Newsgroups: comp.arch
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: EFLOP architectures: when and for how much?
Message-ID: <1990Oct27.235949.6451@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <2581@ux.acs.umn.edu>
Date: Sat, 27 Oct 90 23:59:49 GMT

In article <2581@ux.acs.umn.edu> dhoyt@vx.acs.umn.edu writes:
>>An instruction cannot be executed in a time shorter than the time
>>it takes for a light beam to traverse the processing device.
>  This may or may not be true.  It is certianly possible for an 'electron'
>to pass from once side of a gap to the other side, with no elapsed time.

Um, references please.  My recollection is that the transition is *not*
instantaneous.  Contrary to popular belief, it doesn't even jump the gap
without occupying the space between:  the notion that it is forbidden to
occupy said space is an attempt to apply classical dynamics in an area
of severely non-classical behavior.

If you are talking about the collapse of wave functions, that is a
totally different story.  One can argue about whether that phenomenon
is "real", but it is inarguable that you *cannot* use it to transmit
information, which is what we're talking about.  The electron doesn't
"pass from one side to the other side"; it starts out on both sides,
and then decides which side it's on.

If you believe in (a) cause and effect, and (b) special relativity --
both of which are rather solidly rooted in experimental evidence -- then
faster-than-light transmission of information is fundamentally impossible.
(From a suitable viewpoint, the transmission time would appear to be
negative, with cause (transmission) coming after effect (reception).)
-- 
The type syntax for C is essentially   | Henry Spencer at U of Toronto Zoology
unparsable.             --Rob Pike     |  henry@zoo.toronto.edu   utzoo!henry