Slashdot Mirror
50 Years of the Multiverse Interpretation
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.'
Just what we need; the knowledge that there are an infinite amount of dupe posts in the multi-verse.
Try one username/password combination at random. At least one of your instances will get in.
http://michaelsmith.id.au
Somewhere, a goateed version of me is reading the story, because that version has a Nature login.
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.
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... :-)
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.
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.
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
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."
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.
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.
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!
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?
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.