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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.'
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.
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
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.