# Are freeze-weapons possible?

No no Tenebras that’s a great idea. They can form a superhero team called The Extinguishers. They’d fight arsonist magma-men from the center of the earth, preventing them from turning the surface of the planet into the sort of burning hell they find comfortable. I mean, c’mon, a firehouse is a ready-made secret headquarters!

Sorry magma-morons, but we’ll have to put you on ice! Literally!

Hmm… actually, you’re right. Also, they have a fire pole, already in the building!

Put your beer in a container with a lot of ice, some water, a a mess of salt. Nearly ice cold beer in a few minutes. If you could also put something in to circulate the wat\er, that would cool it even faster.

Possible? I used to date one.

Okay, it turns out typical RPG-7 ammunition travels at about 300 m/s. That’s more than 600 mph. Waaay overkill for this application, although I don’t know why cryo-grenades can’t just be manufactured with much weaker rocket motors- although at lower speeds they might be a lot harder to aim. Typical RPG-7 ammunition apparently also has significant range- well over half a mile- which can probably be given up here. Probably the best way to deliver the coolant is for the grenade to explode with a small charge a meter or so before impact, although how to trigger such a detonation without seriously messing up the target (still assumed to be fleshy) escapes me. The tandem system used on reactive-armor-piercing weapons is probably inappropriate here.

Maybe someone who knows their chemistry can do a little math that also applies to the ‘flamethrower’ version:

How much -196 °C LN2 boiling off of 80 kg of meat at 37 °C will it take to lower that meat to -5 °C?

I don’t even know how to begin to calculate that. I vaguely remember something called ‘specific heat’ being able to tell you exactly how much ‘heat energy’ was in a given mass of a given chemical at a given temperature or something, and how much energy it would take to raise that matter 1°C; but how can you account for the efficiency of heat conduction?

Also in regards to the ‘flamethrower’ version, I’ve heard it said in discusions of futuristic weapons that “A plasma cannon won’t work for the same reason that a steam cannon won’t.” Although I’ve never seen that elaborated on, from the context I always assumed it meant hot, high-pressure gasses can’t really be effectively ‘projected’, rapidly diffusing after leaving a nozzle, especially when hitting an atmosphere. Since LN2 is kept cold by allowing it to continuously boil off, does that mean you would have the same problems spraying it through the air? (On the flip side, the fact that it’s boiling in a sealable tank means it’s self-pressurizing.)

Its ok guys i found somthing to cool my beer quickly. No need for a freeze ray gun any more.

I was going to post a similar question because of a story I’m writing. How long would it take to freeze somebody solid if you dropped them into a big vat of liquid nitrogen? How long would it take to lose consciousness if they were awake at the time?

I tried to figure it out with the equations for rate of heat loss, but I made a huge mess of it.

how about a tank style weapon

I’m curious about this though. So you can actually make a War of the worlds style Heat Ray?

Yeah, no problem, at least in theory: If you can get enough infrared-frequency photons on target, you can make the molecules rotate and vibrate faster and faster until they’re not molecules any longer, because the atoms have enough energy to fly off. The molecules would likely move out of the way first, though, which you’d see as melting or some other phase change in the bulk matter.

(Why infrared? Because things only absorb photons if the photon is enough energy to make that thing do something new: If it’s too little energy or too much, there’s no interaction. That’s a large part of the ‘quantum’ in ‘quantum physics’. It turns out, infrared light has enough energy to make molecules change their rotational and/or vibrational motion, and that is heat. That’s what heat is, once you get down to the level where you can see individual molecules. Ionizing radiation is light with enough energy to make electrons leave their atoms and embark on a life of radicalization; how much energy that is depends on the atom, with things like carbon needing more energetic photons to pry their electrons away than you need to get a rise out of rubidium’s electrons, but gamma radiation photons are enough energy to tear a lot of different shit up.)

So you’d need a source of IR and lenses which can focus IR on a point target, both of which we know how to make: Every modern TV remote control is a really pitiful source of IR, and the existence of infrared photography means we know how to make the lenses.

I don’t see the problem with this suggestion.
Fire liquid nitrogen, or whatever, at a target in some kind of capsule. The capsule doesn’t even need to be a particularly good insulator; it’s mainly there to hold the liquid together for the time it takes to reach the target.
…which doesn’t need to be particularly fast, nor does it need to penetrate the target.

The only issue is whether this is too far from the OP’s conception of a freeze ray.

I actually can’t think of any video games in which freeze-rays show up.

Duke Nukem for one, had a freeze-ray gun. Bioshock had some sort of freezing power (but I don’t think it was a gun). A lot of the time, it is actually a magic power of some sort that does the freezing.

I’m pretty sure Borderlands had tons of guns with freezing effects.

Unsurprisingly, I haven’t played any of those. I still object to OP’s usage of ‘show up all the time’ though I think they show up quite rarely.

Painkiller had a freeze grenade on the shotgun; WoW had Frost mages. Frost was actually not a power effect in Borderlands. “Tired of shooting lots of bullets? Get yourself a Maliwan and SET SOME PEOPLE ON FIRE!!!”

With my freeze-ray I will stop

the world.

Derleth, you don’t actually need infrared. Anything that will be absorbed by the target will have the same effect. Like, say, visible light. The only reason that people associate infrared with heat is that most terrestrial objects that we think of as “warm” (animals, fire, asphalt roads on a summer day) are of such a temperature that most of the energy they give off is in the infrared range. But a hotter object will give off shorter wavelengths, and any form of radiation will be converted to heat when it’s absorbed.

Okay - so I ran some back of the envelope calcs on this :

A> Assume an average American manweighing 195 lb need to be frozen with liquid nitrogen.
B> 60% of the human body is water - that makes it 117 lb of water. Lets neglect all other parts and just look at how much liquid nitrogen is theoretically needed to freeze 117 lb of water.
C> Assume that the freezing process is 100% efficient - that is no heat is lost to the surroundings and the final temperature is about 32F for both the Nitrogen and the Water. The starting temperature of the human body is 98F and of Nitrogen is around -320F.
The calcs show that you will need around 45 lb of liquid Nitrogen (~7 gallons) - lets not forget the caveat that we have ignored other parts of the body (fats / bones /etc) - and we have assumed 100% efficiency.

The actual amount needed will be more than twice this and still it wont be instantaneous - it will take a while for the internals to cool down.

Ahhh, they’re 2007-style “Freeze Rays”.