175

Joe, this is the HQ. It's likely the ants do not really melt the glass. In the 20th century some material scientists on Earth developed a kind of photoresist (called spin-on glass) which, after exposure to UV or e-beam and curing, would become what is for all intents and purposes, glass: randomly arranged SiO$_2$ chains. The principle is fairly similar ...


174

No Ten (or more) knights would grab him by the arms and legs, bind him in iron chains, and then chuck him in a dungeon. No matter what kind of armor or melee weapon you have, you are still limited to the strength of one human; you will be overpowered almost instantly by a group of people.


167

There are numerous problems. Diamonds are brittle Hard, but relatively easy to crush, if you happen to hit just right. Armor would be crushed before your hero knows what happened. See Why does diamond have lower tensile strength than Iron? on Physics Stack Exchange. Diamonds are flammable Sure, it takes about 900 degrees Celsius to start diamond fire, but ...


159

I'm sure this is outside of the range of temperatures you were interested in, but in the spirit of "truth is stranger than fiction," Helium-3 actually does this: The temperatures we are talking about are ridiculously small (fractions of degree above absolute zero), but note that the Solid region actually dips down around 0.3K. This means you can have a ...


134

Build a Pyramid The Pyramids are halfway to your desired 10,000 year life span already. They are a little worse for wear, but they are definitely still standing. First, lets assess the criticism that the pyramids are not skyscrapers. The great pyramid at Giza (139m) was the tallest building in the world until the Lincoln Cathedral was completed in 1311. ...


120

Anything someone values can be made into and used as money. That ought to be Rule of Acquisition no. 1, but it ain't. The point being: if you want to make currency out of concrete or cement, it is indeed technically possible. CaM's answer is thus half wrong, because of Renan's answer. I'm assuming you want something something a little more portable than ...


114

My character lives on a medieval world, and is a female knight, she is looking for marriage and is trying to look more attractive for potential candidates without losing too much protection. I think you need to look at this differently. Marriage, especially among the knighted classes, in medieval times was not primarily about looks (and not even in the ...


97

Replicas The blacksmith did his job to perfection - the equipment just never got to the army. The saboteurs act as middlemen in the delivery system. The carriages holding the gear are intercepted midway and swapped with shitty quality replicas that look exactly like the blacksmith's equipment. This could work in at least two ways: The saboteurs have a ...


93

They aren't really ants, they are Thermites. Your ants deposit a line of thermite in a new tunnel, then ignite it (bonus points if they use a glass lens and sunlight for it) after scrambling the hell out of reach. I'm not enough of a chemist to say how they'd produce the thermite, but nature will find its way. (Maybe they use some symbiotic bacteria?)


82

Most known accounts of women in medieval era war have them wearing armour designed for men. One exception is Joan of Arc who had a suit of plate armour specially built for her. No known images exist from her lifetime, but one depiction (drawn from written accounts) shows the armour as very similar to armour worn by men, albeit slightly smaller and gathered ...


80

Make the material flexible. Consider Kevlar: it's an ultra-strong fiber that can be woven into sheets of highly tear-resistant fabric. Thick, interlocked layers of this fabric are used to spread the force of a bullet out over a large area. Using it to make a weapon just doesn't work: it's too light to make an effective bullet, too floppy for a long-rod ...


77

That is a surprisingly reasonable project! Let's dismantle the Earth, and use it as building material to Alpha Centauri. The Earth is $5.974 \times 10^{24}~\text{kg}$, and Alpha Centauri is roughly $4.13 \times 10^{16}~\text{m}$ away, so that is almost 150,000 tons of building material per metre. That is enough for any bridge. Even if you stretch it all the ...


70

You will be downed with a few nets, fixated with rope and either buried alive, drowned or launched with trebuchet. In short, no, don't try this at home.


69

There are already organisms that secrete glass without high temperatures. This paper discusses a wide variety of ways organisms handle it: Glass sponges grow a skeleton of glass spicules; Many plants secrete tiny glass crystals called phytoliths to dissuade herbivores; Diatoms and radiolarians secrete a glass protective skeleton. You just need the right ...


69

Normal human durability, and a lot of luck People have survived terminal velocity falls. In 1972, Vesna Vulović fell over 33,330 ft without a parachute after the plane she was in exploded. She didn't exactly walk away from the fall, however. She spent days in a coma, and was hospitalized for months after that. But she did survive. Vulović is not the ...


66

Nope. Diamonds are very hard (10 on the Mohs scale), but this just means that they are very resistant to scratches (which is why they're often used in drill tips for mining). They are very brittle, so they shatter very easily - not a property you want for armour or weapons. If the armour's compromised, the protagonist becomes a lot easier to kill. In ...


66

Colditz Castle An impregnable fortress. An inescapable prison. This is the problem you risk if you make a fortress that's truly impregnable, it could become the prison you spend the rest of your life in. One of the key features of castles is the ability to counter attack. Whether to sally forth with troops, or simply to shoot from the relative safety of ...


61

I wouldn't be so quick to dismiss its usefulness for long swords. In weaponized combat, the use-case and fighting style will vary with each weapon's size, shape, maneuverability, weight etc. With the materials of choice for weapons being steel over the last couple thousand years, we developed combat style for short-and-maneuverable weapons as well as big-...


61

Armor is for protection, not sex appeal. A live woman is a far better marriage prospect than a dead woman. The whole sexy armor troupe is about serving the male gaze, not doing anything for the woman who is fighting. Armor is for actual fighting, not walking around. It's heavy and doesn't breathe and you can't move very well in it. A realistic knight ...


58

Outside-in armor. Armor is bulky, which sucks. No-one can tell how hard you have been working out when you have on all your armor. Phase metal can be used to make inside out armor. You can wear your skin tight fightin' leotard that shows your calves and stuff. All the armor plates are on the inside of the leotard which means they are phased thru your ...


57

Self-healing concrete. It works by embedding tiny capsules in the concrete containing bacterial spores. When the capsules are broken by water penetrating the concrete, the bacteria are released and begin to metabolise - and one of their waste products is calcite (a component in limestone). The calcite seals the crack, good as new. The technology is ...


56

Heat drives a compound out of solution Heat can drive moisture out of a substance. If some substance mixed with water is a very viscous fluid, then driving the water out with heat could leave you with a solid. According to various pottery blogs, moist clay is about 30% water, all of which is driven out in the process of firing. A viscous mixture in ...


56

Frame challenge: You can’t, at least with the limitations imposed You are asking for too much, some of your points contradict each other or ask for something that's far beyond what a sword could do: Able to cut through steel, i.e. through a sword raised in defense or plate armour. Firstly, asking to cut through a steel sword with another sword is hard ...


55

Such a metal would be good for thrusting weapons like a daggers, shivs, and rapiers; mediocre for slashing weapons like cutlasses, scimitars, katana, etc. that rely more on their weight but still use speed and a cutting edge for most of the damage; but poor for a throwing knife (poor balance, affected by wind) or any edged blunt-force weapon (like a long ...


54

Almost, but generally no1 There are no such metal, alloy or pure element which does this within a reasonable temperature-pressure range2; but there are materials which can behave this way. Why does stuff generally melt when heated and not when cooled down?3 All matter in our universe follow the bureaucracy founded within thermodynamics and, as part of that,...


53

Heat up the products above the eutectoid temperature to form austenite and then rapidly quench it to induce the formation of martensite. This will induce the formation of hardened steel which is more brittle. Martensite is formed in carbon steels by the rapid cooling (quenching) of the austenite form of iron at such a high rate that carbon atoms do not ...


51

What you described is an old invention:the wax tablet. Spermaceti from sperm whales is just one of many waxes your underwater people could use. Some of the fishes also contain significant quantities of wax. If you need only a short-term solution, animal fat would also do the job. I couldn't find any seaweed that secretes waxes, so I hope your underwater ...


49

No You don't make a suit to survive a pyroclastic cloud. Much like a hurricane the problem isn't that the wind is blowing; the problem is what the wind is blowing. Sure you could make a 4 ton mech suit; won't stop it from getting trashed by a 6 ton flaming rock. A pyroclastic cloud is much like an avalanche, only that it can contain temperatures hot ...


48

You could, but it probably wouldn't be worth the effort. Yes, diamond is hard, but unless you have an ABSOLUTELY PERFECT crystalline structure all the way down to the nanometer scale, any flaw, even a tiny scratch, would eventually turn into a massive crack as soon as you started applying impact force. You could put a fantastic edge on a diamond sword, but ...


46

How much pressure can he put on the ground? Since you were nice enough to give me the numbers you want, a 0.06 m$^2$ footprint can put $$220 \frac{\text{N}}{\text{m}^2} \cdot 0.06 \text{ m}^2 = 13 \text{ MN}$$ of force before shattering the ground or causing whatever other negative consequences. How long is his foot in contact with the ground? The next ...


Only top voted, non community-wiki answers of a minimum length are eligible