4 ms·
Heat transfer happens by heat conduction and heat radiation, so even in a vacuum you will radiate heat away in the form of infrared photons, at least if the vac
by danbruc 7y ago
Heat transfer happens by heat conduction and heat radiation, so even in a vacuum you will radiate heat away in the form of infrared photons, at least if the vacuum is not at a higher temperature. Heat radiation is however a less efficient process then heat transfer in a sufficiently dense environment. That is also an issue for spacecrafts, they need rather large radiators to radiate away excess heat into space.
- mytailorisrich 7y agoVacuum does not have a temperature. You would probably need very little thermal insulation, if any, for a space walk around Pluto as heat from sun will be quite low as well.
- danbruc 7y agoIf you place a thermometer in space sufficiently far away from all heat sources, it will eventually reach 2.73 K, the temperature of the cosmic microwave background. I am not sure about the correct terminology but at least in some sense this is the temperature of outer space.
- mytailorisrich 7y agoVacuum has no temperature. What you describe is a black body spectrum 'temperature'.
- danbruc 7y agoThat is why I said that I am not sure about the precise terminology. But it still does not change the fact that an object placed in the vacuum of outer space will eventually reach the temperature of the cosmic microwave background, i.e. the temperature of the electromagnetic radiation filling outer space. Also not that I am not talking about any vacuum, I am specifically talking about vacuum of outer space.
- mytailorisrich 7y agoIt does not change the fact that vacuum, any vacuum, has no temperature...
- danbruc 7y agoAlso no perfect vacuum exists which renders this rather irrelevant for discussing what happens in real situations. I also did some reading to figure out the correct terminology - it is certainly correct to say that a perfect vacuum has no thermodynamic temperature as it is defined by the state of motion of the particles making up the system you want to assign a temperature to, however I am still not convinced that it is wrong to associate a temperature with a vacuum based on the electromagnetic radiation filling it.
- mytailorisrich 7y agoYes, vacuum has no temperature. The energy of any radiation that may be going through a vacuum at a given instant is not a property of the vacuum (and is not an actual temperature). I'll leave it here as I think I have repeated the same thing enough though I am not sure it has been heard.
- danbruc 7y agoYou keep repeating a point I never disagreed with, a perfect vacuum has no thermodynamic temperature. My issue with that is that I think it is a too narrow viewpoint for the comment I initially replied to. If one understands temperature as what a thermometer measures, then the temperature of a vacuum will be the temperature of its walls, it will not magically show »undefined« because you insist that temperature means thermodynamic temperature.
- mytailorisrich 7y agoYou say you don't disagree but you keep disagreeing... I made a simple, yet fundamental statement. It's either true or false. There is no need to argue as if you had to out-do me in any way. Vacuum cannot have a temperature. This follows immediately from the definitions. This also means that the temperature of a vacuum's "walls", by which I'm guessing you mean particles in 'contact' with the vacuum, is just the temperature of these particles. It's not an indication of any "vacuum temperature". Have a nice day.