From: John Clark (jonkc@worldnet.att.net)
Date: Fri Oct 23 1998 - 23:27:26 MDT
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Hal Finney <hal@rain.org> Wrote:
>This notion of instantaneous transmission of "encoded" information
>doesn't strike me as a very good analogy.
It's not a perfect analogy, nothing is, but personally I don't think it's bad.
>For one thing, the "speed" of transmission is potentially more than
>instantaneous. If you insist on thinking of this as transmission of
>information, the problem is that it can go into the past as well. It
>can even go into the past light cone of the "transmitter", which makes
>it faster than "faster than light". Also (or equivalently), there is no well
>defined moment of reception.
Some truth in that, if your receiver is a detector of polarized light then
it's not clear if the message was received when you measured the
rotation of your polarizing filter or when you determine if the photon
I sent you makes it through the filter or not; and you could set the filter
even before I sent my message.
>There are enough differences from what we normally mean by the phrase
>that I don't think it is useful to call this phenomenon "transmission of
>information" at all.
It's not faster than light but this phenomenon can transmit information,
teleportation can be used to get information out of a system without
causing quantum decoherence, that's why those who want to make a
quantum computer are interested in it. Something like it has also been
used in real world in quantum cryptography to transfer financial information
between banks.
John K Clark jonkc@att.net
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