This question about exercises relating to nuclear bomb design prompted a couple of complaints about the kind of attention it might bring to the site. I wanted to open a question for community input on this issue. What should our policy be toward questions that involve or relate to potentially illegal or unethical activities?

This has a parallel on the programming-related sites of the SE network, in that people will occasionally ask about software exploits. We can draw on their experience in deciding on our own policy. I'll add to this list as I find them.

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    $\begingroup$ I have no opinion worth adding, but I do like your choice of parallel phenomenon, and will proceed to consider bombs as being "physics exploits." :) $\endgroup$ – wsc Dec 22 '11 at 1:07

It's pretty unlikely that any organisation with the access to materials, technology and fabrication facilities to manufacture a device would be seeking intro physics guidance on SO.

Another physics based forum had a strict rule on not explaining things that people could hurt themselves with, Van der Graff generators, electromagnetic rail guns, penny squeezers, etc - and that they could reasonably build. but it was OK to talk about much more dangerous experiments that they couldn't actually do.

  • $\begingroup$ I think that the amount of damage/hurt should be of concern. If the maker and his/her angry young men friends are stupid enough to play with dangerous weapons is one question, hundreds or thousands of collateral victims is another. The reason Japan was stopped in its tracks was the enormity in numbers of the damage of the A bombs. $\endgroup$ – anna v Dec 22 '11 at 17:16
  • $\begingroup$ Firebombing Tokyo killed more - do we ban questions on making fire? Or do we assume that unless they also have a fleet of B17s Tokyo is pretty safe $\endgroup$ – Martin Beckett Dec 22 '11 at 17:33
  • $\begingroup$ We have an expression in greek : "stored in a pickle jar". Used when we want to say that living is dangerous anyway and only pickles are preserved :). It is the degree of danger: one does not show the use of matches to a two year old, guns to ten year olds etc. Instructions how to make dirty bombs or nuclear guns for use by firebrand young ( and not so young) revolutionaries are in the category of two year olds with matches, imo. $\endgroup$ – anna v Dec 22 '11 at 18:00
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    $\begingroup$ @anna - my view was (danger * likelyhood) so telling somebody about how an H bomb works is ok because likelyhood of building it is 0.0 telling somebody how to build an electromagnet with 220V AC is not OK, although they will only hurt themselves chance of building it is high. $\endgroup$ – Martin Beckett Dec 22 '11 at 18:03
  • $\begingroup$ really i thought making a dirty bomb wasn't all that hard...I guess its a lot easier to be a bio-terrorist then $\endgroup$ – user16438 Feb 6 '14 at 6:52
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    $\begingroup$ @caseyr547 a dirty bomb generally means a nuclear weapon with enhanced radioactiviy. If somebody posts asking "I obtained an ex-USSR nuclear torpedo warhead, how thick a layer of Cobalt should I jacket it with in order to kill the maximum number of infidels?" Then there might be pause for thought. If you really want to be a succesful bio-terrorist, get a job in a hospital kitchen and don't wash your hands $\endgroup$ – Martin Beckett Feb 6 '14 at 16:04
  • $\begingroup$ @MartinBeckett while i do see the humor in your patronizing it is ironic...i was thinking along the lines of making antibiotic resistant bac or antiviral resistant vir airborne....i think dirty bombs are just normal bombs laced with sufficient radioactive material to contaminate a small high traffic area i find the fact that you do not know that unsettling as its on wikipedia $\endgroup$ – user16438 Feb 6 '14 at 16:11
  • $\begingroup$ en.wikipedia.org/wiki/Dirty_bomb $\endgroup$ – user16438 Feb 6 '14 at 16:12
  • $\begingroup$ Concerning the category of experiments that people could reasonably build and hurt themselves with, I have collected the following examples: Shock someone for fun; Don't look at the Sun; Jump without parachute; Will I get shocked by my hair-dryer under water?; $\endgroup$ – Qmechanic Feb 9 '14 at 15:45
  • $\begingroup$ @Qmechanic - A new one for your list: Diving from 50 meters. $\endgroup$ – David Hammen Aug 17 '14 at 10:45

As I was one of the people observing that a serious answer to such a question would draw unnecessary attention to the site, maybe I should expand on my ppoint.

Most of my life I have lived in Greece. Living in Greece is not an intellectual exercise only, though not as dangerous as living in Syria or Egypt at the moment. Living in Athens has meant that ordinary middle class people were caught and suffocated by a fire in a bank, started by a molotov bomb during demonstrations last year. And things will be getting worse rather than better. Now one cannot stop the hot blooded bent on vengeance in making a molotof bomb, since the exercise is simple. But Jeff's question raised the specter for me: how would it be if those masked misguided or guided operators, who intervene in all peaceful demonstrations and turn them into mayhem, could "easily" make a nuclear gun? and instead of five dead people have hundreds and entire suburbs contaminated?

Noting that in most countries it would be illegal to give an instruction manual of point by point creation of a nuclear weapon, the question is also ethical, if somebody used the instructions in the answers provided by the site which resulted in some death and destruction. I think such questions should be closed as not pertaining to physics but to weapons design, and kick the can to another board, engineering or weapons.

Another point: Any self respecting government terrorist-hunting organization will be googling such terms and checking on who reads what in this free internet age. Jeff gave a link to an amazon.com book. I am sure all addresses and addressees are carefully scrutinized by somebody that we do not even suspect, from China to North Korea to US. Even Turkey. Can you imagine the Kurdish resistance with a nuclear gun?

The insidious role of the question asked by Jeff is that it asks for a student exercise. An exercise will have numbers and brass tacks, which one cannot find in the run of the mill webpages on nuclear weapons: they waffle and talk of stuff any nuclear physicist knows, not the stuff that needs years of research and tests. Thus the question gave me the impression that it was asked masking a real intention of getting hands on construction instructions of such weapons. That is not innocent or naive. Hence my questioning whether his identity was hacked.

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    $\begingroup$ This is paranoia! There is no way anything anyone says in a forum such as this could possibly help anyone in any way make any sort of nuclear device more dangerous than a conventional chemical explosive. To make a real nuclear weapon absolutely requires the resources of a nation state. It is like going to the moon. $\endgroup$ – Ron Maimon Dec 23 '11 at 6:21
  • $\begingroup$ @RonMaimon Maybe. Dirty bombs though are not paranoiac. As I am sure I know more nuclear physics and possibilities of experiments than you, I can dismiss your comment, and will certainly not speculate on how and why in my opinion I am not being paranoic. Just remember you are talking of normal scientists building nuclear weapons with all the health protections etc given on the value of the technicians human life and the requirements of accuracy. As for complexity, it takes years to learn how to make a swiss watch while a sun dial is much simpler and can usefully tell time. $\endgroup$ – anna v Dec 23 '11 at 7:07
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    $\begingroup$ The dangers of a dirty bomb are minimal. Without a big nuclear explosion to spread the radioactivity, and without a nuclear reaction to produce more, it can be cleaned up quickly and dispersed to zero adverse health effects. You would get more bang with Sarin. Nuclear models of radiation harm are totally wrong, becuase they use linear no-threshhold model for radiation damage, and this is completely wrong at very low doses, comparable to the natural rate. Such ultra-low doses are either harmless or slightly hormetic (cancer-preventing). That's the charlatanry in your field (the idiot is Garwin) $\endgroup$ – Ron Maimon Jan 15 '12 at 18:31
  • $\begingroup$ @Ron Maimon: That is debated in the medical community (whether or not LNT or hormesis is correct at ultra-low levels) However, a dirty device could produce levels well in excess of "very near background", so even if LNT is wrong at say 10% over background, these things can go much higher, especially if the explosion is relatively small, keeping the stuff concentrated. One needs only look at the Goiânia accident (en.wikipedia.org/wiki/Goi%C3%A2nia_accident) to see how bad some of the stuff that's out there can be. $\endgroup$ – The_Sympathizer Jul 5 '15 at 23:58
  • $\begingroup$ A small explosion might not spread it far enough to kill thousands or millions, but if it kills even ONE innocent person, that's too much, no? $\endgroup$ – The_Sympathizer Jul 5 '15 at 23:59

I seriously doubt anybody on this forum can even begin to comprehend the complexities involved in making a nuclear bomb, let alone make one! As Ron Miamon stated, entire nations, with their wealth and connections have been unsuccessful trying on their own. I would be very surprised if somebody made a bomb based on the expertise of SE:Physics. Perhaps, the only casualties by allowing the question would be those among us who die laughing!

Just remember that the jokers who are determined to cause mischief and mayhem will do so regardless of whether we ban them or not. Perhaps it is better served to let people who ask know that they are wasting their time on a ridiculous endeavor?

I do agree with Anna that some discussions such as making bombs from home chemicals (a la Steven Segal in Under Seige) are best left unanswered, or closed, or bumped off to SE:Chemistry. Those are not Physics questions.

Of course, the site admin has to decide on liability issues as there are always morons who try to sue at the drop of a hat.

  • $\begingroup$ The complexities of making a nuclear bomb mostly come from the sheer scale of the industrial facilities needed to manufacture the materials, and to a lesser extent, from the incredibly tight tolerances on implosion-type weapons and the habit of plutonium bombs to pre-detonate. Anyone with a degree in physics should be able to design a gun-type uranium bomb. $\endgroup$ – Mark Apr 7 '17 at 2:05

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