QM Many Worlds Interpretation

[BenTheMan]

Having read Einstein's pronouncements concerning Special Relativity ad nauseum, I am totally perplexed to try to remember where, in all his illustrious texts, he predicted that Special Relativity predicts an infinite number of reference frames.

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.

 

[RJBeery]

Anyway here's what wiki has to say...

Ahh I see. Let me guess...this is what wikipedia says?

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:

each element of which contains a definite observer state and a corresponding system state

...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.

there is no single unique state of the observer

...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:

 

[BenTheMan]

Quick one, you.

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.

In other words, each system state is as I said "complete and real".

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

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.

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?

...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?

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?

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.

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.

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:

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.

 

[quadraphonics]

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.

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

In addition, I'm not convinced that this definition is self-consistent.

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.

And if a single observer has multiple states, what is the definition of observer exactly?

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

We certainly are not able to "observe" more than one state of ourselves or anything else

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.

 

[RJBeery]

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.

"Complete and real" means that any aspect of the Universe is measurable (without giving a superpositional answer).

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

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?

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".

 

[BenTheMan]

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".

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.

 

[BenTheMan]

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).

 

[quadraphonics]

If you insist on using the word "worlds", one could say that each of the worlds is disconnected from each other.

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

 

[RJBeery]

The wavefunction is not observable.

Everett says each element is observable.

no one observer can observe the entire wavefunction.

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.

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.

I agree, it is obvious.

At the measurement event which would traditionally be called the "wavefunction collapse", we now have two completely divergent worlds

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.

 

[BenTheMan]

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

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

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.

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

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.

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.

 

[RJBeery]

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.

I and others are offended because you think critically, make a mistake, and then refuse to admit that you're wrong, even when shown the proper logic, or told the correct answer by someone who HAS put in a life commitment to answering these questions.

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

No. You don't understand the basics, so how am i supposed to argue with you?

This is just because of your ignorance of basic quantum mechanics

Ahh I see. Let me guess...this is what wikipedia says?

your argument is based on an incomplete understanding...

Berry, all I see you do is make claims about theories you don't know about. QM, SR and now GR. Put a sock in it.

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!).

 

[BenTheMan]

Measuring it would not be a problem but the answer depends upon whether you believe in MWI.

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.

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.

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

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.

and

My resolution to this is that matter does not actually cross the horizon, ever. Call it a "throw away" comment if you wish but I'm willing to bet I'm not the first person in the world to think of it.

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.

 

[RJBeery]

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.

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!

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.

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...

 

[BenTheMan]

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.''

 

[RJBeery]

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.

 

[BenTheMan]

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

 

[RJBeery]

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.

 

[RJBeery]

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.

A Universe from Nothing


Mercury, Mar/Apr 2002 Table of Contents

Universe from Nothing
Courtesy of AURA/NOAO/NSF.

by Alexei V. Filippenko and Jay M. Pasachoff

Insights from modern physics suggest that our wondrous universe may be the ultimate free lunch.

Adapted from The Cosmos: Astronomy in the New Millennium, 1st edition, by Jay M. Pasachoff and Alex Filippenko, © 2001. Reprinted with permission of Brooks/Cole, an imprint of the Wadsworth Group, a division of Thomson Learning.

In the inflationary theory, matter, antimatter, and photons were produced by the energy of the false vacuum, which was released following the phase transition. All of these particles consist of positive energy. This energy, however, is exactly balanced by the negative gravitational energy of everything pulling on everything else. In other words, the total energy of the universe is zero! It is remarkable that the universe consists of essentially nothing, but (fortunately for us) in positive and negative parts. You can easily see that gravity is associated with negative energy: If you drop a ball from rest (defined to be a state of zero energy), it gains energy of motion (kinetic energy) as it falls. But this gain is exactly balanced by a larger negative gravitational energy as it comes closer to Earth’s center, so the sum of the two energies remains zero.

The idea of a zero-energy universe, together with inflation, suggests that all one needs is just a tiny bit of energy to get the whole thing started (that is, a tiny volume of energy in which inflation can begin). The universe then experiences inflationary expansion, but without creating net energy.

What produced the energy before inflation? This is perhaps the ultimate question. As crazy as it might seem, the energy may have come out of nothing! The meaning of "nothing" is somewhat ambiguous here. It might be the vacuum in some pre-existing space and time, or it could be nothing at all – that is, all concepts of space and time were created with the universe itself.

Quantum theory, and specifically Heisenberg’s uncertainty principle, provide a natural explanation for how that energy may have come out of nothing. Throughout the universe, particles and antiparticles spontaneously form and quickly annihilate each other without violating the law of energy conservation. These spontaneous births and deaths of so-called "virtual particle" pairs are known as "quantum fluctuations." Indeed, laboratory experiments have proven that quantum fluctuations occur everywhere, all the time. Virtual particle pairs (such as electrons and positrons) directly affect the energy levels of atoms, and the predicted energy levels disagree with the experimentally measured levels unless quantum fluctuations are taken into account.

Perhaps many quantum fluctuations occurred before the birth of our universe. Most of them quickly disappeared. But one lived sufficiently long and had the right conditions for inflation to have been initiated. Thereafter, the original tiny volume inflated by an enormous factor, and our macroscopic universe was born. The original particle-antiparticle pair (or pairs) may have subsequently annihilated each other – but even if they didn’t, the violation of energy conservation would be minuscule, not large enough to be measurable.

If this admittedly speculative hypothesis is correct, then the answer to the ultimate question is that the universe is the ultimate free lunch! It came from nothing, and its total energy is zero, but it nevertheless has incredible structure and complexity. There could even be many other such universes, spatially distinct from ours.

I was about to concede the point but it occurred to me: the total energy of the Universe is not *quite* zero!

The idea of a zero-energy universe, together with inflation, suggests that all one needs is just a tiny bit of energy to get the whole thing started (that is, a tiny volume of energy in which inflation can begin). The universe then experiences inflationary expansion, but without creating net energy.

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.

 

[RJBeery]

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.

 

[Pandaemoni]

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.

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.