Hot answers tagged

118

There are many examples of this in the real world, including the religious bans on pork and shellfish, the historical avoidance of tomatoes, and counter-examples such as the laborious process to transform poisonous raw cassava into something that's not just edible, but a staple in many parts of the world. In addition, many perfectly palatable foods have a ...


62

Artificial satellites orbiting around Earth are pretty easy to spot, since they appear as bright fast moving objects across the night sky. This even in a light polluted environment like a modern city. I remember I spotted satellites moving in the sky as a kid looking up at the sky with no knowledge of astronomy. Spotting them was even more exciting than ...


53

You could emulate Volta's pile if you could find some zinc and copper metal, and some acid, however the purity of such items might be pretty questionable. Which means you might get more voltage than you expected and damage the phone, with no possibility of repair. The cells Volta made produced about 1.1V so 5 of them would be about right (perhaps a bit high)....


40

Something else eats the plant, and that thing is revered. For example, suppose the people revered a giant bird because it eats rats and thus keeps away plague. If that bird also devours large quantities of the plant during mating season, the plant might become taboo because it is reserved for the bird. Whatever the reason that the people care about the ...


39

As many other comments have suggested, orbit altitude is a key parameter in determining how visible the recon satellite would be. However, orbital altitude also determines how long the object will stay in orbit—specifically the perigee (lowest-point) altitude. Let's say the recon satellite was in a roughly-circular¹ orbit of 400km, which is approximately ...


35

A single car accident could do the trick Emperor Hirohito had a younger brother named Takamatsu. In 1930-1931, Takamatsu chose to travel across the US and Europe to improve relations with Western Civilization and became much more fond of and respectful of Western nations than his brother. He was fairly successful at this and garnered a lot of respect ...


33

Don't try to charge the battery inside the phone. Build a 10 cell lemon battery with copper and lead electrodes, which produces ~4.35V with a maximum current of about 1~5mA. Remove the battery from the phone and connect it to your lemon battery with the correct polarity (copper electrode is positive). At this low current there is no risk of damaging ...


32

It's a fairly short answer, but historically solid. No Or they'd have bridged the Bosphorus that's 2450ft wide at its narrowest point. In practice the Bosphorus wasn't bridged until 1973, which tells you quite how hard a job it is.


30

They mistake it for some other food or something "A human civilization, civilization X, decides that food Y is not fit for consumption" Long ago when these groups of people came to settle the land they saw a fruit or whatever. This fruit looks very similar to the fruit of their old homeland that is poisonous. They decide not to eat it. As time goes on ...


30

Because it can't be managed Out of all the edible plants out there, only some are suitable as large-scale crops. A plant might not be suitable for mass cultivation, or even cultivation at all, not because it's not nutritious and delicious, but because: it's thorny/brambly and hard, or even impossible, to harvest as a result (raspberries are a niche crop, ...


25

Solar Charging Electro-magnetic Flechette gun How advanced is the most advanced world you've encountered? A Coil-gun is perhaps the most reliable weapon imaginable. It fires reliably underwater, in space, in mud.. The entire weapon can be sealed in plastic and it has virtually no moving parts whatsoever. It cannot jam, it doesn't misfire and requires ...


24

Yes, technically The thing here is that a bridge isn't required to have supports all 375 feet deep if it doesn't need supports. Or, that is to say, so long as it can just float on the surface, then the bridge could work. And now I introduce pontoon bridges. Pontoon bridges can, given the right equipment, be built very quickly and over wide stretches of ...


23

Best solution is to skip the gunpowder - too difficult to manufacture while traveling or carry vast quantities, and a bit of a pain to deal with anyway. Of course if you are relying upon the giant cloud of smoke to obscure you and the target and loud bang to scare the primitives off, then go with black powder, but honestly I would rather shoot them than ...


23

Los Angeles? Salt Lake City? Or maybe even someone local by 1931. The first neon sign in Las Vegas went up in 1928. http://captainhistory.com/wordpress1/2018/02/25/the-first-neon-signs-in-las-vegas-nevada/ If you want there to be some adventure and finagling involved your characters could go on a road trip to Los Angeles, which would be a good contrast ...


22

I think that if you made two changes to history, that it would be believable that the USA and Japan became allies. The first change is to alter the Meiji Restoration to be more defensively focused and less conquest motivated. If the outcome of the Meiji Restoration was to make Japan a leader in the fields of modern technology and comfortably able to defend ...


19

I'd recommend the Colt Pocket Percussion Revolver, possibly supplemented with a good muzzleloader (they've got easy-to-maintain modern ones now) for ranged shots. Sorry, I'm sticking you with ball and powder. Modern ammunition is pretty great, and not hard to make with modern techniques - but that's the thing. It's best with modern techniques to get the ...


19

I suggest reading Isaac Asimov's 1941 novelette "Nightfall". It is very similar to your plot, depending on an eclipse that happens once every 2,000 years causing a global catastrophe. Civilization never lasts more than 2,000 years before collapsing. Each time, the eclipse fades into myth and religious texts before the cycle repeats. The story ...


16

I think you have to ask (and answer) multiple questions. When will it be detected as a recurring object in the sky? L.Dutch suggests the naked eye will do; that might depend on the size and height of orbit. When will it be recognized as an artificial object? Here you should keep in mind that it has always been there. People will come up with theories of the ...


15

You could build a dynamo. One of the simplest designs for a dynamo is the homopolar generator, also known as a Faraday Disc. You'll basically need a: magnet copper disk commutator brush Line enough of them up and you should be able to produce the necessary voltage and current. With a skilled jeweler, you could then create gold wires to hook up to the +V ...


13

It is possible to make a battery using electrolytes from vinegar, apples, etc. Depending on the type used you can get different voltages. If they do not match 5 V, put them in a series or parallel combination to get close enough to 5 V. A side issue is to create a Volt meter to measure voltage output (you don't want to damage your mobile phone having a too ...


11

Easy answer: No0 It's certainly true that if you store written documents (paper and ink) in a perfect vacuum, sealed away from changes in temperature and all light (think: "all electromagnetic radiation") suspended such that gravity had a minimal effect on the natural deformities of paper and the changes in density caused by the saturation of ink — ...


11

No Even with today's technology building a bridge over a transform fault** is a perilous endeavor - non-trivial displacements over time preclude a rigid bridge and the presence of the fault will trigger major earthquakes frequently. At the best today one may try a suspension bridge, but it won't last long if it ever get to be build at all. As for a ...


11

The old tales aren't taken seriously because science wasn't and still isn't very advanced in your civilisation. The Greeks kept records but they made little distinction between actuality, heroic tales and the activities of gods. The current scientists might say, "Oh well, something might have happened but maybe a volcano erupted and spread ash across ...


10

You've picked a very difficult thing to do. Besides the electrical problems, you also have the mechanical problems of making the connector. USB micro connectors are very precisely made, and you are going to have to connect wires to some very fine pins. I think what you want is beyond what you could reasonably accomplish. I mean you've got like two days ...


10

I'm going to branch off of what Puppetsock posted and get a bit more theoretical. While he's absolutely correct that economic expansion in the conditions of the first world war is extremely unlikely, you could get more 'alternate history' and make those conditions more agreeable. The main issue that made WW1 so bloody was that military leadership hadn't ...


10

All you really need is heat and knowledge. Copper and tin were very common metals in the world you describe, so the brass to manufacture ammunition is no problem. Gunpowder existed - but only in China - so the early Europeans just hadn’t found it yet. It was there. He needs to be really good at making very precise recipes from natural ingredients. We are ...


10

In 1620 even the warped phlogiston theory was in the future; Lavoisier's and Dalton's chemistry based on atoms was in the far future. Mendel's laws of segregation and independent assortment were not even on the horizon. To summarize, in 1620: They didn't know that atoms existed. They thought that combustion was basically a reaction of decomposition; that ...


9

Depends on how good of a chemist your time traveler is. While the purification methods on many of the needed materials were not discovered until the 1900s a good chemist, craftsman, and historian could go back further to the discovery of the ores he needs. To make the alloy you will need Iron, Titanium, Vanadium, and Aluminum: Iron has been around for ~...


9

This depends very much on the safe. A "fire safe" meant only to protect papers from a house fire would be trivial; the one I have is a fairly soft plastic shell filled with unreinforced concrete; it seals in a fire by the shell melting, effectively welding the safe shut and keeping oxygen away from the papers inside -- they may brown from the heat, but ...


9

As an example from real life you can look at the Jewish taboo against eating pork. Part of the reason we historically don't eat pork is because pork blood has been used to desecrate the temple (we didn't eat pork before that, but this solidified the animal as absolutely taboo). You could use something similar, have something traumatic happen to your civ that ...


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