A Mathematical Answer To the Parallel Universe Question 566
diewlasing writes to mention that Oxford scientists have proffered a mathematical answer to the parallel universe question that is gaining some support in the scientific community. "According to quantum mechanics, unobserved particles are described by 'wave functions' representing a set of multiple 'probable' states. When an observer makes a measurement, the particle then settles down into one of these multiple options. The Oxford team, led by Dr. David Deutsch, showed mathematically that the bush-like branching structure created by the universe splitting into parallel versions of itself can explain the probabilistic nature of quantum outcomes."
Ummm . . . (Score:5, Insightful)
Raises the question (Score:3, Insightful)
Re:Why is this news? (Score:4, Insightful)
Commenting in New Scientist magazine, Dr Andy Albrecht, a physicist at the University of California at Davis, said: "This work will go down as one of the most important developments in the history of science."
I would image something that is 'one of the most important developments in the history of science' might qualify as news. Don't you think? Even if proven not to be 'one of the most important' it certainly qualifies for recognition based on that possibility, IMHO.
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Re:Publication? (Score:4, Insightful)
Seriously though, there's no sign of a citation from any of the people running the story (most of which are nearly identical, so they're probably just copying from the same press release), and there's no sign of it on arXiv or from a quick trawl of journal feeds, so it's a very good chance that it's either unpublished work, or a conference paper somewhere. Not surprising, given how many "most significant discoveries in the history of science" turn out to be much less dramatic under the cold hard light of review than when they're first reported.
Re:Raises the question (Score:2, Insightful)
You got it 180 degrees out. The answer is the equivalent, but the reverse, of the Anthropic Principle. Every parallel universe also has copies of him asking that same question.
circular dependency (Score:5, Insightful)
The problem with quantum mechanics interpretation is that as of now, no interpretation exists which is not bizarre in our traditional world view. Parallel universe is just one of them.
Re:Why is this news? (Score:4, Insightful)
Re:Raises the question (Score:3, Insightful)
Re:Why is this news? (Score:3, Insightful)
1 = 2? (Score:4, Insightful)
omgz i made the number trees line up! (Score:1, Insightful)
many worlds is the answer to a question that didn't need asking. why assume that superposition means that each state is uniquely there and existing, like a huge OR statement?
look. we get it, it's weird. a particle can't "spin" both ways. the cat can't be alive or dead. it makes your brain hurt, and keeps you up at night.
but you know what? i don't care. neither does reality. it's going to just keep on being whatever it is. and as far as we can tell, that is: things behave like waves. then we observe them, and they behave like particles.
why are you worried about the other possible states? you're just making a philosophical assumption, that they were there to begin with. just accept the fact that things can behave according to probabilistic models, and we can all get on with our lives.
Re:Occam's razor (Score:3, Insightful)
We're in the only universe, which just happens to be perfectly suited and tuned to our existence.
There's an infinite number of universes, and we're in one where we're possible.
idiotic circular logic (Score:3, Insightful)
Or in other words, this science fiction nonsense about parallel worlds, unscientific because it can never be tested or proven, and which was inspired by observations of quantum mechanics, is now supposedly able to explain, guess what, ... quantum mechanics, the very concept that the nonsense was built on in the first place.
The absurd number of parallel universes that would have to be created is mind boggling, since, at the very least, an entire universe would have to be created every single time any atom decayed (one for the universe where that atom happened to decay at that instant, another for the case where that atom didn't happen to decay). Strange that none of the wackos who advocate this, and I use the term very loosely, "theory", bother to expain where all of the mass and energy is coming from for all of these extra universes. Note that we are talking about far more universes than atoms in our own universe. Absolute hogwash.
Re:Why is this news? (Score:3, Insightful)
Re:Occam's razor (Score:2, Insightful)
Re:Standard of evidence is getting low these days (Score:3, Insightful)
Just look out of your window.
Truly, what IS new about this??? (Score:3, Insightful)
Are they trying to claim that their mathematical probability tree corresponds to a "real" probability tree? If so, on what basis do they make that claim?
To them, I say: "Show me evidence, and I will believe. Until then, stop bothering me with old ideas."
Re:Ummm . . . (Score:3, Insightful)
So, given two axioms:
1. Laws of physics are invariant
2. Unitary quantum mechanics describes the universe
We obtain a wide variety of predictions, from transistors to molecules, and so on. One of the predictions is "the universe exists in a global superposition." The proliferation of branches is consequence of the theory, not an axiom.
We may find the prediction uncomfortable, but without a logical (or empirical) reason to discard it (but retain all the other predictions, which we like better), how can we ignore it? (Honest question... I'm not an expert in philosophy so perhaps I'm committing a fallacy.) To emphasize, nothing is being posited (beyond the axioms mentioned; I'm assuming no one is disputing that science and quantum mechanics can say something meaningful about the universe).
Besides, the point is that unitary quantum mechanics is actually reductionist. It does away with a (superfluous?) ad-hoc assumption (about 'collapse of the wavefunction'). The resulting theory predicts a single object: a global wavefunction. That you or I call its various branches 'universes' doesn't mean anything is actually proliferating. It's important to emphasize that the "Many Worlds" predicted by modern unitary quantum mechanics are not really the "wacky possibilities" seen on shows like Sliders. They represent the branches of superpositions of a global wavefunction. If you branch from a current position, the possibilities are deterministic and mostly uninteresting (e.g. an atom decays a moment later in one branch than another).
Yes, the global wavefunction would include many variations (maybe even variants where historical events played out differently because millions of quantum branches biased events a certain way instead of another way), but all of these variations are ruled by the same deterministic physics. And, importantly, it's not a matter of "whatever universe you can imagine is out there somewhere!"--the possibilities are strictly limited by deterministic evolution of the wavefunction and the initial conditions of the universe.
Re:Well if you can't believe in God.... (Score:3, Insightful)
Re:Occam's razor (Score:3, Insightful)
Of course, it is worth pointing out that speculation about a creator merely pushes the question of origins back a level: where did this hypothetical creator and his/her/their universe come from?
Re:Occam's razor (Score:2, Insightful)
Now, which theory is simpler:
Theory 1: As long as we don't look, everything follows law A, but as soon as we look, shit happens, and we have to apply law B.
Theory 2: Everything follows law A, all of the time. The true reason why law B seems to apply is that law A also applies to us.
Theory 1 is the standard Copenhagen interpretation. Theory 2 is the MWI.
It's not mass, it's information... (Score:5, Insightful)
The mass and energy isn't coming from anywhere, because there's no new particles being created. The particles are the same ones, in all universes, their state is just getting more complex, and each "parallel universe" is just a description of one consistent state of all the particles of the universe over all histories. We only observe the particles as as having measurable (subject to Heisenberg) positions and velocities because we're using other particles to measure what those positions are.
A better question might be "where is the information needed to describe the state of the particle stored". Or to put it another way "how many bits does God's Computer have, and can we hack it?"
Re:Ummm . . . (Score:3, Insightful)
Long answer:
First off, some of the discussion here is getting confused because people are equating the "many universes" of the Many-Worlds Interpretation with the "parallel realities" espoused by other theories (but, most prominently displayed in sci-fi), where "anything goes" or any possible arrangement of atoms (or even laws of physics) is possible, or even exists.
I'm talking about Many-Worlds, which is an untested prediction of modern quantum theory. I'm not talking about parallel realities (for which there is currently no proof and which no mainstream theory predict). In Many-Worlds, the branches evolve deterministically from the current state (according to the equations of quantum mechanics). This means that along each branch (each "universe" if you prefer), the laws of physics are invariant, and are exactly what we are used to (quantum mechanics + relativity). Moreover, because the universe is evolving from a specific initial state, there are constraints on what the branches will look like. You won't get "every wild thing you can imagine": only those branches which can evolve from a current state will be represented in the global superposition.
So the various branches of Many-Worlds look pretty much exactly like the universe you are comfortable with (planets, stars, galaxies). Along one branch an atom might decay and along the other branch it might not decay (yet)... In principle some branches may have quantum choices such that normally improbably things occur, but that's balanced out by the vast majority of branches which are, basically, boring.
Re:Occam's razor (Score:3, Insightful)