Re: Roadrunner Supercomputer using 12,960 CELL Processors Hits 1 PetaFlop ?(1000 TeraFlops) of double-precision FP Performance

In article <2Ft4k.11782$Ri.7590@[EMAIL PROTECTED]
>,
Robert Redelmeier  <redelm@[EMAIL PROTECTED]
> wrote:
>In comp.sys.ibm.pc.hardware.chips Cydrome Leader
<presence@[EMAIL PROTECTED]
> wrote in part:
>> I find it unlikely they still don't know how nuclear weapons work,

You'd be amazed.
I was just at a funeral in Livermore yesterday.

>> especially considering they're mature technology and
					eee. Hardly.
>> they've been around for decades.
				That's part of the problem.

>A two-stage thermonuclear warhead is a surprisingly complex
>device -- look up Teller-Ulam.  To work properly, the design has to
>transfer enough light energy to ignite and burn the fusion secondary
>before the fission primary shock waves disassemble the device.
>There's _lots_ to simulate here in at least 2D over many timeslices.

Complex yes, but that's not the problem.  The unclassified problem is
stockpile stewart****p.  Look that up not Teller Ulam.

>Yes, we know how to make them go bang.  Just follow the recipe.
>But we don't always know the critical parts of that recipe, and
>what parts we could change.
>
>In general, the whole field of Finite-Element computation is
>still short of cycles and can swallow everything available.
>Multi-CPU clusters are still being built.  Imagine being able
>to simulate vehicle collisions -- designers would be able
>to determine where metal could be added or other changes to
>improve occupant survival.

The problem is that regardless of how any one feels about weapons, WWII
introduced a substance on the face of the planet we don't understand.
Rather than suggest that one buy or borrow a copy of the Pu-metallurgy
book, J. Bernstein has a new book titled "94".  There's also a slightly
older simpler IEEE Spectrum article.  You can't use common sense to
deduce how it will behave.  It's not stable like other substances in
common every day experience.  We are only now learning how it ages
(poorly).  Weaponized Pu is constantly degrading.  Most people haven't a
clue that these weapons have known shelf-lives (amazingly short before
they requirement maintenance).  And you can't merely think about what's
in your nation's stockpile.  You have to think about the stability of
the other guys' (note plural possessive) stockpile.


I once asked an old boss of mine if he had ever designed a dud. *
He was a new boss at the time, and I didn't have a clearance (still
don't).  And he answered: Technology walks a very fine line.
Years later he admitted Yes.  He had.  But that didn't stop others from
using his code which went into the bunker buster in current use. 
He's proud of that.


* Why the design of this I'll likely never know.  I can think of people
who would know, but the vast majority of the semi-interested public are
too biased by early WWII weapons history to reason rationally and
consequentally have no Need to Know.  I don't expect any further answer
from him so he can retain his Q-clearance.

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