> Date: 11 Jun 99 20:35:58 MDT
> From: Paul Derbyshire <[EMAIL PROTECTED]>
> Subject: Re: [Re: Inane Stuff (Was: Mersenne: M38, SETI, and other random
stuff )]
>
> Chris Nash <[EMAIL PROTECTED]> wrote:
>
> > 10^12Hz... wow! Can you imagine the technical innovation needed to get a
> > machine where light only travels 0.3mm in a clock cycle? That's some
> > densely packed, erm, stuff... probably not silicon, the sort of thing
> > we probably can't conceive right now (electron obedience school?)...
>
> The technical term is "superconductor" and I can conceive it quite fine
:-)
One of the problems of incresing clock speed is obvious from Chris' post: if
light only travels .3mm during one clock cycle, how does one keep the clock
coherent across a much larger die?
As far as superconductors are concerned: don't count on it. They would
*only* solve the heat problem, since they have no resistivity below Tc.
Right now the problems with those susbstances are:
-crystal growth: in most cases a single crystal larger than .5mm is
considered huge
-they are "dirty": in many cases it is not quite clear what's actually in
the crystal (!)
-nobody has demonstrated what we call "particle-hole-symmetry", i. e. that
you can make a given crystal both n-type and p-type, which is of course
essential for making transistors and circuits
-there is no real consistent theory about high-temperature superconductivity
-and of course, room temperature is far away: the record is around 135k with
some Mercury-compound (Hg-1223, I think), which is not entirely stable and
toxic on top of that....
I think that's enough physics for one day ;-)
Martin
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