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: http://nuclearweaponarchive.org/Nwfaq/Nfaq0.html 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 position. 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:-), rgb -- 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 _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
