It can't be done. The mere knowledge that such weapons did exist is clue enough. (Update: Just ask an aerospace engineer!) Simple fission weapons are just not that tricky if you've got sufficient resources. (And you can put me down in the "and that sucks" column. Doesn't change what is).
An article on the (official) blog of Charles Day, the editor of Physics today and a sharp cookie indeed, ends on a different note:
Hearing about nuclear weapons is gloomy. Fortunately, an uplifting note came from the symposium's cohost and first speaker, Hirotaka Sugawara, who directs JSPS's Washington office. He challenged physicists to devise ways to detect and thwart nuclear weapons:It's an interesting idea. I tried to leave a comment but ran up against a setup similar to my own ban-comments-on-older-posts. I'll share it here, just 'cos I can:The nuclear bomb is a product of "devil's work" by physicists. If the tragedy of Hiroshima and Nagasaki should be repeated again somewhere, sometime by someone, physicists should seriously consider contributing to "God's work," which is to nullify the nuclear bombs.
Sugawara acknowledged that the goal would be dificult. But, to quote another physicist, Phil Anderson, about another unmet goal, understanding high-Tc superconductors, "Since when did physicists stop working on something because it's hard?"
"The dire reality is that a nuclear-weapon-free world is impossible; the simple knowledge that it can be done is clue enough, certainly for fission weapons.
"To nullify such weaponry -- by physics, not mere agreement -- is Good Work indeed. But it should be undertaken in the full awareness of the other arms race that answered armor with the longbow and improved arrow design, that answered naval cannon with the ironclad, that brought tanks to trench-war stalemate; and every 'weapon too horrible to use,' every 'weapon so terrible men will turn from war' that, ultimately, was used.
"What stops a fission or fusion reaction at a distance -- and how will it be weaponized?"
One shudders to think. --One shudders more at being the second to think of it.