On 10/27/2014 11:47 PM, LizR wrote:
On 28 October 2014 08:58, meekerdb <[email protected] <mailto:[email protected]>>
wrote:
On 10/27/2014 3:38 AM, LizR wrote:
It would be nice if Mr Clark would EITHER stop joining in with discussions
just to
say that he doesn't care about comp, OR state what he agrees or disagrees
with in
Bruno's stated argument.
Just saying it's "obviously wrong" doesn't really cut it. So far the only
real
(non-sarcastic, non-insult-based) objection I've heard comes down to a
semantic
quibble to do with redefining our concept of an individual person. This is
exactly
the same redefinition that was brought up by Everett in 1957. It isn't in
itself
contentious - a physicist who believes the MWI to be correct will come to
the same
conclusions about indeterminacy that someone using Bruno's matter
transmitter would
- that it's a phenomenon experienced from a first person perspective
because of the
person in question being split into two copies. The phenomena actually map
onto
each other, because both comp and Everett allow for the possibility that
from the
third person viewpoint the duplication could be observed - quantum
computers rely
on precisely that fact.
Quantum computers (of the circuit type) rely on interference to pick out
the right
solution. Interference implies superposition in the same world. I highly
recommend
Scott Aaronson's blog http://www.scottaaronson.com/blog/ , for straight
talk about
quantum computing (his book "Quantum Computing Since Democritus" is also
very good).
What exactly is "superposition in the same world" in the Everett view?
You can't identify superpositions as defining "worlds". An UP polarized photon is a
superposition of a LEFT and RIGHT polarized photon. "World" has to mean a subspace that
isn't coherent, doesn't interfere, with other subspaces.
As far as I can make out from David Deutsch's explanations qcs involve a temporary
splitting into two or more worlds, (or the equivalent - differentiation or whatever).
But to say the split is temporary is to violate the idea that they are separate
worlds.
So a quantum calculation involves a mini multiverse being created and collapsed again
under controlled conditions. Have I misunderstood that?
I'd say that's a rough and possibly misleading metaphor. But read Scott Aaronson. He's a
lot more knowledgeable than me and he good at explaining it.
Brent
TBH I can't actually see what else a superposition /could/ be, in the Everett picture
(although I assume if you're looking at things from a path integral view or pilot wave
(etc) then you have something that really is more or less duplicated in one universe,
like Schrodinger's cat in the popular conception being "both alive and dead"...)
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