[Beowulf] Re: "hobbyists"

Robert G. Brown rgb at phy.duke.edu
Thu Jun 19 06:58:44 PDT 2008

On Wed, 18 Jun 2008, Jim Lux wrote:

> So.. if your (foreign person) buddy is designing thermonuclear devices in 
> their garage, and they complain about how slow it is to run the hydrocodes to 
> simulate stuff, better not hand them that old copy of Sterling, et al., or 
> even worse, give them rgb's website. (the latter would be too suspicious, 
> since rgb *is* a physicist, doing monte carlo simulations no less, while Tom 
> Sterling is *just a computer scientist*)

Ah, taking my name in vain I see...;-)

Don't forget, at one time, the shocking subversive rgb had a mirror of
the NWFAQ:


on his personal website, which contains nearly all the instructions for
making nuclear bombs one could ever need even without a cluster.

At this point the whole idea of computers (clusters or not) as weapons
is just plain silly.  My cell phone and PDA are "weapons" by the
standards set a mere fifteen years ago -- as far as being capable of
running fast enough complex enough codes to solve the problems of
designing "good enough" nuclear weapons is concerned.  Well, I'm not
sure about my cell phone, but my PDA has 64 MB of memory and a 400 MHz
processor -- that is more than enough.  Or my son's PS3 playstation, if
you don't like the floating point on my PDA.  Who cares?

Compare the computing available to the people who actually DESIGNED the
early thermonuclear devices to a single dual CPU, quad core (8 core
total) 64 bit, over the counter compute "node" with 16 GB of memory
(total cost WAY less than what I paid for my original IBM PC with its 15
MB of attached storage even ignoring the significant inflation
accumulation since 1982).  A joke, man, a joke.  My laptop -- even my
old one and not my new one or my still newer one that should get here
tomorrow or Monday -- can design nuclear bombs, thermo or otherwise, and
any halfway competent computational physicist can write the code needed
to do so using the excellent numerical libraries that are readily
available within any distribution of linux.

Remember, building nuclear bombs ranges from VERY easy to not terribly
difficult, until you want to build a BIG one, or a small one, or one
that has to be "precise" in its performance.  Terrorists need none of
these things -- sloppy to the point of being a fizzle of sorts is still
more than good enough.

Building a kiloton-range U-235 suicide bomb (given the U-235) I could do
in roughly a day, reusing a 12 gauge shotgun already in the house.  I'd
probably have to buy a metal lathe or small metal smelter, I admit,
depending on how the Uranium was delivered to me.  To make a really GOOD
(efficient) bomb and get into the 10 KT range might take me a week or
more to run down a few more materials -- a neutron source and reflector,
some concrete, a remote trigger (suicide not being all that appealing to
me), a superior propellant to gunpowder (e.g. a lump of TNT, homemade or
otherwise).  Handling or making the explosives would be the most
dangerous or difficult part of the process as I'm not a chemist and it
is very easy to blow yourself up, but I'm certain that it is still quite
easy to get TNT and commercial triggers if you really really want to and
have timescale months to acquire them legally and have no criminal
record and have a legitimate construction project of some sort that
requires blowing up some rocks on your property in the country.

Building a plutonium bomb (given the plutonium) is considerably more
difficult and not a project for MY garage even with a lathe.  Plutonium
is downright dangerous to handle, and the construction requires shaped
lensing charges, which in turn requires an ability to make precision
casts of at least two different explosives with differential burn rates
and to set them off with high speed triggers at exactly the same time.

However, "exactly the same time" very probably means something quite
different now from what it did in 1945.  Again, my PC contains
nanosecond clocks; over the counter electronics can probably provide
enough switching speed and power to get within the range that will
suffice for an implosion device, especially one slightly overengineered
in other respects.  Sure, the government controls known fast switches,
but I very much doubt that they control the knowledge of how to make
them, and I doubt that they are that hard to make.  I'd say a plutonium
bomb (given the plutonium) is a project that would cost somewhere in the
$100K range up to a few million, for a small team that includes an
explosive expert, an electronics expert, a physicist, and a computer
geek, to get (again) to the 10+ KT range.

Thermonuclear fusion and the 100+ KT to MT range are similarly
straightforward.  From what I recall, one can just monkey around with
building bigger bombs surrounded by more fissile material and get close
to the latter, adding fusile material such as tritium (expensive and
dangerous) or deuterium (plentiful and harmless) and lithium into spaces
between trigger and a U-238 casing.  To get to MT, one has to build a
proper dual implosion device so that the trigger causes both heating,
compression, and neutrons to all happen at the same time to a
significant volume of fusile material.  The NWFAQ doesn't contain
engineering specs (as it proudly and irrelevantly announces).  So it is
entirely possible that one could try for MT and only end up with a 100
KT or so.  However, range of total destruction scales like the 1/3 power
or thereabouts of the energy, so a 1 MT device only does roughly twice
the damage of a 100 KT device anyway.  Code and my laptop might up the
odds of making a MT+ device work the first time, but...

...from the point of view of strategic war or tactical war these
differences matter, I suppose.  A 100 KT "fizzle" might let a hard
shelter survive where a 1 MT non-fizzle would kill it.  Getting too big
or two small an explosion can either kill your own troops or not kill
all of the enemy on an actual battlefield.  Tactical devices like
neutron bombs require significant engineering and experimentation to
achieve and are not garage projects, I suspect -- get them wrong on the
one side and they're thermonuclear devices that are far more powerful
than you anticipate, get them wrong on the other and they don't make a
significant flux of neutrons and the enemy soldiers overrun your

However, from the point of view of terrorist bombs NOBODY CARES -- or
should care -- a 1 KT "near fizzle" bomb is the moral equivalent of two
million pounds of TNT, 100 panel trucks loaded full of TNT and set off
all at once.  Set off in the right place, it would do billions of
dollars in damage and kill as many as hundreds of thousands of people,
especially if it were surrounded by e.g. a ton or so of cobalt.  I could
do that with my shotgun.  A plutonium bomb that COMPLETELY fizzled would
fizzle by prematurely fission of imperfectly compressed ball of
plutonium blowing apart before a large "enough" fraction of the total
mass fissions, spreading highly radioactive plutonium and various
radioactive fission byproducts over a few hundred acres of presumably
expensive and densely populated real estate and STILL would likely
achieve at least billions of dollars in damages and a death toll in the
thousands to tens of thousands, the latter spread out over ten or twenty
years and from horrible things like leukemia and other cancers.
"Chernobyl" in the middle of the city of your choice.

The only solution to the threat of nuclear terrorism is to change the
conditions that give rise to terrorism in the first place.  Poverty,
ignorance, scriptural theistic religion (with its absolutes and myths
that lead to irrational action), hopelessness, nationalism,
overpopulation, scarcity, human greed.  If we as a species fail to do
this, then SOONER or LATER, somebody is going to end up with few chunks
of sufficiently pure U-235, a garage, and a shotgun, or more likely will
end up being provided a properly engineered and tested design plutonium
bomb all "ready to use" and will then -- not terribly surprisingly --
use it on us.

Bad as it is, this beats the hell out of the condition I grew up in --
living just outside of DC but well within the radius of TD expected for
a 10 MT airburst over the Washington Monument, with MIRV'd ICBMs
targeted on both sides and a single moment of insanity away from MAD --
but it isn't terribly desireable.  No matter what the holding action, no
matter what the defenses, it is just too easy.  Put a shotgun-bomb into
a freighter as machine parts or a nameless lump of concrete down in the
bilge, sail it up the Saint Clair river, there goes Detroit, or maybe
Chicago.  SF, NY, Miami, New Orleans, Washington, Baltimore, Boston --
all vulnerable.  Or unload it, put it on a truck, and anyplace is a
target.  The government could uncover and stop thirty such plans in a
row, but the thirty-first loses a city.  Guantanamo isn't the answer,
because it doesn't address the right questions, eliminate the root
cause, it is at best a finger in the dyke that creates still more leaks
from its own nontrivial contribution to the sheer injustice of it all.

Poverty, despair, scriptural religion, social injustice on a global
scale ... nothing else will do but eliminating them, and it will take
fifty years of CORRECTLY directed action to do much about them, all the
while sticking fingers into the dyke whereever we discover a leak. In
the meantime, well, one day we'll lose a city.  Or worse.  All it takes
for evil to triumph is for humans of goodwill to do nothing, and we've
been doing the WRONG thing (much of it being nothing) for far too long
to escape unscathed.

Depressingly and politically yours (and not ENTIRELY off topic -- I did
talk for a BIT about computing at the very beginning:-),


Robert G. Brown                            Phone(cell): 1-919-280-8443
Duke University Physics Dept, Box 90305
Durham, N.C. 27708-0305
Web: http://www.phy.duke.edu/~rgb
Book of Lilith Website: http://www.phy.duke.edu/~rgb/Lilith/Lilith.php
Lulu Bookstore: http://stores.lulu.com/store.php?fAcctID=877977

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