Re: Many-worlds (was Re: [sl4] Re: Uploads coming first would be good, right?)

From: Charles Hixson (
Date: Fri Mar 06 2009 - 23:05:28 MST

Matt Mahoney wrote:
> --- On Thu, 3/5/09, Stathis Papaioannou <> wrote:
>>> Many-worlds is indistinguishable from the case that
>> ...
> .
> Remember that probability is a model of belief, not of reality. In quantum mechanics, the square of the modulus of the wave function fits our model of probability only in the absence of other knowledge. For example, if constraints such as conservation of mass-energy, electric charge, momentum, and angular momentum restrict the possible combinations of observations we could make, we call that entanglement. As another example, the probability of observing a radioactive decay over one half-life interval is 1/2 only if that interval is in the future. But if you knew the quantum state of the universe, you would know everything about the future and probability would be a meaningless concept.
> The reason we expect a coin to come up heads with probability 1/2 is because of the way our brains compute probabilities based on past experience.
> -- Matt Mahoney,
I can remember that you have claimed that "probability is a model of
belief, not of reality ", but that won't convince me that you have
asserted a true statement. And if I am understanding the model of the
Many-Worlds hypothesis that you are expounding, I'm not sure that it's
the standard version. The one that I prefer goes like this:
"The state vector does not collapse. What you are interpreting as the
collapse of the state vector is the bifurcation of the wave state into
discrete 'segments'."

In other words, both events happen with a probability density, and the
wave state of the universe maintains consistency by preventing differing
histories from re-encountering each other. This can be modeled as the
universe splitting, i.e. as numerous little tiny ping-pong balls
suddenly duplicating and moveing at right angles to everything else so
that a branch of the universe is created, but that's just a mental
model. All that really happens is that the state vector doesn't
collapse. You don't receive A measurement, you receive a vector of
measurements, but each you only responds to one of the measurement
elements. AhhhhGG! That's lousy! I'm paraphrasing someone else's
explanation of their understanding of the math, and not being very
successful, but the essence is that the state vector doesn't collapse,
and the universe has a lot more dimensions than you can imagine.

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