fleshing out the Many Worlds Interpretation

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fleshing out the Many Worlds Interpretation

Postby hyksos on May 12th, 2018, 11:17 pm 

Many Worlds Interpretation MWI

The Many-Worlds Interpretation of quantum mechanics is not going away quietly into the night. It is, in fact, gaining more young adherents on campus at each passing year. Sitting in the corner pouting is no longer an option in defeating this mathematical ideology. We must prepare for war.

The military strategist, Sun-Tzu, told us that to defeat your enemy soundly, you must know him like you know yourself. We will prepare our legions against MWI by first getting deeply into their mindset. When we finally encounter them in open battle, we will be able to cut them off at any pass their arguments may lead.

I will build a bridge into the MWI mindset by laying out a number of binding axioms that the Many-Worlder subscribes to , prior to them laying out their final claim. That "Final claim" looks roughly like : "There are copies of every desk, tree, leaf, rock, water droplet, animal, car, and human in a plurality of co-existing physical realities". Those additional physical "realities" are , rest assured, as identically real as the one you experience now.


deutschliterallytrue.png

David Deutsch, a famous Many-Worlder. Their way of looking at things suggests the raw equations of QM literally imply MWI without the addition of extra metaphysical baggage. Notice he says "literally true".


  • The world is a giant wave. The crux to understanding the world as a "universal wave function" is the peculiar way in which waves interfere with each other. If two waves are traveling down a taught string, upon meeting at the same location, they will constructively interfere "add together". Or if a peak meets a trough, they will destructively interfere "cancel out". Image
  • Wave Interference is weird. Wave Interference challenges our traditional notions of "materiality". Unfortunately, this GIF does not contain destructive interference (cancelling out). But it is indicative of the basic gist of where I'm going. When peak approaches trough they begin to cancel, and for a vanishing moment both waves completely disappear. A very moment later they reform again. This is the way to really understand physical reality. A thing need not be present/extant to exist. This type of cancelling-out is found all over physics, even for example in two really large forces both acting against each other at the same time and "cancelling out" creating motionlessness.
    littleinterferers.png



  • The Universal Wave Function is continuous in space. The wave function is not a local desciption of an isolated object. (it's not just located inside an atom). The universal wave function is everywhere .. like everywhere in the universe. Furthermore, it does not have discontinuities in it anywhere. There is no special boundary where the UWF stops, and restarts at a different value. Because of this assumed continuity, a consequence of QM is entanglement. Measuring an entangled photon at a distance from its partner, will necessarily cause the partner to collapse into an eigenstate. This is not magic -- it follows naturally if you declare that the Universal Wave Function has no discontinuities in it.
  • The Universal Wave Function is continuous in time. THe UWF is not just continuous in all space, but is continuous with its previous configurations in time. The UWF extends into the past, (and more woo-woo ) extends into the future. One consequence of this is something called a Delayed Choice Quantum Eraser. If I may describe this thing very briefly without creating more confusion. Imagine we have measured Alice's photon, and got a particular state from it. Bob's photon then collapses and no longer produces an interference pattern. (That's expected from entanglement. Check.) If we then erase the information we just learned bout Alice's photon, what happens to Bob's photon? In other words, once collapsed, always collapsed? For a person who understands the Universal Wave Function, you already have your answer to this question. The universe will literally make Bob's photon go back into a superposition and form an interference pattern. That is to say, if you destroy the information you had about Alice's photon, then the UWF will "go back in time" and change the past in order to act as if you never measured Alice's photon, and then make it a reality that Bob's photon is not collapsed either. Yes -- this has been demonstrated in controlled laboratory conditions. The reason your psychology recoils from this being impossible or untrue, is likely because you are not properly visualizing the Universal Wave Function as being "everytime" in time.
  • There are no Observers. The Copenhagen Interpretion of QM reigned supreme in the early decades of the development of QM. It still had a strong contingency on campuses up to the late 1980s. Observers were traditionally considered distinct entities from the physical systems being examined in labs. This thinking will need to be dispensed with. Now instead of several separate systems, you must consider a giant system composed of (Apparatus , Observer , Environment). Now the UWF is continuous amongst all three of these formerly distinct realms. There is now "one big wave function" describing an observer looking at a system while they are both in a "heat bath" of the surrounding environment.
  • Measurement is replaced by Decoherence. Since we eliminated the Observer as a special system, and bound him into the UWF, as a consequence, there can be no more "observations". There are no observers to do observing. Copenhagen had a magical moment of "scientist measures the photon". No longer. Now we say that the portions of UWF have "decohered" and whenever that happens. Decoherence may or may not refer to a scientist doing something. Scientists are as much part of the UWF as any other object in the lab -- or the lab itself. Or the earth... (or etc).

These are the basic axioms to start with. Once we start stirring the ingredients together in a large mixing bowl, the Many-Worlds Interpretation will materialize .. very soon below.

We have this basic problem that the objects in the world around us, all energy and all matter are built up out of fundamental particles. But those particles don't act like classical objects. They act quantum mechanically. So how is it that the world we humans observe from day-to-day is so consistent, so mechanical, and so regular looking? The world I live in while driving in traffic, things are in a particular location at all times and have a particular velocity and don't teleport. I don't see spoons and desks and trees in "Two positions at once". I don't see semi trucks "Go both ways" and "interfere" with themselves. Fundamental particles do all this and more.

So what gives?

MWI provides an answer to this question.

Consider a coffee cup on a table. That big object is always at a certain place. It acts mechanically. It is where it is. But it is also composed of fundamental particles who don't play by those rules. So why does big human see the coffee cup in a particular location? MWI says that an enormous plurality of different versions of the cup exist in a branching tree of "realities". There are lots and lots of various copies of that cup all in slightly different positions in each of the "realities". All the cups are real. You see your cup in particular location only because that is the 'branch' you rode on the Tree of Many Worlds.

The next question that should be begged is : Okay but why did I ride that branch of reality instead of the other ones?

MWI answers: There are copies of you also. It is not the case that you see a particular coffee cup position , but that you are a particular copy of you in all the reality branches. There are "other yous" in the other branches, all experiencing an entanglement with some-or-another version of the copies of the cup. There exists a you "out there" in the Universal Wave Function who is literally seeing the cup somewheres else.

MWI insists --- requires -- that these copies of you and the copies of the coffee cup are as equally physically real as you are.


{{ Intermission Music }} {{ Court is in recess. Giving the reader some time to digest and mull over what you just read. }} Go outside and take a long walk alone. Meditate on the above ideas.

Now What?
A few words on psychological recoil. Perhaps MWI is the ponderings of nutty professors on the edges of academia, who have wild hair and clothing that doesn't quite match and been relegated to the "corner office" at the end of the hall. Perhaps MWI can be safely ignored for that reason. Tonight you can rest your head on your pillow and sleep like a baby, without having nightmares about copies of yourself in a billion other realities.

Unfortunately this is not possible anymore. 65% of the students in the physics department believe this is actually happening. Pouting and denial are not viable ways proceed.

In the realization that you now have to confront this wacky theory, you might "man up" and want to know why the (bloody hell) do these physicists believe this? Where are they getting this "branching" from?

To gain insight, I point the reader back the Universal Wave Function, the UWF, and how it is continuous in both space and time. There are no "walls" that stop it. While waves pass by each other, interact, cancel out, and so on, they do not vanish, are never destroyed. Waves keep going. Portions of these waves ARE the other realities --- the other "worlds" if you prefer. In a geometrical/mathematical sense, they must exist, as we exist, because the alternative would be some kind of selective erasing of those portions of the wave.


As the waves passes by each other, they "entangle" and their individuality erodes. When the waves get knocked around by an outside environment, their histories diverge, and they become separate entities again, in a process called Decoherence. This is why when a big scientist probes a quantum system, it loses superposition, and adopts an eigenstate. The scientist is playing the role of the "big environment out there" disconnecting the photon from its prior entanglements.

You might then ask what performs the association between copy-of-me with copy-of-cup in a 1-to-1 mapping. The answer again has to do with the geometry of waves. What is observed in a system must be so-called "non-commuting observables". The reason is because the alternative is incoherent in terms of how waves are shaped in higher dimensions.

But why do I, the person that I am, experience that cup there? (It may feel like this has not been resolved completely).
MWI_Im_special.png

We feel special. All of us do. But in MWI, there is another copy of you feeling just as special as you do; a copy of you in another World asking the same questions and feeling the same emotions. Your copy perceives the cup in a slightly different position than yours appears.
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Re: fleshing out the Many Worlds Interpretation

Postby mitchellmckain on May 13th, 2018, 3:26 pm 

In the following, I am using a light colored font for the portion which is purely philosophical (or even theological) rather than scientific and these may be entirely ignored as completely meaningless if you so choose.

I am neither an advocate nor an opponent of the Everett interpretation. I happen to think it is entirely compatible with the Copenhagen interpretation and even helpful in fleshing it out. The thing is, that these proposed other worlds are no more physical than Santa Claus. Now that might sound like I am disparaging it until you know that I am a theist and acknowledge that the same can be said of this God I believe in. So instead, I am saying that you CAN believe in Santa Claus and in an endless branching of possible worlds, and I will defend the rationality of this along with both theism and atheism.

Why should I oppose the MWI when the fact is that this is a huge victory for the libertarian. It is saying that saying that the all the endless possibilities of life are completely REAL. In some ways the difference from the Copenhagen interpretation is little more than semantics. In Copenhagen interpretation the future is a superposition of possibilities and then a decision is made and only one of them becomes real while the rest of them vanish. This is not so different from the Everett interpretation where these other possibilities branch off into universes which we (the version of us who belong to this particular branch) cannot see, touch, or measure in any way.

Now some might argue that these other worlds are physical. But that also is a matter for semantics. For what I mean by saying they are not physical is that they are not measurable by those of us in this branch of the superposition, and this is the case because it would contradict the very mathematics of the MWI which has the superposition expanding to encompass the observer. To measure these other worlds would mean merging with other components of the superposition and there is nothing in the math/physics to even suggest such a possibility.

So are these other worlds real or not? In that regard I am pretty much an indifferent agnostic: "what difference does it make when this cannot possibly have any impact on our lives?" Well... I suppose you can answer this with the arguments I might use in response to indifferent agnosticism with regards to God. The knowledge/belief in the existence of these things can make a difference in how we think and live our lives. So I guess it just matters whether you personally see an advantage in thinking this way. But then there is the atheist response that such an advantage only supports using such a belief as a pragmatic tool of the mind, which we can use as far at it is useful and yet remain disbelieving in spite of this.
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Re: fleshing out the Many Worlds Interpretation

Postby Watson on May 13th, 2018, 8:28 pm 

I don't wish to comment, but would like it to come up in "My Posts" so I can follow along. Carry On.
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Re: fleshing out the Many Worlds Interpretation

Postby hyksos on May 15th, 2018, 6:04 am 

Now that the intellectual stage is set, we can start going to work poking holes in the MWI.

One of the first obvious questions would be, if there are so many billions of simultaneous worlds, how exotic or different do they become in practice as they branch?

For example, is there a "branch World" somewhere out there where the earth is very different from the one we see? If yes, how different is it? Is there a planet in one of the branches that is occupied by flying unicorns? It's certainly a worthy question. The answer is resounding no. Unfortunately, there is no planet occupied by magical talking ponies, and no planet like that would be found anywhere in the large branches caused by the Universal Wave Function branching off into worlds.

How do we know?

Classical Superselection

Classical Superselection may not be a word the reader is familiar with, and I point anyone towards the primary literature on the topic. Something is always crucially lost in the translation to a synopsis, but bear with me. C-S is basically a collection of rules where nature prohibits the formation and sustenance of a superposition among some property. These are very interesting and more so eyebrow-raising .

  • Charge. Nature does not allow any particle to take on a superposition of negative and positive charge.
  • Mass. Nature does not allow any particle, nor a collection of particles, to occupy different masses at the "same time". In other words, mass does not go into a superposition, ever.
  • Total angular momentum. Take particle, or a system of them bound in an atom. That system's total angular momentum will never be seen in a superposition, and nature will prohibit you from forming interference patterns using it.
  • Fermionic/Bosonic Nature prohibits particles from being in a superposition of Fermion and Boson at the same time. (there are exceptions which I will not digress into at this time. They exceed the scope of this thread.)

Okay that's nice and all --- but what does all this have to do with flying unicorns that talk? Well, consider a particle of of charge c, mass m, angular momentum L, and it is a fermion. More specifically consider we found such a particle in our "branch" of the multi-world of realities , presuming MWI.

Riddle me this: If we jumped to a distant branch in the Many-Worlds and found that same particle again, what would we find there?

Classical Superselection demands the answer: We would see a fermion of charge c, mass m, and angular momentum L. And what if we then jumped branches to another World/Reality and found our particle there. What then? WE would again see a see a fermion of charge c, mass m, and angular momentum L. Jump again. Same thing. In fact , anywhere we jump/slide into any of the various branches of the Everettian Multi-verse, we always see that particle with (c,m,L) exactly the same in all of them.

Now sure, we might see our particle with a different spin state in a different world. WE may see it at a slightly different position. If it were an electron, it would be perhaps, occupying a different atomic orbital. Fine. Despite the quantum tomfoolery , it will always be a negatively-charged electron with the same mass and same angular momentum regardless.

This has huge implications for whether or not we would find flying magical ponies in another branch of the multiverse. We would not. The restrictions on superposition are equal-parts restrictions on possibilities in other worlds, and the restrictions are quite rigid in many places.

The MWI branches on certain things yes. But there is a whole laundry list of things is does not branch on. That's kind of peculiar and all-too-convenient. The "laundry list" is basically called Classical Superselection Rules by arrogant grad students and their distinguished colleagues.

Quantum Zeno Effect
continuing in our one-two punch to the face of MWI, we turn to the quantum Zeno effect. We have established that while worlds branch, they don't ever branch too far from what we experience. Then we might ask, that if they could branch will they branch? Once branchable always branchable?

Well.. no. If an electron could possibly be in a superposition between Spin UP and Spin Down, must it definitely be in a superposition of Spin Up and Spin Down? Again, no. It turns out that scientists can stop a particle (or atom , or system) from going into a superposition by constantly and repeatedly measuring it. This suppression mechanism is called the Quantum Zeno Effect

So not only do the Branching Worlds of MWI never fall "far from the tree" the act of branching itself can be suppressed in labs. The branching can be suppressed by human scientists... or grad students, or even in a lab at a community college.

At this point, the MWI is looking less and less like some sort of profound Buddhist-mystical approach to cosmic existence --- and its beginning to sound more like some story a used car salesman is trying to work over on you.

"The MAny-Worlds Intepretation of Hugh Everret is so profound and deeply indicative of the nature of existence. It means we can time-travel and have Free Will and travel around the galaxy in a spaceship and cure cancer and talk to other Beings in different univ---"

Stop right there. That type of thinking, while seductive, should have been thrown cleanly out the window a few paragraphs ago.

Collapse Theories

There are other interpretations of Quantum Mechanics, learning them will strengthen you from being seduced by MWI's quasi-mysticalism. Quantum Zeno effect came up in other threads on this forum (somewhere). Personally, I am an advocate of G.O.C. ("Gravitational Objective Collapse").
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Re: fleshing out the Many Worlds Interpretation

Postby Watson on May 15th, 2018, 3:49 pm 

Personally I have never thought the MWI made much sense in the real world. So I'm fine with any and all of the above. But even with rules governing when and how often there is bifurcation, there are infinite number of Universes developing into, and existing in "something"? What are they made of?

A Universe can not just drift off, equally into two different dimensions, or realities without some mass/energy losses, or at the very least a detectable fluctuation. So, No, not buying it.
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Re: fleshing out the Many Worlds Interpretation

Postby hyksos on May 17th, 2018, 2:20 am 

So are these other worlds real or not? In that regard I am pretty much an indifferent agnostic: "what difference does it make when this cannot possibly have any impact on our lives?" Well... I suppose you can answer this with the arguments I might use in response to indifferent agnosticism with regards to God. The knowledge/belief in the existence of these things can make a difference in how we think and live our lives. So I guess it just matters whether you personally see an advantage in thinking this way. But then there is the atheist response that such an advantage only supports using such a belief as a pragmatic tool of the mind, which we can use as far at it is useful and yet remain disbelieving in spite of this.

I don't mind the idea of a coffee cup being in a slightly different configuration of its molecules. Maybe those coffee cups all 'exist'. Or more palatable : a photon has a doppleganger that took a different path in an optics lab. The existence part is not really what hangs me up about MWI.

It is this idea that there are identical copies of me that is very distasteful. Does this mean that every choice I could have made in life, was actually made by one of my copies?
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Re: fleshing out the Many Worlds Interpretation

Postby mitchellmckain on May 17th, 2018, 2:53 am 

hyksos » May 17th, 2018, 1:20 am wrote:I don't mind the idea of a coffee cup being in a slightly different configuration of its molecules. Maybe those coffee cups all 'exist'. Or more palatable : a photon has a doppleganger that took a different path in an optics lab. The existence part is not really what hangs me up about MWI.

It is this idea that there are identical copies of me that is very distasteful. Does this mean that every choice I could have made in life, was actually made by one of my copies?

Hmmm... According to the standard dogma, life is all about reproduction -- making copies of yourself to populate the world. LOL

OK... so they're not perfect copies. But how different do they have to be that their existence would not bother you? And what sort of similarities make them distasteful? DNA -- is it all about genetics? Memories -- are these what you want exclusive ownership of? Since I tend to see my identify most fully represented by the choices I make, these others who make different choices than I do, don't feel all that similar to me.

If DNA is the issue, then does the fact that chimpanzees are 98% the same bother you? Perhaps not. What is there to dislike about chimpanzees? I find much more to be repelled at in my fellow human beings and I could indeed feel some shame anything I might have in common with them, which includes 99.9% the same DNA. And what of twins, where the genetic similarity is 100%? Does that creep you out?

I suppose I could understand better if the issue were memories. Where would the privacy of your own mind be if there were hundreds of others with access to the same memories you have? Of course, as soon as we make different choices, our memories will diverge.
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Re: fleshing out the Many Worlds Interpretation

Postby hyksos on May 21st, 2018, 6:05 pm 

But how different do they have to be that their existence would not bother you? And what sort of similarities make them distasteful? DNA -- is it all about genetics? Memories -- are these what you want exclusive ownership of? Since I tend to see my identify most fully represented by the choices I make, these others who make different choices than I do, don't feel all that similar to me.

This is a harangue of personal questions. Nevertheless I'm willing to answer them honestly. I am not happy about the implications of the theory of evolution at all, even generally speaking.


If DNA is the issue, then does the fact that chimpanzees are 98% the same bother you?

No , it definitely does bother me.

A more startling fact is that my body uses DNA molecules to build and construct my skin and bone cells -- bread mold uses the same molecule to grow its network of cells. (I expect you to ignore this fact, as you have ignored it in the 6 or 7 other times that I have posted it.)

DNA is so conducive to self-replication, that DNA is carried around by half-alive bags of organic material that we call 'viruses'. The sole existence of viruses is to do nothing more than smuggle their genetic material into the inside of a living cell, so as to hijack the machinery there for their own replication. This works wonderfully well on this planet , and so viruses are everywhere. On all surfaces. Under every rock. In every pond and stream. On my skin, in my eyelids, likely inside me too.

"That's fine though because viruses are beneficial." No, actually they cause infections, make us miss work , cause enormous suffering to children -- and in parts of Africa they outright kill people. The crowded urban environment of Asian cities have given rise to these H1N1 variants that mutate and jump from animal to man.
The 1918 flu pandemic (January 1918 – December 1920), also known as the Spanish flu, was an unusually deadly influenza pandemic, the first of the two pandemics involving H1N1 influenza virus.[1] It infected 500 million people around the world,[2] including people on remote Pacific islands and in the Arctic, and resulted in the deaths of 50 to 100 million (three to five percent of the world's population),[3] making it one of the deadliest natural disasters in human history


I'm a happy about this? You must be kidding -- this is simply terrifying.

Then there is HIV, which after infecting a person, goes into a "dormancy period" where the victim shows no symptoms. During that period, the infected will likely have sex with a new partner, having no idea they are infected, and the virus spreads to a new host. The dormancy period lasts years. That is just plain vicious.

Ironically, it would be more comforting if these terrible things were happening out of viciousness. Because then there would be a sense that one could avoid it by being a "good person". What is more terrifying is that children are suffering not out punishment for a crime (or 'viciousness') but because of statistics. It is mathematico-statistically viable that viruses exist, and for that reason alone, they do exist.

The virus is not slowly torturing and killing you out of malice. It is doing this because it is a machine -- a mindless molecular machine that was forged by a trillion accidents of precursor viruses.

Our bodies are born "stupid" about the nature of these invisible, silent, killing machines. So we are forced to become infected by them so our "stupid" immune system becomes less stupid. This is the same function of vaccination. The reason why all of this is happening in the first place is due to the fact that the internal machinery of ourselves is itself a mindless molecular machine. Our cells do not have "intelligence" enough to identify rouge DNA, The virion squirts its DNA recipe into the cells in your nasal passages, your cells grab that and start making copies of it in a complete state of oblivion. Three days later you are laid out in bed growning from body aches with a fever of 102.

So our cells are dumb molecular machines. And viral infections don't kill us because we happen to have an immune system.

Am I happy about this?


Pffft! you must be kidding.
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