Re: Planetary rovers, SETI and other musings, was Re: update.356(fwd)

[Steve Schear <schear@lvdi.net>]

At 8:28 AM -0600 1/28/98, Jim Choate wrote:
>Forwarded message:
>
>> Date: Tue, 27 Jan 1998 23:44:50 -0800
>> From: Steve Schear <schear@lvdi.net>
>> Subject: Re: Planetary rovers, SETI and other musings, was Re: update.356
>>  (fwd)
>
>> I guess I'm over my head in such matters.  From my, admitedly, shallow
>> understanding of wave function collapse, etc., I was under the apparent
>> misimpression that once collapsed (e.g., by Alice entangling a 'modulation'
>> photon M (of a known polarization) with one member (photon A) of an
>> entangled pair, one of which was sent to Alice and the other (photon B)
>> which was sent to Bob, photon B's polarization state was determined and
>> could not subsequently be altered by Bob's measurement with his receiver.
>> Could you recommend a good article which explain this paradox to a
>> non-quantum mechanic?
>
>The state is determined *at the time of collapse*. Once the collapse occurs
>the synchronization is no longer present and subsequent events can indeed
>alter the polarization of one particle without altering the other. Simply
>bouncing that photon via refraction off a surface can alter the
>polarization.

If that is the case, I still don't understand why and out-of-band signal is
required.  If the sender collapses the wave function shortly before the
signal reaches the intended receiver its unlikely to have changed
polarization again.

--Steve