On 11 Nov 2014, at 21:55, John Clark wrote:
On Mon, Nov 10, 2014 Richard Ruquist <[email protected]> wrote
> I questioned Bruno's statement that MWI universe splitting
proceeds at the speed of light on the basis of EPR experiments which
seem to suggest that the splitting proceeds faster than the speed of
light. Could you comment on this? I was unable to understand Bruno's
response.
I didn't understand Bruno's response either.
It is the standard explanation by "many-worlders". You can consult the
(not too bad) "Everett FAC": http://www.hedweb.com/manworld.htm#local
or
http://www.hedweb.com/manworld.htm#faq
I have heard some say that Many Worlds is a local theory but I
disagree. Suppose you and I each have quantum entangled coins,
So you met once to build the entangled qubit.
you are on Earth and I am in the Andromeda Galaxy 2 millions light
years away.
Is there not a pronoun problem ... hmm?
"You" are in the state [1/sqrt(2)(you I0>I0> + you I1>I1>)]. There is
an infinity of couples of you + the other guy.
We both start flipping our coins and keep a record of the sequence
of heads and tails. You then get into your spaceship and travel at
99.999% the speed of light and after 2 million years you reach
Andromeda. We meet each other and compare our records. We discover
that 2 million years ago we produced identical sequences of heads
and tails. The only way Many Worlds can explain that is if the split
happened faster than light, in other words if it was non-local.
Indeed it's a good thing it's non-local because we know from Bell
that at least one of the following 3 things must be false:
1) Freedom, sometimes called the no-conspiracy assumption. It means
that if you decide to set your polarizing filter at 122 degrees to
measure a photon from a distant quasar your decision to set it at
that angle was not determined by the nature of the photon which was
created 10 billion years ago. In other words we assume that the way
we decide to set our measuring instrument is not determined by the
state of the system being measured.
2) Realism, sometimes called "counterfactual definiteness" by those
who wish to unnecessarily complicate things with obscure jargon. It
means that my coin flips and the sequence they produced actually
existed even before you traveled to Andromeda and saw them with your
own eyes 2 million years later.
3) Locality. It means that influences can't move faster than light.
Every experiment ever performed, including those involving Bell's
inequality, assumes that #1 is true, scientific progress would be
impossible if we did not. And until Copenhagen came around every
scientific theory also assumed that #2 is true. If we had to get rid
of one of the above assumptions (and the violation of Bell's
Inequality tells us that we must) then abandoning #3 seems the least
damaging to me, and that is what Many Worlds does.
If Many Worlds were local it would mean we'd have to get rid of #2,
in which case it would be no better than Copenhagen or even worse
get rid of #1 in which case Science is over.
We keep "freedom", realism (of the entire wave) and locality. But the
state of the subsystem are relative, and the math shows that they are
correlated, but no FTL needs to be invoked at any point. It looks like
(and has to look like that) only if we throw away the terms of the
waves, that is, only if we introduce a collapse, or if we introduce
bohmian initial boundary hidden variable conditions, but in that case
the guiding potential has to act non locally. Not so if we keep all
terms "alive", in which case the Bell violation are pure first person
correlation.
We keep physical realism, but we lose "counterfactual definiteness"
given that all outcomes are realized. In fact CFD is pretty
equivalment with "unique outcome assumption", the negation of many-
world. I would not use the term "realism" for that, but I know some
author do that.
It should be obvious that the MW is local, as the time evolution is
described by a linear wave. You can look et Price explanation on EPR
and Bell, which is closer to mine, except that I interpret all states
by infinities of (quantum) computations.
Bruno
Bruno
John K Clark
--
You received this message because you are subscribed to the Google
Groups "Everything List" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
http://iridia.ulb.ac.be/~marchal/
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
