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188

Human engineering can, 100%, keep out a horde of zombies. In The Walking Dead things fail because if they didn't the show would be boring. In real life, there exist castle gates hundreds of years old which would hold, no questions asked. First and foremost, realize that thousands of zombies will never be pushing on the gate all at the same time. They will ...


186

A spaceship is a very expensive piece of hardware. So expensive that very few entities could afford to buy one outright. Most spacefarers would have to buy theirs on credit. And as we all know if you buy something on credit and can't make payments, that something, whether it's a car or a space freighter, gets repo'd. But if the delinquent owner doesn't ...


150

Software licencing. Software for your automated maintenance and refuelling robots was under a 999-years licence (similar to common law permanent lease) . After it ran out, the licence was automatically renewed for another 999 years, payment pending. As no payment was received during that time the licence lapsed, and the plant went into a controlled shutdown ...


116

A similar concept has been mentioned in other answers, but one way to make a train like this viable would be to have pods at stations that "dock" with the main train rather than many trains running at different speeds. There would be a period of acceleration followed by the pod locking on firmly. Here's an example where a pod docks to the top of a train at ...


110

We humans are pretty good at building gates to keep people out. We've been doing it for a long time for military purposes and to stop thieves. Why Do We Have Gates? Because there has to be some way for friendlies to get through the defenses while keeping the bad guys out. From a military perspective, a gate isn't there to stop people from getting in. They'...


110

Yeah. For the spiders, this is gunna suck, but it’s not undoable. I do suspect it will be more of an exo-exoskeleton than a suit though. There’s a couple of reasons why it won’t be particularly pleasant. The first has to do with how unbelievably sensitive spiders are. Their bodies are covered in a variety of specialised hair like structures that give them ...


97

Ash cloud. Your tower is hollow, and the interior is a conduit to the underworld - perhaps the column extends straight down through the underworlds of K'n-Yan, Yoth and N'Kai all the way to the hellish interior. Strong winds and gouts of charged ash emerge from the black cloud which plumes forth from the apex, and as with volcanoes the cloud crackles with ...


96

Requirements: One large hollow rock One dwarf One large pair of pliers One tunnel One loud voiced announcer of who is about to try to pull the sword out Tunnel under the rock for your dwarf to get access, make sure he knows the name of the eligible person to release the sword for when the loud voiced announcer calls it out. All you need now is a mechanism ...


83

While hopping on one moving train seems reasonable for a healthy young adult, hopping two hundred seems a little excessive and dangerous... Also I would imagine that most people going on a long distance trip will be bringing luggage. I'm sure I could jog up and on to a slow moving train unhindered, but a little less sure about doing so with a suitcase in ...


82

The AI in the ship is not the very first one to go rogue, and probably will not be the last one either. Hence all ships have an outside panel where the AI cannot see and reach, as a safety measure for such cases. So a typical case of AI going rogue could have a dialog along the lines of: Dave: open the pod bay doors, HAL. HAL: I'm sorry, Dave. I'm ...


79

Send your torpedos through sub space. They go "underneath" so they're torpedos. Missiles travel through normal space. Different tactics and countermeasures apply to the distinct types of weapons.


78

Announce that you are building a resort. Put up a website. Make it look nice. Don't take reservations. Make people think its real Hire some (doltish but good looking) celebrities to come vacation there. This is actually common behavior for resorts. Tell the celebrities you cleared out the place so they can enjoy it in peace, by themselves. Keep the ...


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 ...


74

These aren't long-span bridges, but causeways The current record for a single span is just under 2km long, and any single vehicular span over oh, 100 to 200m long is going to require modern truss or suspension bridge technology. However, it has been possible to span far longer distances over water for much longer periods than that, using only pre-Roman era ...


70

In clock-making such a feature is called a complication. Movements with complications are quite common, from simple-minded calendars (which need to be reset at the end of every month shorter than 31 days) to true perpetual calendars and indications of the phases of the moon. The specific complication described in the question seems to be perfecly possible ...


69

Hi and welcome on board the star cruiser Pedant's Dream! On board this state-of-the-art warship we carry plenty of weaponry- railguns, lasers, missiles, torpedoes- What's the difference between those last two, you ask? Good question! It's really a matter of semantics. In general, lighter munitions used for antifighter and self-defense purposes are ...


68

They don't need a spacesuit just oxygen Warning - Video of a spider in a vacuum chamber (it walks around and lives to tell the tale). https://youtu.be/tA9jcIwvge0?t=243 Judging by the video, they don't even need oxygen for a short space walk. In response to temperature concerns It really depends where in space they are. Right next to a star they would ...


65

It needs to be hot, at least the top of it does. If you create a constant low pressure zone over your tower, by heating the air around the top of it so that said air rises, this will create a condensation zone over the tower and, due to the convective system set up thereby, a perpetual thunder cloud with all the storming you could need. Lightning will ...


62

'Lock' the blade in place Give the sword blade a fuller, the groove used to lighten some blades, and end it before the tip of the blade. It can then be inserted into a well crafted, close fitting, slot in the stone and a 'key' used to fit into, and interfere with, the fuller holding the blade in place in the slot. Inside the stone there needs to be some ...


60

Remember Y2K? Software is hard, programmers are human. If you want your readers to know exactly what went wrong, you can babble at length about data types or speculative branching or null references or race conditions. But I propose that if your characters don't know what broke or how to fix it, then maybe your readers shouldn't either. The software has a ...


56

The same way you put weapons elevators in a warship The US Navy has lots of very large boats that use elevators. Of specific interest are the weapons elevators on aircraft carriers, since these have many things in common with the elevators you are interested in: they must be fire-resistant, watertight, they are large (about 40 foot vertically) and high ...


56

In the event the interior of the ship is hazardous If I owned a spaceship I would take every reasonable step to ensure that spaceship could be recovered in the event of a disaster. If there were some catastrophic event that prevented the crew (or AI) from controlling the ship, providing a (suitably encrypted) means of remote control would be ideal. As a ...


56

Okay, so a did a bunch of research into legged robots for my thesis and they aren't going to replace armored vehicles any time soon. The most basic reason, they aren't as efficient in doing what armored or wheeled vehicles are specialized in. They are also very complicated to program, since you have 4/6/8 or more legs which all need to interact versus 2 ...


53

The tower is normally invisible and can only be seen during storms. This is bending the requirements of the question a bit, but may serve for the purposes of your storytelling. Let's say that, being a villain, you are hiding your terrifying lair in plain sight. An invisible skyscraper in the Seattle area, maybe. Something about darkness and high winds ...


51

Have a look at Rama's Bridge here. It is 48k long and runs between the southern tip of Tamil Naidu and one of the northern islands of Sri Lanka Investigations suggest that a chain of atolls was connected and brought above the water by manual labour. The entire length was above water until the 15th century. Given the right geomorphology and backstory I see ...


49

I would actually use... cement, because your premise is wrong: On lifeless planets there is no organic materials such as limestone because there was never any life. Limestone is not an organic material (I guess the right word would be an "organic compound"). Limestone is just calcium carbonate. And there's no reason why there couldn't be sedimentary ...


49

The Fast and the Furiously Crazy Since you've eliminated the sensible solution (bypasses or double tracks), let's go with an insane one! All your trains have rail tracks running on top of them and extra wagons with ramps at the front and back. When a priority train approaches, they lower the ramps onto the rails and the priority train drives straight over ...


47

During the roman empire they didn't know modern cement, but they built "small thingy" like the Pantheon by using pozzolan, which is basically volcanic ash. That would be a good material to use.


47

I'm going to go in a different direction here and say that instead of making a space suit, make a space pod with mechanical spider legs. Have an enclosed pod that the spider can sit inside with legs folded and have mechanical arms/legs that support the pod and allow it to walk around. For simplicity, the pod could have 4 or 6 legs, but there could also be ...


46

The Victorian engineer--say for example Mr. Isambard Kingdom Brunel--would of course be interested in having a method which would give the exact weight of a ship; but in practice he would settle for a method which gave an approximate result, provided the result was not too wrong, because he would need to design his installation with a considerable factor of ...


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