Quantum Theory and The Many Worlds Theory

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Originally Posted by mal4mac

I did! In the "everyday" model the sun orbits the Earth and the Earth stands still and the Earth is flat.

In the Copernican, Kepler, and Newtonian models the Earth orbits the sun.

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Does the sun actually orbit the earth, or not? You really don't know the answer to the question? I suggest you are being evasive because answering correctly "no, the sun does not orbit the earth" undermines your argument that all we have are models. Do you seriously expect us to believe that you think the question of whether the sun orbits the earth is undecided or undecidable, because in some models it does and in others it doesn't? If that really is your answer, it's the exact same answer the Church gave some 400 years ago and which brought Galileo before the Inquisition.

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I'm not trying to force anyone, and how can I dictate anything? I can't get my Inquisition torture equipment down the internet superhighway. Why can't one question how interesting a topic is? Anyway, you're the one keeping the conversation going, if you find it repellent then stop conversing!

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You're confused again. It's you who finds the conversatin repellant, yet for some reason you keep conversing. I said that what I found repellant is how you set yourself up as arbiter of the things that should and should not be discussed.

I finished chapter 2 of Deutsch's The Fabric of Reality and I think I can describe an experiment that could be constructed to test whether there are parallel worlds or not.

According to Deutsch, when photons interfere in the double slit experiment there are tangible photons and shadow photons involved. The tangible photons are the ones that the experimenter sees and the shadow photons are in the parallel worlds. They only interact to make the interference phenomenon work. Otherwise, they cannot be detected.

What that means is that these worlds must be synced together so that the interference can occur or not occur depending on whether the experimenter opens both slits or covers one of them up. Deutsch claims this about parallel universes (page 51):

It is the explanation--the only one that is tenable--of a remarkable and counter-intuitive reality.

I think Penrose has a way to consider photons being in two places at once without requiring parallel universes, so this is not the only tenable explanation regardless of Deutsch's claim. If Penrose is right, his approach would also lead to a deeper understanding of the universe and not just compound the counter-intuitiveness of reality.

But in any case the many worlder's need an experiment to prove that these other universes exist. I think the following would work.

Shine a single photon through a double slit until it reaches a photomultiplier that will signal a computer to generate a random number. This random number will be the seed to a series of random numbers that will either cover the second slit or open it depending on whether the random number is even or odd. If the slit is covered there should be no interference. If the second slit is open, interference should be detectable. Set up a mechanism to automatically register whether the interference pattern occurred when it was expected to occur or not and look for a situation when the interference pattern was missed. Automate the test so it can be repeated as rapidly as possible to generate many tests results.

If there really are other universes the interference pattern should be missed every now and then. That would be the proof that the many worlds exist although it would contradict the double slit experiment's expected results.

If the interference pattern is never missed the many worlders then need to explain how this counter-intuitive synching process occurs. That would not prove they are wrong, but it would make one wonder what difference it makes to compound a simple counter-intuitive observation with an explanation that is way more counter-intuitive and which cannot be detected by experiment.

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Originally Posted by YesNo

If there really are other universes the interference pattern should be missed every now and then.

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Why? I don't follow your logic here.

Regardless of which interpretation of QM is correct, if any, the wave interference pattern always appears when the experimental setup is right. That's part and parcel of the theory, and if the wave interference pattern failed to appear, QM would be a false theory.

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Originally Posted by Cioran

Why? I don't follow your logic here.

Regardless of which interpretation of QM is correct, if any, the wave interference pattern always appears when the experimental setup is right. That's part and parcel of the theory, and if the wave interference pattern failed to appear, QM would be a false theory.

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I agree with that. If this test actually showed a miss on the interference pattern it would show that QM is false and WMI is correct for some other theory, not QM. The interference pattern should always work correctly if QM is correct.

But if it works correctly, and it involves a syncing with parallel universes, how does this syncing occur? Deutsch doesn't provide any information on that at least so far. What the experiment is trying to show is the existence of these other universes by seeing if the syncing fails occasionally. I'm looking for a validation that these other worlds actually exist that is stronger than Deutsch just insisting it is true.

What evidence is there that these other worlds exist? The interference patterns are not in themselves evidence. They are what one is trying to explain.

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There would also be a concern if the syncing process occurred faster than the speed of light or if these other universes occupied the same space-time location.

If these universes were in the same space-time location so that there is no distance between them, that seems to be as counter-intuitive as claiming a photon can be at two different space-time locations at one time.

If they were at different space-time locations is the information that allows them to sync traveling between the different universes going faster or slower than the speed of light?

I'm not sure what you mean by synching, but just briefly (no time for larger points now), Deutch's evidence is not that he simply "insists that it is true." His evidence is the fact that quantum computation is a physical process that can employ resources many times greater than available to our visible universe. They are real, physical processes involving mass and energy. Where is this stuff coming from, if not from the many worlds? That is his question.

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Originally Posted by mal4mac

Yes, I prefer things that give delight to mechanical understanding.

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Again, I have no problem with that; I'm more of an aesthete than a scientist/logician myself, but I don't confuse my aesthetic preference for the most effective methods of understanding how reality actually functions.

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Originally Posted by mal4mac

The map being close to reality stuff is nonsense

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Why so? It's probably the best metaphor available for describing the relationship between reality and how we understand it: http://wiki.lesswrong.com/wiki/The_m..._the_territory Your recent posts about the different "models" of how the sun/earth revolves around each other is dangerously reminiscent of this: http://lesswrong.com/lw/om/qualitatively_confused/

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Originally Posted by mal4mac

So are sunsets or Picasso's paintings predictive models?

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Neither helps us understand how reality works. They may help us appreciate it, they may help us to see it, feel it, and think about it in different ways, but no experience of natural phenomena or mimetic representation of phenomena is going to aid in answering the questions of how these things work, or why we experience them as we do.

Wikipedia is often justly criticized, but its essay on Many Worlds, which I had never read before tonight, is superb. It is here.

It basically answers all the objections to Many Worlds and emphasizes the point that impresses me: Many Worlds, in actuality, is far less weird than all other QM interpretations; in fact it restores the world to common sense, rather then dethrone it from common sense as QM in its original iterations did.

The article is geared toward intermediate understanding. One must have some understanding of QM and related science issues, but if one does it is non-technical enough to be very understandable.

I also learned some amazing things I did not know. Hugh Everett, way ahead of his time, evidently believed in quantum immortality (don't ask. If you must ask, Google "quantum immortality" and "quantum suicide.")

The most surprising thing is that empirical tests for MWI have actually been proposed, and the idea that there is no relation or communication possible between the parallel worlds is debunked. Indeed, it turns out that if the parallel worlds exist, it may even be possible to send television images between them. :eek:

YesNo I am trying to understand what you have posted.
There is a lot of information there indeed. You are very well read.
If I may take bits and pieces in my own way to make some sense in my head.

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I finished chapter 2 of Deutsch's The Fabric of Reality and I think I can describe an experiment that could be constructed to test whether there are parallel worlds or not.

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About parallel universe this make think this:
If there was a parallel world why are we not able to see it?
We see all the rest of the planets such as the sun the moon and so. If there is such a thing then juxtapositions should be able to reflect the parallelism for us to see.
As far as light is concerned there has to be a reflection. Everything including us have a reflection.

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According to Deutsch, when photons interfere in the double slit experiment there are tangible photons and shadow photons involved. The tangible photons are the ones that the experimenter sees and the shadow photons are in the parallel worlds. They only interact to make the interference phenomenon work. Otherwise, they cannot be detected.

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Why a photon?
How about vibrations. If one is to vibrate an object then there is a movement that we see. That is a parallelogy to a photon silt.
The movement is seen on the computer say whilst the object vibrate. The traces it leads to are the only parallelism there is.
The same with heart beat. A computer picks a graph that is the only parallelism that exist between a phenomena and that is trough movement. Movement creates a visible parallel.
Again the same with music. Hit a note and gives you sound. Read the notes and then make music. A note is a shape. That is again a parallelism.
If you observe sunlight peeking through a window one can see a ray of dusts held again say a screen. That ray of dust particles is the only parallel there is to light.
Light embodies shapes.

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Originally Posted by cacian

About parallel universe this make think this:
If there was a parallel world why are we not able to see it?
We see all the rest of the planets such as the sun the moon and so. If there is such a thing then juxtapositions should be able to reflect the parallelism for us to see.
As far as light is concerned there has to be a reflection. Everything including us have a reflection.

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According to those supporting Many Worlds the after effects of these parallel universes are seen when quantum particles make an interference pattern.

There are two basic ways to explain this interference pattern: (1) a single particle in a single world can be in more than one superposition state at a time, or (2) more than one particle is involved, the one we see and the other "shadow" particles each from a different parallel universe with no superposition for any individual particle.

So, the evidence for the parallel universes is the existence of interference patterns for quantum particles sent through a double slit experiment one particle at a time. The MWI expects an interference pattern to imply that more than one particle was causing the interference on the other which leads to a deterministic explanation. However, the interference patterns are also evidence that quantum particles have superposition states which leads to a non-deterministic explanation.

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Originally Posted by cacian

Why a photon?
How about vibrations. If one is to vibrate an object then there is a movement that we see. That is a parallelogy to a photon silt.
The movement is seen on the computer say whilst the object vibrate. The traces it leads to are the only parallelism there is.
The same with heart beat. A computer picks a graph that is the only parallelism that exist between a phenomena and that is trough movement. Movement creates a visible parallel.
Again the same with music. Hit a note and gives you sound. Read the notes and then make music. A note is a shape. That is again a parallelism.
If you observe sunlight peeking through a window one can see a ray of dusts held again say a screen. That ray of dust particles is the only parallel there is to light.
Light embodies shapes.

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The interference pattern is not restricted to a photon. An electron would work as well as some larger objects, so I've heard.

An isolated system is in superposition.

The universe is an isolated system (there is nothing outside it)

Therefore, the universe is in superposition and evolves deterministically according to the Schrodinger wave equation. Therefore, we get many worlds. In getting the many worlds, we get rid of all the weirdness of quantum mechanics: indeterminism, spooky action at a distance and the inexplicable wave function collapse.

Experimentally, objects as large as Buckyballs and molecules with as many as 240 atoms, according to my latest knowledge, have been placed in superposition in the two-slit experiment. Everything is in superposition all the time, if MW is true, so in theory we could send a superposed person through the two slits, but in practice this could not be done.

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Originally Posted by Cioran

Does the sun actually orbit the earth, or not? You really don't know the answer to the question? I suggest you are being evasive ...

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I don't think I am, you just don't get my "everything is a model" argument. In a plastic model of the solar system does the earth go round the sun. No the little plastic ball goes round the other little plastic ball!

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Do you seriously expect us to believe that you think the question of whether the sun orbits the earth is undecided or undecidable, because in some models it does and in others it doesn't? If that really is your answer, it's the exact same answer the Church gave some 400 years ago and which brought Galileo before the Inquisition.

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The church can have their model if the want, it might not be so usable for sending out moon shots as NASAs, though. The inquisition were a nasty bunch, but some nice people have been attached to an Earth centred model. Are you really trying to argue that because the SI were nasty their model isn't allowed?

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Originally Posted by Cioran

An isolated system is in superposition.

The universe is an isolated system (there is nothing outside it)

Therefore, the universe is in superposition and evolves deterministically according to the Schrodinger wave equation. Therefore, we get many worlds. In getting the many worlds, we get rid of all the weirdness of quantum mechanics: indeterminism, spooky action at a distance and the inexplicable wave function collapse.

Experimentally, objects as large as Buckyballs and molecules with as many as 240 atoms, according to my latest knowledge, have been placed in superposition in the two-slit experiment. Everything is in superposition all the time, if MW is true, so in theory we could send a superposed person through the two slits, but in practice this could not be done.

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One of the things I am having trouble with is the way MWI treats the word "superposition". Deutsch seemed to clarify this for me with the following from chapter 2 of The Fabric of Reality, pages 44-45:

I shall now start calling the interfering entities 'photons'. That is what they are, though for the moment it does appear that photons come in two sorts, which I shall temporarily call "tangible" photons and "shadow" photons. Tangible photons are the ones we can see, or detect with instruments, whereas the shadow photons are intangible (invisible) -- detectable only indirectly through their interference effects on the tangible photons. (Later, we shall see that there is no intrinsic difference between tangible and shadow photons: each photon is tangible in one universe and intangible in all the other parallel universes -- but I anticipate.)

What this means to me is that superposition is not at the level of the states that a single particle could have, but is a way to represent the superposition of worlds. In the MWI view each particle can be in only one state.

There is a problem with associating a probability with each particle's state. I think you attempted to resolve that by increasing the number of worlds so there are 30 worlds to represent 30%. That seems very arbitrary. The probability value could have an arbitrarily large number of decimal points. So you would need infinitely many worlds just to represent that number accurately--for each item you measured!

Without accuracy the determinism falls apart. Of course, in practice, we can use approximations, but MWI is claiming that reality is deterministic, so those infinitely many worlds for each measurement would have to exist for their position to be correct.

I am amazed to what extent people will go to keep determinism. It isn't worth keeping.

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Originally Posted by mal4mac

I don't think I am, you just don't get my "everything is a model" argument. In a plastic model of the solar system does the earth go round the sun. No the little plastic ball goes round the other little plastic ball!



The church can have their model if the want, it might not be so usable for sending out moon shots as NASAs, though. The inquisition were a nasty bunch, but some nice people have been attached to an Earth centred model. Are you really trying to argue that because the SI were nasty their model isn't allowed?

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Laugh out loud.

You just really can't stand to admit that you are wrong, can you?

Does the sun orbit the earth, or not?

As to "SI." I don't know what you mean by that. Whatever "SI" is, to argue that because "SI" (whatever that is) is nasty, SI's model "isnt allowed," is to commit the logical fallacy of ad hominen. Nothing that I would do, but that is something surely that you might do.

Does the sun orbit the earth? Are you able to answer the question?

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Originally Posted by YesNo

I am amazed to what extent people will go to keep determinism. It isn't worth keeping.

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Yet again, determinism is not a precondition of the Many Worlds interpretation. It is a consequence of it. If it so happens that determinism is rendered false in any interpretation of reality, then this fact (if it is a fact) does not impeach the Many Worlds interpretation. It just means that whether MWI is true or not true, determinism is false. What MWI does is restore classical determinism. If it so happens that classical determinism turns out to be false, then it is false regardless of whether MWI is true, and so has no bearing on the truth or falsity of MWI.

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Originally Posted by mal4mac

Are you really trying to argue that because the SI were nasty their model isn't allowed?

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I wanted to return to this again, to stress the point:

Please point out where I have committed a classic ad hom argument, as charged above. If you can't point out where I have done so, please retract the charge and apologize for making it.

Spoiler alert: I've made no ad hom argument, and you won't retract your charge that I did, nor will you apologize for your false charge.

Now, I'd like you to answer the following question:

Does the sun revolve around the earth?

Sorry, I had to make it big and bold, to counter your weaselly evasiveness.