On 1/10/2015 12:44 am, Stathis Papaioannou wrote:
On 28 Sep 2015, at 12:26 AM, Bruce Kellett <[email protected]
<mailto:[email protected]>> wrote:
It's possible that there are no copies of you, but it seems
implausible. There would have to be infinite copies of other
things, but not you. What makes the non-copied configurations special?
Nothing. It is just that they are a priori as likely as any other
configuration.
In an infinite random sequence of numbers it is possible that my
phone number appears once and never repeats, while other eight digit
sequences appear multiple times; but I wouldn't bet on it.
An infinite random sequence of digits has certain well-defined
probabilistic properties. In particular, ll digits are equally likely,
and all sequences of any particular length are equally likely. If that
were not so, the sequence would not be random. So your phone number will
occur many times. But this is not a good analogy because it relies of
the definition of a random sequence of digits. We do not have any
comparable uniformity definition for a collection of universes.
And even if you are duplicated as Tegmark suggests, so that there are
many copies far outside our O-region, or even our particle horizon,
then there is absolutely no possibilitiy of any interaction between
these copies, so their existence or non-existence can have no effect
on you, so they are irrelevant -- in principle, not just FAPP.
They cannot interact with each other, but they are psychologically
continuous with each other.
That is a meaningless assertion. Can you suggest any operational way
in which you could establish the truth of such an assertion? Are you
suggesting that psychological influences can travel faster than
light? Objects outside our Hubble volume cannot now interact with
us; objects outside our particle horizon can never have interacted
with us and can never do so in the future. The expansion of space
makes these interactions impossible. Psychology is not exempt from
these physical facts.
It follows from the meaning of the words "psychologically
continuous". If I have the same psychological properties as I did
yesterday then I am psychologically continuous with my yesterday
self. It is nonsensical to assert that yes, I remember everything I
did yesterday, I have the same personality that I did yesterday, the
same cognitive abilities that I did yesterday, etc., but I am not
actually psychologically continuous, because there has been some sort
of physical discontinuity. In fact, it is reflecting on this that
should make it clear that physical change is irrelevant to
psychological continuity except insofar as the physical change makes
a psychological difference. If you feel the same, look the same,
behave the same etc. today as you did yesterday but you are informed
that advanced aliens performed a procedure X on you in your sleep,
then that means that whatever X was, it did not affect psychological
continuity.
That is irrelevant to the point being made. I was talking about
purported copies far outside our present particle horizon -- beyond any
possibility of physical influence either way. I contend that applying
the words "psychologically continuous" in this context is simply
meaningless. Psychological continuity is dependent on physical
continuity -- even if only in the transfer of a memory stick from one
computer to another. If there is no physical interaction of any kind,
particularly if such interaction is physically impossible, then the two
persons are different, and have nothing other than a chance resemblance.
Nothing that happens to one can have any effect on the other.
Consequently, I maintain that the idea of psychological continuity over
and above physical continuity is meaningless.
The situation then is just like that with the disjoint worlds of
the MWI in QM: the separate worlds are disjoint -- non interacting
-- so their existence has no bearing on you or your future. In
fact, Susskind and others have identified Tegmark's level I
multiverse with the MWI of quantum mechanics. I think this
identification is nonsense, but the relevance of the potential
copies is the same in both cases -- zero!
It is not zero if you could be any of the copies.
It is generally held that there is no difference in the empirical
predictions of the various interpretations of QM, so some physicists
consider it is a waste of time even thinking about it.
They have a point.
Demonstrate to me how this makes an operational difference. If it
makes no measurable or operational difference, then, the relevance
of the copies is precisely zero.
There is one difference between the MWI and other interpretations,
revealed through the quantum suicide experiment, but this can't be
used to gather evidence to convince anyone else.
Whether the idea behind the quantum suicide notion makes any sense is
debatable. But, as you say, it is not a way in which one can gather
empirical evidence one way or the other, though the absence of people
10,000 years old tends to count against the idea.
There is reason to believe that in fact the universe is infinite
and uniform; but if it is not, which is possible, the conditional
argument still stands. So, do you think you would experience the
world differently if there were infinite copies of you and of
every possible variation of you?
No. Not that I believe that there are such copies, but even if
there were, they would be of zero consequence for anything whatsoever.
What would it mean for probability if your mind were spread over
infinite copies?
Nothing, because it would make no operational difference to anything
-- even if such a concept made any sense at all.
You have IIRC said that there is a problem defining probabilities in
an infinite multiverse. Given that we observe certain probabilities,
what does this mean for the hypothesis that we are living in a
multiverse?
Nothing much. Probabilities are simply the result of ignorance -- we
don't know what the outcome will be, so we gather evidence from the
outcomes in previous similar cases and calculate the chances. We do not
have this facility in the many worlds scenario since we only ever have
evidence from one world.
Many worlds is nothing more than a hypothetical construct. There is no
concrete evidence one way or the other. And science goes with the
evidence -- in the absence of any evidence we have to say that we simply
do not know. Many worlds ideas are not without their problems, so it is
by no means clear that such scenarios have any intrinsic advantage. If
the worlds are non-interacting, as almost certainly is the case, then
they have absolutely no consequences for psychology or the problem of
consciousness.
Bruce
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