Skip to main content
47 votes
Accepted

Deflecting an incoming star, railgun style

You've got this the wrong way around. You're trying to deflect an entire star, which engineers refer to as very very heavy. You're doing this to save a planet, which those engineers might refer to as ...
Starfish Prime's user avatar
22 votes

Can PDCs stop a railgun attack?

You leave out a critical variable: distance at time of detection. Suppose I am an ass. I have an old tennis ball and I am going to throw it at your head because I think people will like me if I do. ...
Willk's user avatar
  • 305k
17 votes
Accepted

Underwater motion detector

Pressure waves are easy to detect underwater (source: fishes use the lateral line to detect motion caused pressure waves even in muddy waters). Just install rings of detectors at known distances and ...
L.Dutch's user avatar
  • 289k
10 votes

Deflecting an incoming star, railgun style

TL;DR don't move the red dwarf - move your planet. During those six thousand years, adjust the planet's orbit so that, during the encounter - which will last no more than about two months - the planet ...
LSerni's user avatar
  • 55.4k
8 votes

Can PDCs stop a railgun attack?

I did some quick math; Assuming that the weight of the slugs is negligible the impact of a slug against a railgun round would have around ~4.7 $\times$ 105 joules (1.13 kilograms moving at a relative ...
The Square-Cube Law's user avatar
7 votes

Deflecting an incoming star, railgun style

A few comments: The question implies that the civilization has just discovered the red dwarf star and is frantically asking for suggestions from far more primitive civilizations. It also states that ...
M. A. Golding's user avatar
7 votes

Deflecting an incoming star, railgun style

I'm going to do some rounding and assumptions. Also usually for orbital mechanics there is a whole lot of mathing for approaches, but for stars approaching each other on an orbit around a galaxy ...
The Square-Cube Law's user avatar
6 votes

How effective would the White House serve as a fortress or makeshift Forward Operating Base/FOB?

No, it wouldn't work: It's too small, it's too hemmed in, it's too vulnerable, and it takes too many resources to bother overcoming those shortcomings. Too expensive: A defensive fortification located ...
user535733's user avatar
  • 28.9k
6 votes

Deflecting an incoming star, railgun style

If ɹɐqooɟ lives in a dense cluster, this is a problem that will need to be solved periodically. That means there must be a better solution. Fortunately, if ɹɐqooɟ's civilization has built half a ...
Zeiss Ikon's user avatar
  • 45.9k
6 votes

How effective would the White House serve as a fortress or makeshift Forward Operating Base/FOB?

The White House was fortified well before the apocalypse. https://mideastconflicts.wordpress.com/2014/10/21/mortar-shells-explode-in-fortified-district-housing-us-embassy-in-baghdad/ Depicted: the ...
Willk's user avatar
  • 305k
6 votes

How would the police protect against magic users?

The police can detect it, and unless all magic somehow protects the magician from bullets, nets, tear gas, etc, they will deal with the magicians like any other armed criminal. Perhaps they have their ...
Amadeus's user avatar
  • 34.7k
5 votes
Accepted

How Can River Nomads Protect Themselves?

No different from merchants with extra benefits Being on a boat already gives protection, especially if anchored in the middle of the water. Anyone wanting to get to them needs a boat or certain ...
Trioxidane's user avatar
  • 37.1k
5 votes

How Can Medieval People Defend Themselves Against Plopup?

Stories and testing Many stories have similar enemies and can provide an answer. Demons cannot stand silver, or cold iron. A simple test is used to determine this. They need to touch the weakness. Two ...
Trioxidane's user avatar
  • 37.1k
4 votes

Deflecting an incoming star, railgun style

I'm putting this in another answer, because it's very much different from my other one. FRAME CHALLENGE: In a dense cluster, planets that can develop life must be exceedingly rare -- perhaps ...
Zeiss Ikon's user avatar
  • 45.9k
4 votes

How effective would the White House serve as a fortress or makeshift Forward Operating Base/FOB?

You certainly wouldn't want the White House to be a Forward Operating Base and primary residence of POTUS and the First Family at the same time. The White House is enabled for communications with ...
hszmv's user avatar
  • 10.8k
4 votes

Nymphs and Mermaids: Sinister Seas

Frame Shift. Mermaids are already magic: Okay, so Mermaids are born of the same magic as nymphs. Therefore, they don't get amplified by the addition of magic, because they already ARE magic. Mermaids ...
DWKraus's user avatar
  • 63.6k
4 votes

Why dummy skyscrapers used to trap large monsters are being demolished one by one?

Someone figured out that digging a huge hole (with optional spikes in the bottom), covered with tarpaulin and some earth is much cheaper, can be done rapidly (even just-in-time if a monster emerges), ...
Radovan Garabík's user avatar
4 votes
Accepted

How would a medieval village protect themselves from invisible monsters?

Poison. Your invisible creatures are much like lions. They are predators. They eat what they kill. You can poison them. http://www.livingwithlions.org/lion-poisoning.html When lions or hyenas kill ...
Willk's user avatar
  • 305k
4 votes

How would a medieval village protect themselves from invisible monsters?

They would move I suspect this isn't the answer you're looking for, but the scenario you describe is pretty horrifying: Every couple of months a swarm of gargantuan, armored, invisible predators ...
Tom's user avatar
  • 14.7k
4 votes

How would a medieval village protect themselves from invisible monsters?

Sexy MAN-tis Decoy If I were The Mantis God, I would tell my mantises to pick a random spot in the grain fields and turn invisible. When the farmer walks by, snatch him up and eat his face off. Then ...
Daron's user avatar
  • 66.2k
3 votes

Deflecting an incoming star, railgun style

Propel the star using fusion rockets made of starstuff. Your railgun projectiles are made of uranium and plutonium. They are designed to undergo fission when compressed in the outer layers of the ...
Willk's user avatar
  • 305k
3 votes

How Can River Nomads Protect Themselves?

hiring mercenaries, paying people off. Bah. They are masters of their martial art! This fighting style is a close kept secret, integral to the religion and culture of these people. Witnesses of the ...
Willk's user avatar
  • 305k
3 votes

How Can River Nomads Protect Themselves?

They defend themselves just like anybody else transporting valuables, with soldiers, lookouts and weapons. You might be thinking of them as 100% merchants and moneylenders, but no nomadic group is ...
Amadeus's user avatar
  • 34.7k
3 votes
Accepted

Nymphs and Mermaids: Sinister Seas

Ok have some options but None of them are particularly good you have kind of within yourself into a bind. Kill all the nymphs. Often the best way to kill a predator is to get rid of their primary ...
Bryan McClure's user avatar
3 votes

Can PDCs stop a railgun attack?

Better solution than the PDCs... Go down to the colony nursery and grab all the sand that can be spared. Throw it out the rear hatch such that it disperses in your wake. Wait for the railgun ...
Henry Taylor's user avatar
  • 69.2k
2 votes

Can PDCs stop a railgun attack?

Depends on the rest of your setting. If a PDC hits one of the incoming railgun projectiles with at least one round (never mind nano or composite, mass matters here), it will impart some kinetic energy ...
o.m.'s user avatar
  • 116k
2 votes

Deflecting an incoming star, railgun style

Why bother trying to save a sinking ship, when you (should) already have lifeboats? ɹɐqooɟ's civilization is a post-type-I Kardashev, which guarantees they have the ability to colonize other worlds, ...
Ian Kemp's user avatar
  • 1,045
2 votes

How Can River Nomads Protect Themselves?

They pay them off, or their enemies. People don't normally just become pirates. Local lords sponsor them, or warlords have groups of soldiers foraging for supplies. They negotiate passage with local ...
Nepene Nep's user avatar
  • 39.4k
2 votes

How Can Medieval People Defend Themselves Against Plopup?

My read is that there's not much danger of a Plopup infiltrating human society and then wielding power in a harmful way, because Plopups aren't sophisticated enough. Humans are very good at noticing ...
Tom's user avatar
  • 14.7k
2 votes
Accepted

How would the police protect against magic users?

There are a few assumptions here, and I'll try to note them (and will update if comments point out ones I miss). Primarily, I'm going to use the perspective of a developed, relatively wealthy nation. ...
EvilGardenGnome's user avatar

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