Interpretations of Quantum Mechanics

[nikman]

Personally, I hold a similar view as to that of Lee Smolin - "From the most sceptical critics to the most strenuous advocates of string theory, you hear the same thing: We are missing something Big."

Without this missing Big, we don't know what we are talking about and all this talk of interpreting reality from what we currently know of it from physics, is nothing but a pipe dream.

Smolin's also suggested that the problem may be that you can't genuinely observe a universe from inside that universe:

"But, beyond even this, a quantum theory of gravity must be a theory of cosmology. As such, it must also tell us how to describe the whole universe from the point of view of observers who live in it — for by definition there are no observers outside the universe. This leads directly to the main issues we're now struggling with, because it seems very difficult to understand how quantum theory could be extended from a description of atoms and molecules to a theory of the whole universe. As Bohr and Heisenberg taught us, quantum theory seems to make sense only when it's understood to be the description of something small and isolated from its observer — the observer is outside of it. For this reason, the merging of quantum theory and relativity into a single theory must also affect our understanding of the quantum theory. More generally, to solve the problem of quantum gravity we'll have to invent a good answer to the question: How can we, as observers who live inside the universe, construct a complete and objective description of it?"

 

[Fredrik]

All this talk of a world is misleading. There is NO world except for our perceptions of it.

That makes about as much sense as it would for me to say that you didn't actually post that. I do however perceive it to be nonsense.

He asked specifically about the many-worlds interpretation of quantum mechanics. Your answer has nothing to do with the MWI.

How old is the world? 13.7 billion years? Wrong. There is no privileged frame of reference to ascertain that the universe is 13.7 b. years old. There are almost infinite frames of reference where the universe is 1000 years old, 1 billion years old, etc., etc., etc.

This is true, since you can define coordinate systems almost any way you want. But 13.7 billion years is the maximum possible proper time for any timelike curve in spacetime with one endpoint at the event "right here, right now". It's also close to the proper time of a curve that represents motion from the big bang to "right here, right now", such that any physical observer temporarily moving that way would perceive the background radiation as homogeneous and isotropic. (Every galaxy in the universe moves that way, to a good approximation). It's not like people don't have a good reason to call that number "the age of the universe".

Andrew Strominger
Ed Witten
Nathan Seiberg
David Gross
Andrew Strominger
David Gross
Albert Einstein
Lee Smolin

What's with all the quote mining? That's a really bad way to argue for something.

 

[jambaugh]

Every physical theory needs an interpretation. Without an interpretation to connect them to experiment, your just pushing meaningless symbols around on paper.

There are two levels of interpretation. (You've heard me go over this before!)
Distinguish ontological interpretation (what is being debated here) with praxic interpretation what you are talking about being necessary. QM in CI has its praxic interpetation:

Born's probability law and the Eigen-value principle
(plus what operators and hilbert spaces we associate with given physical observables and systems)

That I think is all that is necessary to do an experiment in the lab and see if it matches what the theory predicts.

You are pulling a fast one trying to confuse this type of interpretation with the metaphysical speculations of the various ontological interpretatons.

 

[Fredrik]

Thanks for the answer, it does clarify my issue. However, it does seem to apply, that at the creation of the universe (the omnium I assume), it was created already including all the many different worlds that would be needed, given all the quantum experiments that would be performed during the course of its existence. Is this correct?

No need to mention words like "creation". That only complicates things. What we need to know is that this "omnium" can be identified with a particular mathematical structure, a complex infinite-dimensional separable Hilbert space.

There can't be less worlds than would be needed or we're back to energy conservation problem.

The "worlds" are subspaces of that Hilbert space, or equivalence classes of subspaces, so no need to worry about energy.

There also can't be more worlds than would be needed,

The worlds are subspaces by definition, so no need to worry about worlds that aren't subspaces.

The universe/omnium would have to contain exactly the number of worlds needed for the lifetime of the universe, and to me, this seems like an awfully big assumption to make.

It's not. All the complex infinite-dimensional separable Hilbert spaces are isomorphic to each other (i.e. they are essentially the same space, described in different ways). So we don't have to worry about which Hilbert space represents the states of the omnium.

 

[kote]

QM in CI has its praxic interpetation:

I've never heard of praxic vs ontological aspects of theories, and I can't seem to find a good link. The word "praxic" isn't used anywhere in the Stanford Encyclopedia of Philosophy. Do you have a link or suggested source on this? Is there some more popular theory it would be similar or equivalent to?

Thanks.

 

[nikman]

The word "praxic" isn't used anywhere in the Stanford Encyclopedia of Philosophy.

I hope that every time you mention the SEP you make a note to send them at least one buck at some later date. Seriously. Where would the "world" be without them? Also if you donate maybe they'll stop badgering me all the time.

But not even Ed Zalta's on top of everything.

"The Praxic Age is a period of time in Arbre history, from about -500 to 0, immediately following the Old Mathic Age. This time is marked with great and rapid praxic advances, culminating in the Terrible Events and the Reconstitution. During this time, the scholars lived extramuros with the saeculars."

http://anathem.wikia.com/wiki/Praxic_Age

 

[DrChinese]

I hope that every time you mention the SEP you make a note to send them at least one buck at some later date. Seriously. Where would the "world" be without them? Also if you donate maybe they'll stop badgering me all the time.

But not even Ed Zalta's on top of everything.

"The Praxic Age is a period of time in Arbre history, from about -500 to 0, immediately following the Old Mathic Age. This time is marked with great and rapid praxic advances, culminating in the Terrible Events and the Reconstitution. During this time, the scholars lived extramuros with the saeculars."

http://anathem.wikia.com/wiki/Praxic_Age

ROTFL...

And all this time I thought praxic was a home remedy for gout.

 

[jambaugh]

I've never heard of praxic vs ontological aspects of theories, and I can't seem to find a good link. The word "praxic" isn't used anywhere in the Stanford Encyclopedia of Philosophy. Do you have a link or suggested source on this? Is there some more popular theory it would be similar or equivalent to?

Thanks.

Pardon the obscure usage, Replace "praxic" with "operational" in this context.

The root is from the Greek praxis(πρᾱξις) and I used it in the context of:
http://en.wikipedia.org/wiki/Praxis_%28process%29"

[edit: changed to better link + added greek unicode for "flavor"]
[Edit: PS I used it here to parallel the greek ὄντος root to ontology ]

 

[WaveJumper]

That makes about as much sense as it would for me to say that you didn't actually post that. I do however perceive it to be nonsense.

That was a misrepresentation of my post, i said "there is no world apart from our perception of it", not "nothing exists but perception". The thread is about how qm should be interpreted in respect to how we perceive the world. Are you saying that outside the human interface(the human body), there exists a thing that you are insisting on calling a 'world'? What do you mean by 'world'? Do you know the nature of time? Can you elaborate if you do? How does Time fit into your idea of a 'world' in GR and QM? I am very interested to know why you'd call whatever exists outside of our perception(if it exists at all) a 'world'? What law in physics implies that something exists apart from our perceptions of it? It's definitely not something that has to do with passage of time.

And yes, I am extremely skeptical of the outside world as we perceive it.

He asked specifically about the many-worlds interpretation of quantum mechanics. Your answer has nothing to do with the MWI.

But my answer had to do with the impossibility to make an interpretation that would make sense.

What's with all the quote mining? That's a really bad way to argue for something.

I am definitely not a string theorist, i am not even that interested in ST, unless they make a prediction that may be tested. But those guys are some of the best physicists on the planet today, there is no question about it. And since their points are relevant to the point i was trying to make and i have to take their statements at face value, i posted them so others could comment and find faults with them(if there are any). But feel free to correct Ed Witten and co., i will refrain as i lack knowledge into their field.

I see my post has caused confusion so i'll sum it up in one sentence:

In my opinion, all interpretations of QM are religion in disguise. A description of reality that makes sense, is impossible with our current knowledge of QM.(that's one of the reasons i resorted to quotes by physicists working on a TOE)

 

[Fredrik]

WaveJumper, I think we actually agree about most of these things. I don't really consider questions about what "exists" meaningful, at least not without a definition of what that word means. (It really bugs me when people think it's intuitively obvious). To me, a theory is a set of statements that tells us how to compute probabilities of possible results of experiments, and science is the process of finding new theories and doing experiments to find out how accurate their predictions are. So the only way I can make scienctific sense of the question "Does X exist?" is to interpret it as

"Does the theory that defines X mathematically make accurate predictions? And in particular, does it make more accurate predictions than theories that don't include a definition of X?".

That's my definition of what it means for something to "exist". A good example is photons. They are defined by QED. The alternative theory is classical electrodynamics, i.e. Maxwell's equations. When we say that photons "exist", what we really mean is that there are experiments for which QED can make approximately correct predictions, but classical electrodynamics can't. (Note that the definition is still kind of ambiguous, since we can't e.g. rule out that we will find a theory that makes even better predictions than QED without using the concept of photons).

This doesn't mean that I think we should stop saying that photons exist. Our language would be much too awkward if we didn't allow ourselves to simplify things like that, but it's important to be aware of what such claims really mean.

So far we probably agree. However, your claim that "there is no world apart from our perception of it" is far too strong. That statement is almost crazy as it stands, since you say it as if you know it to be a fact.

 

[kote]

So far we probably agree. However, your claim that "there is no world apart from our perception of it" is far too strong. That statement is almost crazy as it stands, since you say it as if you know it to be a fact.

Playing Devil's advocate a bit here... but what evidence do you have of a world besides your perception of it? We're getting into semantics here (okay, so we've been on semantics for a while), but with no possible evidence of anything beyond our perceptions, isn't it more accurate to call only that which is within the limits of our knowledge "real," while leaving the rest to metaphysics?

 

[RUTA]

I see my post has caused confusion so i'll sum it up in one sentence:

In my opinion, all interpretations of QM are religion in disguise. A description of reality that makes sense, is impossible with our current knowledge of QM.(that's one of the reasons i resorted to quotes by physicists working on a TOE)

“Many scientists are deeply religious in one way or another, but all of them have a certain rather peculiar faith – they have a faith in the underlying simplicity of nature; a belief that nature is, after all, comprehensible and that one should strive to understand it as much as we can. Now this faith in simplicity, that there are simple rules – a few elementary particles, a few quantum rules to explain the structure of the world – is completely irrational and completely unjustifiable. It is therefore a religion.” Sheldon Glashow in The Quantum Universe, co-produced by WETA-TV and The Smithsonian Institution, 1990.

 

[Dmitry67]

WaveJumper, I think we actually agree about most of these things. I don't really consider questions about what "exists" meaningful, at least not without a definition of what that word means. (It really bugs me when people think it's intuitively obvious). To me, a theory is a set of statements that tells us how to compute probabilities of possible results of experiments, and science is the process of finding new theories and doing experiments to find out how accurate their predictions are. So the only way I can make scienctific sense of the question "Does X exist?" is to interpret it as

"Does the theory that defines X mathematically make accurate predictions? And in particular, does it make more accurate predictions than theories that don't include a definition of X?".

That's my definition of what it means for something to "exist". A good example is photons. They are defined by QED. The alternative theory is classical electrodynamics, i.e. Maxwell's equations. When we say that photons "exist", what we really mean is that there are experiments for which QED can make approximately correct predictions, but classical electrodynamics can't. (Note that the definition is still kind of ambiguous, since we can't e.g. rule out that we will find a theory that makes even better predictions than QED without using the concept of photons).

Thank you, I really like your definition.
Especially because virtual particles are "real" based on that definition (and I agree with it)

 

[Fredrik]

Playing Devil's advocate a bit here... but what evidence do you have of a world besides your perception of it? We're getting into semantics here (okay, so we've been on semantics for a while), but with no possible evidence of anything beyond our perceptions, isn't it more accurate to call only that which is within the limits of our knowledge "real," while leaving the rest to metaphysics?

It would be more accurate, but much more awkward. I think it's OK to sacrifice some accuracy to get read of the awkwardness when we talk about these things, at least when we all know what the simplified statements really mean. Unfortunately the stuff I've been talking about isn't taught at universities, and very few people have really thought this through, so most people won't understand it unless you explain it to them.

If you read the text you quoted again, you should see that what I'm objecting to isn't what you're talking about. WaveJumper didn't "call only that which is within the limits of our knowledge real". He stated something unknowable as a fact.

 

[WaveJumper]

If you read the text you quoted again, you should see that what I'm objecting to isn't what you're talking about. WaveJumper didn't "call only that which is within the limits of our knowledge real". He stated something unknowable as a fact.

I didn't say what we know and experience was unreal, i said that the world we experience does not exist apart from our perception of it(perception is real). It exists only in our, err, perception of it.

But if you want to make a tangent to what is real(barely ontopic), why would you consider what we experience real, when more than 95% of the mass/energy content of the proton/neutron comes from virtual particles that pop in and out of existence from the quantum vacuum where space and time break down?(latest 2008 data puts the figure at 99%). The other <5% of the mass is theorized to come from virtual Higgs bosons that derive their energy from virtual processes as well.

So, how real is real? If time and space break down at the Planck scale and all reality appear to stem from there, is that a real reality or is what you are experienceing as spatially differentiated objects in space not that real, but only marginally real at best(when the universe is looked at from a bird's perspective, inferred from our findings in QCD)?

Would you call the singularity at the centre of a black hole real? The theory of GR and its equations come up with a singularity, so according to your definition of "real", the singularity is real.

I would say, that "real" only pertains to our perceptions of it, not to something that physics can define without resorting to the human interface(body and consciousness). And that generally has always been a problem in physics - the human baggage - space, time, infinity, continuity and the contradictions they raise.

What do you think of general relativity's General covariance? How do you interpret it wrt to our experience?

Are space and time fundamental in your opinion? (this is a pretty central point in discussing what is real)
Can there be a theory of the universe's boundary conditions? (another pretty central point wrt what is real)


I'd say that it's likely that the future theory of quantum gravity will re-define how we view 'something' and 'nothing' in a radical way(there are already good idications about that).

At various academic conferences in the last years on quantum gravity, (reportedly)one can find philosophers at physicists' gatherings and physicists at philosopher's events. What, in your opinion, can explain this trend except that we are nearing a new revolution in physics that will turn our understanding of nature and reality upside down?

 

[kote]

At various academic conferences in the last years on quantum gravity, (reportedly)one can find philosophers at physicists' gatherings and physicists at philosopher's events. What, in your opinion, can explain this trend except that we are nearing a new revolution in physics that will turn our understanding of nature and reality upside down?

I blame physics for getting so confused with itself that it's reverting back to questions philosophers never left . Empiricism and ontology have always been part of philosophy. The Copenhagen Interpretation is basically QM as viewed through logical positivism. Einstein's arguments with Bohr were based on his ontological "criterion of reality" and his epistemological criterion for completeness. You can read 17th century empiricism or even rationalism and swear you're reading about QM.

Bohr wrote Atomic Theory and the Description of Nature, and his essays "on Atomic Physics and Human Knowledge" were split into a few different books. Heisenberg wrote Physics and Philosophy: The Revolution in Modern Science. Bohm published in philosophy journals.

The link between physics and philosophy is nothing new, and physicists involved in paradigm shifts are actually (and consciously) doing a lot of philosophy. It wasn't long ago that physicists and mathematicians were just called "philosophers." It's a tough line to draw.

 

[Naty1]

What do you think of general relativity's General covariance? How do you interpret it wrt to our experience?

You might find this thread of interest:https://www.physicsforums.com/showthread.php?p=2310836#post2310836 (I posted this because I can't help but wonder if transforms more general than Lorentz might suggest broader formulations for gravity.)

Peter Bergmann, a former student of Einsteins, says in THE RIDDLE OF GRAVITATION (pg72).

Reliance on the principle of general covariance drastically restricts the range of potential mathematical-geometric relations that might be considered as representing the laws of gravitation.

Together with the idea that any formulation for gravity approach the laws of Newton under reasonable conditions, these

..are sufficient to remove all ambiguities and lead to a single possible law of gravitation.

So seems like covariance/invariance got us off to a good start. The question is can we do better with it? I just checked the index for Roger Penrose THE ROAD TO REALITY his thousand page summary of mathematical physics: oddly, nothing shown for covariance nor invariance. What a surprise!

Are space and time fundamental in your opinion? (this is a pretty central point in discussing what is real)

Very much so, a personal opinion...but if everything pops out of some sort of bang (big or finite) seems like in some way space and time are as physically real and fundamental as energy and particles, maybe fields...Maybe energy spawns space and time, but the opposite seems plausible as well...

Posts here asking others to think about the physical vs mathematical aspects of spacetime brings out some vitriol...also some insights by those who remain calm...many here,but not all, think that the existing rules and regulations are "law"..for example, if something is not in the standard model, well its very suspect...forgetting that gravity is omitted..likely the most ubiquitious force in the universe. That apparently makes it difficult to "think beyond the box"..maybe that's why so many breakthroughs come from theorists young enough not to know what "can't be possible". (Beckenstein and Hrtle come to mind)
So good luck...You might also check causual dynamic triangulation...some recent discussions here reflected current efforts at building models from which spacetime can "spontaneously" emerge...and offer interesting insights.

Is Spacetime a physical entity might be of interest:
https://www.physicsforums.com/showthread.php?p=2300751#post2300751


Can there be a theory of the universe's boundary conditions? (another pretty central point wrt what is real)

Sure, Hawking and Hartle (among many others I'm sure) have worked on it...don't recall where he/they came out nor if they changed minds over the years...Here's one snippet: THE UNIVERSE IN A NUTSHELL (2001)

..the universe need have no beginning or (may) end in imaginary time. Imaginary time behaves just like another direction in space. ..If histories of the universe went off to infinity like a saddle or plane one would have the problem of specifying what the boundary conditions were at infinity...but one can avoid having to specify boundary conditions...if all histories of the universe in imagniary time are closed surfaces, like the surface of the earth.

I'd say that it's likely that the future theory of quantum gravity will re-define how we view 'something' and 'nothing' in a radical way(there are already good idications about that).

To reconcile GR and QM will likely take a majopr paradigm shift...

What, in your opinion, can explain this trend except that we are nearing a new revolution in physics that will turn our understanding of nature and reality upside down?

I don't personally think its that..in fact, not much major has happened for maybe twenty/forty years...Lots of improvements, I think, can't think of anything major...seems like experimentlists may have made more breakthroughts than theorists...black holes, dark matter,dark energy,Hubble expansion, and very recently, findings "planets like ours"...etc...maybe that is about to swing towards theorists??

 

[Fredrik]

The Copenhagen Interpretation is basically QM as viewed through logical positivism.

I've heard this claim before. (Maybe it was you that time too, I don't remember who I was talking to). Can you justify it? How do you define logical positivism and what does the CI have to do with it?

Edit: OK, I'm reading the Wikipedia page on logical positivism, and also the first few pages of Popper's "The logic of scientific discoveries", using the "search inside" feature at amazon.com. It seems to me that the logical positivists, or at least some guy named Reichenbach (who according to Wikipedia is one of the originators of logical positivism), thought that it must be possible to logically conclude the truth of universal statements ("all swans are white") from the truth of singular statements ("this swan is white"). They didn't know how, but they were sure that it was possible. Reichenbach claimed that this was "unreservedly accepted by the whole of science". (There are other crazy Reichenbach quotes in Popper's book).

Popper rejects this nonsense, and starts talking about falsifiability and so on. Wikipedia says that "he argued that the positivists' criterion of verifiability was too strong a criterion for science, and should be replaced by a criterion of falsifiability". This is exactly how I interpret the first few pages too. If this is an accurate representation of logical positivism, then this school of thought is clearly based on some heavy wishful thinking. Scientists would of course want to find the truth and then prove that it's the truth, but logically, this isn't possible.

The Copenhagen interpretation strikes me as being very far from all of this nonsense. It contains precisely what you need to turn the mathematical model into a (falsifiable) theory. Nothing more, nothing less. So what does it have to do with logical positivism?

 

[Fredrik]

I didn't say what we know and experience was unreal,

I didn't say that you did. I said that you stated something unknowable as if it was a fact.

...the world we experience does not exist apart from our perception of it(perception is real). It exists only in our, err, perception of it.

You can't possibly know that for a fact. It might be true, but there's nothing you can do to prove that it is, even to yourself. So it's an unknowable. By making this claim, you're implying that you have knowledge that no human can possibly have. That's why it sounds crazy.

 

[kote]

I've heard this claim before. (Maybe it was you that time too, I don't remember who I was talking to). Can you justify it? How do you define logical positivism and what does the CI have to do with it?

Probably was me! I can't prove historically that one school of thought influenced the other, but the ontological, epistemological, and semantic views are virtually identical. They were also fleshed out at about the same time. I can only recycle quotes at the moment, but here's what I've got on hand:

A subsequent measurement to a certain degree deprives the information given by a previous experiment of its significance for predicting the future course of phenomena. Obviously, these facts not only set a limit to the extent of the information obtainable by measurements, but they also set a limit to the meaning which we may attribute to such information. We meet here in a new light the old truth that in our description of nature the purpose is not to disclose the real essence of the phenomena but only to track down, so far as it is possible, relations between the manifold and aspects of our experience.​

Niels Bohr. Atomic Theory and the Description of Nature. (London: Cambridge University Press, 1934) 18.​

Notice here that Bohr admits that he doesn't and can't know anything about "the real essence of the phenomena." He also puts "meaning" in italics in the original. This is important because subsequently he stops referring to any underlying "real essence" and simply calls obtainable information "real" at the basic level. He explains the change in how he talks about or expresses reality on page 94:

It lies in the nature of physical observation, nevertheless, that all experience must ultimately be expressed in terms of classical concepts, neglecting the quantum of action.​

And on page 123:

For describing our mental activity, we require, on one hand, an objectively given content to be placed in opposition to a perceiving subject, while, on the other hand, as is already implied in such an assertion, no sharp separation between object and subject can be maintained, since the perceiving subject also belongs to our mental content. From these circumstances follows not only the relative meaning of every concept, or rather every word, the meaning depending upon our arbitrary choice of view point, but also that we must, in general, be prepared to accept the fact that a complete elucidation of one and the same object may require diverse points of view which defy a unique description.​

There is no separable objective reality, and words must be defined from the point of view of subjective experience, necessarily. Additionally, subjective experience is classical, so it can never truly represent the meaningless concept of the underlying "manifold," which is not classical.

Compare this to:

A 1929 pamphlet written by Neurath, Hahn, and Rudolf Carnap summarized the doctrines of the Vienna Circle at that time. These included: the opposition to all metaphysics, especially ontology and synthetic a priori propositions; the rejection of metaphysics not as wrong but as having no meaning; a criterion of meaning based on Ludwig Wittgenstein's early work; the idea that all knowledge should be codifiable in a single standard language of science; and above all the project of "rational reconstruction", in which ordinary-language concepts were gradually to be replaced by more precise equivalents in that standard language.

http://en.wikipedia.org/wiki/Logical_positivism​

There is nothing besides subjectivity, and we should redefine words that are commonly thought of as referring to objective reality with meanings based only on subjectivity, which is the only thing that is within the limits of our knowledge.

Edit: With regard to verifiability, there are a few steps to the process for Bohr, which are quoted above.

Step 1: "Reality," as in "the real essence of the phenomena," is not verifiable.
Step 2: "Reality," as we usually think of it, and as used in step 1, is therefore meaningless.
Step 3: Let's redefine what's real in terms of verifiable subjectivity so that we can still call things "real."
Step 4: Voila; I can say that real objects exist in space-time. I can also say that every other concept we naively call real, such as color or sound, are just as real as particles or anything else. "Reality:" fixed, and verifiable (just don't try to visualize any underlying objective phenomena - to do so is meaningless anyways).

Edit2: Popper was a realist and objected to CI .

 

[Fra]

At various academic conferences in the last years on quantum gravity, (reportedly)one can find philosophers at physicists' gatherings and physicists at philosopher's events. What, in your opinion, can explain this trend except that we are nearing a new revolution in physics that will turn our understanding of nature and reality upside down?

I see several connections between fundamental physics, and the nature of information and knowledge and thus the fundamentals of science and law as such - and the latter certainly has philosophical dimensions.

With this I refer mainly to the "inside views", "inference views" and the physical basis of law and symmetry and the physical nature of time. Smolin for example has objected to the notion of eternal timeless laws, and his argumetens are philosophical that suggest that law must have a physical context, and that in general even laws are evolving.

QM is a measurement theory, but contains a lot of fixed baggage needed to define the information structures. Now in a true intrinsic measurement theory, this structure itself is dynamical too, and thus observer dependent. In the inside view there is no baggage, like gigantic timelss state spaces etc. This can dependending on your interpretation lead to evolving laws and emergent symmetries, that produces the interactions along with the process - ie you don't put in a hamiltonian in manually, the interactions are produces as part of the process.

This is also my preferred view on QM, which suggests that in the new understanding (not yet existing), QM structure will be understood as a limit case of kind of preferred inside view where the observer is very massive relative to the system. And a lot of what is now postulated of QM structure and some of that parameters and symmetries of the standard model might be understood as an evolution problem.

To make sense out of this, a lot of philosophical issues arise, that concern the philosophy of science and the nature of physical law.

Except for my own thinking, Smolins evolving law, Olaf Dreyers internal relativity, and Ariel Caticha program to infere the laws of physics from generic rules of inference are sniffing onto this.

IMHO at least, these radical views, has implications also for the context where QM formalism as expected to emerge. In these views the context of QM should emerge, rather than be put in by hand, or postulated.

For example, a bit simplified most of the standard model more or less "follow" from a series of symmetry assuptions. Thus, to explain, understand and solve the fine tuning problems, it seems a key is to understand the process whereby symmetries emerge in processes - rather than looking for the perfect big master symmetry - becuase the question would still remain - why this symmetry. I find this to be extremely interesting and promising but also difficult and yet undeveloped, and questions like that would get attention in this reasoning.

/Fredrik

 

[WaveJumper]

I didn't say that you did. I said that you stated something unknowable as if it was a fact.


You can't possibly know that for a fact. It might be true, but there's nothing you can do to prove that it is, even to yourself. So it's an unknowable. By making this claim, you're implying that you have knowledge that no human can possibly have. .

ok, let's take a different approach - take the mind/observer/ out of the equation(suppose it was possible). What do you 'see'? Where is everything in this relative to the FOR world of electromagnetic physicallly-looking phenomena? Where is the electron in this relative space of ever-shifting haze of probabilities of non-local manifestations of wave-like entities? Is there movement in continuous space and true observer-independent time, or are we the observers(whatever that means for electromagntic creatures like us) an essential part of this fluid-like, amorphic reality? What could give confidence that the electromagnetic fields masquerading as physical objects in relative space and time are real outside of our twisted perception of them?
Do you 'see' an absolute, material universe that is background-dependent? If you do, i think envy you.

That's why it sounds crazy.

You are right, it does. What is your favourite interpretation of quantum theory that you think makes sense and does not sound crazy?

 

[Fredrik]

ok, let's take a different approach - take the mind/observer/ out of the equation(suppose it was possible). What do you 'see'? Where is everything in this relative to the FOR world of electromagnetic physicallly-looking phenomena? Where is the electron in this relative space of ever-shifting haze of probabilities of non-local manifestations of wave-like entities? Is there movement in continuous space and true observer-independent time, or are we the observers(whatever that means for electromagntic creatures like us) an essential part of this fluid-like, amorphic reality? What could give confidence that the electromagnetic fields masquerading as physical objects in relative space and time are real outside of our twisted perception of them?
Do you 'see' an absolute, material universe that is background-dependent? If you do, i think envy you.

Those questions don't make much sense. I can't even make sense of the language in the "where is everything" question. Where is the electron in what space? You need a theory to define the concept of time, and you didn't specify one. What does it mean to be an essential part of reality? What I said in #100 answers your question about electromagnetic fields (if "are real" means the same thing as "exist"). I have no idea what it would mean to see an absolute material background-dependent universe. The word background-dependent is especially confusing in this context.

You are right, it does. What is your favourite interpretation of quantum theory that you think makes sense and does not sound crazy?

See post #11. If the word "algorithm" bothers you (apparently it bothered someone), just replace "an algorithm" with "a set of rules". See also #27.

 

[RUTA]

There are two levels of interpretation. (You've heard me go over this before!)
Distinguish ontological interpretation (what is being debated here) with praxic interpretation what you are talking about being necessary. QM in CI has its praxic interpetation:

Born's probability law and the Eigen-value principle
(plus what operators and hilbert spaces we associate with given physical observables and systems)

That I think is all that is necessary to do an experiment in the lab and see if it matches what the theory predicts.

You are pulling a fast one trying to confuse this type of interpretation with the metaphysical speculations of the various ontological interpretatons.

Did you read my post on particle physics earlier in this thread? Do you think a Hilbert space structure "is all that is necessary" to generate particle physics data? Read that post and ask yourself, What if we didn't believe particles were responsible for the clicks? That's an ontological (not praxic) question and it has lots to do with the way information from experimental devices is turned into "data" in particle physics. Don't confuse "data" with "instrument readings." Instrument readings are worthless without metaphysical assumptions.

 

[kote]

Did you read my post on particle physics earlier in this thread? Do you think a Hilbert space structure "is all that is necessary" to generate particle physics data? Read that post and ask yourself, What if we didn't believe particles were responsible for the clicks? That's an ontological (not praxic) question and it has lots to do with the way information from experimental devices is turned into "data" in particle physics. Don't confuse "data" with "instrument readings." Instrument readings are worthless without metaphysical assumptions.

Agreed. All theories must have at least implicit ontology for them to have any applicability. All theories have variables representing some property of reality. You may not think the theory is complete or accurate, or you may not believe the ontology of the theory, but in the context of the theory itself that ontology still exists and is necessary.

 

[jambaugh]

Did you read my post on particle physics earlier in this thread? Do you think a Hilbert space structure "is all that is necessary" to generate particle physics data? Read that post and ask yourself, What if we didn't believe particles were responsible for the clicks? That's an ontological (not praxic) question and it has lots to do with the way information from experimental devices is turned into "data" in particle physics. Don't confuse "data" with "instrument readings." Instrument readings are worthless without metaphysical assumptions.

In your earlier post you a building a straw man. The device in question is not studying the paths of the particles [edit: or the particles themselves] but the behavior at the center of the collision. Dissassociating the clicks is just disassembling your measuring device. The whole of the tracks once reconstructed using the prior verified theory is the single "click" associated with a particle of a certain mass and momentum (range). Or more specifically a specific configuration of particle paths is the single "click" for a particular resonance at the collision center.

This is the point in CI of treating your measuring devices classically. In so far as the collision experiment goes the particles detected are the the measuring device and you'll note the theorests interpreting the data do not treat such particles as localized at their detectors in the equations they write down. Rather the system cut is between the detector array and the collision center. The input beams and output spray of particles are both part of the measuring device when outside and part of the system when they are near the collision center.

If one is looking for say a top quark interaction you don't seriously mean they expect the top quark to create a path in their detector array? So you should view the detector array no differently in terms of this discussion than say the electrons in a photo-multiplier tubes designed to detect photons.

Similarly when one is measuring the spin of an electron with an SG magnet or rather its magnetic moment one is using the electron's position and momentum as a classical measuring device. This is inherent in the |up> or |down> kets one writes and in the ignoring of the HUP with regard to localizing the electron's lateral position while assuming zero lateral momentum.

The metaphysics of these paths of which you speak is necessary only as a practical convenience in so far as one is treating the measuring device itself as a classical system.
Our language is very object oriented and so being careful to describe all the tracks phenomenologically would be painfully tedious.

"We observed conserved electronic charge-spin-mass causally propagate in this direction"
vs
"We observed an electron with this momentum"

It is important to distinquish a "quantum particle" from "a particle" in the classical sense. The definition of a "quantum particle" is a quantum system with non-trivial irreducible Poincare group representation. It is not an object it is a system of activity, a process.

Hence we may in the "quantum particle" context speak of ghost and virtual particles which are component processes in a resolution of many quanta interactions but are not even associated directly with "clicks of a detector". But when one is invoking say ghosts or virtual particles one gets into deep stuff trying to apply metaphysics.

Let me ask you, what is the metaphysical status of a phonon? Can you make any meaningful metaphysical assumptions about phonons?

[EDIT: In fact I think you have pinned down a key point. When you find it necessary to make metaphysical assumptions you must have crossed the system cut from quantum system to measuring device/mechanism! This is exactly the "why" of the CI postulate that we must treat our measuring devices classically.]

 

[Dmitry67]

I wonder what Quantum Computing guys are thinking about the CI. They deal with systems of few atoms that DO measure. They deal with systems of few atoms configured differently - and these configurations DO NOT 'measure', passing the superposition or storing the superposition for some time.

 

[nikman]

I wonder what Quantum Computing guys are thinking about the CI. They deal with systems of few atoms that DO measure. They deal with systems of few atoms configured differently - and these configurations DO NOT 'measure', passing the superposition or storing the superposition for some time.

Amazingly, one of the pioneers in the quantum computing field is the IQOQI in Vienna, and of course we're dealing again with Zeilinger, Brukner et alii. Zeilinger is on record as preferring the CI for its "austerity".

Entanglement is the key, and entanglement's right up the CI's alley. It all harks back to the Bell Inequality experiments of Alain Aspect. In the quantum computing literature you see "Bell entanglement" mentioned frequently.

And in the end you DO measure. And the qubit superposition collapses into a "0" or "1" classical bit. Otherwise what's the point?

FWIW the IQOQI are also the people who conducted the highly successful entanglement and teleportation experiments in the Carnary Islands (144 km between La Palma and Tenerife two summers ago).

Go measure.

 

[nikman]

In the event anyone cares, and in re: upthread stuff ... it's sometimes claimed that Wittgenstein never discussed QM. But he did on at least one occasion:225 A proposition, an hypothesis, is coupled with reality -- with varying degrees of freedom. In the limit case there's no longer any connection, reality can do anything it likes without coming into conflict with the proposition: in which case the proposition (hypothesis) is senseless!

All that matters is that the signs, in no matter how complicated a way, still in the end refer to immediate experience and not to an intermediary (a thing in itself).

All that's required for our propositions (about reality) to have a sense, is that our experience in some sense or other either tends to agree with them or tends not to agree with them. That is, immediate experience need confirm only something about them, some facet of them. And in fact this image is taken straight from reality, since we say 'There's a chair here', when we only see one side of it.

According to my principle, two assumptions must be identical in sense if every possible experience that confirms the one confirms the other too. Thus, if no empirical way of deciding between them is conceivable.

A proposition construed in such a way that it can be uncheckably true or false is completely detached from reality and no longer functions as a proposition.

The views of modern physicists (Eddington) tally with mine completely, when they say that the signs in their equations no longer have 'meanings', and that physics cannot attain to such meanings but must stay put at the signs. But they don't see that these signs have meaning in as much as -- and only in as much as -- immediately observable phenomena (such as points of light) do or do not correspond to them.

A phenomenon isn't a symptom of something else: it is the reality. A phenomenon isn't a symptom of something else which alone makes the proposition true or false: it itself is what verifies the proposition. (Philosophical Remarks, pp 282-3)

 

[kote]

A phenomenon isn't a symptom of something else: it is the reality. A phenomenon isn't a symptom of something else which along makes the proposition true or false: it itself is what verifies the proposition. (Philosophical Remarks, pp 282-3)

Bohr anyone? Also, since we've mentioned positivism, most of that movement was explicitly based on Wittgenstein's thoughts on language, meaning, and verification.