Re: Interested in thoughts on this excerpt from Martin Rees

From: Bruno Marchal <>
Date: Sat, 5 Aug 2006 16:10:59 +0200

Hi Stathis,

I agree with what you say. Note that quantum information is very
different from classical information. Quantum information in general
cannot be copied or cloned, so that there is no relative local back-up
possible. That is why in quantum teleportation, the annihilation of the
"original" is unavoidable.

But it is easy to explain that this is already a "simple" consequence
of comp. Any piece of "matter" is the result of a sum on an infinity of
interfering computations: there is no reason to expect this to be
"clonable" without cloning the whole UD, but this would not change any
internal measures (by Church thesis and machine independence).

Of course we can prepare quantum identical states, as the UD cannot not
emulates them all, or their rational approximations, which by linearity
of the quantum laws, are enough (from the 1-person point of view).

QM explains well how bits emerge from qubits, but comp promises a
reversed transformation: how qubits are necessarily "dreamed" by bits.


Le 05-août-06, à 15:34, Stathis Papaioannou a écrit :

> CW writes:
>> It's like teleportation. Maybe you can demonstrate with 1 or 2
>> particles in
>> QM.
>> But it's another very different thing when we are talking about human
>> beings
>> (or simple animals).
>> Maybe other very knowledgeable prof. (like "scerir"???) in this list
>> can
>> provide useful ref.
> There is a distinction between quantum teleportation and classical
> teleportation.
> Quantum teleportation involves transmitting the exact quantum state of
> an entity
> and has actually been demonstrated experimentally with handfuls of
> particles in
> the past decade. Here is reasonably simple summary:
> The cited article states that for reasons of *engineering* difficulty
> we won't be
> teleporting people around in the near future, but there is no
> theoretical reason
> why it couldn't eventually be done. A person who quantum teleports
> from A to
> B would arrive at B in an *identical* physical state, which is
> actually more than
> can be said if he had walked, since our quantum state changes every
> moment.
> So, if we remain the same person when walking, we should remain the
> same
> person when quantum teleporting. It is theoretically possible that
> there is some
> non-physical factor necessary for consciousness which does not survive
> perfect
> physical duplication but there is no reason whatsoever to believe
> this. It would be
> like saying that there is some non-physical factor in my computer, and
> a perfect
> physical copy of it would not be functionally equivalent because it
> would lack this
> factor.
> Classical teleportation cannot copy something exact to the quantum
> level, but
> rather involves making a "close enough" copy. It is obvious, I think,
> that this is
> theoretically possible, but it is not immediately obvious how good the
> copy of a
> person would have to be (what Bruno calls the "substitution level") in
> order to
> feel himself to be the "same" person. But as mentioned above, I don't
> think we
> need to insist on perfect duplication to the quantum level, because
> this doesn't
> even happen from moment to moment in everyday life.
> Stathis Papaioannou
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Received on Sat Aug 05 2006 - 10:13:02 PDT

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