- #36
setAI
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JoeDawg said:The problem with this idea is that cause/effect is something we observe in our universe, but as soon as you expand your ideas beyond 'our universe' to some kind of theoretical multiverse, talking about probabilities becomes meaningless, since we really have nothing to compare our universe to. All we can really say is that our universe exists and try and model a theory based on what we observe. As far as I can see the 'multiverse' isn't really any less of a 'cheat', at least with current understanding, than saying 'god did it'. Also note that time is a function of 'this' universe, so infinite time... for our universe to happen... doesn't really make sense, unless time exists outside our universe, which we couldn't possibly know and really, it might have completely different properties even if it did.
to deny the Multiverse would require some new and absurd physics which posits an omnicient demon that magically destroys the very computations and sub-computations that allow the observed universe to have consistant physics and exist itself-it would be rather like a magical computer which can factor any number by simply 'guessing' the correct factors the first time instead of searching the products of every combination until it finds the answer- this search process is a fundamental property of all causal systems-
The physical laws that we have discovered provide great means of data compression, since they make it sufficient to store the initial data at some time together with the equations and an integration routine... the initial data might be extremely simple: quantum field theory states such as the Hawking-Hartle wave function or the inflationary Bunch-Davies vacuum have very low algorithmic complexity (since they can be de-fined in quite brief physics papers), yet simulating their time evolution would simulate not merely one universe like ours, but a vast decohering ensemble corresponding to the [Quantum] multiverse.
Max Tegmark
from http://arxiv.org/abs/0704.0646
All Universes are Cheaper Than Just One
In general, computing all evolutions of all universes is much cheaper in terms of information requirements than computing just one particular, arbitrarily chosen evolution. Why? Because the Great Programmer's algorithm that systematically enumerates and runs all universes (with all imaginable types of physical laws, wave functions, noise etc.) is very short (although it takes time). On the other hand, computing just one particular universe's evolution (with, say, one particular instance of noise), without computing the others, tends to be very expensive, because almost all individual universes are incompressible, as has been shown above. More is less!
Many worlds
Suppose there is true (incompressible) noise in state transitions of our particular world evolution. The noise conveys additional information besides the one for initial state and physical laws. But from the Great Programmer's point of view, almost no extra information (nor, equivalently, a random generator) is required. Instead of computing just one of the many possible evolutions of a probabilistic universe with fixed laws but random noise of a certain (e.g., Gaussian) type, the Great Programmer's simple program computes them all. An automatic by-product of the Great Programmer's set-up is the well-known ``many worlds hypothesis'', ©Everett III. According to it, whenever our universe's quantum mechanics allows for alternative next paths, all are taken and the world splits into separate universes. From the Great Programmer's view, however, there are no real splits -- there are just a bunch of different algorithms which yield identical results for some time, until they start computing different outputs corresponding to different noise in different universes.
From an esthetical point of view that favors simple explanations of everything, a set-up in which all possible universes are computed instead of just ours is more attractive. It is simpler.
Juergen Schmidhuber
from http://arxiv.org/abs/quant-ph/9904050