What kind of ambient cold damage would near absolute zero do?

[Flyndaran]

Originally Posted by Anaraxes

Temperature, or pressure differences? An HVAC system often intentionally increases or lowers the pressure in a building relative to the outside.

Really? I assumed it was just a scaled up version of what happens when our house is much warmer than the outside. My mistake.

[Donny Brook]

Originally Posted by Anaraxes

This is one of the times that the "buy the effect, not the name" mantra comes in handy. If a character wants to kill people by freezing them, buy an Innate Attack that freezes people, and have the fluff description say that the character is bringing down the temperature of the immediate envionrment, rather than trying to speculate on "logical" physical consequences of some general ability like Create Cold or Control Temperature. That path just leads to lots of arguments and abuse.

I don't think your advice is helpful when the task is going in the opposite direction. The character has an ability to do at thing, and the GM needs to know the realistic implications of doing it.

[Harald387]

Originally Posted by Donny Brook

I don't think your advice is helpful when the task is going in the opposite direction. The character has an ability to do at thing, and the GM needs to know the realistic implications of doing it.

I consider 'I need to figure out what your power does that the system doesn't cover, because you've made it so powerful' to be a BIG red flag for 'you should not take this power at this level'. If a player came to me and said 'I want to take Temperature Control 25 (Cold, -50%) [63], and that'll let me chill an area to absolute zero! That's gonna hurt people, what does it do?' I'd say 'Please reconsider your power choices, or buy an innate attack.' In fact, Temperature Control *explicitly* does not deal damage on its own, based on its power description, so really, I'd want to ask the OP for specifics here: what actual ability is the player taking? How does the player expect it to work? And, as they're the GM, just how happy are they with this?

[Anaraxes]

Originally Posted by Anaraxes

An HVAC system often intentionally increases or lowers the pressure in a building relative to the outside.

Originally Posted by Flyndaran

Really?

Yes. Apparently it's often desirable in some climates to move cool(er), dry, air through the walls to prevent moisture collecting in them, so the buildings have positive pressure during summer and negative during winter. Other places maintain positive pressure all the time because the unconditioned air from outside costs more than letting some conditioned air escape -- or because that outside air has other issues, like odors or contamination, that you don't want to pull in. Too much differential, of course, and it gets to be hard to open doors and creates drafts. There are also special cases, like hospitals that like to maintain positive or negative pressure in certain rooms even relative to the rest of the building to keep infections out or in, or high-tech "clean rooms".

There are also unintentional effects, like the "stack effect" when hot air inside rises, creating higher pressure upstairs and lowering the pressure downstairs. That may be what you were experiencing in your house. (If you felt pushed inward, that is.)

[Nymdok]

In my defense folks, Ive never been out in -40F degree weather. I think the coldest day Ive ever seen in my life is 15F. God Bless Texas ;)

My only real reference was what I could quickly google and what I remember from reading 'To Build A Fire' by Jack London. At -70 he wrote that spit 'crackles' (here I believe it to be the outside freezing) at -70F. Thats where I got that from.

I tried to assess the numbers in a way that would be dramatic and playable.

If your looking fro something a little more vigorous you can apply the various equations to the problem.

https://en.wikipedia.org/wiki/Therma...vity#Equations

But I dont know they're really going to be that satisfying.

Originally Posted by Bruno

Reality check: I've been out and about in -40F repeatedly. Never in shirtsleeves because I'm not a masochist, but I'm familiar with it.

Your sweat isn't going to crystallize in one second flat at -40F, but yes, it'll be BOY IS IT COLD weather. The air is not painful to breathe, unless you mean that really unpleasant feeling of your nose-hairs freezing, or the acute "OH HOLY COW COLD!" error message you're getting from your skin. Your throat and lungs will not be in pain, unless you're silly enough to take great big gasping breaths through a gaping mouth. Which you can't do in the one second you're sitting at -40F.

It takes a minute or two for exposed superficial bits (ear tips, nose) to start becoming painfully cold, rather than just really really miserably uncomfortably cold.

I 100% buy checking for stunning for suddenly facing -40F, however. Even when you're dressed up it's a bit of a slap in the face.

Edit: It also takes minutes to freeze something with liquid nitrogen, so I'm not really buying 1.5 inch etc freezing after taking seven seconds to reach the -315F point.

At -40F ::shrug:: feel free to move the results down to the -95F. Im not writing Thermodynamic Law here, I just thought it'd be dramatic and gameable. Its no more or less bizzare than seeing people get shot by Batman's Mr Freeze, or the X-Men's Bobby Drake :)

Originally Posted by weby

Yes, I would agree on the -40F at least likely not being that dramatic. Cooling down takes actually a fair amount of time in those temperatures.

I cannot recall having stepped out at exactly that cold, but I have gone out from a house (at about 20c=about 70F) to outside at very cold(about -37c=about -35F) in inside clothes to go plug in the car heater. Total time outside about 20-30 seconds and it is extremely cold, but I was definitely not in any special pain to breathe or anything.

On the colder temperatures, I doubt the freezing is that fast, given how long it took to freeze things with liquid nitrogen. Though most of that is because the liquid nitrogen boils away when it hits so much warmer object, and a cooling of only 30K/second would not be enough to counter that fast, but would eventually have an effect.

Liquid oxygen on the other hand is a more problematic case and I cannot say how the strong oxidizing agent effect will react with a human. In playing around with it, even small things like a small spark caused objects to start burn violently. Also of note is that the oxygen is liquified slightly before nitrogen and I have no idea what effect that would have.

As for taking a fair amount of time I assumed perfect thermal dynamic conductivity across VERRY small distances. Again, I assumed that the environment dropped to the stated temperatures and let air flow in (also at the Destination temperature.) so I wouldnt have to muck about with pressure.

For grins,
to freeze a 80Kg body of water solid,
That has a surface area of 1.9 m^2,
and a thermal conductivity of .6,
from 98.6 (310K),
Assuming that skin to core is no more than about 9 inches
And the environment is absolute zero.

Then were pumping out about 38e6 J
4180*80*37 + 333000*80 = 38e6
Heat Transfer (simple version)
.6*1.9*310/.11 = 1536 J/s

Which is gonna take about 12000 seconds/200 minutes/3.25 hours


The top 1/4 inch of skin (about 22kg) takes about 3 minutes.
4180*22*37+333000*22 = 11e6J
.6*1.9*310/.0064 = 55000 J/s

If we take the Lungs as cold due to the air inside them, it goes much faster. If we consider that your blood pumping is this scenario is actually working against you by gleefully carrying the heat to the surface Id think it would go much faster.

Originally Posted by afnord

I agree

as in this video he states a heart gets frozen solid in 10 minutes.

https://www.youtube.com/watch?v=zLWEemhtdbE

Webby is right to point out the 'heat shielding' from the Leidenfrost effect. Shown here. (same dude, different video)

https://www.youtube.com/watch?v=gjsMV1MglA4


On the Topic of the heart. for a 300g 12cmx8cmx6cm heart with a 1.1 cm wall thickness immersed in (and of course filled with) 196K liquid nitrogen

4180*.3*37 + 333000*.3 = 146e3 J
Heat Transfer (simple version)
.6*.0432*233/.005 = 1200 J/s

Which I show as being roughly about 2 Minutes

See? Yes you can do the simple math, but its not really that gameable or exciting ::shrug::

Nymdok

[Culture20]

Originally Posted by Harald387

I consider 'I need to figure out what your power does that the system doesn't cover, because you've made it so powerful' to be a BIG red flag for 'you should not take this power at this level'. If a player came to me and said 'I want to take Temperature Control 25 (Cold, -50%) [63], and that'll let me chill an area to absolute zero! That's gonna hurt people, what does it do?' I'd say 'Please reconsider your power choices, or buy an innate attack.' In fact, Temperature Control *explicitly* does not deal damage on its own, based on its power description, so really, I'd want to ask the OP for specifics here: what actual ability is the player taking? How does the player expect it to work? And, as they're the GM, just how happy are they with this?

And enhanced move does not deal damage in the power description, but slam attacks do, just like severe cold does have game-rules for its effect. Does temperature control (heat) not set fires if it gets too high? If temperature control doesn't really control temperature, why does it exist as an advantage?

[Harald387]

Originally Posted by Culture20

And enhanced move does not deal damage in the power description, but slam attacks do, just like severe cold does have game-rules for its effect. Does temperature control (heat) not set fires if it gets too high? If temperature control doesn't really control temperature, why does it exist as an advantage?

If you want your Temperature Control to deal damage, buy an Innate Attack. This isn't just a case of 'enhanced move lets you slam better': the power itself says 'to deal damage, buy an innate attack'.

Or, to put it differently: If you want to be able to control temperature to the point where you freeze people solid or set things on fire, 'Temperature Control' is the wrong power; you want 'Innate Attack', which is priced appropriately for doing that sort of thing.

Off the top of my head, Fatigue Attack 20 ought to do it, averaging 70 damage - which is enough to eat 10 FP, then 60 HP, on the average person. Add Freezing Hazard, Area Effect, Selective, Malediction, whatever you like - and pay your 200+ points.

Again, if a player came to me and said 'I want to pay 60ish points for the ability to casually turn people into popsicles', I'd say 'no', and in this case the RAW absolutely backs that.

EDIT: And, of course, I'm making an assumption that the OP's post refers to players in his game looking to buy Temperature Control at very high levels. It might not; without details like 'my players want to buy X power at level Y, what does this do?' all we've got in this thread is people talking physics, not GURPS.

[Ottriman]

Originally Posted by Harald387

If you want your Temperature Control to deal damage, buy an Innate Attack. This isn't just a case of 'enhanced move lets you slam better': the power itself says 'to deal damage, buy an innate attack'.

Or, to put it differently: If you want to be able to control temperature to the point where you freeze people solid or set things on fire, 'Temperature Control' is the wrong power; you want 'Innate Attack', which is priced appropriately for doing that sort of thing.

Off the top of my head, Fatigue Attack 20 ought to do it, averaging 70 damage - which is enough to eat 10 FP, then 60 HP, on the average person. Add Freezing Hazard, Area Effect, Selective, Malediction, whatever you like - and pay your 200+ points.

Again, if a player came to me and said 'I want to pay 60ish points for the ability to casually turn people into popsicles', I'd say 'no', and in this case the RAW absolutely backs that.

EDIT: And, of course, I'm making an assumption that the OP's post refers to players in his game looking to buy Temperature Control at very high levels. It might not; without details like 'my players want to buy X power at level Y, what does this do?' all we've got in this thread is people talking physics, not GURPS.

The bolded part is the most ridiculous parts of create and control, the incredibly contrived limits placed on it to prevent anyone being damaged with it despite the actual implications of what things like reduced temperature or hundreds of pounds of acid would actually have.

And this purchase was in fact not meant to kill people as its main goal, we just wanted to know what side effects such cold would have when he would make his exotic ultra-cold ice castle (he is healed by cold, so are some of his minions).

Though he would also like to be able to use this to reshape a battlefield to his minions advantage if it comes to that.

We were simply interested in the logical consequences of the power since power that doesn't actually go through with its logical consequences would absolutely rankle our suspension of disbelief.

[Nymdok]

Originally Posted by Harald387

EDIT: And, of course, I'm making an assumption that the OP's post refers to players in his game looking to buy Temperature Control at very high levels. It might not; without details like 'my players want to buy X power at level Y, what does this do?' all we've got in this thread is people talking physics, not GURPS.

Im sorry folks, it wasnt an attempt to derail the thread. Just some quick and simple calc to solve the 'plausibility' and 'reality check' questions I got when I opened with a 'narrative gameable' response.

Nymdok
When the only tool in your toolbox is a hammer, all your problems start to look like nails.`

[Harald387]

Originally Posted by Ottriman

The bolded part is the most ridiculous parts of create and control, the incredibly contrived limits placed on it to prevent anyone being damaged with it despite the actual implications of what things like reduced temperature or hundreds of pounds of acid would actually have.

They're not 'contrived limits'; they're an acknowledgment that the cost of the power doesn't include the cost of the innate attack, and that the power's price isn't balanced with 'hurting people' in mind.

If you want to lower the temperature of an area, and simultaneously damage the people in that area, buy Innate Attack and Temperature Control both. Link them. Now you have Temperature Control and its "logical consequences", at a price that's balanced for gameplay.

If you want to model creating hundreds of pounds of corrosive acid with Create, and want to damage people, buy Innate Attack with a big area effect, probably one or both of cyclic and persistent, and call it a day.

I'd still give any player asking to buy 'enough temperature control to go to absolute zero' the side-eye, whether he intended to (or whether I let him) hurt people or not, because the game doesn't model temperatures that low very well. Quite frankly, theoretical physics doesn't model temperatures that low all THAT well.