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A Mathematical Answer To the Parallel Universe Question
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."
Yeah, yeah, I know it only affects physical outcomes. Laugh anyway. It's Monday.
I've fallen off your lawn, and I can't get up.
It's just the Many Worlds interpretation of quantum mechanics, and I don't see anything in the article that's a shocking new revelation about it. The article's just a rehash of an idea that's been around since the 50s.
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
But can this explain why all the men have goatees?
. . . so it "can" explain (mathematically) the outcome of quantum level observations using the many worlds theory. But is it falsifiable?
How does this reconcile with reality as we see it?
From my perspective, even if this mathematical "proof" is true, it is only true in the ontological sense, i.e. that these branches can happen and maybe do happen, but not in reality. Then again, I believe the entire basis for the universe is ultimately ontological but that's a different matter.
My point is that these alternate "universes" may only exist in infinitesimally-small times (possibly below the Planck time threshold) and then simply cease to exist again as compared with our reality in the next moment, moment after moment.
Think about the "mind-body problem" Okay ...
I did ... and here's my solution. Basically, there are other branches where life sucks less, and others where life suck more, etc. I'm going to find the one where life sucks less and kill my alter ego so I can take their place!!!!!!!! (Of course, that means that there's ANOTHER me in an even suckier universe gunning for me, so better be quick!)
You'd better watch out - there may be a doppelganger of you looking to do the same thing...
Kevin Smith on Prince
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.
There is a circular dependency here. The author assumes that the parallel universe interpretation is correct and then argues that if this interpretation is correct, then we can derive probabilistic nature of quantum of mechanics. All this means is that the parallel universe is a self-consistent theory. Nobody has argued against this for the last 50+ years.
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.
Where does the energy come from to give existence to this second universe? This whole splitting of the universe thing seems common in physics, so I'm sure I'm not interpreting this correctly. It seems like there's entire universes being created because of the uncertainty of a single particle.
I would very much like to find the publication of this, or least more details given by the authors if anyone can fine a link.
By the way, Deutsch is a well known physicist, not some crackpot. One of the first problems discovered to be theoretically sped up by a quantum computer is named after him (link).
So they say they have a mathematical description of the parallel universe theory. One can construct a mathematical model that describes the geocentric solar system perfectly well, but the the heliocentric version is much simpler.
So, which is simpler?
(1) Shit happens.
(2) Shit happens. Parallel universes are created.
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Here is the New Scientist article being cited:
http://space.newscientist.com/article/mg19526223.700-parallel-universes-make-quantum-sense.html
However it is behind a paywall. See Google Groups for the whole thing.
There is a great quote by physicist Max Tegmark: "The critique of many worlds is shifting from 'it makes no sense and I hate it' to simply 'I hate it'."
As far as the meat of it, traditionally the Many-Worlds Interpretation has had two technical objections raised. The first is called the basis problem, and the second is deriving correct probabilities. The basis problem is that when the universe "splits" it's not clear how it should split. The math allows for infinite different ways to split, but we only see one way. This has been solved in recent years by the study of decoherence, which in MWI terms is like looking at the splitting process up close. Turns out it can only happen one way in practice. So that one's done.
The article is more about the other one, deriving probabilities. Actually it's easy to derive probabilities in the MWI, but they're wrong. The right probabilities are what is called the Born rule, and it's been hard to get those. David Deutsch came up with a new idea in 1999 where he proposed tying it in to decision theory. He said that we really care about probabilities because they influence how we make decisions about what to do. If we can derive a reasonable decision theory within the MWI, then we've essentially explained probabilities. His work had some shortcomings but subsequent efforts have largely resolved those.
So now for the first time, the two traditional technical problems with the MWI have reasonably good solutions. Hence we are back to, as Tegmark says, "I hate it" as the main objection to the theory. Since that's not really a good argument, it can be said that the MWI should be considered the most compelling candidate for an interpretation of QM.
One final link, here is one of the papers that extends Deutsch's idea about decision theory and pretty much closes the holes: http://arxiv.org/abs/quant-ph/0312157. It's pretty technical but still a lot more readable than most physics papers.
It worked once before. Calculations of the orbit of the planet Uranus were noticeably inaccurate; the planet wasn't quite where it ought to have been. One explanation was that this was the result of the gravitational effect of a large amount of dark matter. This dark matter was later found and named Neptune.
Real Daleks don't climb stairs - they level the building.
I'm not sure if you were already aware, but there is indeed a concept called "Quantum Darwinism" which helps explain (using the results from quantum decoherence) why we observe things "classically" (single outcomes of experiments, non-entangled macroscopic states, etc.) despite the universe being fundamentally quantum.
Briefly, the theory shows (rigorously) how pseudo-classical states are the only ones that are robust against decoherence. Hence, those are the states that tend to persists for measurable periods of time. And those pseudo-classical states are the ones that give rise to other pseudo-classical states.
Moreover the main developer of these ideas (Wojciech Zurek) describes in his papers how what we typically term "memories" are inherently classical states (it's either "a" or "b"--not a superposition of both). He explains how macroscopic states will tend to be pseudo-classical, so of course any biological (macroscopic) creature will evolve to assume that reality is classical (it's an adaptive advantage and a good approximation of reality).
The point is that these larger-scale superpositions do indeed exist, but that local observers (e.g. instruments, or ants, or humans) can inherently only record/remember classical states, not quantum ones. So, our perception of reality (and memory of reality) is inherently a classical one.
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.
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?"
Computers are useless. They can only give you answers.
-- Pablo Picasso