Timeline for How to build a trap to last the ages?
Current License: CC BY-SA 3.0
18 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 22, 2018 at 12:06 | comment | added | Daron | You might be interested in this question on Physics Exchange. There is one answer so far but I think that person has misunderstood the question physics.stackexchange.com/questions/401251/… | |
| Apr 22, 2018 at 1:22 | comment | added | Loren Pechtel | @Daron If that's not long enough, use U-235. | |
| Apr 21, 2018 at 6:23 | comment | added | Daron | Still you can only keep adding 'backup mass' until both elements reach critical mass and then you have to stop. That puts a theoretical upper limit on how long the trap can last. I am unaware of the formula to calculate that. | |
| Apr 20, 2018 at 21:13 | comment | added | Loren Pechtel | @Daron Use more Pu-239 than you actually need to make it work. Make sure your mass will go prompt critical even after thousands of years of decay. | |
| Apr 20, 2018 at 20:41 | comment | added | Daron | I'm not sure what you mean by overbuilt. | |
| Apr 20, 2018 at 20:17 | comment | added | Loren Pechtel | @Daron U-235 half life = 700 million years. Pu-239 half life = 24,100 years. The latter would still work for several millennia if the pieces were deliberately overbuilt for the purpose. The former would almost certainly outlast any structure in which it was placed. Note that I am considering a mass sufficient to go prompt critical, not merely critical like some of the accidents you'll find on Wikipedia. (All the incidents involving twisting the dragon's tail--since the device survived it wasn't prompt critical.) | |
| Apr 20, 2018 at 13:24 | comment | added | Daron | Okay I have realized the most part of readers would not be comfortable enough with nuclear physics to dream up the idea of a fizzled atomic bomb, and certainly not comfortable enough to realize the short shelf-life of such a thing. So this is certainly good enough for a plot device! Upvoted! | |
| Apr 20, 2018 at 12:22 | comment | added | Daron | The cylinder and ring decay decay in the same way before the trap is triggered. | |
| Apr 20, 2018 at 4:48 | comment | added | Loren Pechtel | @Daron Once the trap is triggered there is such decay, but it is also destroyed in the process so it becomes a moot point. | |
| Apr 19, 2018 at 8:54 | comment | added | Daron | I should really say 'idealised atom'. | |
| Apr 19, 2018 at 8:47 | comment | added | Daron | The definition of half life is a property of an individual atom. It ignores any possible interaction between the different atoms in the lump of material. This makes it inaccurate for describing the decay rate of large lumps of material where the atoms interact very strongly with each other through radiation. Atoms used for nuclear reactions, by definition, react very strongly with each other in this way. | |
| Apr 19, 2018 at 0:47 | comment | added | Loren Pechtel | @Daron U-235 has a 9-digit half life. I don't think decay is a big problem with such a mechanism. And note that I have no delicate trigger mechanism, just a very crude means of taking it supercritical. Note that I said "fizzled"--Wikipedia's page on criticality accidents lists four incidents similar to what I'm picturing here. All were caused by too much of the wrong liquid together, no fancy mechanism. | |
| Apr 18, 2018 at 12:27 | comment | added | Daron | But the delicate trigger mechanisms would decay long before that. See this answer: worldbuilding.stackexchange.com/a/34122/14322 | |
| Apr 18, 2018 at 12:26 | comment | added | Daron | And lumps fissile material, by definition, have short shelf lives because the radiation they produce is essentially and atomic blast in slow motion. After however many years/decades they have decayed so much there is no juice left for the real explosion. | |
| Apr 18, 2018 at 12:20 | comment | added | Daron | You can not rely on gravity alone to product an atomic blast. Proper atomic bombs rely on other elements to mash together two lumps of fissile material with immense force and precision. Simply placing the lumps next to each other results in both slowly heating up, much like a pebble bed reactor. | |
| Apr 12, 2018 at 14:38 | comment | added | Enric Naval | @Alchymist, treasure will get returned because it's "cursed". Looters will be punished by sickness. People who paid the looters will also be punished, since they will want to touch the treasure and put it on their homes. People who helped transport the treasure will also be punished! And it's an area-effect curse. Anyone travelling near the looters will be affected! Legends will be refreshed and new warnings erected around the location. | |
| Apr 10, 2018 at 11:06 | comment | added | Alchymist | A variation would be to make treasures themselves out of radioactive material, say uranium with a thin gold coating. Then just wait for the delvers to gather them all into one bag ... | |
| Apr 10, 2018 at 3:02 | history | answered | Loren Pechtel | CC BY-SA 3.0 |