Quantum Physics / Quantum Mechanics

[Capitalism Forever]

Google <hidden variable> or wiki <hidden variable theory>

Well, if I have to Google what is supposedly my own position, chances are it's never been my position to begin with, right?

I didn't put forward or advocate any subatomic theory in any of my posts in this thread. All I did was point out the flawed philosophy of existing ones.

As you can see, you last post left me speechles for over eight months , during which I tried to guess what was your point, given that the subject was quite interesting.

I had a hypothesis or two, but I think I'd better ask.

So: what idea are you trying to illustrate with your so called formalism and, generally, with this post?

Oh, was that addressed at me? The quote function is our friend.

My post was a "proof" that Kolker is a crackhead, based on the premise that if a theory makes predictions consistent with the operation of computers and GPSs, then that theory is the unquestionable truth.

[Grames]

The electron size ("classical electron radius") is of the order of 10^(-15) meters, the characteristic size of an electron "cloud" (Bohr radius) is 10^(-11). The electron is 10'000 times smaller than it's "delocalization". Thus, the electron's size (or, better, "size") is out of the picture in our context.

Alex

No, the deBroglie wavelength is the size to reference, which is λ=h/mv

Thus when the electron is slower, such as when bound to an atom, it is bigger. Big enough to be the size of a hydrogen atom.

The assumptions used in calculating the radius of the classical electron are a spherical structure of constant charge density or a sphere with the charge on the surface. These are arbitrary assumptions. In contrast the Davisson-Germer experiments demonstrate the deBroglie relation holds true for electrons for a variety of velocities.

[AlexL]

No, the deBroglie wavelength is the size to reference, which is λ=h/mv

How does the de Broglie wavelength help us here?

Sasha

[AlexL]

My post was a "proof" that Kolker is a crackhead, based on the premise that if a theory makes predictions consistent with the operation of computers and GPSs, then that theory is the unquestionable truth.

I am afraid that this does not advance me much.

I'll venture a hypothesis: you hold that Quantum Mechanics is in some respect similar to your "theory", and the similarity is that QM uses unjustified arbitrary formulas, which depend on a number of parameters, and is applied to reality by simply adjusting these parameters to fit the observations. IOW, you believe QM is nothing but a curve fitting technique disguised as a physical theory through crazy interpretations of those crazy formulas?

Am I correct in my supposition?

Sasha

Edited July 3, 2008 by AlexL

[Grames]

How does the de Broglie wavelength help us here?

Sasha

It integrates observation into our identification of the electron.

[Capitalism Forever]

I am afraid that this does not advance me much.

I'll venture a hypothesis: you hold that Quantum Mechanics is in some respect similar to your "theory", and the similarity is that QM uses unjustified arbitrary formulas, which depend on a number of parameters, and is applied to reality by simply adjusting these parameters to fit the observations. IOW, you believe QM is nothing but a curve fitting technique disguised as a physical theory through crazy interpretations of those crazy formulas?

You're making this much more complicated than it needs to be. I was simply going along with Kolker's premise ("GPS, ergo true") and showing that it can be applied to any "theory" that happens to make correct predictions, no matter how philosophically flawed.

[AlexL]

I was simply going along with Kolker's premise ("GPS, ergo true") and showing that it can be applied to any "theory" that happens to make correct predictions, no matter how philosophically flawed.

OK, let's forget about your "theory" and what it was supposed to illustrate.

However, if you think that Quantum Mechanics is a "'theory' that happens to make correct predictions", you did not justify your claim, and, besides, you are mistaken. QM is very well integrated in the rest of physical sciences, including the classical physics. Thus, for example, QM was arrived at by induction from:

- numerous surprising new observations from around the year 1900, and

- from the physical theory of that time, now called classical physics, primarily from the Newtonian mechanics

It is least of all an ad hoc construct: it extends the classical analytical mechanics(*) from macroscopic to atomic particles, following a careful analysis of what macroscopic properties can and cannot be ported to atomic particles.

Even if the analysis and interpretations were often flawed by subjectivism and pragmatism, this does not negate the validity of QM as a theory about reality. As to a non-pragmatic, non-subjectivist, but realist and objective analysis and interpretation, it can and has been done.

QM is, therefore, a meaningful theory, whose predictions do not just "happen" to be correct; it is correct because it was induced from facts and existing theory, under the constant assumption that the reality is the ultimate judge.

Sasha

-----------

(*) I am thinking here about the fact, that QM takes over from the classical mechanics the Hamiltonian H (which generates the equations of motion, essentially the 2nd law of Newton a=F/m for a specific system) and constructs the QM equation of motion - the Schrödinger equation , which shows how a system's state evolves in time.

[crizon]

I think one fundamental thing about QM is the role of the subject. I hope I'm not distorting things, but i think interpretations of QM are saying that you need 2 sets of explanations: One for a system without a subject and one for a system with a subject.

You can no longer exclude the observation itself.

If I'm not correct on this one, please correct me. I'm currently reading Dr bertelman's socks, but I'm not finished yet.

[AlexL]

I think one fundamental thing about QM is the role of the subject. I hope I'm not distorting things, but i think interpretations of QM are saying that you need 2 sets of explanations: One for a system without a subject and one for a system with a subject.

You can no longer exclude the observation itself.

If I'm not correct on this one, please correct me. I'm currently reading Dr bertelman's socks, but I'm not finished yet.

No, the observer is not a necessary element of QM or of the interpretation of QM. It is smuggled into QM, without necessity, despite being incompatible with the formalism of QM and against philosophical principles of objective science, just because of once fashionable philosophies of pragmatism and of subjectivism.

The observer, or the scientist, is necessary only to formulate, interpret, experiment and veryfy the theory :-)

Sasha

[crizon]

Don't you then disagree with all important figures of QM? I'm not even close to really understanding QM and the various interpretations.

Is there an accepted QM interpretation that follows your claims?

[AlexL]

Don't you then disagree with all important figures of QM?

I must confess that I do. With most.

Is there an accepted QM interpretation that follows your claims?

Try Mario Bunge, Philosophy of Physics, it's quite intriguing. Out of print. In libraries only. "Limited preview" here.

Sasha

Edited April 21, 2009 by AlexL

[crizon]

That is interessting

So what interpretation does Mario Bunge follow? Is his interpretation non locally?

What is your explenation for Quantum leaps? Why do you think Bohm's interpretation is wrong?

[Devils_Advocate]

Here's just my quick take on the subject, if no one minds:

Quantum mechanics is certainly flawed in many areas, but we've also got to remember that it is an incredibly complex and relatively new science; you can't expect it to be completed in a few years, or even decades. I'm sure that, after enough study, someone will revolutionize our understanding of quantum physics the same way Einstein revolutionized our understanding of Newtonian physics. I don't think arguing about this subject on a philosophy forum is really beneficial.

[AlexL]

So what interpretation does Mario Bunge follow?

His own, based on the following views of knowledge ("critical realism"):

1) There are things in themselves, i.e., objects the existence of which does not depend on our mind. (Note that the quantifier is existential, not universal: artifacts obviously depend on minds.)

2) Things in themselves are knowable, though partially and by successive approximations rather than exhaustively and at one stroke.

3) Knowledge of a thing in itself is attained jointly by theory and experiment, none of which can pronounce final verdicts on anything.

4) This knowledge (factual knowledge) is hypothetical rather than apodictic, hence it is corrigible and not final: while the philosophical hypotheses that there are things out there, and that they can be known, constitute presuppositions of scientific research, any scientific hypothesis about the existence of a special kind of object, its properties, or laws, is corrigible.

5) Knowledge of a thing in itself, far from being direct and pictorial, is roundabout and symbolic.

Is his interpretation non locally? What is your explenation for Quantum leaps?

What do you mean by those?

Why do you think Bohm's interpretation is wrong?

And you, why are you still beating your little sister?

Alex

[crizon]

I think you missed my questions. These points you quoted are no interpretation of QM, because the experimental findings and mathematical formulas that describe them are not interpreted.

I obviously don't expect a thorough explanation more like a rough overview of his interpretation.

About your other question:

http://en.wikipedia.org/wiki/Bell%27s_Theorem this might explain what i mean.

[AlexL]

I think you missed my questions.

I understood your question very well.

These points you quoted are no interpretation of QM...

That is why I listed them under the title "Bunge's views of knowledge", not of QM. They were meant to be more like an appetizer.

I obviously don't expect a thorough explanation more like a rough overview of his interpretation.

Maybe. If I'll have some more time. What about doind yourself some reading meanwhile?

About your other question: http://en.wikipedia.org/wiki/Bell%27s_Theorem this might explain what i mean.

You expect me to read this article in order to understand what do you mean by "non locally interpretation" and "quantum leaps"?? No, sorry, it doesn't work that way.

Sasha

Edited April 22, 2009 by AlexL

[Grames]

When someone uses the phrase "quantum leap" I think of that TV show.

Edited April 23, 2009 by Grames

[Gramlich]

When someone uses the phrase "quantum leap" I think of that TV show.

Me too

[skibum_not]

This thread initiated by "Capitalism Forever" is nothing but a rant by someone with little to no comprehension of physics, let alone QM. And s/he should know that nothing is forever ... not capitalism, not QM, or any of our progressively more accurate (but still feeble) theories to understand the inner workings of nature, QM inclusive.

Obviously, many, if not most of our electronic technologies today would not be possible without a good understanding of QM. New devices and processes for designing integrated circuits, light-emitting diodes, solar cells, thermoelectrics, ... the list goes on, would not be possible if the engineers designing them did not engage in what is known as "band-gap design/engineering". FYI, band-gaps are a purely quantum effect. How else could you design them unless your working assumptions were based on a meaningful theory? If you got it once, maybe I'd call it luck. But when you get it right over and over again, I call that skill and knowledge, which is not meaningless.

The culmination of our understanding of QM is evident in the latest technologies for quantum communications and quantum computation, which would not be possible without the mathematical underpinnings offered by QM.

Everyone in the scientific community knows that QM is an incomplete theory because it doesn't reconcile with general relativity in certain corner cases. But anyone saying QM isn't a meaningful theory is either ignorant or stupid. And from the way this thread has progressed, I'm beginning to believe it's the latter.

[Capitalism Forever]

Welcome to forum, please read rules.

[Plasmatic]

skibum

What interpretation of QM are you even referring to? And how does this interpretation lead as the only explanation of the "band gap" you refer to? Id love an elaboration because the idea that QM makes computers possible is a cover all dismissal to critics of certain interpretations of QM. Also perhaps you may consider checking your premises on Relativity. Its not an axiom.

[Plasmatic]

Alex Ive just read the first bit of Bunges chapter The Referents of A Physical Theory.Its interesting.

Edited May 15, 2009 by Plasmatic

[AlexL]

Alex Ive just read the first bit of Bunges chapter The Referents of A Physical Theory.Its interesting.

Please come back with your opinion as soon as you have one.

Some parts of the book are on Google Books here:

Preface

Chapter 1 / Philosophy: Beacon or Trap

Chapter 2 / Foundations: Clarity and Order

Chapter 5 / Quantum Mechanics in Search of its Referent

Alex

[Q.E.D.]

I don't understand the assertion that a successful predictive theory is meaningless. Nonetheless, there is a misconception about Quantum Theory I'd like to point out.

{My interpretation will always be Copenhagen}

Okay, I'll give your quantum physicist a hydrogen atom and if he predicts where exactly he'll find the electron, I'll give him ten thousand dollars.

The "meaning" of Quantum Theory is not that every system is unpredictable, its just that many systems have an infinite number of "eigenstates" which a quanto-particle may inhabit, UNTIL AN OBSERVATION IS MADE. After an observation has been made, the quanto-particle is then confined to a much smaller number of eigenstates. If you put the quanto-particle into a single eigenstate, you should then be able to predict quite certainly what the time evolution of the quanto-particle's state will be.

Observable [Linear Momentum]

Associated Operator [P = -i*h*d/dx]

Possible Value for Momentum [p]

Electron eigenstate [s]


Ps = ps[/code]

Examples here


This equation says that if you find the electron has the momentum "a", then you are able to find the eigenstate or eigenvector "s" associated with that state. Once you put the electron into a single eigenstate, from that point forward the electron's state evolves deterministically, allowing for the kind of "prediction" you are asking for. 


The "probability" aspect of QM isn't a failure; its the way the universe IS. Reality doesn't care if it makes no intuitive sense to us or not, that's just how it is.

Edited May 29, 2009 by Q.E.D.

[Pearlist]

Lately I've spent some of my freetime trying to understand the basics of QM and especially the problem of interpreting what QM tells us.

As an objectivist, (hopefully) sane human being this stuff just is way above my head, how real P.hD's are debating whether the universe exist when we don't look at it, whether it's in all states until we look at it, whether it splits into infinite universes, whether everything is waves and particles, whether it's all just math...

Some of these got subjectivist characteristics, which I've chosen to ignore: Copenhagen interpretation, Consciousness-collapse and the like.

The only 2 realist interpretations (that I've read of) is Many Worlds and the Casual interpretation.

At first, the universe splitting into (almost) infinite branches every time an atom changes it's spin sounds crazy...

However when you examine QM evidence, what do you get?

In the double slit: wave behaviour.

At first I thought: "Well, shouldn't we then see this "splitting" ? but then it quickly dawned upon me, if MWI is true, we split too, and therefore its only reasonable that we only see "one branch" (I'm not sure whether this is the justification real physicist use for the fact we only observe one branch).

I still feel this is too weird and would hate it to be true, however as a objectivist, we don't choose =\

The other is pretty straight foreward:

The universe is both a wave and particles, the wave(which they claim is physical) push the particles around to it's positions.

In this view the double slit is explained like this:

"When we emit photons at the double slits, the wave goes through both, hence causing the waves to collide, which in return decides where the particle end up.

This does not make sense as in this view I would think particles would always end up the same spot?

If it's a wave thats as real as a water wave(why can't see observe it) why would it go different the other time you emit photons?

Both do away with the Collapse due to decoherence.

MWI dodge problems with Einsteins relativity, while The casual or Bohm interpretation doesn't.

MWI sounds insane, Bohm not so much.

I'm a amateur in physics, so I'm hoping there are some who will want to join in the debate and defend their position, over at PF.com most "Interpretational" discussions are considered philosophy, not physics and put in the philosophy section, which is unfortunate, because there anyone who have seen "The Secret" or some other bullshit scifi movie can jump in and voice their opinion.