Many-worlds true quantum event generator

[rodsika]

This is getting rather philosophical, but my question here would be, what does it mean to "experience" superposition? Suppose we replace Schroedinger's cat with an intelligent being capable of communication (perhaps a person, but slightly more realistically it could be an A.I. running on a quantum computer), and instead of the random radioactive decay either killing them or letting them live, the outcome of the decay just determines which of two hidden photographs will be uncovered and shown to this being. The subject of the photos isn't known in advance to the being and they could be absolutely anything, perhaps one is a photo of a painting of George Washington and the other is a photo of a duck. So would "experiencing" superposition of (left photo uncovered, right photo remains hidden) and (right photo uncovered, left photo remains hidden) involve being aware of what was in both photos at once? The problem is, suppose we ask this being to then write down a story about whatever it is he has seen...obviously we'll get a superposition of stories, and significant amplitude will be assigned to both stories involving George Washington and stories involving ducks, but the amplitude assigned to stories that actually involve George Washington interacting with a duck will be totally negligible (perhaps not exactly zero since a person who just sees a picture of George Washington might by chance happen to write a story which also involves a duck and vice versa, but the amplitude to "George Washington interacts with a duck" stories shouldn't be any less negligible than "George Washington interacts with a tiger" or any other random animal). So, if you claim that this individual has "experienced" a superposition of George Washington and a duck, it seems like you have to say that somehow the individual can't act on this composite knowledge when writing a story (or superposition of stories), which seems to indicate a radically dualistic view of the relation between their "experience" and the actual behavior caused by their physical brain.

JesseM, going back to this message about the person experiencing both the drawing of George Washington and duck in superposition and why it's not possible because it can indicate a radically dualistic view of mind and brain. This is not a strong refutation because there is still fierce debate in consciousness research about this. What other reasons could forbid such actual superposition in one world. Let's go to the simple one electron at a time double slit experiment. Why. If the electron actually duplicated physically in one world and they both enter both slits. Would there be experimental differences to the data in the measurement such as the charge increasing by two or other anomaly? Or would there be no difference, what do you think?

I guess it's really more like superposition is simply superposition of possibilities, not the actual object. But then if not the actual object, then it just vanish or stay at the side while the possibilites are in superposition. This doesn't make a lot of sense unless the particle can be push just like the quantum potential in Bohm interpretation but this one conflicts severely with lorentz invariance

It seems we are being trapped in the corner that Many Worlds may be the option left. The reasoning is that in the 430 atom buckyball. If we have to believe that the wave is only wave of possibility, and the buckyball is not physically there.. then it doesn't make sense it just vanish into thin air. And it doesn't make sense the buckyball duplicated itself physically while being isolated. I guess we can detect changes in the data if there are 2 copies isn't it.

But not if there are in separate worlds just like in Many Worlds. Btw.. when interferences form, the destructive interferences are supposed to be places where the buckyball ball in different worlds at in the same space, hence they just dislodge themselves from that spot to make the region of the destructive inteferences empty? Is this the reason for the interference patterns? Also this proves that objects in different worlds can still affect one another or else there would be no interferences so can't we use this possibility to contact other parallel many worlds?

 

[JesseM]

JesseM, going back to this message about the person experiencing both the drawing of George Washington and duck in superposition and why it's not possible because it can indicate a radically dualistic view of mind and brain. This is not a strong refutation because there is still fierce debate in consciousness research about this.

Even for dualists I think there are very few who would really suggest that I could have experiences which I was utterly unable to act upon in any way. Even if you suggest this, it's a useless hypothesis to talk about because you'd never be able to verbally affirm that you were having such an experience, you would continue to speak and write exactly as if you hadn't had any such experience.

What other reasons could forbid such actual superposition in one world.

I didn't say there couldn't be such superpositions in one world, just that I don't know what it would even mean to say an observer is "experiencing" such a superposition. Are you just imagining a sort of blurry/double vision like being drunk, or something totally alien to our ordinary experience and impossible to visualize/imagine? To me it seems like an observer in superposition would really imply different parallel experiences, and then you really just have the MWI again.

Btw.. when interferences form, the destructive interferences are supposed to be places where the buckyball ball in different worlds at in the same space, hence they just dislodge themselves from that spot to make the region of the destructive inteferences empty?

I don't really think the current versions of the MWI allow for such a concrete picture of why interference patterns form, you just kind of have to accept the math of wavefunction evolution as fundamental. Perhaps someone might someday derive the wavefunction from some slightly more intuitive axioms involving interactions between parallel versions of the same particle, who knows, but it hasn't been done yet anyway.

 

[StevieTNZ]

Hey

Just a quick question - if decoherence were actually a mechanism for creating the classical world - wouldn't this refute any other interpretation that supposes quantum mechanics applies to the macroscopic world? I say this because as far as I know, decoherence only creates a more complex superposition, not a mixture... but people seem to claim that it solves the measurement problem... but there is no actual outcome from the basis states is there?

 

[Dmitry67]

In some sense it refutes Copenhagen int, because (as Decoherence is a part of QM, not any particular Int, so it exists in ALL interpretations) in CI there are 2 mechanisms to explain the same thing: Decoherence and Collapse. And it does not make any sense.

decoherence only creates a more complex superposition, not a mixture - it creates ALMOST an exact mixture, FAPP you can ignore terms with quotients like 10^-22 or so.

Decoherence solves the first part of the measurement problem. It explains how do we get a mixture of the outcomes, but it does not tell what outcome is 'real'. Then you have a choice between BM and MWI.

 

[StevieTNZ]

it creates ALMOST an exact mixture

Decoherence solves the first part of the measurement problem. It explains how do we get a mixture of the outcomes, but it does not tell what outcome is 'real'. Then you have a choice between BM and MWI.

So it doesn't create a mixture? If its almost one... but almost one doesn't make it one.

But if it did create a mixture... there would be a definite physical state of a particular quantum system - we just don't know it?

 

[Dmitry67]

1 So it doesn't create a mixture? If its almost one... but almost one doesn't make it one.

2 But if it did create a mixture... there would be a definite physical state of a particular quantum system - we just don't know it?

1 Why should we care?
We don't refute 2nd law of thermodynamics because *theoretically* water in a glass can separate itself into hot and cold, and pieces from a broken vase can jump from the floor to form an unbroken vase. It is possible, but the probability is so tiny, that we can ignore it and call an approximate law a *law. The same is true for the decoherence, theoretically it is possible to ‘undo’ the measurement, but again the probability is too low.

2 The state is exact and is known as ‘universe wavefunction’. However, we observe only a tiny slice of it, so we can’t calculate it. Also, the definition of a ‘system’ in MWI is very complicated.

 

[sparkypaul]

Well MWI suggests for every random event, the universe splits into available options. I think "Random Event" is the key here. Because some things can't be mathematically modeled right now doesn't mean they are random.

Actually i will go as far as saying, almost everything above atomic level can be very well mathematically modeled from the beginning of the universe. Your conciousness is a product of this material world, so considering your actions as random is absurd :)

I thought that consciousness was being considered as a quantum event taking place within an area of the brain involving the tubules. No?

 

[JesseM]

I thought that consciousness was being considered as a quantum event taking place within an area of the brain involving the tubules. No?

No, the Penrose/Hameroff microtubule theory is a view few other scientists find credible, for one thing it's thought to be impossible to maintain large-scale quantum coherence in biological tissue, see this paper (though there are some criticisms of that paper here, and further discussion here), and the wikipedia article discussing their theory also mentions:

Orch OR is no longer considered a good candidate for a quantum source of consciousness. In 2009, Jeffrey Reimers et al. showed that coherent Fröhlich condensates, the states Hameroff and Penrose implicated as the basis of Orch OR, could not exist in biological tissue. They found that coherent Fröhlich condensates of the sort required by Orch OR would require temperatures of between several thousand to several million kelvins, an environment not possible in biological tissue. If the energy required to keep the oscillators in a coherent state for the required 500 ms came from a chemical source, it would require the energy equivalent of a C-C bond being formed or broken every picosecond. The GTP mechanism proposed by Hameroff and Penrose would require the hydrolysis to GDP of approximately 4 or 5 GTP molecules every picosecond, a phenomenon that does not appear to occur in biological systems. [28]

 

[StevieTNZ]

1 Why should we care?
We don't refute 2nd law of thermodynamics because *theoretically* water in a glass can separate itself into hot and cold, and pieces from a broken vase can jump from the floor to form an unbroken vase. It is possible, but the probability is so tiny, that we can ignore it and call an approximate law a *law. The same is true for the decoherence, theoretically it is possible to ‘undo’ the measurement, but again the probability is too low.

I care, because its obvious decoherence doesn't create a mixture. So claiming it does is incorrect. You can't ignore something because it has a low probability. This was my point in another post in another thread on here - even if something has 98% probability for happening, and something else 2%, clearly it is possible for the 'something else' to happen.

 

[sparkypaul]

No, the Penrose/Hameroff microtubule theory is a view few other scientists find credible, for one thing it's thought to be impossible to maintain large-scale quantum coherence in biological tissue, see this paper (though there are some criticisms of that paper here, and further discussion here), and the wikipedia article discussing their theory also mentions:

Thanks Jesse.

 

[Dmitry67]

I care, because its obvious decoherence doesn't create a mixture. So claiming it does is incorrect. You can't ignore something because it has a low probability. This was my point in another post in another thread on here - even if something has 98% probability for happening, and something else 2%, clearly it is possible for the 'something else' to happen.

It is not 98% or 99.9%
Non-diagonal elements decay in few nanoseconds to 10^-23 or so.
You have more chance seeing a dancing red elephant merging in air from randomly moving air molecules, then dealing with the fact that mixture is not complete.

If you are still claiming that such probabilities are important, then you should also accept that 2nd law of thermodynamics is WRONG.

 

[StevieTNZ]

It is not 98% or 99.9%
Non-diagonal elements decay in few nanoseconds to 10^-23 or so.
You have more chance seeing a dancing red elephant merging in air from randomly moving air molecules, then dealing with the fact that mixture is not complete.

If you are still claiming that such probabilities are important, then you should also accept that 2nd law of thermodynamics is WRONG.

Clearly it is wrong, if one were to give truth values to it being correct or not. Approximation is not an exact representation of reality.

The percentages I gave in my other post were made up to represent what I'm trying to get across.

 

[Dmitry67]

"Clearly it is wrong"? Any details?

Decoherence depends on the number of degrees of freedom of an observer system. So non-diagonal elements became very small after an interaction between a quantum system and an observer. How small - it depends on the number of atoms in an observer. It is about 1/(Avogadro number)

 

[JesseM]

"Clearly it is wrong"? Any details?

Decoherence depends on the number of degrees of freedom of an observer system. So non-diagonal elements became very small after an interaction between a quantum system and an observer. How small - it depends on the number of atoms in an observer. It is about 1/(Avogadro number)

But one can argue that any time there is any level of superposition rather than a statistical mixture, the notion of assigning "probabilities" to different outcomes becomes problematic (if we perform an imperfect measurement in the double-slit experiment which reduces the interference pattern on the screen to almost a non-interference pattern but still with a little remaining interference, does it make sense to assign a "probability" to whether the particle went through the left slit or the right slit?) One of the most prominent MWI advocates, David Deutsch, takes this position, I'll quote him from p. 332 of https://www.amazon.com/dp/0684814811/?tag=pfamazon01-20:

From the point of view of the interpretation of quantum mechanics, I think decoherence is almost completely unimportant. That's because decoherence is a quantitative matter. The interference phenomena never completely vanish; they only decrease exponentially until you can't be bothered to measure them anymore. The question of what the [interference] terms mean is still there, even if the coefficient in front of them is very small. It's like being a little pregnant. Those terms, however small, raise the same problem. If the argument is supposed to be that superpositions occur at a microscopic level but not to macroscopic objects, that's a bit like saying that you believe your bank is honest at the level of pennies but is cheating you at the level of pounds. It just doesn't make sense. It can't be that there are multiple universes at the levels of atoms but only a single universe at the level of cats.

 

[Dmitry67]

The values of "probabilities", or "intensity of existence" how it is called in MWI, have an exact value in MWI as it is defined by the wavefunction. Instead of 0.5/0.5 you have say 0.5-1^-23, which leaves a room for the interference terms. So it makes sense to assign a probability.

I agree that outcomes in MWI are never definite, and (even very unlikely) you can arrange particles in a way to even 'undo' there measurement. Also, as the very definition of a "system" is fuzzy, the "outcome" is fuzzy as well.

Still, I fail to understand why Deutsch find thee 10^-23 important. THese numbers are always below any noice, created by macroscopic systems. In fact, if you observe something really weird, like unicorns, you can';t tell if it happens bacuse of the non-zero non-diagonal terms or because 2nd law of theormodinamics is violated.

 

[JesseM]

The values of "probabilities", or "intensity of existence" how it is called in MWI, have an exact value in MWI as it is defined by the wavefunction. Instead of 0.5/0.5 you have say 0.5-1^-23, which leaves a room for the interference terms. So it makes sense to assign a probability.

That doesn't make sense to me, are you assigning a distinct probability to the "interference terms"? If that 1^-23 possibility occurred, what kind of "world" would that be? Interference terms aren't distinct possible measurable states as I understand it (they aren't eigenstates of any observable), nor do I think it even makes sense to see them as distinct possible state vectors in a mixed state, since the number of terms in a density matrix can be greater than the number of state vectors in the statistical ensemble making up a true mixed state, see the simple example I looked at [post=3245596]here[/post] where there are just two possible state vectors in the ensemble but the density matrix has 4 possible entries.

 

[Dmitry67]

Well, you're right, I was not clear. Of course interference terms can't be associated with the distinct worlds/outcomes.

However, I don't understand the stress which StevieTNZ and Deutsch puts on the interference terms. Is it for the sake of mathematical purity? If so, then yes - it is NOT an axect mixture as interference terms are not exactly zero.

However, FAPP they are zero for the big macroscopic objects, which agrees with the observation.