What types of tactics would humans develop against creatures that are hurt by light in a literal dark post-apocalyptic world?

Question

In a post-apocalyptic world, monster-like creatures have taken over most of the planet, and twenty years later, only a few clusters of humanity still remain with somewhat functioning governments, and with "towns," as in places with apartments/buildings that have barely functioning water and electricity and other necessities that people live in, that are scattered across what's left of America. These “towns” also have a pseudo-military force that both protects the citizens from the creatures, and also tries to reclaim the lost territory to these monsters, as they are not invincible, and do have a weakness.

Light. As in, any form of visible light on the electromagnetic spectrum, and also certain forms of UV light, specifically the kind produced by high electrical discharges. Now, this might seem like a weakness that should cripple these monsters, because hey, the sun should be making short work of them, but it doesn’t. Because the day these monsters started appearing was the day near-total darkness covered the world and blocked all forms of light coming from the sun, making a world that is near-pitch black. And yes, this should cause the extinction of all life, but for this question, assume that the darkness is magic and that any of the issues caused by the sun being blocked out by clouds of darkness aren’t an issue because the plants, people and planet in general adapted due to, again, magic.

So, these creatures don’t like light. Seemingly, the greater the intensity, the more it actually hurts them. Bits of their skin seems to turn into little black motes that fade into the air, seemingly burning them and causing varying degrees of pain depending on the light in question. The survivors of this world have made a list of how each type of light hurts them. Here is this list in question:

1. Fire

   Fire seems to irritate the creatures greatly. A large campfire would make one these creatures growl and hesitate for a moment, but they would, eventually, move on, and it would cause them no real damage. A forest fire, on the other hand, would cause the creatures harm and make the creatures back off.

2. Flashlights

   Flashlights seem to do some damage, burning skin on the area on which the light was shone and causing the “black mote” effect as mentioned previously, but this is more likely to anger them and cause them to attack whoever shone the light, rather than scaring them off.

3. Spotlights

   Spotlights do greater damage to the creatures than flashlights, and would be enough to convince a single creature to back off if there were say, three of them being pointed in their general direction, but if the creatures were in a large group, than they would be convinced they could destroy the lights before they could do serious damage to them and attack the people shining said lights on them.

4. Flashbangs

   Flashbangs seem to greatly upset the creatures even more so than spotlights. Not only will it burn them, but it will also heavily disorient the creatures for several seconds. Enough exposure to the flashbangs explosions will eventually kill the creatures if they don’t get out of the blast radius. If an adequate amount of flashbangs are used, say a few dozen, than if the group isn’t large enough, say less than fifty, they will retreat. However, they are likely to return with reinforcements to try again, say anywhere between half-an-hour to an hour.

5. Lightning

   Lightning, and electrical discharges on a similar scale, seem to hurt the creatures the most. Any time lightning strikes near these creatures, even if it strikes a place hundreds of feet away, it will cause great burns to the creatures and kill them if they are close enough. The creatures in question will also tend to avoid any areas where lightning or similar electrical discharges have gone off for a few hours, as for some reason, if they enter that area within the stated time, it burns their skin. The only exception is if the creatures know there are humans in that area, as they will go back there once they gather enough forces, even if the area itself is still harmful to them.

Regular guns and ammunition do seem to damage them, but in the same way a rock would damage a gorilla. It hurts, definitely, and with enough of it could even kill them, but it’s just as likely to piss off the hulking mass of muscles as it is to kill them (Note: Not all the creatures are like this, they come in various shapes and sizes, this is just one example, but they do all share the same level of durability).

Given all of this information, and assuming that the survivors have an adequate supply of ammunition and weapons on hand that will last them a while so long as they are used reasonably, what tactics could the remnants of humanity come up with to deal with these creatures? Both in terms of protecting their “towns,” and for killing the creatures in their own territory as the humans try to regain what was once theirs.

Answer 1

This fits more with the "post-apocalypse" tag than the "magic" one, and assumes years to decades after the fall (your 20 years).

You mention "some forms of UV". A photon (or the monster it hits), doesn't know what generated it, only what wavelength it is. Of course the sheer brightness of lightning may also be significant, but that's relatively easy to achieve in a narrow beam.

So what about the spectrum? Temporal and radiometric statistics on lightning flashes observed from space with the ISUAL spectrophotometer has details of the major wavelengths in lightning. One of particular interest is the UV nitrogen line at 337 nm. I suggest that's something they're vulnerable to. A nitrogen laser is one of the easiest lasers to build, in fact it's possible to make it lase out of both ends with no mirrors, using air as the gain medium. You need some electronics parts (ideally the transformer from a neon sign) and skills. They're pulsed, but can be fast enough that you wouldn't notice, and the peak power can be 100 kW (for a few ns). They could be portable (probably a backpack power supply based on recovered car or even laptop batteries).

Nitrogen arc lamps, perhaps tripwire activated, could provide perimeter defence/area denial. If we're not that specific about wavelength, banks of UV LEDs could provide serious power with a short range as they're very divergent.

Xenon strobes (disco type or high power camera flashes, perhaps in banks) would be pretty potent given what you've said in the question, which seems to permit electircity. Overall, given what you say about spotlights, nightclubs and theatres would be a good resource - a nice change from gun stores.

Sticking with the theatrical theme, limelights were very intense and gas powered (oxy-hydrogen, but you could use a welding torch). They use quicklime (which might be useful in other ways). That won't have kept as it reacts with atmospheric CO₂ but it's fairly easily made

You'd need the usual fences and patrols for places being defended, but chainlink wouldn't block the light so would be useful. Your raiding/eradication parties will try to stay dark; if looking for confrontation (as opposed to scavenging) they'll try to attract the monsters to a defensible location (a few candles should be a giveaway/provocation) before deploying their weapons - a fairly standard trap. Night vision googles will be extremely useful for moving about until the trap is laid. Corralling the monsters by using sufficiently powerful light and fairly rapid movement should get them somewhere they can be destroyed by more conventional means even if not by fire.

Answer 2

The creatures in question will also tend to avoid any areas where lightning or similar electrical discharges have gone off for a few hours, as for some reason, if they enter that area within the stated time, it burns their skin.

Ozone generators.

source

The electromagnetic radiation is long gone. What remains so long after is the result of the energetic discharge: free radicals. One of the main ones is ozone. It is produced by lightning dissociating oxygen, which recombines as an oxygen radical.

I can imagine ozone burning a sensitive creature. Ozone is commercially used for exactly that: oxidatively destroying odor causing molecules and also pathogens; ozone has taken over the role of chlorine in sanitizing swimming pools.

Your creatures don't like ozone. It is easy to generate ozone. I would marry an ozone generator to a vortex gun and shoot these creatures with ozone-containing vortices.

Riffing a little more — there is nothing that special about ozone except it oxidizes and electricity makes it from the air. But if your creatures are that sensitive to oxidative damage you might experiment with other oxidants. You could fill a supersoaker gun with hydrogen peroxide or bleach. Try that when you have your wingman ready with the ozone vortex and carbon arc light if it doesn't work.

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Fricking Lasers!

Seems like a no duh. They are very bright and energy efficient. And awesome. You can carry many, in a bandolier. As a light weapon they offer obvious advantages over a flashlight. Best of all you can get a giant array from a rock concert laser light show and blast monsters to sweet rock and roll. Fog machine optional. Dancing non-optional! Dance that night away!

Answer 3

War as Usual

The bullets may not hurt them, but the tracer rounds should do some damage. The usage of miniguns come mind.

Oh, since the battle is in darkness, bright flares will be in use.

Bombs still produce some bright light, even if for a few moment.

Once humans figure out their weakness is light, phosphorous weapons become mandatory.

Flame throwers produce light. And once something burns...

Speaking of burning target, Molotov Cocktails might work.

And speaking of putting things on fire...

I just love the smell of napalm in the morning.

Bio Warfare

Lightning bugs, glow worms, etc. But, more for parameter deterrence than defense.

ok. this section is a joke. Even for the beasts, they would be a joke.

Light Offense

Spotlight have been mentioned as a way to kill them.

The ultimate light source would be a laser. If a laser can take down a drone, it can probably easily kill a platoon or 3 before being destroyed.

Lightning

Electric fences can generate sparks.

The best portable "lightning generator weapon" would be a Taser. 12 gauge shotgun? yes, please!

For stationary target, a Van de Graph Generator should do quite nicely.

Fun for the whole family

"4th of July" will last all year round; Same goes for the Chinese New Year. Kids with Roman Candles will get to have some fun as they take part in the genocide of these dark creatures.

Glow Stick are still fun. Especially after you cut them up and pour the liquid on the beasts. I'm sure someone will figure out how to make them into paint balls. Amazon listing.

Need something that last longer? Radioactive based glow-in-the-dark paint balls.

Hospitals

For the battle worn soldiers, come to Las Vegas.

Last Question

Why did they come here? I don't think they have any hope of surviving.

Answer 4

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Fun premise!

Any sort of creative, photonic assault that could be dreamed up .. could no doubt be turned into something all the nastier with a couple of hundred-thousand strategically placed makeup mirrors!

In fact, with a couple of those IR lasers that @Willk probably mentioned, and a bag full of reflectors, I managed to set up a perimeter that the monsters just love walking past. Of course, the frog-croaky thingy that lets us all know 'someone needs service', now let's us know 'somethings need to be served!' "safeties off. click."

Answer 5

The first step in protecting the towns is architecture. Human habitations would be built as concentrated as possible, and fortified. (Walls have to be of some use in delaying them so you can bring light to bear.)

Furthermore, the buildings would be built to maximize line of sight. Medieval fortresses were build with round towers to make it harder to use rams on them. You don't want that. Straight lines.

Towers would spread the light as far as possible, though there's a trade-off in how the light disperses with distance. The lights would need to be as close to the edge as possible, to prevent shadows -- unless you specifically set it up to lure the monsters into traps at the wall's edge.

Everything around the fortress would be razed as far as your spotlights can reach. Not so much as a blade of grass to cast a shadow, because small plants turn into large ones, and cast shadows.

Situate your traps and lights to maximize damage. One strategy would be to have an apparently weak spot that is a death trap, but the question arises whether they are intelligent enough that this trick would stop working, and whether it would stop quickly enough that it's not worth the effort.

Also, lightning rods. No point in letting lightning go to waste when it could protect your settlement.

As for the offense against them, I think that may be a separate question, because there are questions vital to the strategy. Do these creatures have lairs? Do they live in lairs as humans do in towns and cities, or does each one have its own? Do they communicate enough that an offense that didn't exterminate every monster it found would be common knowledge? If they do not have lairs, do they wander randomly, or along predictable paths, or even predictable times?

Answer 6

You may find the following - an old US Army field manual concerning battlefield illumination - useful: https://www.bits.de/NRANEU/others/amd-us-archive/FM20-60%2870%29.pdf .

Given it's from the 1970's it's somewhat dated, but the lower tech level may be beneficial to the survivors of your world - hopefully some or all of it is within reach of their manufacturing capabilities. Included are details on flares, spotlights, battlefield illumination artillery, field improvised illumination, and so on.

Apparently an M485 155-mm illuminating shell puts out ~1,000,000 candlepower and can light up an area ~2km in diameter for 150 seconds - I'm sure something useful could be done with this, especially if airburst at half the usual altitude or so.

Answer 7

Spotlight traps and flash grenades seem like a good way to go. According to what you said, it'd seem like the light of the lightning does as much damage as the lightning itself. What you might want is a way to arm a trap using spotlights, flash grenades and Faraday cages. If you make a zone with many spotlights and activate them once the beasts are inside, you'd be able to cause decent damage. To prevent them from destroying said spotlights, they could make use of Faraday cages, with the spotlight unharmed inside while powerful currents run on the outside of said cages, damaging the beasts as soon as they tough them and increasing the spotlight lifespan. To further avoid them getting to close from the cages to begin with, the use of flash grenades could help keeping them away (not sure if the flash helps it but yeah.

While this happens, just have your soldiers on a plataform above with some additional spotlights and responsible for both throwing the grenades (remember to close your eyes) and making it rain on them. This ambush strategy should help kill them while having the overall advantage on terrain and conditions.

For references of other strategies against light sensitive monsters (although relatively weaker ones), I suggest taking a look at a zombie game called "dying light" as their safe zones have to deal with zombies with similar weaknesses during the night.

Answer 8

Ever seen "Dusk Till Dawn"? Quentin Tarantino move? It's a kidnap/roadtrip movie that takes a hard left turn near the end. Anyway, sunlight suddenly becomes really helpful... and when it strikes the spinning

Mirrored Disco Ball

just about everything in the room catches some rays. And you say light burns them? DISCO INFERNO baby!

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How about repurposing some retail barcode scanners. These scanners are red lasers aimed at a rapidly spinning mirror. Yes, more spinning mirrors, but these would be far more available than disco balls. Every retail outlet would have a couple, and the really big stores will have lots.

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Magic you say? The plants are still alive 20 years later without apparent sunlight... someone will study it. The first spell most wizards learn in all those stories? Some way to create light (or fire which is a valid light source).

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Ooh! "Spark mine". A gizmo rigged up such that when weight is applied to the top, there's a brief arc of electricity. Monsters that step on it get hurt or killed. And they wouldn't work just the one time. Every time something puts more than N pounds of pressure on top, you get a spark.

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Fire geyser! Break the top of an oil derrick and light the resulting oil geyser. They burn for years. Down side: can't live too close (burn), can't live too far (eaten).

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Laser perimeter. Mirrors plus laser equals laser fence, one that would hurt/kill your monsters given enough power.

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Arc light perimeter. Jacob's ladders aren't hard to construct, you just need a high-volt/low-amp power source, which is relatively easy to create mechanically.

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Ground level light tower. Alternatively, a fixed light source with various mirrors rigged up to route the light to where it's needed. You'd almost certainly want to use an arc light given that's what appears to affect them most.

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Gasoline with some styrofoam mixed in is a good homemade napalm. Mix in a little magnesium powder so it burns brighter.

Answer 9

Star shells, flares, LEDs, lasers, and mirrors.

Star shells, launched from a cannon or mortar, will illuminate a large area, enough to make any of these critters pause,

Flares are local defense. Shoot it anywhere near the critters.

LED lights LED flashlights are VERY power-efficient, obviously.

Lasers already mentioned by everybody... lots and lots of photons in one concentrated burst, assuming pulse lasers. Line of sight only, but if regular light hurts, lasers may just kill them if aimed at sensitive spots.

Mirrors imagine humans carrying polished steel shields with embedded LEDs for illumination in one hand, and a flare pistol with a flashlight in the other.

I'd suggest that the scientists would conduct some sort of experiment, to determine if the critters are more affected by any particular spectrum of light, i.e. could the critters be driven off or even killed.

Which sort of also begs the question... WHY are these critters attacking anyway?

Answer 10

Since light does the damage lasers and flares seems like a good option to start with, but they have the drawback of needing power, being bulky and, quite frankly, too delicate to survive a real fight with the spawns of darkness, so you might have some success, but at a lot of risk.

But don't worry, there's a simpler way, inspired by one of the world greatest heroes:

The DOOM guy

And so i present you with...

Dragon Breath Shotgun

A nice, simple and convenient way to blind, burn and have fun with a photofobic target, and when you pair it with things like a semi-automatic shotgun you get a nice way to defend yourself

They also have the advantage of being quite common (lot of demand apparently), easy to transport in bulk, and no special training to use, just point and enjoy.

For extra splash damage i would recommend this as your battle suit.

Answer 11

If humanity is surviving darkness, these creatures cannot do anything to them. Here is what would happen:

Scouts will be traced to their dens, then here comes the light show. This will keep their number in check. The more creatures there are, it will be easier to find their place. I don't believe any creature will be able to survive against a bunker buster hit on top of their den. If they do, use white phosphorous. If that doesn't work use nukes. Also, if enough bullets can kill them, why not go bigger. We are trying rail guns going 2.5km/s (in 2008). In lab, they reached almost 50km/s. With Staballoy rounds, they could penetrate several M1 tanks before stopping. If your creatures somehow stop the bullet from turning them to mush, the impact will probably create enough plasma to emulate lightning strike. Go humans, there is no Geneva convention protecting those poor beasts.

For protection, how well your creatures swim? Human settlements can be built on top of the ocean, powered by whatever magic is keeping plants alive as well as tides if they are big enough. If they do swim, creating plasma arcs in salty air is easier, surround your settlement with arc lights (mini lightning). Use infrared cameras to detect the monsters to activate the lights. Also, seed oceans with light emitting algae. They will accompany your creatures from shore to the settlement, making those trips very taxing. Also also, create a short wall around the perimeter that will allow creatures to scale it, but not directly jump over. Get industrial cutter lasers underneath them. Activate the lasers on pressure. You don't need light sensitive creatures for those lasers to be deadly.

Final nail would probably be a biological weapon against those creatures. If something is living, there is another living organism that will prey on it. Covid-19 reminded us that. And that is a random mutation, wait until humans try building a virus.

Answer 12

Phosphorus allotropes are bioluminescent, could be used. They also burn or react with water to produce poisonous gases like phosphene and have the ability to cause explosions when mixed with some other chemicals.

So stuff like amulets and blow drier powder guns etc and other imaginary weaponry can be fashioned.

Imagine, luring a big monster in one their human dwellings and dumping a bucket of bioluminescent stuff on it, just like pranks played by children who keep chalked up duster on the upper edge of the door.The monster would die even if it can fly.

These are also present in fish in deep sea so their can be a whole class of humans responsible for mining this stuff to stave off monsters.

Answer 13

How about a somewhat different approach: Robot "guns". Build something that can discern the monsters (say, a light source coupled with a ranging system. Anything sufficiently dark but present is a monster) and it fires a pulse from a powerful laser at the target. That should do some serious damage to the monster if not kill it outright.

Since these monsters are at least semi-intelligent they will quickly learn to stay outside the range of the guns no matter what. That means they can't cross a line of guns. You will need a lot of guns to push them back but it can be done. Eventually humanity will corner them into the places where a line of guns can't be placed (sufficiently rough terrain), those areas will need other ways to clear them but if you can merely stop them from moving about they should eventually starve.

Answer 14

Car Batteries, a set of jumper cables (or stick welding leads) and a sheet of metal grounded to the other lead. Car battery welding is an emergency type of welding you can do if you really need to stick some metal together... in an emergency; gotta stress that part.

BUT I could see shock troopers geared out like so:

• Speed glass welding helmet
• Car battery on Back pack
• Steel shield on one arm (Connected to battery terminal)
• Thick protective leather glove and smaller metal cover to form a sort of Arc-claw

This Arc-claw would be connected to the other battery terminal and dragged across the front of the shield would generate bursts of intense light. This could be used to quickly generate bursts of light or holding the metal a short distance away to maintain an arc. For the purposes of car battery welding just about any metal rods will work (because we don't really care about weld quality at this point do we?) Rebar, nails, etc.

Answer 15

I see nobody has mentioned fireflies/bioluminescence. A quick google search shows raising fireflies is a feasible feat, and raising them in enough numbers to release them as a defense may be doable (they can get extremely close to the monsters)

Kill a monster, and selectively breed fireflies to a) be attracted to the monster's meat (fireflies are carnivorous apparently, who knew) and b) have long/predictable flash patterns. A firefly that can approach silently, land or closely approach the monster, and then suddenly and consistently flash light will do lots of damage, as well as attracting other fireflies to the area (I know they signal for breeding, so you'll have to stretch this a bit).

Moats (would have to be saltwater) filled with the bioluminescent algae that we see videos of makes wading through impossible, so they'll have to go over the moats (presumably where there's fireflies). Fill your moats with bioluminescent jellyfish for added spicy factor.

I've seen talk of bioluminescent trees attempted. In post-apocalypse this may be more difficult, but if you can pull it off, there's another line of defense. When all else fails (under extreme siege), light your wall of trees on fire.

Edit: take up beekeeping while you're at it. Pissed off bees (most people breed for calmness, but you want the opposite, breed for aggressive bees) carrying bioluminescent pollen/nectar. Maybe eventually (or with some cross breeding) they'll also evolve to be bioluminescent. Not only are you getting stung by a horde of angry bees, but now the stingers glow once they're in? I think that screams "get out of my fort". You'll need bees anyways to pollinate your food sources