Re: more teleportation

Hal Finney (
Fri, 23 Oct 1998 11:07:46 -0700

John Clark, <>, writes:
> I can instantly change the state of your receiver 1000 light years away
> but I can't send you a message. The message is "encoded" and until you
> get the equivalent of a one time pad it looks random to you. I can't send
> you the one time pad ahead of time because I don't know what it will be,
> I only find out when I actually send the particular message and quantum
> process create one, so now the only way I have to get the one time pad to
> you is by old fashioned radio. 1000 years from now when you receive the
> one time pad you can confirm that I have instantly changed one apparently
> random state of you receiver into another apparently random state. They
> weren't really random of course but they would look that way to you
> until you got the pad.

This notion of instantaneous transmission of "encoded" information doesn't strike me as a very good analogy.

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. Particularly in the case of quantum teleportation, where you are not making measurements of the receiving system, you can't point to a time at which the information was received. You almost want to say that the information travelled backwards in time to the point where the reception particle was created, then forward with that particle throughout its lifetime until the teleportation was done.

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.