The Many-Worlds Interpretation of QM

[nazarbaz]

If physicists were more interested in philosophy, they would know that the diversity of interpretations is unsolvable and that there's no point to choose one of them over the others. My "personal view" (and I say this with a bit of detachment and irony) : if you could make a different choice, then don't choose at all : that's the only interesting aspect of the "shut up and calculate" approach.
The idea that science is self sufficent and self consistent is worst than the worst philosophical non sense I know of, though : it's an essentialist dogma or a religious belief. The real interest and function of philosophy is to exceed our actual limitations and to build an understanding to our experience : contain it into a mere epistemology is to underestimate and misuse it. Thinking about science results is dangerous but necessary. In that regard, philosphy - the real one - always begins when science stops.
The most fundamental issue modern science has to address is to know more about the way mathematics relates to reality : otherwise, we wouldn't be anything else than blind kids playing with colors and light. I doubt that the scientific method itself has something to say about it.
There's is no mystery per se out there, just a beautiful cosmic process yet to be discovered.

PS : sorry for my terrible english.

 

[Alexis1304]

M.Kaku

Folks, have alook how M.Kaku commented on Nobel Prize 2012, and how he talks about "electron been at 2 places" .He says "it means the universe has splitted":

http://bigthink.com/dr-kakus-universe/nobel-prize-awarded-to-two-quantum-physicists


Is electron at 2 places a "double slit" experiment?

For some reason,lately Kaku was criticized by few physicists

 

[Quotidian]

the human brain cannot cause a collapse when the computer does not.

Nowhere is it suggested that 'the human brain' causes a collapse. The act of observation 'collapses' the probability wave, but here the word 'collapse' is strictly metaphorical. A probability wave is not an actual phenomenon in the first place: it is simply the odds of locating the 'particle' in a particular location at the time the observation is made. Until the observation is made, the particle cannot be said to exist in a particular location. When it is observed, the chance of it being in some other location, apart from the one it was measured in, 'collapses' to zero. And this doesn't mean it was lurking somewhere until it was measured; until it is measured, it has no particular location. That, I believe, is the import of 'superposition'.

So the 'probability wave' itself is a purely intellectual construction. It is a way of predicting results, but it does not exist in reality. As an 'intellectual construction', I suppose one needs a brain to be able to grasp it, but the degree to which it 'exists in a brain' is surely a moot point.

Also with regards to your assertion of the equivalence of minds and computers - there's a very fundamental point you're missing in all of this. Minds understand the nature of representation. When a mind represents something by way of a symbol, the interpretation of the meaning of the symbol is the act of an intelligence. The etymology of the word 'intelligence' is from 'inte-legere', 'to read between'. Computers themselves never do that. They are entirely symbolic, not conscious or intellectual. Essentially a computer is a very complex abacus. This is the subject of John Searle's Chinese Room argument. But that is a separate topic.

The most fundamental issue modern science has to address is to know more about the way mathematics relates to reality

As you say, not a scientific question, as such. I rather like the Pythagorean approach, however, that number constitutes reality. If you contemplate the degree to which nearly everything in physics and cosmology is articulated by way of number, this might not seem such an exotic idea.

You might be familiar with this classic essay, but if not, it's worth knowing about - http://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.html by Eugene Wigner.

 

[mfb]

Nowhere is it suggested that 'the human brain' causes a collapse.

Good. I read some posts where I got that impression.

So the 'probability wave' itself is a purely intellectual construction. It is a way of predicting results, but it does not exist in reality.

That is a possible interpretation, but not the only one.

Also with regards to your assertion of the equivalence of minds and computers - there's a very fundamental point you're missing in all of this. Minds understand the nature of representation. When a mind represents something by way of a symbol, the interpretation of the meaning of the symbol is the act of an intelligence. The etymology of the word 'intelligence' is from 'inte-legere', 'to read between'. Computers themselves never do that.

Computers do not do that as they are not programmed to do that. That is just a software thing, however.
Ignoring engineering issues: If you can fully scan and simulate a human brain on the level of individual molecules, the results of that computation (the simulated interactions with the environment) should be the same as the result of a real brain. The simulation can be written in current programming languages. I think an effective model of the cells would be sufficient to get the same results, but that is a technical detail.


@Maui: Okay, I am not going to reply to posts from you again, that is just pointless.

 

[Quotidian]

If you can fully scan and simulate a human brain on the level of individual molecules, the results of that computation (the simulated interactions with the environment) should be the same as the result of a real brain. The simulation can be written in current programming languages. I think an effective model of the cells would be sufficient to get the same results, but that is a technical detail.

Not. No matter how many, and what kind, of bricks you assemble, you can't build a violin. Violins are not made from bricks. That is an analogy for what you are suggesting here. 'An idea' is not something that exists in symbolic form. 'An idea' can be represented in symbolic form, but it always takes a perceiving subject for it to actually be 'an idea'.

The reason this is so easily overlooked is because you can safely assume that those to whom you are speaking are subjects and are conscious. Those subjects will understand the nature of representation, becuase they're intelligent. So it is then easy to project that ability onto artificial systems. But what you're seeing there, is simply a projection of your own intelligence. It is not something that the device actually possesses. It is not as if the device is actually intelligent. It seems intelligent, because humans know enough about intelligence to imbue the device with the simulcrum of intelligence. But it is not actually intelligent.

So saying that computers are not intelligent because they are not programmed to be intelligent, is like saying that they don't defy gravity becuase they're not programmed to defy gravity. Of course, they can't defy gravity, it is not something a device can be programmed to to.

This is all simply one of the common delusions of the technologicl society. But as it is tangential to the main point, I won't pursue it further.

 

[bhobba]

You also have no idea how the 'environment' induces collapse, so it's hardly relevant what belief you subscribe to. Believing this wonderful classical world can emerge out of potentials which are not even grounded in anything physical, is as much a fairy-tale as believing in gods. It's dubious if it's even valid philosophy.

There is a very large amount of scholarly literature and even standard textbooks that say otherwise eg:
https://www.amazon.com/dp/3540357734/?tag=pfamazon01-20

There are issues and they are being actively investigated but by no stretch of the imagination is the situation as bad as you say. For example the emergence of a classical world from the quantum is now pretty well understood. And the reality or otherwise of a system state has nothing to do with that emergence. The reason something 'real' can emerge from something that may be simply a theoretical concept is what emerges corresponds with what we experience. Its the same way gas laws emerge from the laws of probability even though probability does not exist is a real sense exactly like some think of quantum states.

The truth of the matter is eloquently described by the following Wikipedia article I linked to before and will quote again because it sums up the situation well:
'Decoherence does not generate literal wave function collapse. Rather, it only provides an explanation for the appearance of wavefunction collapse, as the quantum nature of the system "leaks" into the environment. That is, components of the wavefunction are decoupled from a coherent system, and acquire phases from their immediate surroundings. A total superposition of the universal wavefunction still exists (and remains coherent at the global level), but its fundamentality remains an interpretational issue. "Post-Everett" decoherence also answers the measurement problem, holding that literal wavefunction collapse simply doesn't exist. Rather, decoherence provides an explanation for the transition of the system to a mixture of states that seem to correspond to those states observers perceive. Moreover, our observation tells us that this mixture looks like a proper quantum ensemble in a measurement situation, as we observe that measurements lead to the "realization" of precisely one state in the "ensemble".'

The issue here is 'Decoherence does not generate literal wave function collapse. Rather, it only provides an explanation for the appearance of wavefunction collapse, as the quantum nature of the system "leaks" into the environment.' Some believe we need more that an explanation of the appearance of wavefuntion collapse - but that is a matter of opinion - which this whole interpretational thing is - a matter of opinion - not the bleak picture you paint.

Thanks
Bill

 

[bhobba]

For some reason,lately Kaku was criticized by few physicists

The issue with Kaku when I have heard him wax lyrical about quantum stuff is he will say some very controversial statement such as the electron is in two places at once that is very interpretation dependent then say - get used to it. Not the most balanced view.

Thanks
Bill

 

[bhobba]

These are both the same. The argument is whether a machine recording a reading and displaying it to a wall, chair or a bridge without there ever being a way for it to be read by a perceiving observer is the same as the result being read be an observer.

That view is logically unassailable but leads to a very quirky view of the world especially from the view of computer science. It would mean the bits of information that travel around a computer system and studied by computer scientists do not objectively exist because they have not been observed. If you promulgated that view in a CS class its unlikely anyone would take you seriously. It wouldn't matter if your view was the only one that is possible but it isn't - not by a long shot.

Thanks
Bill

 

[bhobba]

If physicists were more interested in philosophy, they would know that the diversity of interpretations is unsolvable and that there's no point to choose one of them over the others.

They know that, philosophy or no philosophy. And most physicists don't ague about it - they have some interpretation that allows them to apply it and that's it. Sometimes research appears like Bells stuff and decoherence that sheds light on the issue and people may now think it suggests a new interpretation, makes a different one more appealing, or even disproves some previous ones. To apply QM you must choose an interpretation even if its the shut-up and calculate Minimal Statistical Interpretation that is simply the math - its unavoidable.

Thanks
Bill

 

[bhobba]

If you can fully scan and simulate a human brain on the level of individual molecules, the results of that computation (the simulated interactions with the environment) should be the same as the result of a real brain. The simulation can be written in current programming languages. I think an effective model of the cells would be sufficient to get the same results, but that is a technical detail.

I think you are correct and believe anyone who thinks otherwise is a bit kooky, but it must be said there are people like Roger Penrose who do not agree with it. The tenant of books like the Emperors New Mind is that consciousness has qualities that can not be simulated. I suspect it is that kind of view the consciousness causes collapse crowd adhere to.

As an aside I actually did believe in another view of Penrose's - the literal existence of a Platonic world where the truths of math and physics literally reside - nearly everyone believed that was kooky as well - but it did explain some puzzling things like what was espoused in Wigners famous essay:
http://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.html

Then I came across some writings of Murray Gell-Mann on how emergence solves the issue and quickly converted to it. My suspicion is the consciousnesses causes collapse crowd haven't understood the latest research such as decoherence that also renders consciousness causes collapse redundant in the same way. Wigner did - but for some reason it still holds sway in certain circles.

Thanks
Bill

 

[Quotidian]

As regards Wigner's 'kooky' essay on 'the Unreasonable Efficiency of Maths', let's not loose sight of the fact that he won the Nobel for atomic physics. I seem to recall he was one of the pioneers of the concept of mathematical symmetries. This has actually proven to be an extremely influential notion in physics, has it not? Yet it is all based on mathematical predictions, that is, patterns of symettry that appear in the purely intellectual realm, which have been subsequently validated, in some cases, by real-world discoveries. In other words, mathematics makes accurate predicitions about nature, which we would have no way of knowing through mere experience. Through mathematical reasoning, Einstein made predictions which could not even be validated until half a century after he made them. as the instruments did not exist.

Or Galileo, who said that 'the book of nature is written in mathematics'. Is that also 'kooky'?

As regards Penrose's view of Platonism - it is not a matter of trying to imagine a literal 'realm' within which numbers are 'real' floating around 'out there'. Number is, in some sense, simply an abstraction of a general attribute of reality itself. Why? Because it holds in regards to all different kinds of material particulars. If you have 'three' of something, then it doesn't matter what kinds of thing you are referring to - bananas, electrons, or planets. Similarly with logical laws, like the law of the excluded middle: these are not true in regard to particular things. They express general truths about the nature of thought itself. That is why they are called 'the laws of thought'. So the general Platonist idea is that such things as logical and numerical truths, are on a deeper level of truth than material particulars, because they are true in all times and places. Indeed it was that type of understanding which made the whole notion of a general theory possible, and one of the main reasons that the scientific revolution happened in the West. But now science has lost sight of the very type of reasoning which made it possible in the first place.

In actual fact, Wigner, Heisenberg, and many other scientists came to the view that the fundamental constituents of reality were much more like numbers than like material objects. And the point about numbers is, they are only real for a rational intelligence. Creatures are incapable of grasping such ideas, because they are not rational. Only a rational being is capable of grasping rational concepts such as number, and in the natural realm, there is only one type of being that satisfies that requirement.

The tenant of books like the Emperors New Mind is that consciousness has qualities that can not be simulated.

'Tenet'. Indeed he does say that. It has never been remotely shown that an artificial device is conscious. As I said above, in order to believe that, you have to believe that a symbol is itself capable of awareness, which is obviously fallacious. A computer is a box of switches that manipulates code which represents symbols that are understood by humans. The computer understands nothing in its own right, however.

Actually there's an amusing irony that I have thought about. I note many people vehemently deny that a human is anything other than a computer. If you take issue with that, they become annoyed.

Do computers become annoyed?

 

[kith]

A computer is a box of switches that manipulates code which represents symbols that are understood by humans. The computer understands nothing in its own right, however.

I agree as far as present day technology is concerned, but not in principle. Natural history suggests that unconscious beings evolved into conscious ones. If we accept this, I don't see a reason why a sophisticated enough machine shouldn't be capable of consciousness as well.

 

[ImaLooser]

I agree as far as present day technology is concerned, but not in principle. Natural history suggests that unconscious beings evolved into conscious ones. If we accept this, I don't see a reason why a sophisticated enough machine shouldn't be capable of consciousness as well.

Concepts that assign a superior status to human beings tend to be more popular.

 

[mfb]

Not. No matter how many, and what kind, of bricks you assemble, you can't build a violin. Violins are not made from bricks. That is an analogy for what you are suggesting here.

Bricks are not Turing complete, but computers (with software) are. It is possible to accurately simulate the interaction of particles in a computer, and a brain is made out of particles - no experiment found anything else yet.

'An idea' is not something that exists in symbolic form. 'An idea' can be represented in symbolic form, but it always takes a perceiving subject for it to actually be 'an idea'.

You can share ideas with others via the internet. In other words, it is possible to encode an idea in a computer (in strings of English, for example). You "just" need a software which can work with those ideas, like a human brain can do it.

Only a rational being is capable of grasping rational concepts such as number, and in the natural realm, there is only one type of being that satisfies that requirement.

Sure, but there is no known law of physics "a rational intelligence has to be a human", and I think such a law would be really strange. There is no sharp line between humans and other animals anyway - we evolved out of other species!

It has never been remotely shown that an artificial device is conscious.

It has never been shown that a spacecraft can travel at 1% the speed of light either, but there is no reason to expect a fundamental problem with that. In addition, consciousness is hard to define and quantify, even for humans.

A computer is a box of switches that manipulates code which represents symbols that are understood by humans.

A human is a box of neurons that manipulate electric potentials and currents. Its output can be understood by other humans (sometimes).

Do computers become annoyed?

If the AI is good, it will probably have something which can be described as "annoyed".

 

[jambaugh]

If physicists were more interested in philosophy, they would know that the diversity of interpretations is unsolvable and that there's no point to choose one of them over the others. My "personal view" (and I say this with a bit of detachment and irony) : if you could make a different choice, then don't choose at all : that's the only interesting aspect of the "shut up and calculate" approach.

Your are correct about there being no point in choosing one over the other but...It is solvable within science via the power tool of Occam's razor. The lack of empirical distinction between ontological interpretations prescribes that we excise ontological interpretation!
And as you say the proper choice is "not to play the game" (of ontological [re]interpretation). QM already has an existing operational interpretation before these questions of re-interpretation come up. Your conclusion is exactly the resolution made in the Copenhagen Interpretation. Since the "underlying reality" is not empirically testable it is meaningless in the context of science and should be excised along with the luminiferous aether and other such artifacts of our reflex to build models. So abandon reality and "shut up and calculate" so to speak.

The idea that science is self sufficent and self consistent is worst than the worst philosophical non sense I know of, though : it's an essentialist dogma or a religious belief.

Not true! science is self sufficient (sufficiency being contextual) it is just that e.g. science is insufficient to tell me what tastes good, only how to better prepare something with a given taste. It is not sufficient to define aesthetics, but it provides knowledge about techniques for achieving aesthetic goals. Add two or three other examples here from ethics, politics, et al.

Science is a specific discipline of epistemology, a specific school of thought within a specific branch of philosophy. Few advocates of science that I've ever heard of claim it is sufficient to all branches, but I as a positivist claim it is sufficient as an epistemology to all branches.

Logic can only bridge assumptions (axioms) to conclusions (proved statements). To test one's assumptions one has to invoke some epistemological method. I can invoke an authority but you may not accept that authority. Which authority to accept (which religious text or prophet e.g.) is a meta-epistemological question. Accepting any authority on faith is an abdication of one's personal responsibility to one's self to find the best means to truth. (Take my word for that, I got a PhD so you shouldn't question me!) The meta question of whether to accept a given authority is again resolvable via the epistemology of empiricism. Has that authority in the past been correct on their testable claims? The positivists like myself point out that the only epistemological foundation which can be shared in a social setting (e.g. a courtroom) is the epistemology of science. IT says, don't take my word for it if you doubt, go and do your own empirical observations and you will see what I see, or if you don't, tell me and I'll recheck my premises.

The real interest and function of philosophy is to exceed our actual limitations and to build an understanding to our experience : contain it into a mere epistemology is to underestimate and misuse it.

Firstly "exceeding one's actual limitations" is an oxymoron. If exceeded they were not limitations. The phrase is properly used with the implied qualifier "(perceived) limitations" and in that context you're use is improper. Secondly you're reversing things here, science does not claim to be all of philosophy (that is to say, scientists don't make that claim). The positivist claims it is the culmination of epistemology, the first best method. Only you have made this underestimation and misuse. I perceive that you are setting up a rationalization in your mind to disregard the value of science in the way you are "twisting" claims here. Rethink your motivations in this and see if I'm off base or not.

Thinking about science results is dangerous but necessary. In that regard, philosphy - the real one - always begins when science stops.

By what criterion do you select "the real one"? and why should I accept your criterion? How do we decide? This is a question of semantics, what is "the real philosophy"?

The most fundamental issue modern science has to address is to know more about the way mathematics relates to reality : otherwise, we wouldn't be anything else than blind kids playing with colors and light. I doubt that the scientific method itself has something to say about it.
There's is no mystery per se out there, just a beautiful cosmic process yet to be discovered.

PS : sorry for my terrible english.

You're English is quite good, better than some of my students' (in the US btw). I agree with your last sentiment except there are mysteries to resolve about the nature of that beautiful cosmic process. I don't quite agree with your "most fundamental issue". Specifically science isn't just doing the math. It can be done without mathematical tools. When a chef doesn't simply take the time in the oven as given but sticks a knife in the pie to see if it is done, he is practicing science, i.e. knowing by checking empirically. In the courtroom where empirical evidence must be presented in support of the assertions of the accuser, or else their claims are rejected, then you again have science. Again it is the only rational means to knowledge in a social setting and I become quite passionate about defending the integrity of science when some attempt to twist its meaning into mysticism (believe in e.g. realities which can't be observed), or side-step it (implementing policies in government based on assertions with no foundation in empirical evidence...).

I don't see this as just an academic debate. It is an issue of the foundations of our civilization and quite literally life and death hang in the balance. (And I despair sometimes at the trends I see in our society to move away from or disfigure science.)

 

[Quotidian]

Good post above. Well stated.

A human is a box of neurons that manipulate electric potentials and currents

Says who? Humans are obviously not boxes, and neurons obviously not switches. Fails even as a metaphor.

a brain is made out of particles

Which explains what? There once was a time when the idea that 'things were made out of particles' was thought to be explanatory of practically everything. Now, however, the 'particles' themselves are things which are devilishly hard to explain - hence this thread, hence a lot of what is written in this forum.

In addition, consciousness is hard to define and quantify, even for humans.

You got that right.

 

[yossell]

You're English is quite good

Irony much? (Sorry - I couldn't resist! Did like your post though!)

 

[bhobba]

As regards Wigner's 'kooky' essay on 'the Unreasonable Efficiency of Maths', let's not loose sight of the fact that he won the Nobel for atomic physics. I seem to recall he was one of the pioneers of the concept of mathematical symmetries. This has actually proven to be an extremely influential notion in physics, has it not?

Sorry if what I wrote wasn't clear.

Wigner was a very great Nobel prize winning mathematical physicist - one of the greatest that ever lived. That essay was not kooky in any way - in fact it raised a very difficult to answer issue that led me to the kooky view of Penrose for the literal existence of a Platonic realm. However I recently came across some writings by Murray Gell-Mann on emergence that solved the issue to my satisfaction without invoking such a weird idea.

BTW Penrose is also a great mathematical physicist and when I say his ideas are a bit kooky that's because they are a bit different to the generally held views - his stature means they must be taken seriously.

Thanks
Bill

 

[Alexis1304]

The issue with Kaku when I have heard him wax lyrical about quantum stuff is he will say some very controversial statement such as the electron is in two places at once that is very interpretation dependent then say - get used to it. Not the most balanced view.

Thanks
Bill

Hi Bill,
What exactly is controversial? I think "electron at 2 positions at the same time" is known fact in Quantum Mechanics,the question is what it means? For Kaku and some others it means the universe "splitted" but as I understand there is no consensus about it. And the work of these Nobel Laureats was great achievement in that one team succeded to put photons in superposition and another to put ion at different energy at the same time. But I'm puzzling by Kaku's statement about electron in 2 places as "universe splitted".

On the side note, I aksed one of the most known quantum physicist of Great Britain about this article of Kaku about Nobel Prize. He responded,that it is great achievement,but just confirmation of standart QM predictions

 

[Nugatory]

What exactly is controversial? I think "electron at 2 positions at the same time" is known fact in Quantum Mechanics, the question is what does it mean?

The known fact is somewhat weaker, something more along the lines of "we get really good predictions of experimental results from a mathematical formalism that doesn't always allow us to ask which position the electron is in".

But you are right about the question: What does that mean? "It means the electron is in two positions at the same time" is one possible answer, but it that is neither non-controversial nor the only answer.

 

[Alexis1304]

The known fact is somewhat weaker, something more along the lines of "we get really good predictions of experimental results from a mathematical formalism that doesn't always allow us to ask which position the electron is in".

But you are right about the question: What does that mean? "It means the electron is in two positions at the same time" is one possible answer, but it that is neither non-controversial nor the only answer.

Hi,thanks for the reply.

Have You read the article by Kaku that I linke in one of my previous posts? He analyzes the work of Nobel Laureats, but I think his mention of "electron in 2 positions" was well known before this work of Wineland and Haroche. He also says that until now this superposition was only theoretical but they demonstrated is as practical.Anyway, I think that "electron in 2 places" is a well known double-slit. Or I am wrong

 

[bhobba]

I think "electron at 2 positions at the same time" is known fact in Quantum Mechanics,the question is what it means?

Well some interpretations of QM like the ensemble interpretation do not ascribe any proprieties to an object like an electron until its measured. Its subtleties like that that Kaku glosses over with statements like that. But to be fair its not really possible get across QM in shows like Kaku appears on without broad statements like that. I am certain he knows more than enough of QM to realize its not quite that 'easy'.

Thanks
Bill

 

[bhobba]

The known fact is somewhat weaker, something more along the lines of "we get really good predictions of experimental results from a mathematical formalism that doesn't always allow us to ask which position the electron is in".

But you are right about the question: What does that mean? "It means the electron is in two positions at the same time" is one possible answer, but it that is neither non-controversial nor the only answer.

Like it

Thanks
Bill

 

[bhobba]

Anyway, I think that "electron in 2 places" is a well known double-slit. Or I am wrong

That's only one way of looking at it - others exist. Its neither right or wrong simply interpretation dependent. Pick one - anyone - and decide for yourself. As you learn more QM you may change it - but that's cool.

Under my interpretation it doesn't have any property until its made 'real' as a mixed state by decoherence.

Thanks
Bill

 

[Alexis1304]

Well some interpretations of QM like the ensemble interpretation do not ascribe any proprieties to an object like an electron until its measured. Its subtleties like that that Kaku glosses over with statements like that. But to be fair its not really possible get across QM in shows like Kaku appears on without broad statements like that. I am certain he knows more than enough of QM to realize its not quite that 'easy'.

Thanks
Bill

So, You mean that "electron being in 2 places at one" DOESN'T nescesseraly mean "universe splitted" and other interpretations of that are available?

 

[Fredrik]

So, You mean that "electron being in 2 places at one" DOESN'T nescesseraly mean "universe splitted" and other interpretations of that are available?

No one knows for sure if the electron really is at two places at once, or what that would even mean. What we know is that the wavefunction has peaks at both places. We don't know how to interpret that.

 

[Alexis1304]

Thanks, folks
Another question arises
I think this article "Nothing happens in the Universe of the Everett Interpretation' was already discussed here

http://arxiv.org/pdf/1210.8447v1.pdf

The article itself is critical towards MWI, but starts that "why MWI is attractive" and mentions that with decoherence entangelment and brancing is "totally natural".
If branching is totally naturall, then why all other discussions?Why no everybody just accept MWI and the case closed?After all, the branching is natural, thanks to decoherence...

 

[Nugatory]

If branching is totally natural, then why all other discussions?Why no everybody just accept MWI and the case closed?After all, the branching is natural, thanks to decoherence...

De [STRIKE]gustibus [/STRIKE]interpretationes non est disputandum.

What's natural to one person isn't necessarily natural to another... try feeding brussels sprouts to a four-year-old if you don't believe me.

 

[Alexis1304]

De [STRIKE]gustibus [/STRIKE]interpretationes non est disputandum.

What's natural to one person isn't necessarily natural to another... try feeding brussels sprouts to a four-year-old if you don't believe me.

Not sure this is good analogy,though.As I learned, branching is natural thanks to decoherence.It just may mean differnt things,perhaps

 

[Fredrik]

...with decoherence entangelment and brancing is "totally natural".
If branching is totally naturall, then why all other discussions?Why no everybody just accept MWI and the case closed?After all, the branching is natural, thanks to decoherence...

The MWI is perhaps the simplest and most straightforward way to interpret QM as a description of what is actually happening, but there are other interpretations, and also the possibility that QM simply can't tell us what's actually happening. This has been discussed earlier in the thread.

Not sure this is good analogy,though.As I learned, branching is natural thanks to decoherence.It just may mean differnt things,perhaps

"Branching is natural thanks to decoherence"...I'm not sure were you learned that, but it's not that simple. See the discussion earlier in the thread.

 

[Alexis1304]

Hi Fredrik,
thanks for the reply,
Well,as I told I got that - "branching is natural thanks to decoherence- ironically in the article that overall is critical to mwi, but starts why mwi is attractive- "Nothing happens in the Universe of the Everett Interpretation' was already discussed here

http://arxiv.org/pdf/1210.8447v1.pdf

I just found that this article was posted here on previous pages,as claiming that preferral basis is not solved in mwi. ironically, the conclusion in the article in the opinion of the author is that if mwi is taken alone it is "empty picture". only in combination with copehnagen it makes sense, like they 2 complement each other. by the way I sent e-mail to the author and got interesting response - maybe it is good idea to post his full response here. In his opinion neither Copehnage nor MWI is "complete" ot "true" ,and whatever You said - "the possibility that QM simply can't tell us what's actually happening." - he is in full agreement with that.

By the way folks, did you discuss already the lates book by Steven Weinberg "lectures on quantum mechanics"? I'm not physicists, so was reading only the chapter about interpretations, and for me was pretty technical. But I got his overall conclusion, seems rather radical...

Thanks,
Alexis

 

[Quotidian]

However I recently came across some writings by Murray Gell-Mann on emergence that solved the issue to my satisfaction without invoking such a weird idea.

The idea that 'number is real' is really not such a weird idea when you think it through. Heisenberg once gave a lecture on 'the relationship between Plato and Democritus'. Plato represents mathematical realism and classical idealism - the notion that ideas and number are real in their own right - whereas Democritus was one of the early proponents of atoms.

Heisenberg comes down in favour of Plato on the grounds that the most fundamental elements of existence can only be satisfactorily conceived in mathematical terms, and that they don't 'exist' in the way that 'stones and flowers' exist. Although he acknowledges that the ancients couldn't, and didn't, understand many fundamental things that science has subsequently discovered, he says that such discoveries have vindicated Plato's 'ideas' over Democritus' 'atoms'.

The way I have started to conceptualize the idea is that the nature of reality itself can be understood in terms of relationships rather than entities. When I say 'relationships', this refers to the fundamental ratios and regularities which seem to govern nature on many levels (among other things). For instance there's the 'six constants' that Martin Rees talks of in his 'http://amzn.com/0465036732 . But the intuition of the existence of 'rational relationships' actually goes back to Pythagoras and is the very basis of the idea of 'rationality' and reason itself. It seems to me that 'natural law' operates on a deeper level of reality. But the problem is, empiricism doesn't recognize 'levels'. In its view, things either exist or they don't exist. Whereas the mathematical/rationalist view is that natural and logical laws, and the like, actually dictate what happens in reality, even though they are obviously not available to empirical examination. We can examine the effects of the laws, but the laws themselves are, as it were, sewn into the fabric of the Cosmos.

All that kind of thinking is traditionalist, but it was part of the tradition that enabled science to develop in the first place. (I am firmly of the view that the reason that modern science developed in Western Culture was because of Pythagoras.) However the radical empiricism of the modern period has cut itself off from all that and even rebelled against it. That, I think, is why you find such ideas as 'mathematical realism' to be 'weird'. They are simply out of step with the zeitgeist.

 

[bhobba]

That, I think, is why you find such ideas as 'mathematical realism' to be 'weird'. They are simply out of step with the zeitgeist.

I am a mathematical realist and I would say most people of a mathematical physics bent like I am are as well. I, and I suspect those of a similar bent, and Penrose is definitely of that bent, believe the reality is the math. However Penrose goes further and believes in the literal existence of a Platonic realm our mathematical intuition is somehow in touch with and it is that realm that really determines 'reality'. That is the idea that is viewed as a bit kooky and when I held it freely admitted that - I held it because it resolved the issues in Wigners essay. Now I believe it is simply a result of emergence and the phenomena of self similarity where we find the deeper we go the same thing seems to repeat with perhaps a small variation. This is one of the results of the effective field theory approach to physics and is a deep insight.

Thanks
Bill

 

[bhobba]

I just found that this article was posted here on previous pages,as claiming that preferral basis is not solved in mwi.

Frederic and I have discussed that one. The skinny is the MWI contains decoherence as any interpretation of QM must that conforms its formalism. The consensus is that decoherence does solve the preferred basis problem and that is the view presented in standard textbooks on the subject such as the book by Schlosshauer that is my bible:


The key point that the naysayers attack is the ability to arbitrarily break a system into any subsystems you like. I think most physicists think that assumption is fine but, to the best of my knowledge, key theorems are lacking proving its true.

While it is generally accepted it solves the basis problem decoherence only gives the appearance of wavefunction collapse. It is a matter of opinion, and the particular interpretation you hold to, if that solves the measurement problem

Thanks
Bill

 

[Fredrik]

The consensus is that decoherence does solve the preferred basis problem and that is the view presented in standard textbooks on the subject such as the book by Schlosshauer that is my bible:


The key point that the naysayers attack is the ability to arbitrarily break a system into any subsystems you like. I think most physicists think that assumption is fine but, to the best of my knowledge, key theorems are lacking proving its true.

The consensus is that given a decomposition into subsystems, decoherence selects a basis. But as far as I know, there's no consensus about the basis being independent of the decomposition. I see no reason to think that it is. I expect the bases corresponding to different decompositions to be extremely different.

So I don't see any reason to claim that the "preferred basis problem" has been solved. However, I have never thought of it as an actual problem. It's a problem only if you insist on thinking that at any instant, there's exactly one way to view the universe as consisting of classical worlds. It's not a problem if you're OK with thinking that at any instant, there are many inequivalent ways to view the universe as consisting of classical worlds.

I don't know if anyone is attacking the ability to arbitrarily break up the universe into subystems. I know I'm not.