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50 Years of the Multiverse Interpretation

Posted by Zonk on from the one-of-my-favorite-verses dept.

chinmay7 writes "There is an excellent selection of articles (and quite a few related scientific papers) in a special edition of Nature magazine on interpretations of the multiverse theory. 'Fifty years ago this month Hugh Everett III published his paper proposing a "relative-state formulation of quantum mechanics" — the idea subsequently described as the 'many worlds' or 'multiverse' interpretation. Its impact on science and culture continues. In celebration, a science fiction special edition of Nature on 5 July 2007 explores the symbiosis of science and sf, as exemplified by Everett's hypothesis, its birth, evolution, champions and opponents, in biology, physics, literature and beyond.'

31 of 198 comments (clear)

  1. So in another universe of the multiverse... by Anonymous Coward · · Score: 2, Funny

    There was no Sliders, no Crisis on Infinite Earths, no quantum mirror in Stargate?!

    1. Re:So in another universe of the multiverse... by MichaelSmith · · Score: 5, Funny

      Who wants to loan me their account at Nature so I can log in?

      Try one username/password combination at random. At least one of your instances will get in.

      --
      http://michaelsmith.id.au
    2. Re:So in another universe of the multiverse... by DoraLives · · Score: 2, Funny

      It appears to be working just like you said it would, but unfortunately I don't seem to be able to access the universe that it's working in.

      Can I now borrow your username and password for that universe?

      --
      Is it fascism yet?
    3. Re:So in another universe of the multiverse... by qbwiz · · Score: 4, Funny

      Just rig up your computer to kill you instantaneously if you don't get access. Then, you'll never experience the problem of not having access.

      --
      Ewige Blumenkraft.
  2. Nothing for you to see here. Please move along. by Moth7 · · Score: 2, Funny

    Looks like I got landed with the Universe where Slashdot didn't run the story.

  3. SF by Skadet · · Score: 2, Funny

    explores the symbiosis of science and sf...
    Maybe it's because I live in California, but San Fransisco is the first thing I thought of when I saw "sf".

    Wait, no, that's not why. It's because they're the same thing.

    ;)
    --
    Sony ha
  4. Oh, great! by tomhudson · · Score: 3, Insightful

    Just what we need; the knowledge that there are an infinite amount of dupe posts in the multi-verse.

    ... and that another almost-me is wasting time on a Friday night posting on slashdot, while another almost-me is partying it up like there's no tomorrow (of course for trhat doppelganger, there may not be a tomorrow ...)

  5. MWI is cool and all.... by Creepy+Crawler · · Score: 2, Interesting

    But I'd like to know what consists a measurement.

    Quantum mechanics does weird stuff when you measure it (probability field of position/velocity).

    When something is measured, it collapses it... What causes the collapse?

    Perhaps consciousness?

    --
    1. Re:MWI is cool and all.... by MichaelSmith · · Score: 2, Informative

      Perhaps consciousness?

      Greg Egan wrote a book on that topic. Aliens were relying on non-collapsed wave functions as a part of their normal life. New instruments like the Hubble Telescope were causing mass genocide in the observable universe, which got some aliens pretty pissed off.

      --
      http://michaelsmith.id.au
    2. Re:MWI is cool and all.... by Citizen+of+Earth · · Score: 2, Insightful

      Perhaps consciousness?

      There is no good reason to believe that such a thing exists.

    3. Re:MWI is cool and all.... by mazarin5 · · Score: 4, Informative

      When something is measured, it collapses it... What causes the collapse? Perhaps consciousness? No. It's just that once you've measured where something is, the probability of it being somewhere else is drastically reduced for a while. What's the probability that I left my keys in the kitchen instead of the bedroom? Let's say 50%. "Oh," a friend says, "I just saw them in the bedroom." so what does that probability become? 0%. It was measurement, not some mystic force, which reduced the area in which my keys are most likely to be found. It's no different with quantum mechanics.

      --
      Fnord.
    4. Re:MWI is cool and all.... by dissy · · Score: 2, Informative

      But I'd like to know what consists a measurement. Generally at the quantum level, a measurement or observation is when you bounce a particle (usually a photon) off another particle.
      It's similar to how you see things. Light bounces off of a thing, and that light bouncing into your eye is how to observe and measure things. Just lower the scale to a single photon of light (or even a smaller particle) and youre set.

      The reason you can't measure all the details of a particle at this level is because when the photon you bounce off it actually hits the particle youre measuring, the photon will disturb what you are measuring and thus changes it.
      Similar how if you rolled one pool ball on the table to hit another.. It disturbs the other ball and moves it too, so any data you can draw from your reflected ball is no longer accurate since it modified what you just measured after the fact.
    5. Re:MWI is cool and all.... by mrpeebles · · Score: 5, Funny

      Except that I've never had the probable state of my keys being in the kitchen destructively interfere with the probable state of my keys being left in my bedroom to make my keys more likely to be on the key ring... :-)

    6. Re:MWI is cool and all.... by thc69 · · Score: 2, Interesting

      Thanks for the tip. Seems like a book I'd enjoy.

      The premise of encasing the solar system reminds me of a book I read where earth was encased for, IIRC, a similar reason. I just googled around until I found it. It's Spin by Robert Charles Wilson.

      --
      Procrastination -- because good things come to those who wait.
    7. Re:MWI is cool and all.... by brunos · · Score: 3, Informative

      In the many worlds interpretation of quantum mechanics the wavefunction does not collapse (that is the copenhagen interpretation).
      Rather, all the *possible* outcomes of a quantum measurement do happen: each one in a different universe.
      When you measure one particular outcome, that means that you are in the particular universe where you measure that outcome: by definition.

      A measurement consists in an event that translates "quantum information" into "classical information": quantum information is very complex as essentially it means that you are keeping track of what happens in ALL the universes, at some point, you stop doing that, and you become concerned with only what happens in you particular universe: that action constitutes a measurement. And it is from that action that you find out in which universe you happen to be.

    8. Re:MWI is cool and all.... by Lane.exe · · Score: 2, Insightful

      Except for, you know, qualia.

      --
      IAALS.
    9. Re:MWI is cool and all.... by Chemicalscum · · Score: 4, Informative

      When something is measured, it collapses it... What causes the collapse?

      No in the MWI the wavefunction does NOT collpse. This is the whole point of the MWI, in the Copenhagen interpretation the wave function collapses on a measurement to a single state. In the MWI a measurement splits the world into two different states there is no collpse of the wavefunction.

      The Copenhagen interpretation abolishes physical reality and brings in the idealist concept of a conscious observer collapsing the wavefunction. The MWI restores physical reality in quantum mechanics.

      Let's take the Schrodinger cat thought experiment: <cat alive|cat dead>

      This gives rise to the density matrix:

      cat alive ...................... cat alive + cat dead

      cat alive - cat dead ..... cat dead

      The CI supporters would say the MWI didn't explain why we don't see the off diagonal mixed states. But the modern approach to the measurement problems in MWI uses the concept of decoherence which is the interaction of the isolated quantum states with the macro environment. It has been shown that the mixed states are destroyed by interference when decoherence from interaction with the environment occurs. Thus in this experiment the world is split into two, one where the cat is alive and one where it is dead.

      The decoherence approach in conjunction with the MWI abolishes the necessity of observers and restores the independent physical reality abolished the the CI. The proliferation of many worlds is the price we have to pay for physical reality and the unitary evolution of the wavefunction.

    10. Re:MWI is cool and all.... by Citizen+of+Earth · · Score: 3, Interesting

      Except for, you know, qualia.

      Going beyond the semantic issue, the GP seemed to be implying that consciousness is something special, some unknown part of nature.

      However, suppose that you ask a person if they are sane. Should you believe their answer? The only means you have to evaluate the experience of your own consciousness is your own consciousness itself. If your consciousness wasn't some supernatural thing but instead was a little program in your brain to fool you into protecting your existence above all else by creating the illusion of being something special and supernatural, you wouldn't be able to tell the difference.

      Now consider everything that we know about reality. Does the universe work more like a precise machine or more like some transcendental mystical metaphysical drug hallucination? Consider everything we know about the mechanics of the brain. It is organized a lot like and its components are a lot like a computer. Is this a description of a ghost trap or of a computational device?

      The Earth sure does look flat, though, doesn't it?

    11. Re:MWI is cool and all.... by realmolo · · Score: 3, Informative

      You are mistaken.

      The reason you can't measure all the details of a particle at the same time is NOT because photons bounce off of it and disturb it. The reason you can't measure all of the details of a particle at the same time is because that is JUST THE WAY IT IS. It has nothing to do with interference from other particles. There is no "reason" for it. No one knows why it works that way. It's called "complementarity", and it's the fundamental quantum mystery.

    12. Re:MWI is cool and all.... by kaidadragonfly · · Score: 2, Insightful

      I'm not a physicist but at least from what I've read that's a rather common misconception.

      It is the act of measurement itself, not the interaction of the particles that causes changes we see in the particles. The collapse of a wave function is different from anything that we have in the macroscopic universe, it simply does not happen in every day life to an extent that we can view it.

      Quantum mechanics/physics/theory doesn't work like normal life.

      Analogies don't work properly when you try to explain QM, because it is so counter intuitive.

      Electrons are not simple particles, and our measurement doesn't cause them to be perturbed, they actually exist as a probability. This is, at least what I've understood, as the reason for the wave-particle duality that is exhibited in the double-slit experiments.

    13. Re:MWI is cool and all.... by Citizen+of+Earth · · Score: 2, Interesting

      Myself, I'm a supervenient physicalist, meaning I think that consciousness supervenes on the physical, but cannot be explained by, reference to physical laws alone. Consciousness, and the study of it, inhabits its own scientific sphere that is not reducible to physics or biology or some other "basic" science.

      Well, good for you. Of course, your explanation above is the exact equivalent of someone telling me that they believe in God and thumping "the good book", or that they believe in magic. You may believe what you wish and read as much as you like, but you are asking me to put faith into more than objective reality for no particularly good reason. Religious people will refer me to Bible passages and writings of philosophers, but it's all meaningless because it is all made up by people who have no greater means to objectively study these subjects than I do. How many angels can dance on the head of a pin?

      Myself, I'm an expert on computational processes (something actually real). I'll keep my faith in reality and avoid explanations that are more complicated than the subject they are describing, especially when there is an explanation that doesn't violate everything we objectively know about reality.

  6. *Interpretation* by rrohbeck · · Score: 2, Informative

    Wasn't it proven that the multiverse interpretation is mathematically equivalent to the other more traditional approaches like wavefunction collapse and decoherence?

    I like SF as much as probably most people here, but I can't see the scientific significance.

    --
    thegodmovie.com - watch it
  7. Mirror, Mirror by hedgemage · · Score: 5, Funny

    Somewhere, a goateed version of me is reading the story, because that version has a Nature login.

  8. Personal experience of the Multiverse by rjamestaylor · · Score: 2, Interesting

    Ok. I'm going public with this craziness of mine...

    I've observed many times that I "should have" died. It struck me that, perhaps, I did die in an alternate universe, but I (whatever I "is") continue on in at least one of the multiverses. In those multiverses in which "I" experience the death of a close friend or family member... well... that just is how it goes. But they, too, continue in an instance of the multiverse. Perhaps I do not.

    Anyway... "They're coming to take me away, ha ah..."

    --
    -- @rjamestaylor on Ello
    1. Re:Personal experience of the Multiverse by lawpoop · · Score: 5, Interesting

      I had a friend and former roommate who was in an apartment fire. He was sleeping in bed when his cat woke him up by clawing at his face. He startled awake and saw that the ceiling was covered in flames. He escaped, certain that he was moments away from death.

      Luckily he made it out alive. But he suffered severe PTSD for a few years afterwards. He would just be walking to the grocery store and be suddenly struck with the terrifying reality that he wasn't walking to the store at all -- this was the final hallucination of his mind moments before he perished in the apartment fire. Instead of his past flashing before his eyes, this was his mind's final, desperate attempt to comfort itself, by creating a reality where he lived out the rest of his life.

      I try not to think about it because it's creepy. If I really start to think about it I get terrified.

      --
      Computers are useless. They can only give you answers.
      -- Pablo Picasso
    2. Re:Personal experience of the Multiverse by Jerf · · Score: 3, Interesting

      Quantum immortality.

      Note that this is not a very exciting kind of immortality. Especially since a goodly number of worldlines coming from here will produce computronium. At least some of which will simulate you, yes you personally for an unspeakable amount of subjective time (possibly infinite if even one non-zero probability path leads to that outcome), during which you will in some cases experience what can only be described as "as close to a literal heaven as you can get", and in other cases "as close to a literal hell as you can get", and the full range of things in between. If Quantum immortality is "true", there are things worse than death, and we will more or less all get to experience them on some worldline.

      Note further that it is not meaningful to wish that "you" will end up in one of the good cases; if QI is true, all cases lie in your future equally. "You" will end up in the good and the bad and the inbetween, all at once. Perhaps some people consider this a form of escapism, but it is also fairly horrifying if you follow the implications out beyond "In some very real sense, I can not experience death."

    3. Re:Personal experience of the Multiverse by pureevilmatt · · Score: 2, Interesting

      That sounds a bit like Donnie Darko.

    4. Re:Personal experience of the Multiverse by resonte · · Score: 2, Insightful
      Strange...I just made a post relating to QI.

      Life is suffering. If the mutliverse is true, then absolute hell really does exist in one instance of a Universe. If QI is true, is there ever really a way to escape 'reality'? Does everyone experience every form of existence for eternity? or instead do some of us go into loops of existence, and never escape the loop? Can we direct our path to a desirable loop?

      Some forms of Buddhism teach something very similar to QI, except that Nirvana is the end of all suffering, and the end of the ego, the end of self, and that once Nirvana is reached it is eternal. Perhaps Nirvana is a way to achieve death in a deathless Universe?

      The universe is a really scary place when you sit down and think about it. It puts your own desires into perspective.

      --
      \(^o^)/
  9. Re:50 year of an untestable hypothesis by azenpunk · · Score: 2, Funny

    someone just got his report card for physics.

  10. Old by alexgieg · · Score: 5, Informative

    The multiverse hypothesis is an ancient idea. I remember reading about a poetic image used in Hinduism to describe it: that of "Shiva's Necklace". It's said that the god Shiva, which together with Vishnu and Brahma form the (main) Hinduist Trinity, the Trimurti, wears around his neck an infinitely long necklace with an infinite number of beads. Each bead is a full universe, ours being just one among them, and Earth with us just an infinitesimal aspect of that single bead.

    It would be nice if scientists, when talking to non-scientists, drafted lively images like this one. IMHO, it would go a long way in bridging the gap between them and "normal" people, who don't think in terms of numbers and mathematical concepts.

    --
    Conservatism: (n.) love of the existing evils. Liberalism: (n.) desire to substitute new evils for the existing ones.
  11. Re:50 year of an untestable hypothesis by DamnStupidElf · · Score: 3, Insightful

    Quantum computing is equally bunk since it is based on the idea that a quantum property can have multiple states simultaneously, that is, when nobody is looking. ahahaha... Reminds me of the kid I knew who insisted that he could jump as high as a tall building but only when nobody was looking. Whatever happen to empiricism? Talk about pseudoscience! Everett, Schrodinger (and his stupid cat) and that lunatic David Deutsch are crackpots of the worst kinds. Only physicists can get away with such quackery. They should all be stripped naked, tarred, feathered and paraded down Fifth Avenue in New York as an example to undergraduates. ahahaha...

    Sorry, your computer now refuses to work because it no longer obeys quantum mechanics. The electrons are just stuck at the N-P junctions and nothing happens because they're all in a fully defined position with no way of jumping across it at the energy levels they have. Bump the energy up, and they behave classically and just burn their way through without any of the nice semiconductor properties that make computation with them possible.

    On the upside, now you'll have a lot more time to tar and feather the quacks who made your nonfunctional computer!