On 21 Jan 2014, at 06:47, Pierz wrote:
The question is whether a whole universe is created for each state
in a superposition. Deutsch seems unequivocal that it is.
Hmm, Deutsch might have change his mind. he was also sure that there
is a base problem, but he changes on it.
Liz is right. The differentiation of the universe is a local
phenomenon. But the universe is full of intracting things, and this
made the differentiation spreading (at sub-light speed though).
I'm just questioning a) whether that's what he really means and b)
whether that is necessary.
Deutsch prefers to abandon the idea of splitting universe. I follow
him on that, but this is almost a problem of vocabulary, and in
english what happens is hard to simplify.
Imagine a particle in the state up + down, and imagine me, not looking
at the particle.
The quantum state "me X (up + down)" is the same state as (me X up +
me X down). Is there one me, or two me. Deustch would say "two me, but
two fungible me". There is only one 1p, but you have the choice of two
3p or one, according to the equality
me X (up + down) = (me X up + me X down).
The same happens for the rest of the universe. If I look at the
particle, in the {up, down} base, then I will differentiate (the two
3p me get two 1p me), or I will bifurcate, that is there is one more
3p me.
In fact those wording are exactly equivalent by linearity.
I don't dig on that issue for two reasons.
- One general: I just do not find an infinity of universe extravagant.
A finite numbers of universe would seem more extravagant to me (and to
most everythingers, by definition).
- One with comp: there is zero such universe in that case, which
nullifies that "extravagance" problem. There is only {0, 1, 2,
3, ...}. Or {K, S, KK, KS, SK, SS, ...}. It is equivalent.
Bruno
It's necessary that that local states be able to decohere, but that
doesn't to me seem to necessitate the duplication of the entire
universe. The splitting can be a diversion of information states at
an entirely local level, mediated by local interactions. The
multiverse only needs to be big enough to accommodate the
information required at each local branch point. Why bring the whole
rest of the universe into it?
On Tuesday, January 21, 2014 3:01:13 PM UTC+11, yanniru wrote:
My understanding is that a different universe really means a
different spacetime.
On Mon, Jan 20, 2014 at 10:53 PM, LizR <liz...@gmail.com> wrote:
Yeah, I believe that's how it's supposed to work. They're all in the
same background spacetime but once detangled have no influence on
each other. (However a TOE might have something to say about
"background spacetime")
On 21 January 2014 16:45, Richard Ruquist <yan...@gmail.com> wrote:
I prefer a theory where every superimposed quantum state is realized
physically but in the same spacetime.
Is that theory feasible and does one already exist?
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