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While considering Ancient Light Trigger Mechanism, it occurred to me that any ancient trap mechanism is unlikely to work very long without regular maintenance. It seems far too easy for dust to clog the triggering mechanism, or for animals to burrow close enough to the hidden mechanisms to disrupt them, and for any organic materials to rot.

How do I design a trap to last the ages? My (eventually) ancient ruin isn't going to protect itself without them!

The traps need to:

  • pose a legitimate threat - a dart-shooting trap that has lost most of its strength and shoots a dart without enough force to penetrate skin is a no-go.
  • be reliable - a practically unavoidable trap that causes injury is better than an easily avoidable trap that kills you.
  • last as long as possible - a broken trap isn't really a trap at all.
  • bonus: being able to use the trap more than once

I'm going to open this up to all levels of technology - I'm curious to see if someone can figure out how to do this with ancient technology, but this seems like it could be challenging to modern technology as well.

Rob Watts
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    VTC as off-topic. How is this a worldbuilding question? – JBH Apr 09 '18 at 22:31
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    @JBH Trying thinking of it as "Can a trap be built to last the ages and, if so, how would it be done?" Then it starts to sounds similar to something like this. Which one would assume is about Worldbuilding... – Samuel Apr 09 '18 at 22:53
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    @Samuel, A better question to take me to task would have been this one. Nevertheless, my question, while barely within the rules (I expected it to be closed) was about a world (the condition of a planet and its societies), not about a single object or item type. Time is not what makes something about worldbuilding. (And with your rep and time on site, shouldn't you have known all this?) – JBH Apr 09 '18 at 23:07
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    @JBH "And with your rep and time on site, shouldn't you have known all this?" Have you considered that maybe I do know all this and you're in the wrong? Check out the first item on the help page for on-topic items: "Creation of elements of a world (languages, species, buildings, etc.)". I think it's would be trivial to argue that an ancient trap falls under the category of "an element of a world", wouldn't you? In fact all three on-topic bullet points easily apply to this question. – Samuel Apr 09 '18 at 23:12
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    @Samuel, Though I believe I have justly VTC'd this question, I certainly can be wrong. I've asked a meta question about this to better see if I've become too strict. – JBH Apr 09 '18 at 23:31
  • @JBH Fair enough. – Samuel Apr 10 '18 at 00:24
  • many pyramids and tombs become traps over the ages... I'm just saying. – user6760 Apr 10 '18 at 03:22
  • I'll say the question is moot because if your civilization is clever enough to make a trap that can do the job after centuries of neglect, then your civilization should be clever enough to persist so that the trap isn't necessary. – EvilSnack Apr 10 '18 at 03:24
  • @EvilSnack but the trap-filled ruins have to come from somewhere... – Rob Watts Apr 10 '18 at 03:30
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    The answer largely depends on timescales involved. If you could specify either we are talking aeons or mere thousands of years -- there would be a difference, – Gnudiff Apr 10 '18 at 08:06
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    See also https://worldbuilding.stackexchange.com/questions/28659/killing-off-indiana-jones – Fillet Apr 10 '18 at 09:32
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    The bonus condition is just as important as the others. A trap that gets clogged with corpses will quickly lose effectiveness. – Kelly Thomas Apr 10 '18 at 14:18
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    @KellyThomas I don't know - a bunch of corpses near the entrance of the ruins would be a fairly effective deterrent. – Rob Watts Apr 10 '18 at 16:45
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    @JBH It doesn't take much to see that bullet points one and three for on-topic apply, making the question clearly on-topic. Can you explain how it is off-topic? By explain, I mean relational argument not I think it is so. To justly VTC the question, this must done on the basis of WB's criteria for either on-topic or off-topic. Anything else is bunkum. – a4android Apr 11 '18 at 13:11
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    @EvilSnack: A society with really good engineers can still fall. Rome springs to mind. – Beta Apr 11 '18 at 16:26
  • @EvilSnack have you considered the trap may have been necessary during the civilization's existence, not just after it has fallen? – CactusCake Apr 13 '18 at 17:14
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    @EvilSnack Ah, right, like how the civilization that built aqueducts sturdy enough to last over two thousand years had to last forever. After all, if a civilization is advanced in one respect, it can't possibly ever have any problems in leadership, be surpassed by other civilizations, have internal strife, or be affected by things beyond their control –  Apr 13 '18 at 17:59
  • This has realworld applications as well. - http://www.videoproject.com/intoeternity.html – KalleMP Apr 15 '18 at 17:02
  • This question is central to my scorn for tomb-raider-type films (otherwise I enjoy them a lot). All these cute traps in working order after 10^n years. All of these traps except the hard radiation (detectable) and di(m)ethyl-mercury/lead can be defeated by a prepared modern day explorer. The spores and cantilever pit traps are perhaps the best balance of technology and durability. I cannot think of a way to make anything protecting valuables that cannot be bypassed by rigorous inspection if it can be located. – KalleMP Apr 16 '18 at 08:55
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    Here's the most effective trap that has lasted for several centuries and will possibly last for several more: become a mass leader, die without naming a successor. Result: people will be trapped forever into determining the "true" descendants of the "true" successor. They will even drag into their conflict other people who were not followers of the original guy. – Masked Man Apr 16 '18 at 16:58

25 Answers25

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A simple pit trap.

Have a simple pivot counterweight trapdoor that resets the trapdoor after someone falls in.

The parts are simple and would last virtually forever. A build up of dust would actually help camouflage it.

A (very) simplified diagram: Simplified diagram of counterweighted trapdoor

Chronocidal
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Thorne
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    Your answer could benefit from an illustration of some sort - what are the simple parts needed, what can they be made from, and how are the mechanisms hidden from the casual explorer? – Rob Watts Apr 10 '18 at 03:06
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    A pivot hinge is the simplest form. Think of a seesaw. The hinge is underneath. It could be made from bronze, copper, brass or iron. The trapdoor is slightly heavier on one side so it automatically moves back into the closed position. – Thorne Apr 10 '18 at 03:35
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    The trap won't last all that long because you need hinges. Hinges suck for durability. Heck, there are houses less than 30 years old with hinges too rusted to move the doors. – DonFusili Apr 10 '18 at 07:59
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    @DonFusili he did say hinges made from bronze, in comment. Bronze does not rust https://www.quora.com/Why-does-bronze-not-rust – Gnudiff Apr 10 '18 at 08:05
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    @DonFusili house doors get used dozens of times per day, at that rate your 100m deep pit would be full of corpses in matter of months (weeks?). I'd assume a trapdoor, especially if there are many of them in the "choose the correct path" -kinda layout, would be used once every blue moon. So if you used non-corrosive materials, not too tight fits, etc - they should last pretty long. – DocWeird Apr 10 '18 at 08:20
  • @DocWeird Fair enough, good points. – DonFusili Apr 10 '18 at 08:37
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    You wouldn't even need a real hinge for such a simple mechanism. Just balance a large stone plate on a ledge so that it tips when you put weight on one side. If you want this trap to reset, craft it in a kind of T-shape or add some sort of hook to the bottom so that it does not fall in. – mlk Apr 10 '18 at 11:05
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    @Gnudiff While bronze doesn't technically rust, it can still corrode. Bearings do not last forever - even without corrosion, sitting under such weight will lead to distortions as the material slumps over centuries, or even from contact welding. A simple protrusion on the bottom of the lever, resting on a stable surface, would be the most robust as a pivot, but what of the lever itself? A stone platform would likely snap when it fell back into resting position (the sudden stop when it hits its supports), but anything else would rot/corrode away (or maybe stick out as an obvious trap). – pluckedkiwi Apr 10 '18 at 19:49
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    Agreed with @mlk; you don't need a hinge, just a floor that's not flat on the bottom; a fulcrum at the right point and a hook or protrusion to prevent it from tilting too far would do the trick. The whole thing could be made of stone or other highly durable material. – Paul Apr 10 '18 at 20:14
  • @pluckedkiwi: Cover the trapdoor in stainless steel, gold, platinum, titanium … – Michael Apr 11 '18 at 05:25
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    +1 for coloring the spikes red in panels 4 & 5. – user1008090 Apr 11 '18 at 17:30
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    -1 because eventually the bones will pile up and block the spikes, thus rendering the trap useless and not lasting the ages :) – David says Reinstate Monica Apr 12 '18 at 03:14
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    Should I draw a dingo eating the corpse? – Thorne Apr 12 '18 at 04:09
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    Maybe replace the spikes with a very large (lake size) pool of acid. I think that would help everything. – NL628 Apr 12 '18 at 05:00
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    Magma pool, Temple of Doom style...... – Thorne Apr 12 '18 at 05:10
  • Even if it "fails", you would probably still fall to those spikes through the hole in the floor. – Headcrab Apr 12 '18 at 07:01
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    It doesn't need to be spikes: If it dropped you into an underground river that comes out of a cliff-face as a 60' waterfall/drop, that'd work too. Spikes are just an "obvious danger" for a simplified diagram – Chronocidal Apr 12 '18 at 07:50
  • It would work better if it dint involve the rope and weight and if thet slab would just be a cantilever of unstable kind. – joojaa Apr 13 '18 at 07:12
  • A piranha-infested lake below the trap would be more effective than spikes to keeping everything clean and tidy – AutoBaker Apr 13 '18 at 11:51
  • @Tomy-rex why? so they can tickle you to death? ;) – CactusCake Apr 13 '18 at 17:22
  • You need a body disposal mechanism too. Else all the old bodies might act as coushins for the new adventurer – Anvit Apr 14 '18 at 06:39
  • What materials would you use to make the cable and its casing? – Nicolas Raoul Apr 16 '18 at 07:12
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    A torsion bar pivot made of a long core of basalt or granite can supply the restoring force and provide the pivot bearing. – KalleMP Apr 16 '18 at 09:02
  • @Gnudiff Bronze does not rust, but it does tarnish. I am dubious that any mechanism reliant on moving parts will prove durable; bronze or not. – Jack Aidley Apr 16 '18 at 13:47
  • @CactusCake at least it's a pleasant way to die :P – AutoBaker Apr 19 '18 at 07:56
  • @RobWatts the latency period of the harm from radiation might seem like a hindrance to this being an effective deterrent, but a small change to the trap described above might change that: don't make the radiation a secret. If you somehow convey to visitors that they are being exposed to severe carcinogen risks, it might not matter that the trap has no physical stopping power. Just knowing that the temple is radioactive might be enough to keep people away. Even if the intruders have 20th century technology, there are levels of radioactivity that no rad suit can protect you from. – Pink Sweetener May 03 '18 at 00:16
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Radiation The trap that keeps on trapping! Just powder your passageways with large quantities of plutonium dust.

Then you and your comrade can come and go as you wish, simply by donning lead-line clothing and sealed breathers. Would be thieves and future archaeologists probably wouldn't think to scan for radiation until after finding the bones of their predecessors. And by then, it would be too late.

Henry Taylor
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    Radiation does not last forever. Radioactive isotopes decay. – StephenG - Help Ukraine Apr 10 '18 at 01:48
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    While radiation doesn't last forever it's going to tens of thousands of years. – Loren Pechtel Apr 10 '18 at 02:50
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    While it would kill the deaths would be very slow--you're not going to find those bones. – Loren Pechtel Apr 10 '18 at 02:51
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    This is more useful than I expected, but like Loren said it's not going to be a quick death. Then again, I did specify guaranteed injury makes for a decent trap. If nothing else, this could be used as to make sure the ruins have a reputation as being cursed. – Rob Watts Apr 10 '18 at 03:02
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    Another thought here: There was a question a while ago about making a cursed tomb and I worked some numbers for using radiation for a reasonably quick kill--out of the question, the tomb got too hot before it could administer a lethal dose. – Loren Pechtel Apr 10 '18 at 03:04
  • @RobWatts If they even make the association between the lung cancer deaths and the tomb they visited years ago. And if they do the cause is pretty obvious--something they breathed. The next team goes in with respirators and test gear. – Loren Pechtel Apr 10 '18 at 03:05
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    https://en.wikipedia.org/wiki/Demon_core Related to Loren Pechtel's answer below. – user137 Apr 10 '18 at 05:19
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    @LorenPechtel what about radioactive dust - specifically a beta source that can be breathed in? beta sources typically have a longer half-life than alpha sources, and as they produce ionising particles instead of gamma rays, they "pack a punch" without needing to be so hot. You do need to breath them in though, or your skin does block most of them. Once inside though... – Baldrickk Apr 10 '18 at 11:28
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    The problem with radiation is that it needs a short enough half life to be effective and a long enough half life to last. The two conditions don't overlap. –  Apr 10 '18 at 13:52
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    @HansAdler from the link in my previous comment - "Plutonium has a half-life of about 24,000 years." The other thing about it is that the body absorbs the plutonium, so you're dealing with heavy-metal poisoning and having the radiation source being inside your body. – Rob Watts Apr 10 '18 at 16:50
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    @HansAdler yes, but the decay products of long half-life materials are often a bunch of short half-life materials, plus the stray high-energy particles will convert surrounding originally-inert material into potentially radioactive isotopes. So the room will actually become steadily more radioactive over time until all the decay products and conversions reach saturation. Best to start the trap with some short-lived elements for immediate potency and add some plutonium to keep it sizzling for a few millenia. – Perkins Apr 10 '18 at 20:34
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    @StephenG Sure, radiation doesn't last forever, but neither does anything. On long enough time scales, entire continents are subsumed under the crust and melted, the planet is engulfed into the sun, all stars go out, everything is consumed by black holes, and then those black holes evaporate and all that is left sparse individual particles. But, if you chose the right isotope, you can make sure something remains radioactive for billions of years which is far longer than multi-cellular life has yet existed. – Shufflepants Apr 11 '18 at 14:59
  • @Shufflepants: Radioactivity alone isn't enough. Every plant and animal on Earth is radioactive due to C14. Effing dirt is radioactive. In order to kill someone, the radiation must also be emitted at high enough levels to cause damage. That requires a massive amount of distilled/concentrated/enriched material, and/or a short half-life. – cHao Apr 11 '18 at 15:48
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    @cHao Yeah, and that's why the answer suggests plutonium rather than trace amounts of C14. All you've said is that the dose matters. Nothing about the question limited technology or resources, so the answer is of course "more". Unless you're claiming that you've done the math to show that even if you made the whole place out of pure subcritical alloys of uranium and/or plutonium, that this wouldn't be enough to keep it a death trap for millennium to come. – Shufflepants Apr 11 '18 at 15:59
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    @Shufflepants: Stop that. Radiation is not magic dust. Building the whole thing out of uranium and plutonium doesn't fix the problem. Just makes it worse, actually. Uranium's hundreds-of-millions-of-years half life makes it pretty stable as far as radioactive elements go, and its density makes it even better than lead at stopping radiation (though it heats up in the process). Frankly, you build a whole room out of the stuff, you're more likely to end up with spontaneous fission than you are a relatively-stable trap. – cHao Apr 11 '18 at 16:41
  • This is all assuming that the adventurer isn't wearing some level of protection against radiation. This will also make it easier to detect the ruin in the first place. – Razmode Apr 11 '18 at 16:41
  • @cHao There are places where people can't go unprotected for even a minutes or die. You're telling me that there's no combination of radioactive isotopes you could build a structure out of that would leave it deadly to anyone without a really good radiation suit for thousands of years? – Shufflepants Apr 11 '18 at 17:41
  • Another thing that make Plutonium dust unsuitable is that all Actinides have an extreme affinity for... stone. The reason that underground repositories are considered the prime solution for storing nuclear waste for 100 000+ years is because in case of a breach of the containers, just plain chemistry will see to it that the long lived substances — like Plutonium — are bound to the rock. – MichaelK Apr 11 '18 at 18:23
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    @Shufflepants: Not really. The catch with radioactivity is, decay is the cause of the radiation. So the danger of a given substance is inversely proportional to its half-life. The dangerous places, they're where very radioactive stuff (with short half-lives) is. You can make up for that to a small degree with quantity, but past a certain point, the surface absorbs most of the radiation emitted by the subsurface. (Add to that, a huge portion of the emissions are basically charged helium anyway. That's what alpha particles are.) – cHao Apr 11 '18 at 18:23
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    @Shufflepants "The fire that burns twice as hot does it half as long". This is exactly the case for radioactive substances. If you want it "hot", then it will not last very long. If you want it to last long, it will not be very "hot". There is no way you can combine these to to make a room so "hot" that it can kill you for millennia. – MichaelK Apr 11 '18 at 18:26
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    @Perkins: The decay products don't really help, they just make the computation more complicated. The halflife of the original substance determines how quickly the decay products are produced. The halflives of the decay products determine how quickly they vanish and how effective they are. To be effective, the decay products need to have short halflives, hence vanish quickly. Therefore, to exist in sufficient amounts, they need to be replenished quickly, i.e. the halflife of the original substance must be short. Once it's gone, the trap is out of order. –  Apr 11 '18 at 18:29
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    Every radioactive trap has the problem that it is burning its fuel even when there is nobody there. The only way to fix this would be something that changes halflives, e.g. by colliding two stable atoms - which isn't practical. Trying to fix this via decay products is like trying to build a complicated perpetuum mobile. –  Apr 11 '18 at 18:34
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    I wnder if you could combine this with a mechanical trap idea. Step on the plate and suddenly your radioactive rods are much closer to each other... – Zan Lynx Apr 11 '18 at 23:09
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    Plutonium is (apart from being poisonous when ingested) perfectly harmless. Its radiation won't make it through half a meter of air, let alone dusty air, or even human skin. – Damon Apr 13 '18 at 12:13
  • Shorter half-life means more intense radiation, but some isotopes pack more of a punch per individual fission event. If you somehow manage to get enough radium 226, it has a half-life of 1600 years and is hideously radioactive for something so long-lasting. It is probably beyond today's world, though. – Eth Apr 13 '18 at 15:50
  • @user137 Actually, the demon core makes exactly the opposite argument to what you intend. Those cores emitted sufficiently little radiation that they were manipulated with gloved hands. The two fatal accidents were caused during criticality experiments, when manipulating the surroudings of the 95%-critical core caused it to become briefly supercritical and emit huge quantities of neutrons. But you can't have it both ways: while non-critical, it lasts millennia but is safe to handle with gloves; while critical, it's lethally dangerous but would be destroyed in the runaway fission reaction. – David Richerby Apr 15 '18 at 10:36
  • @Damon yes, but hardly anyone believes that Pu239 is relatively harmless, (in sub-crit assemblies). The everyday people, the ones who thiink nothing of injecting themselves wtih botulinus toxin for vanity, are scared to death of plutonium, or of anything 'nuclear'. Throw some long-lived isotopes around whatever the trap is guarding and put up lots of signage that is designed to last, 'Spent Nuclear Fuel Repository, Do not enter' with lots of 'ionising radiation' symbols would probably do to keep people out. – Martin James Apr 15 '18 at 21:18
  • OTOH, that does not count as a 'trap', unless you consider it a trap for the uninformed. – Martin James Apr 15 '18 at 21:22
  • @Eth: No difference to plutonium. 226Ra alpha-decays to 222Rn which also alpha decays. Alpha radiation, no matter how strong, simply doesn't have the potential of being dangerous (in a oh the nuclears sense) when not being swallowed. Half a meter of air, and done. Or your clothes, or the outermost layer of skin (which is dead tissue) provide perfect radiation shields. You can crank up the energy as much as you want, it will be none more damaging than, say, a camp fire. – Damon Apr 16 '18 at 16:20
  • @Damon Oh, right - which opens up heat-based traps, then! Also radium produces radon, but I doubt such quantity of radon would cause health problems fast enough for the explorers to make the link with it. – Eth Apr 17 '18 at 09:24
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Gas

If your structure is underground with limited ventilation and built over a geothermal vent releasing carbon dioxide, the chambers would be filled with an odorless unbreathable gas. Our intrepid tomb raiders would just have time to wonder why there are all these desiccated corpses lying about before losing consciousness.

Likewise if the vent was releasing hydrogen sulfide, there would be a foul smell around the structure (explained by local legends of a "curse") but at the higher concentrations inside, the smell would seem to disappear. People would die before they even realized they were in danger.

Afterthought edit: Hydrocarbon gases (methane, ethane etc.) are not only asphyxiating but they can cause fun explosions when Prof. Jones turns up with a naked-flame light.

smatterer
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    The geothermal vent seems like a good idea. Are there any real-world examples of that? I'm wondering how hard it would be to actually find a geothermal vent like that and make sure it's not going to go inactive in the near future. – Rob Watts Apr 10 '18 at 03:05
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    I don’t off hand know of any ancient structures filled with noxious gas. I had in mind: [1] Most underground mines need artificial ventilation to clear out gases. [2] Some natural cave systems have unbreathable atmospheres and [3] The theory that the Pythia at Delphi was sent into a trance by underground gases seeping into her chamber. I was also thinking of the Lake Nyos disaster even though it was a one-off gassing that occurred outdoors. – smatterer Apr 10 '18 at 03:44
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    A "sour gas" well produces lethal levels of hydrogen sulfide... – DJohnM Apr 10 '18 at 06:38
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    @smatterer what about https://www.livescience.com/61802-gate-to-hell-deadly-secret-found.html? And as it is CO2, it's also undetectable - at least not until the effects are felt. (You do bring a canary on your underground trips, don't you?) – Baldrickk Apr 10 '18 at 11:32
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    Just to bring science in here, CO2 is indeed odourless, but its presence in significant quantities will cause you to feel seriously 'out of breath', long before it will actually kill you. – DJClayworth Apr 10 '18 at 14:13
  • @RobWatts the Pythia at Delphia (where the famous Oracle presided) did have a geological fault. Some things thought to be contained in its gas emissions are CO2, H2S, CH4, and C2H2. – sharur Apr 10 '18 at 17:18
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    Fun fact - aphyxiation is caused by a lack of oxygen. But our bodies don't detect a lack of oxygen - when we were evolving lack of oxygen was usually accompanied by a CO2 abundance, so our bodies detect that instead. Which means that a room full of nitrogen will kill you, and you won't be aware that you can't breathe until you keel over. – Arcanist Lupus Apr 11 '18 at 06:31
  • @DJClayworth so the solution is to use a vent that releases primarily non-CO2 gases... a natural gas well would work quite well for this, primarily venting methane. The only caveat here is that methane is less dense than air and would thus rise and dissipate, so the trap would ideally need a reservoir to trap the methane, and some manner of release valves to saturate a given chamber with it for a short period of time (long enough to asphyxiate the unfortunate adventurer) -- the idea being that the reservoir self-replenishes from the well over a relatively short period of time (say 24-48 hr). – Doktor J Apr 11 '18 at 19:27
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    @DJClayworth: My understanding is that the symptoms of CO2 poisoning depend on the concentration in a complicated way but "CO2 levels of more than 30% act rapidly leading to loss of consciousness in seconds. This would explain why victims of accidental intoxications often do not act to resolve the situation...". – smatterer Apr 12 '18 at 00:44
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    Another real-world danger of CO2 - wells. CO2 is heavier than air, so it tends to accumulate inside wells. Plenty of people have died trying to go down a well (to clean them or rescue something that fell in) only to pass out halfway down. CO2 in fact seems a pretty good trap - it could even occur naturally, without it being explicitly designed for. – Vilx- Apr 12 '18 at 12:08
  • Wouldn't carbon monoxide be better? – RemarkLima Apr 16 '18 at 06:20
  • @RemarkLima: Yes carbon monoxide is far more toxic than carbon dioxide but, unlike the dioxide, carbon monoxide is not naturally occurring in large amounts (AFAIK) and it is not heavier than air so it doesn't pool the way that CO2 does. – smatterer Apr 17 '18 at 00:30
  • I must add that the tomb needs to have geometry that will preserve the hazardous atmosphere even after being unsealed. Otherwise, only the first adventuring party will fall victim to it. Which will most likely be tomb thieves not long after the sealing, so this wouldn't work for ancient ruins. – ivan_pozdeev Apr 18 '18 at 13:58
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Troll the dungeon raiders

Death is just too liberating. Whether it comes fast or slow, it will lift you out of your suffering.

Psychological damage, though, can last for multiple incarnations.

Make sure your dungeon is empty, then paint "overthinking" on a wall. Watch all the strife that it will cause.

A rare safe for work moment

Source: Oglaf. It is a webcomic with usually NSFW content, so I will only mention it rather than linking directly.

Paint can last for millenia, as the egyptians have shown us.

Also notice that past a certain technologic level, people may start endless discussions about the meaning of the trap. Some of these discussions will end up in invocations of Godwin's law, or escalate all the way up to threats of physical violence - thus extending the damage caused by the trap not only through time, but also through space.

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The Square-Cube Law
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    This reminds me of a quest in The Elder Scrolls IV: Oblivion - Shivering Isles. In it, you get to choose how the adventures "die" - be it by actually getting killed by the dungeon, or by turning the adventures insane by greed and the promise of wealth. http://en.uesp.net/wiki/Shivering:Baiting_the_Trap – PlanetAlexanderProjects Apr 10 '18 at 08:08
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    The paint might last millennia, but it's unlikely full knowledge of the written language would. Snippets of knowledge may survive depending on how advanced the future victims are, but the less people remember about the language, the less effective the trap becomes. – Troyen Apr 10 '18 at 10:33
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    @Troyen people are still killing each other nowadays over stuff that was written in long dead languages millenia ago. I think YMMV. – The Square-Cube Law Apr 10 '18 at 12:15
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    +1 for Oglaf reference. Also, psychological damage is a fun idea. – LinuxBlanket Apr 10 '18 at 12:43
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    @PlanetAlexander like dropping thousands of (fake) keys in front of the locked treasure chest :). That was my favourite. – Mixxiphoid Apr 10 '18 at 15:46
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    Have the trap be the treasure, make the paint in "overthinking" out of pure Lutetium oxide pigment. – KalleMP Apr 16 '18 at 09:16
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Tar pits

Why invent a new trap when nature has one that it's been using for thousands of years?

And they're self concealing! A few years of dust and no one will ever suspect that the bones of a few dozen explorers lie beneath their feet until it is too late.

Arcanist Lupus
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  • Tar pits eventually solidify though, don't they? – Jack Aidley Apr 16 '18 at 13:27
  • @JackAidley yes, but new asphalt usually seeps through to replace it. La Brea has several active pits that they have to keep fenced off, and it's been trapping animals since the last Ice Age. – Arcanist Lupus Apr 16 '18 at 13:43
  • I was under the impression that the renewed seep was the result of excavation of old pits and not a natural feature of the landscape? Also, if you want to use it as a trap, then it'd need to be placeable so you couldn't rely on fresh seep since it is in the wrong place. – Jack Aidley Apr 16 '18 at 13:45
  • (Despite the drawbacks, btw, I think this is an excellent answer) – Jack Aidley Apr 16 '18 at 13:45
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    @JackAidley I'm pretty sure that the La Brea pits have several layers from repeated seep-solidify cycles, although excavation probably didn't hurt. I'm not sure what the time scale of the cycle is, though, or how predictable the locations for the new pits are, though. – Arcanist Lupus Apr 16 '18 at 13:59
29

High tech: Fizzled atomic bomb.

Above the trapped door is a tube full of beads of some kind (sand would even suffice but I think it would be more likely to leak out over time.) They are held in place by the door, open the door and they pour out. They were holding up a cylinder of fissile material, it's lowered into a ring of it. The resulting mass is supercritical. U-235 or Pu-239 are both acceptable, U-235 will last longer before decaying.

Assembled this way you're not going to get much of a boom at all--it won't even blow up the room, let alone the whole tomb. The person who opened the door will still be alive afterwards--for a very short while.

Dry, geologically stable and well sheltered from wind-blown dust I could see such a device being operational for many millennia.

Loren Pechtel
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    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 ... – Alchymist Apr 10 '18 at 11:06
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    @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. – Enric Naval Apr 12 '18 at 14:38
  • 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. – Daron Apr 18 '18 at 12:20
  • 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. – Daron Apr 18 '18 at 12:26
  • But the delicate trigger mechanisms would decay long before that. See this answer: https://worldbuilding.stackexchange.com/a/34122/14322 – Daron Apr 18 '18 at 12:27
  • @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. – Loren Pechtel Apr 19 '18 at 00:47
  • 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. – Daron Apr 19 '18 at 08:47
  • I should really say 'idealised atom'. – Daron Apr 19 '18 at 08:54
  • @Daron Once the trap is triggered there is such decay, but it is also destroyed in the process so it becomes a moot point. – Loren Pechtel Apr 20 '18 at 04:48
  • The cylinder and ring decay decay in the same way before the trap is triggered. – Daron Apr 20 '18 at 12:22
  • 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! – Daron Apr 20 '18 at 13:24
  • @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.) – Loren Pechtel Apr 20 '18 at 20:17
  • I'm not sure what you mean by overbuilt. – Daron Apr 20 '18 at 20:41
  • @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. – Loren Pechtel Apr 20 '18 at 21:13
  • 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. – Daron Apr 21 '18 at 06:23
  • @Daron If that's not long enough, use U-235. – Loren Pechtel Apr 22 '18 at 01:22
  • 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 https://physics.stackexchange.com/questions/401251/what-is-the-shelf-life-of-a-gravity-powered-uranium-bomb – Daron Apr 22 '18 at 12:06
29

Something biological is likely to have a fair chance of surviving the ages, as they have the advantage of being "self maintaining".

Put your temple in the jungle, create the ideal habitat for very venomous / poisonous frogs, snakes & spiders within several chambers and it should be good for a few 100 - 1000 years. Suppose it is unlikely to catch everyone, every time, but should see a decent mortality rate for small parties exploring.

Windlepon
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    Or you take a step up and settle a sentient tribe, whit the religion to guard your temple. The trap being hidden goblin tribe ambushing adventurers for generations!!! – Falco Apr 10 '18 at 12:44
  • And place the temple in a cenote (giant sinkhole) in the forest or between mountains. This place now serves as a giant 'poison jar' experiment. The venomous creatures/plants + spores + tar pit defences can even be placed outside the temple. – vinzzz001 Dec 02 '21 at 13:50
22

Spores

There are some nasty fungal spores that will give any intruders a hard time in the weeks that follow their attempts to disturb your treasures. They could wander around carefully but once they start trying to move anything they'll disturb the spores and trigger the curse. "Look but don't touch".

This will keep on making people sick for many visits. Assuming that there are also some heavy-duty doors involved in the design, and maybe some tight squeezes, it could be difficult to get through without disturbance or exposure.

These spores can last for millennia at least, and can't be detected at a distance (unlike say radioactivity).

Joffan
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  • I think fungus spores lasting for millennia or more is a bit of a stretch, but it might be possible. There are only a few known instances of seeds older than ~1000 years sprouting. https://en.wikipedia.org/wiki/Oldest_viable_seed – BurnsBA Apr 10 '18 at 15:51
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    @BurnsBA - spores are not seeds. "Resting spores" can be dormant for thousands of years (although not every species would have this endurance, for sure). – Joffan Apr 10 '18 at 18:28
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    Sorry, I should have been more clear: perhaps I'm searching for the wrong terms, but pages like that oldest viable seed wikipedia page were all I could find when searching for fungal spores sprouting after long dormancy. I'm sure it's possible, but can't find evidence for it. – BurnsBA Apr 10 '18 at 21:00
  • @BurnsBA Pre-glaciation spores have been germinated... again not saying 100% success but an indicator of what is possible. A slightly random search result... Ancient fungus 'revived' in lab – Joffan Apr 10 '18 at 21:36
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    Hm this is a good idea I think. Provide some sort of substrate that can feed the fungi themselves and allow them to continue producing spores -- ideally some sort of organic media, after which the first few triggerings of the trap will provide its own media (the corpses of previous dead adventurers). The fungi may be long dead by the time the next adventurer comes along, but the dormant spores that inadvertently get inhaled still do their work, then germinate in their new host to produce new fungi that will release more spores to lay dormant for the next adventurer :D – Doktor J Apr 11 '18 at 19:30
19

Use the tide

Build your structure between sea level at high and low tide. Build it inland, far enough from the sea for the tomb raiders not to think of the sea. Build a tunnel between your structure and the sea shore. Make the path in your structure long and flat enough to make outrunning the tide impossible.

At every high tide, any intruder will be drowned. The whole structure can be considered as the trap.

Low tide

enter image description here

High tide

enter image description here

Advantages:

  • No mechanic
  • No maintenance
  • Reusable about twice a day
  • The water will wash away the corpses, leading the visitor to think nobody died there before, and that it is hence a safe place.

Disadvantage:

  • Somehow difficult to build a tunnel that last long (but if your structure does, I don’t see why the tunnel wouldn’t)
  • Pretty obvious (“Hey guys, it’s full of dead fishes in there, I wonder where they came from?”)

Make it more lethal (but harder to build and maintain):

  • Floating door, so only possible to enter at low tide, hence not noticing high water on arrival. Or other floating mechanism that delay going down while the water is high, so the explorer will not notice the water until it starts to go up. For instance a floating door hiding stairs.
  • Make some siphons, blocking retreat
  • Make a vane so that the water going down is slower than going up. So even if the intruder see the water when it is recessing, he/she is going to think “if it goes slowly down, surely I will be able to outrun it when it goes up”.
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Legisey
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    That tunnel will become permanently filled with water after the first high tide -- that water doesn't have any way to drain away. I suggest you add a drainage plan somehow. Also, supposing the water is filling and leaving it twice a day, you'll be dealing with erosion from flowing water. If you want this trap to last decades let alone ages you probably need to have a plan for how the erosion gets accounted for. – doppelgreener Apr 11 '18 at 09:18
  • @doppelgreener Yeah I thought of that after i made the drawing. But it is not a problem if the tunnel stays full. It could help prevent intruders from that side. Concerning erosion, depending on the rock type, it could take very long. Granite erosion could be as slow as a few meters per million years. Granted this might be a problem on the very long run, but could be mitigated with good design and materials. – Legisey Apr 11 '18 at 09:39
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    So the trap is the structure with a complicated path part? – doppelgreener Apr 11 '18 at 09:43
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    @doppelgreener yes. The entry is on the left. Explorer will go down first while water is low. Then water will go up faster than explorer can run back up. – Legisey Apr 11 '18 at 09:56
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    You need a second passage from the bottom of the high tide source to a low point in the passage. You want the passage to flood behind them first, so that retreat is difficult. – Sherwood Botsford Apr 11 '18 at 15:48
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    Nice idea but tides only rise about 10-30 feet. Building a tunnel system that takes you 12 hours to get out of in that height will be pretty tricky. – DJClayworth Apr 12 '18 at 03:37
  • @DJClayworth It just need to be flat enough. See for example the tide speed at Mont St-Michel in France. If you replicate this in a tunnel, it will be difficult to survive. Also the highest tides are in Canada and are about 50 feet. – Legisey Apr 12 '18 at 06:09
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    The flow rate of the tunnel will restrict the amount of water going into the structure, so the fill rate will be abysmal. Additionally, the low point in the tunnel will likely get filled in with debris or otherwise be fouled by growth of barnacles or muscles, further choking off the flow rate. – pluckedkiwi Apr 12 '18 at 14:14
17

Make the door part of the structure

Design your building with a really obvious doorway. Label it with all sorts of do not open signs so they really know that this is the way you get in. When an aspiring tomb raider breaks down the door, the whole roof falls down on him. Make sure to give it enough margin of error that it won't just fall over the next time there's a big thunderstorm.

I say door, but this would probably be more like a seal than a door. You would have to break it to get through.

bendl
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Event Horizon

Nothing lasts forever, including black holes, but they are zero maintenance and they are indestructible.

We at Event Horizon Traps® guarantee they might get in, but they ain't getting out ! Your money back if we're wrong.

So ("any level of technology") we can say a Kardashev level 2 culture might be able to construct custom black holes or more complex event horizon based "structures" which cannot be unlocked and can exist for arbitrarily long time frames.

Even when they decay by Hawking radiation (which we'll assume exists), nothing is left behind (including nothing nearby as the end stages of evaporation will be an explosion !).

StephenG - Help Ukraine
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    Well black holes evaporates and tiny ones evaporates very fast. A 10.000 metric ton Black Hole will last just a few hours ans of course will be smaller than an atom, see this – jean Apr 10 '18 at 11:27
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    Another problem is, that the black hole will likely suck enormous amounts of air out of the "ancient ruin"... Well, now that I think about it... Maybe that isn't even a problem - a vacuumed dungeon sounds pretty cool... – Anonymous Anonymous Apr 10 '18 at 15:40
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    @AnonymousAnonymous A more pressing problem, I think, is that any black hole large enough to last will likely swallow the ancient ruin itself, along with the planet it's sitting on. – IndigoFenix Apr 11 '18 at 08:25
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    Black hole the mass of earth would have radius of 9 mm. Any BH that you could put in such structure without destroying structure (along with earth) will be too small to exert much pull or do actual damage to anyone. – M i ech Apr 11 '18 at 11:12
12

"all levels of technology" - you say?

So how about nano-repaired guardians powered by a renewable source of power (sun, geo-thermal, etc)?

Hell, you could even make the nanobots your trap - unless you're wearing a "friend" amulet or something, they will infest you and turn you inside out; "what's that black vein-like coloring spreading from your fingers up your arms after your just touched that glittering, nice statue?"

DocWeird
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A: Curtains dusted with cyanide powder. Moving through them puts cyanide dust in the air. If you use the right fabric, probably get a dozen uses.

B: Sealed bottles labeled "Ambrosia of the Gods" Contents are something like ethylene glycol (tastes sweet) and lead acetate (also sweet.) And of course alcohol. The beverage is designed to taste sweet. Nearby you have the food of the gods, which is salty enough that it encourages people to drink. (Glycol has been used in wine to make it taste better with lethal results.)

C: If air circulation can be restricted enough, a heavy gas such as per-fluorbutane or sulfur hexafluoride. Both are non-toxic, oderless, stable gasses that are several times heavier than air. A smothering gas is wonderful for this, as it doesn't interfere with breathing. You don't feel any distress because you can still get rid of CO2 easily. But over the course of about 5 breaths, you no longer have any O2 in our blood. But you've passed out.

Scenario. A set of stairs that descend down one side of the chasm and climb the far side.

"I smell a trap! Let me go first." Walks down the stairs. Gets about 10 steps down, and keels over. His two companions rush forward. Join the unconscious. After a minute the heart stops. After 6 more, brain death.

The downside of this one is the litter of bones on the first landing.

You can also use this a fill gas for any room with an airtight door. Works especially well if the room is at the bottom of a stair. In any case the room should have several times the volume of the ante-room as you might get a situation where the bottom 3 feet is unbreathable, while the top air is fine.

C: The ruins are underground, and very level. There is 3 feet of water everywhere. You venture in, but it's a slog. There are too many restricted places to use boats. You hike in, and realize there is no place to lie down to sleep. And you're lost.

D: Natural syphons. At some high place there is a lake. There is a cavern that connects to the lake in a gooseneck, such that the top of the gooseneck is below the max height of the lake. When the lake level rises above the top of the goosneck, the syphon starts, and floods the ruins.

Downsides: Once figured out, you only have to be out before the lake gets that full. But also means that the interesting bits of underground city gets soggy periodically.

Sherwood Botsford
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    For option C (1?) the solution is to have a very long set of steep, spiral stairs -- as the hapless adventurer passes out from lack of oxygen, their unconscious body tumbles down the stairs into a vast cavern at the bottom (while the objective might be through a passageway elevated off the path of the stairs shortly before the cavern). Bonus points -- they're basically dead as soon as they lose consciousness because the fall will likely kill them. – Doktor J Apr 11 '18 at 19:46
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    Meanwhile, it'll take LOTS of corpses to pile up enough that they can be seen from above the level of gas (especially once the bodies start decomposing, whereupon they'll basically compress). Added benefit: above the level of the SF6 gas you'll get all the wonderful smells of decomposition from previous corpses, as those less dense gases rise above the SF6. Going down the stairs... "oh GOD what's that smell?!?"... take stairs more slowly... pass out and fall down stairs... contribute to bad smell. – Doktor J Apr 11 '18 at 19:48
7

With modern technology, you have explosives and landmines.

Landmines already have a proven history of being lethal centuries after being placed. You could use fragmentation weapons, which would more or less leave the Temple itself unharmed, or you could just have an 11,000 lb bomb instead of a rolling boulder trap. Best case: the adventurer makes it to the treasure, and then is atomized immediately and without warning. Worst case: the bomb goes off prematurely, taking the treasure and structure with it, thus preventing the removal of the (intact) treasure.

This is an especially good strategy since many explosives of that age no longer rely on electrical signals, as those have decayed long ago. Instead, the merest suggestion of movement is often enough to set one off, meaning that its trigger is literally tied to the explosive itself.

This also has the potential benefit of being reusable. If cluster style munitions are used, not only is the explosive extremely lethal itself, it has a tendency to spread some of the unexploded material around the trap room(called UXOs). This behavior occurs anyway despite cluster weapons not being specifically designed to do so, meaning trap weapons like these could be designed to last a much longer time, with them also designed to sling UXOs deliberately and in a more calculated manner. So as long as you have some of the original mines still left, you have a sort of self healing minefield. One adventurer could stumble upon the place, trigger three mines and be killed, and the UXOs would spread to cover the same area and kill another adventurer 50 years later.

In terms of ancient technology, I'll exclude magic as it tends to be able to generate plenty of its own handwavium anyway. One of the best ancient strategies is stealth. Placing traps will prevent access to the treasure, but doing so means that any survivors or casualties will be tipped off to the potential value of this ruin. Besides, no self respecting Tomb architect places traps willy nilly.

The ruin being inconspicuous and in a remote place will go a long way to preventing the treasure from being found and will help the traps last longer. (Even the mightiest fortress or the cleverest trap will not last forever against a sustained assault.) Having a fake treasure room with a few traps and a significantly less valuable treasure is a good way of faking out adventurers into thinking they have already found the treasure. As for secret doors and fake walls, its almost better to adhere to K.I.S.S. Instead of secret doors, just wall it up solidly. Adventurers cant find a secret passage if there isnt one. Most people won't bother mining through the wall if its plain, thick, and they've already found the "treasure".

Besides, 6000 years later when your Lich-y self decides to go and retrieve the treasure for whatever reason, youll have a strong knowledge of the traps and a few walls won't really hinder your progress if you know where to dig.

Razmode
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    Citation needed for landmines being lethal for centuries. – Paul Apr 10 '18 at 20:19
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    @Paul Explosives from the first World War continue to kill dozens of people a year in Europe. I think I even remember reading about some being killed by US civil war mines. I see no reason to think that trend would not continue. – Razmode Apr 10 '18 at 20:21
  • Neither the civil war no WWI were centuries ago. Explosives actually do deteriorate over time. – Paul Apr 10 '18 at 20:22
  • 153 years for the civil war, 90 for WW1. This including mines that were not designed for longevity like in this question. – Razmode Apr 10 '18 at 20:25
  • My grandfather lived into his 90's when his generation's life expectancy was only into the late 60's/ early 70's. That doesn't mean he was immortal. You're applying faulty logic and anecdote. In any case, the OP asked for traps to last from ancient times, which is millennia not centuries. – Paul Apr 10 '18 at 20:30
  • Deaths from WWI mines are fact, not anecdote. – Razmode Apr 10 '18 at 20:32
  • You don't provide a source for the civil war ones, though, and WWI is less than a century. – Paul Apr 10 '18 at 20:33
  • All technology, but the traps need to last millennia. I'm not sure why you're having such a hard time with a simple request for providing sources supporting your claims. – Paul Apr 10 '18 at 20:34
  • FWIW, I haven't downvoted you, I was just making a recommendation for improving your answer. – Paul Apr 10 '18 at 20:35
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    Here's an example after a quick search. http://www.foxnews.com/story/2008/05/02/virginia-man-killed-in-civil-war-cannonball-blast.html – Razmode Apr 10 '18 at 20:39
  • OK, so it's possible. That doesn't go to likelihood, nor does it turn 153 years into 1000+. – Paul Apr 10 '18 at 20:42
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    Explosives do decay over time, but if you keep out the oxygen, moisture, and sunlight you can reduce the decay rate to extremely low levels. What explosives you use makes a big difference too. Nitrocellulose is not shelf-stable even under ideal conditions, but black powder and nitroglycerine tend to be. I'd recommend a pressure vessel of powdered charcoal and liquid oxygen. that will last as long as the seals do and can be detonated by any strong shock to the outside. – Perkins Apr 10 '18 at 20:45
  • @Paul Which is why I think this discussion over the use of the word "centuries" is more or less, irrelevant. My argument is that just because we haven't had it happen, doesn't mean that it couldn't. And the reason that it hasn't is due to the simple fact that we haven't had the technology for long enough. I've merely stating that based on the trend of the technology, even primitive mines are STILL lethal many years after. And ones specifically designed to last could be deadly for a much longer time. – Razmode Apr 10 '18 at 20:46
  • @Perkins I feel like in this case you would also want something that would be fail deadly, since the goal is essentially "If I can't have the treasure, neither can you." So you would want to engineer the explosives in a way that when it begins to decay to the point that it would not detonate at all, is when it would be the easiest to trigger. – Razmode Apr 10 '18 at 20:53
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    @Paul and Raznarok I don't know what math or calendars you guys use, but WWI was >>exactly<< a century ago. It started on summer of 1914, 104 years go and ended in autumn of 1918, 99.25 years ago. – M i ech Apr 11 '18 at 11:19
  • @Miech yeah, I didn’t bother with counting at all, I was too busy asserting that it wasn’t multiple centuries – Paul Apr 11 '18 at 11:32
  • Welp, oops. That's what I get for responding to comments while doing something else. – Razmode Apr 11 '18 at 11:58
5

I would go with a huge maze. It would be a trap on its own, if it is large enough. And you could incorporate most of the other suggestions into it.

Even if one of them eventually stops working, the made would still be deadly enough.

Lot
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  • you know the way to beat a maze is if you have a choice of left or right always pick one direction (the same direction), eventually you will find your way out. see http://bobscrafts.com/bobstuff/maze.htm for example. its the The wall follower algo. – ArtisticPhoenix Apr 11 '18 at 18:48
  • @ArtisticPhoenix and you'll find every trap along that path, even the ones in the dead ends :) – Doktor J Apr 11 '18 at 19:42
  • @ArtisticPhoenix This only works for mazes without loops. It can easily be prevented, if you have the space for a few loops. Then the only way is by leaving markings. And those might be preventable. – Lot Apr 12 '18 at 07:28
  • @Lot - no it still works you just have to sum up your turns, right +1, left -1. See the Pledge Algorithm. Basically if you make 2 left turn you get a -2, then if you make 2 right turns you get 0, and you know you are heading in the same direction originally, The only marks you need is in you brain, see this video https://www.youtube.com/watch?v=_KxAMV-2tKU – ArtisticPhoenix Apr 12 '18 at 07:51
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    Taken from the wiki description of your algorithm: "However, this algorithm will not work in doing the reverse, namely finding the way from an entrance on the outside of a maze to some end goal within it." – Lot Apr 12 '18 at 09:29
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    @ArtisticPhoenix That algorithm only works when dealing with right angles...throw some odd angles in there and that no longer works. – Rdster Apr 12 '18 at 18:13
  • You could do 3D maze with loops, different turn angles and different slopes, stairs/ladders, then there is no algorithm to escape maze using only local information. You could make all places to look very similar and some of them identical to prevent easy remembering and confuse explorer. – Somnium Apr 15 '18 at 12:36
  • You can even fill it whole with water, making it incredibly difficult to pass and leave marking in it. – Somnium Apr 15 '18 at 12:48
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Coal gasification

Naturally occurring coal reacts with naturally occurring water heated by a nearby volcano to produce Syngas to fill the ruin's chambers. When someone carries a flame source and oxygen into the ruin, the Syngas explodes.

This is self replenishing as long as the coal and water and geothermal sources last.

Note: If you accompany this trap with a sprinkle of radioactive particles, then venting the ruin of Syngas becomes a extremely dangerous process as anyone inhaling the particles will get acute radiation sickness

Henricus V.
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  • Sounds promising - how much damage would an explosion like that cause to a stone room? Also, how much coal and water are we talking about in order to fill a room one time (so people can extrapolate about how much they'd need to make it last for centuries), and how long would it take after an explosion to refill the room? – Rob Watts Apr 11 '18 at 17:57
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A pit of quick sand will last the ages. Organic matter will dissolve in it as it basically will be very much like a septic tank which can be filtered out with chemicals at the bottom of the pit. It's perfectly concealable in any light condition as long as the surface of the ancient ruin.

  • It's self resetting
  • Doesn't get effected by time or the elements (especially if indoors)
  • Is concealed without the need for a mechanism
  • Can kill or at least cause harm where the body is stressed in trying to get out
  • It's reliable as it only required gravity and the weight of the trappee
  • You can use the trap more than once
Aryan Alipour
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Seeing as you open this up to all levels of technology, I'm going to propose a simple pit trap that goes right to the centre of the Earth. There's really not much to go wrong with a hole, and it eliminates a build-up of dead bodies as they would burn up well before arriving at the 'end' of the pit.

user49586
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This pitfall mechanism seems to be good, sorry for my poor drawing skills, but basicially it would be "water wheel" trap. If a person stands in front of it it would drop them, leading to their death.

Now, depending on the weight of the "wheel" and length of the platform, if someone would run forward and hit the wall with enough force it would be possible to pass this trap. (It's good to have a trap that's possible to overcome if someone knows details behind it.)

sketch of the above described trap

Secespitus
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Dirindon
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  • Welcome to WorldBuilding Dirindon! That's a nice idea and the remark about being able to overcome the trap for someone with the correct knowledge is very important. If you have a moment please take the [tour] and visit the [help] to learn more about the site (and earn a little badge ;) ). Have fun! – Secespitus Apr 16 '18 at 11:46
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This will only work on a cloudless, sun intensive world (maybe a desert environment). Might give you some other ideas so here it goes.

Build a long corridor with collapsed hinged floors. Rig a way for light from the sun to close the floors up so people can walk through them, but near the middle or end of the corridor before a closed and locked door, a pressure plate or a sensor, however you wish to rig it, will trigger some mechanics to align mirrors and concentrate the sun rays into that long corridor. Effectively burning anyone in it.

You'd have to make sure the concentration is high enough to actually burn people in seconds, as well as make sure the mechanism specially the mirrors are well protected so thieves or archaeologists can't just break them.

During the night, the floors drop so nobody can go near and its a long and wide enough corridor that its very hard to spider climb the walls.

Still there may be ways to circumvent the trap such as putting up artificial lights at night or slowly building a makeshift floor at night.

Arkhaine
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    The word "mechanics" makes me think this would quickly get rusted up, gunked up or filled with dead flies. – bendl Apr 09 '18 at 23:38
  • Not necessarily. If its in a desert environment then it should still be well preserved (i.e. pyramid booby traps) but yes after the passage of time the mechanisms may fail or rot away. Perhaps substitute the mechanics with crystalline walls or parts with computed angles to make it work would solve it? No moving parts, just angled mirrors, crystals etc. – Arkhaine Apr 10 '18 at 00:04
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    Dust buildup on the mirrors would stop it from working. – Thorne Apr 10 '18 at 01:34
  • Yes, but if it had very low friction and angled so that dust actually flows down to a pit could alleviate this issue. However I recognize that this proposal may be more complicated than necessary and the best traps would be the simple kind so perhaps may not be the best idea but it would be cool to imagine tomb raiders belatedly realising they cannot run fast enough to go back to the exit before they are incinerated no? – Arkhaine Apr 10 '18 at 02:09
  • There was a Mythbusters episode where the team got a school of students (there might of been ~100 pupils) to focus a mirror onto the sails of a ship to try and combine the light rays, ergo combining the energy to create a massive amount of heat. It didn't go very well (I forgot the temp it got up to). So while the mirrors could make people feel very uncomfortable, it probably won't ignite them. – PlanetAlexanderProjects Apr 10 '18 at 08:11
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    Honestly, which is the oldest and still reflecting mirror you know? Solar furnaces are XXth century technology, and you need a way to move the mirrors according to the sun, or it would only work for half a minute a day. – user38304 Apr 10 '18 at 13:16
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Reasonably modern tech to know to do it, but probably could be done at a much lower level if they knew what to do:

Some low-lying parts of the tomb are swampy. What they don't realize is that under that water there is a layer of dimethyl mercury in dimethyl sulfoxide, aka liquid death. One drop on your skin (or even on latex gloves!) and you're going to die, although a dose that low takes months to kill.

I'm not sure how long it will persist, though.

Loren Pechtel
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We need a self resetting stone mechanism, do we?

Well, let's try this:

A door, designed to rise from the floor is arrested in place by a ground plate that - under weight on the far end - tilts to release the door. Door Latch, side view To lift the door, it is resting on a lever, granite reinforced with copper. On the far end of the lever, a weight is mounted that in itself is enough to lower itself and raise the door, but NOT in combination with the weight of the latch. So once the trap is triggered, the door closes.

Now, the reset mechanism: our counterweight sits in a basin, that under some circumstances (like once a lunar month) is flooded by a natural water source. Since the water changes the bouyancy from nothing to existing, a well designed counterweight under water will have too little of a force to keep the door up, thus slowly lowering it back to the ground. At the lowest point the floor plate will again slip into place and keep the door there, until the next person tries to get in.

If the water source dries up the door will remain eternally locked.

Trish
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Vacuum (powered by Air Pumps)

Discovered by Otto van Guericke, I guarantee that a Vacuum will last trillions of years! Just ask that black thing 330000 feet up in the air!

Just attach an Air Pump to the door, so when it opens and closes, the Air Pump turns on. Your little adventurers will die before they can escape!

Warning: Not foolproof against Bombs/Grenades/Anything that can destroy structures

Vikram Durai
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    so you are telling that all those engineers keeping pump active whenever they need to keep a vacuum are just ignorant? Vacuum doesn't last trillion of years, nor do pumps. – L.Dutch Apr 14 '18 at 07:22
  • I don't see this justifying deletion, although the idea is pretty silly. – kingledion Apr 14 '18 at 22:50
  • L.Dutch: The pumps can be triggered through the movement of the door. When our adventurers try to open the door, they don't realize they are actually powering an air pump that may kill them later on. – Vikram Durai Apr 15 '18 at 09:30
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    A venturi pump has no moving moving parts aside from the water (fluid) stream. While a vacuum is easy to defeat by opening a door this might still be a way to draw toxic volcanic gases through the cave system. – KalleMP Apr 16 '18 at 08:49
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Design with biology in mind: To echo a few other suggestions you could make trap supportive of a particular type of poisonous creature and even seed the surrounding environment with a healthy population of them. A great example is actually the snake pit in Raiders of the Lost Ark. By creating a big open cool underground place in a region where that is difficult to come by, makes it a perfect spawning/hibernation area for regional snakes. Also you could use bacteria. Bacterial mats can keep virulent bacteria happy for a long time, and if you happen to get a strain that creates its own spores it could potentially survive thousands of years. Viral agents also have an indefinite lifespan, if they are properly preserved (like under vacuum or really dry or cold air). Or just mix them into the dust on the floor before you seal it up.

Grain Trap: (inspired by Aryan's quicksand suggestion) This trap would need a mechanism but it could be very very simple. People will very quickly drown in grain that is in motion. And grain in an arid environment can last for very long time. Basically you could have a mechanism connected to a trapdoor under the grain room, so when it gets tripped the grain begins spilling into a lower basement. Probably not the most reliable trap. But if you get the geometry of the room right it could be effective.

Flooded Vault: By making your entire vault underwater it gives you more options for preserving the workings, while presenting a formidable barrier. The water could be very alkaline (or very acidic). If you can keep the water still, and mostly deoxygenated then very little will grow in it. You could line the walls, floors, and ceiling then with sharp glass or metal spikes. The water might limit your options, but one shot deadfall traps would work great!

Finally I wanted to point out a couple of things to consider (not really traps in their own right). First is a water pressure activation: If you can seal your vault air tight, then you can use water pressure as an activator in the same way as manometer or a moon pool. If someone breaks the seal of your vault, water rushes up into a channel (or room) to equalize the pressure. The second thing is that if you can simply seal up your vault it will protect the mechanisms in it for a very long time. I had the pleasure once of touring a decommissioned experimental reactor prior to its final dismantling. The building on the outside had been falling apart for over 40 years of disuse, but when they unsealed the containment vessel everything inside was still in good condition.

Meridian
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  • If you've got the tech to use viral agents as a trap, you've probably also got the tech to inoculate friendlies against that virus so that they won't be hurt by the trap. Nice! – Rob Watts Apr 16 '18 at 17:37
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A simple mechanism that is useful if you have access to a stream is a syphon. There is a basin that slowly fills over time until a ceartain level is reached, then it quickly drains all the water from the basin into whatever trap it is connected to and floods/flushes (similar to a toilet). A nice property is that no moving parts are needed and if done right can be self cleaning. Biggest problems are the intake stream or the drain clogging.

Some clarifications:

a stream does not have to be a river, any source of water will do if there is a lake this works too. if the water comes from the bottom the temperature will be almost constant.

not much can be done against erosion except making the trap resistant against it, either by using hard materials or allowing for some damage.

In an alternative trap the basin itself can be a trap by sucking people down with the water. Another mechanism would be needed to make the water rise just enough when people enter.

mocchzt
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  • Streams can dry up or be diverted. In many parts of the world you'd also have to worry about water freezing during winter and causing breakages from that (or from erosion due to moving water) – Rob Watts Apr 11 '18 at 16:50
  • @RobWatts, low enough in the ground, the temperature would stay ~59F preventing freezing. – Nathan Goings Apr 13 '18 at 22:55