 

I think I understand where you come from a bit. I could not easily understand a great many things in physics on contact. What I got from it overtime is that how the universe works does not have to have anything in common with human perception really. What I mean by this is what is now known about the universe through experiment basically proves this. TO add to this the reality is physics could be close, or not very close at all to understanding everything about the universe. For instance dark matter/dark energy. WTF is it really, I mean wow. How about black holes. The reality to me is reality can be weirder then anything you or I can possibly imagine simply because we can only think on what we know.

 

For instance, what if on a QM level matter or energy has some relationship with dark matter we cant currently perceive via math or technology yet? The questions become quite endless really. Its sort of like studying organisms in an evolutionary sense. You see what you have on land, various differences and ecological adaptations towards niches, well you have this in the oceans also. Even in the deepest reaches of the oceans, places where people know more about the moon even life exists, and it takes on some properties that many would simply say could not exist, yet it does. There is a type of fish that can biologically from above look practically invisible. Of course there is a predator type with an adaptation to counter this.

 

The point I am getting at is basically that, who knows really what the heck people will learn about reality in the next hundred years. Maybe some person will find that quarks are made of particles, and those particles are made of particles. Maybe someone will find out what the dark stuff is and its own reality in nature. Maybe we just don’t know enough yet to "see" the whole picture. I think the reason people stick to experiment and physical evidence is its all you can do really as a human. TO go outside of this is fine and dandy, but until its proven what is it? I mean I can say mutants from mars put life here until I am blue in the face, does not make it real until I can prove it. I can say because the universe allowed for evolution and life, that it must be this way on purpose, I can also just as easily say that the environment of the earth and of the universe is pure death to life, or evolution would still have what for life existing? After a bit you have to realize the most simplest divide between science and philosophy, in that science requires empirical validation, and such substance is what science uses to foster growth.