n9020351@unicorn.cc.wwu.edu (james d. Del Vecchio) (12/13/90)
Followups To: sci.space Someone posted that vacuum was an isulator. dsr@mir.mitre.org (Douglas S. Rand) writes: >Radiational cooling is pretty effective, especially when >the surrounding black body temperature is 3 or 4 degrees K. If the >person in the vacuum is in shadow they could probably freeze in just >a few minutes. If they're in direct sunlight then they might boil on >one side and freeze on the other (lots of fun). -------- I don't have a clear idea of how that would work. If the heat in your body isn't going _into_ something (like air), then where is it going? I don't understand the "3 or 4 degree K" outside temp. How can it have a tempature if there's nothing there? Do you just mean an imperfect vacuum where the particles hitting you are at 3-4 deg K? I always had the idea that something being cold was only relavent if it was actualy touching you. What's touching you in space? Jim Del Vecchio
stanfiel@testeng2.misemi (Chris Stanfield) (12/13/90)
In article <1990Dec12.183847.13785@helios.physics.utoronto.ca> neufeld@physics.utoronto.ca (Christopher Neufeld) writes: > I'd be curious to know what is the rate of heat loss which a human >body experiences in 15 degree water or zero degree air, both of which >are surviveable with no special equipment, if not particularly >comfortable. Survivable, yes, but for how long? Obviously, time is a very important fctor in these calculations, as heat loss cannot be instantaneous, however large the delta t may be. Chris Stanfield, Mitel Corporation: E-mail to:- uunet!mitel!testeng1!stanfiel (613) 592 2122 Ext.4960 We do not inherit the world from our parents - we borrow it from our children.
neufeld@physics.utoronto.ca (Christopher Neufeld) (12/14/90)
In article <5722@testeng2.misemi> stanfiel@testeng2.UUCP () writes: >In article <1990Dec12.183847.13785@helios.physics.utoronto.ca> neufeld@physics.utoronto.ca (Christopher Neufeld) writes: >> I'd be curious to know what is the rate of heat loss which a human >>body experiences in 15 degree water or zero degree air, both of which >>are surviveable with no special equipment, if not particularly >>comfortable. >Survivable, yes, but for how long? Obviously, time is a very important >fctor in these calculations, as heat loss cannot be instantaneous, >however large the delta t may be. > In the context of this discussion heat loss will only be important if it kills you in less than about fifteen minutes, and that's really pushing it. By then, anoxia is likely to have started you inexorably on the way to maximum entropy. I'm sure that people could survive for fifteen minutes in the environments I mentioned. I'd just like to know what the rate of heat loss is in those conditions. A human in vacuum, shaded from warm objects, would radiate about 500 watts. >Chris Stanfield, Mitel Corporation: E-mail to:- uunet!mitel!testeng1!stanfiel -- Christopher Neufeld....Just a graduate student | neufeld@helios.physics.utoronto.ca Ad astra! | S = k log W cneufeld@{pnet91,pro-micol}.cts.com | Boltzmann's epitaph "Don't edit reality for the sake of simplicity" |