# QM Many Worlds Interpretation

Discussion in 'Physics & Math' started by RJBeery, Mar 10, 2009.

1. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

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This is off-topic, but the Lorentz factor $\gamma$ is a continuous parameter, which means an observer can be boosted by any velocity between 0 and c.

3. ### RJBeeryNatural PhilosopherValued Senior Member

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Quick one, you.

Not that it matters who's defining what; I'm open to discuss any definition as long as it is made clear. Everett wrote:
...as should be obvious to any intellectually honest person. In other words, each system state is as I said "complete and real". I maintain that this definition still requires an infinite and constant source of energy to represent these additional "wavefunction states" because, unlike the traditional quantum wavefunction, this uberwavefunction has states which are tangible and represented by a reality which contains that energy.

In addition, I'm not convinced that this definition is self-consistent.
...yet he goes on to say that each element of the uberwavefunction contains an observer with a definite observer state. Does the observer have a state or not? If Everett's point was that each observer had multiple states then his use of italics should've been on the word SINGLE rather than the word STATE. And if a single observer has multiple states, what is the definition of observer exactly? We certainly are not able to "observe" more than one state of ourselves or anything else...:bugeye:

5. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

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You expect me to remember every post in this thread? Maybe you don't have better things to do that memorize your old posts, but I surely do.

You never defined what you meant by complete and real'', so I don't know.

This is just because of your ignorance of basic quantum mechanics, I think. The wavefunction is not observable. So in what sense can one have an infinite amount of energy?

This is the same as saying that an electron has no definite spin state, but all spin states are described by the wave function. The wavefunction of an electron describes both a spin up and a spin down electron. Does the electron have a state?

Now you're nitpicking. His emphasis on the word state indicates the quantum nature of the observer---once the observer observes the particle,the observers wave function becomes entangled with the particle. There is no wavefunction collapse.

Again you're falling into the trap of forcing your classical intuition into places where it doesn't belong (you do this a lot). The observer can be another electron, for example, then there is no conceptual problem with the state'' of the observer.

Observation in the Copenhagen interpretation is described by the collapse'' of the wavefunction. In Everett's interpretation, it's described by a discretium of possibilities.

7. ### quadraphonicsBloodthirsty BarbarianValued Senior Member

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Total nonsense. There is nothing special about the wavefunctions in MWI. They are just like the wavefunctions under any other interpretation.

Likewise, nobody else is convinced that you even understand the definition in the first place. And so your criticisms of it aren't very compelling.

The same as the definition of anything else in MWI. An observer is a quantum subsystem that becomes entangled with another subsystem (the observed).

Exactly. That's why it's called Many Worlds Interpretation. The entire idea is to explain how we end up observing a single, definite world line, without using the idea of wavefunction collapse.

8. ### RJBeeryNatural PhilosopherValued Senior Member

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This isn't a long thread. Please read my posts if you want to participate, especially the ones that are directly responding to you.

Wait right there. Everett says that each element possesses a definite system state. We are an element of Everett's "uberfunction". We are not observable? The uberfunction differs from the typical quantum wavefunction in that it has elements of measurable reality, while the quantum wavefunction does not. It is the quantum wavefunction that is not observable. You can't have it both ways, saying that the uberfunction represents all of reality but when it comes time to "pay" for that reality in terms of energy then the uberfunction "isn't really there".

9. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

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No. You don't understand the basics, so how am i supposed to argue with you? Everett says each element is observable. This does Not mean that every element is connected to every other element, in the sense that one state "knows" what is going on in the other states. If you insist on using the word "worlds", one could say that each of the worlds is disconnected from each other. this should be obvious if you think about it for a bit.

10. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

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said another way, no one observer can observe the entire wavefunction. again, this is obvious if you read everetts paper (whose whole text is linked at the bottom of the wiki article with which you are familar).

11. ### quadraphonicsBloodthirsty BarbarianValued Senior Member

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Or, better, say that they are decohered from each other.

12. ### RJBeeryNatural PhilosopherValued Senior Member

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The ball still seems to be moving again, but ok; maybe you're refining your own understanding. If any portion of the wavefunction is observable then that is sufficient to say that the observed element has diverged (or decohered as you said) from other possibilities.

I agree, it is obvious.
Now that we agree that have two divergent worlds, unrelated by any unitary cohesive wavefunction, we must now have twice the mass-energy to represent those worlds. That is my argument.

Is it impossible that the multiverse has a source of constant and infinitely unlimited power to generate each of these infinite elements of the uberfunction? No, it is not. Reality could be that strange, but I doubt it.

13. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

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Yeah I don't understand decoherence as an interpretation of quantum mechanics.

No. Every element of the wavefunction in it's own separate world''.

Your argument is I don't understand it, therefore, it is wrong''.

If there is twice the mass-energy'', you should be able to tell me how you plan on measuring it.

14. ### RJBeeryNatural PhilosopherValued Senior Member

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Measuring it would not be a problem but the answer depends upon whether you believe in MWI. Estimate the mass-energy of our perceived Universe, then run a photon through a half-silvered mirror. Now double your calculation if you're an MWI advocate.

Hawking actually makes the case that the mass-energy of the Universe is zero if you consider gravity fields as negative energy. I need to chew on this more to understand it better, but it appears to be a decent counter-argument to my infinite-energy objection of MWI. It's a pity you missed it.

OK, now I have to address something that's bugging me.

Your insistence that I "don't know anything" gets tiring, Ben. It's almost like any statement I make must be wrong because I'm not a Physicist. Attacking me is not an argument, and I'm not impressed with it. I'm a little confused why these discussions are "arguments" in the first place, rather than an intellectual exchange of ideas. Actually, I suspect I know the reason and it has to do with fragile egos (...Numeric Alphadog! and Ben "The Man" Pwner of Physics!).

15. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

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Ok, then tell me how you'd measure it. Design an experiment that would disprove the Many Worlds Interpretation by measuring this infinite Mass-energy'' that you claim exists.

So, then, are you done talking about physics?

You are the worst kind of ignorant RJB---not only do you not know what you're talking about, you don't know that you don't know what you're talking about. And what's worse, you don't even understand the correct answers when they're presented to you. Crackpots like you are so self-centered---you can't imagine how anyone could possiby be as insightful as you. Comments like

and

showcase this. Do you think that in 50 years of quantum theory since Everett, or in the 93 years since Schwarzschild's paper on black holes that NO-ONE had thought of this? Give people some credit man---I don't know how smart you are, or how much you've thought about these problems, but I guarantee you that I know people who are smarter, and who have thought about these problems more than you have.

So show me how smart you are. Your prediction is that the Many worlds interpretation predicts an infinite amount of mass-energy'', a term which you haven't defined. Tell me how to measure it.

16. ### RJBeeryNatural PhilosopherValued Senior Member

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Wow Ben did you even read my full post? First, I never said infinite mass-energy exists because I don't subscribe to MWI. I said MWI was hard for me to accept because (actually if) it required infinite mass-energy. Then I presented an argument by Hawking that claimed even with an infinite number of worlds the mass-energy would still be zero, effectly negating my own objection. I was suggesting an argument against my own objection!

Wow Ben do you read ANY of my posts? I linked to a paper reviewed and accepted by Physics Review D along with 3 popular media summaries of the paper that described exactly how the concept of matter never crossing the horizon would take place, HERE and HERE. I said I would be surprised if I was the first who had ever thought of it, and I provided an example showing that I was right.

Now you fall back on your argument that I MUST be wrong, not because I'm not a Physicist, but because these problems have been worked on for 70+ years and someone else would've thought of it first if it was true? Jesus...

17. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

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You came to the (erroneous) conclusion that the many worlds interpretation predicted an infinite amount of mass-energy''. I pressed you on that conclusion and your response is I don't believe that the many worlds interpretation is right, therefore I don't have to answer your question.''

18. ### RJBeeryNatural PhilosopherValued Senior Member

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No. I stand by my assertion that if a single "world" or "universe" or "element of Everett's uberfunction" (or whatever you call it) has a non-zero mass-energy then the MULTIVERSE comprising ALL of Everett's "uberfunction" would indeed require an infinite mass-energy. I had assumed that estimating the mass-energy of the Universe would not be an barrier needed to be hurdled in this conversation. I assumed it could be done fairly easily. I will look more into it tomorrow if you're going to hang your hat on this issue, but the calculation doesn't need to be made - call the mass-energy "100 BenTheMan units" and my point still holds; it doesn't matter as long as it is non-zero. The point may be moot, though, because Hawking believes that the mass-energy of our observable Universe is zero if you consider gravity as a negative energy field.

Frankly this conversation is a little surreal. I give you an objection to MWI, you give me nothing, I give you a counter-argument to my own objection, and you demand that I "prove" a trivial point of my original objection which I had already potentially found a problem with. Forgive me if I feel you are just being argumentative.

19. ### BenTheManDr. of Physics, Prof. of LoveValued Senior Member

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What is it you are arguing, RJB? Now you believe Hawking?

20. ### RJBeeryNatural PhilosopherValued Senior Member

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Yes, I believe Hawking that if you consider gravity as negative energy then the mass-energy of the Universe is zero. This MAY, but not necessarily, defeat my infinite-energy argument against MWI. I'm thinking about it and will post a thought tomorrow.

21. ### RJBeeryNatural PhilosopherValued Senior Member

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Ben: OK, since you asked, here's how one could in theory measure the mass-energy of the Universe:

Since mass-energy (aka relativistic energy) is frame dependent, we shall define a system's "true" (for purposes of this discussion) mass-energy as its minimum mass-energy. We shall do this by taking the measurements from the system's center of momentum, which effectively eliminates the system's total linear momentum.

Now calculating the mass-energy of the system is as simple as using its rest mass in E=mc^2. We can estimate its rest mass in any number of ways, but I've seen estimates ranging from 10^53 kg to 10^60 kg. Nevertheless, it is agreed that the mass is greater than zero, hence the mass-energy of the Universe is greater than zero. A mass-energy of the Universe greater than zero is the only requirement that my "infinite-energy objection" to MWI is valid. (As I am reviewing this thread it appears that quantum_wave voiced an objection that is very similar, if not identical, to this one.)

But wait! As I discovered yesterday, this positive mass-energy is able to be reduced back to zero if one associates gravity with 'negative energy'. At this point I thought my objection held no merit. I'm posting a truly excellent summary of the zero-energy Universe that I found today.

I was about to concede the point but it occurred to me: the total energy of the Universe is not *quite* zero!
There is a minuscule amount of energy required to begin the inflation itself which, in the context of a single Universe, is insignificant. However, in the context of infinite Universes, reintroduces my objection! In other words, a quantum fluctuation produced a very small ripple in space-time which effectively caused the inflationary Universe. The parity of the particle-antiparticle annihilation is only present in the "original" or "first" Universe which exists before quantum effects allegedly begin their infinite Universe birthing. The minuscule energy imbalance would then be duplicated across each of the infinite number of Universes allegedly being constantly created by MWI.

22. ### RJBeeryNatural PhilosopherValued Senior Member

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By rough analogy, my objection is similar to throwing a single rock in a still pond, and then multiplying the pond's existence many times over, creating waves with a cumulative total wave energy many times more than the energy produced by that rock entering the water. The only way conservation of energy holds is the if action of the rock dropping into the pond is itself also duplicated. However, these new ponds (or "worlds") are created at points in time after which this has happened.

23. ### PandaemoniValued Senior Member

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Energy is conserved in a closed system, but this is a very open system. I take your point that the multiplication of universes seems to require vast amounts of energy coming from "nothing" but we are arguing angels on the head of a pin here. There is no physics that constrains this process that we know of because physics can only be applied with any belief in its accuracy within a universe. Physics is based on observation, and our observations are always made within a single universe. They cannot be expected to hold true at the level of a multiverse because they are empirically derived.

Imagine you lived in Flatland, I may invest a theory that explains that there is a mysterious "third dimension" and you might not believe me because your empirically derived rules only work in two-dimensions. There, it would be clear that the failure is with the rules being insufficiently generalized, not with the theory of third dimension being wrong.

Many worlds sidesteps the problem officially by positing universes springing orthogonally from a root. Within any one of them, conservation of energy holds, but not amongst them all taken together.