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-273°c in space?

  1. Oct 6, 2012 #1
    Ok so I'm watching the movie "sunshine" and in it, they talked about how you'd freeze to death in outer space, on of them did.

    My question is, since there's no atoms to absorb heat from your body, wouldn't the temperature in space always be the same as your own? since there is not way of space taking heat or giving heat, than talking about temperature in context of an empty space is simply put absurd. Temperature means: the average kinetic energy of atoms and molecules in a given sample. How can space have zero heat, that'd mean that the atoms in it were not moving... but there are NO atoms so there can't be still atoms.

    I know I know, theres infrared radiation so you'd cool by those means, but would it be that fast? do we actually loose a big precentage of heat trough electromagnetic waves?

    in the movie, he freezes to become a human statue, I'd expect the opposite, a rather gory effect... I'd imagine him being depressurized, and his blood would boil among all liquids in his body so he would ooze apart and his skin would rip or liquid and blood would escape trough body openings.

    In short, can we talk about temperature in space, isn't the temperature in space always the same as the thing in it, and is the amount of heat lost trough electromagnetic waves(infrared) a significant cooler?
  2. jcsd
  3. Oct 6, 2012 #2
    With a temperature of 310 K and a surface of 1.8..2 m² the power of the heat emission of a human body according to the Stefan–Boltzmann law is round about 1 kW. At 0 °C the emission is reduced to the half of this value. This is not enough to freeze the complete body within a view seconds but it might be enough for the skin. The evaporation heat of body fluids would accelerate the cooling process.

    Maybe there would be no severe physical damages. In the sixties a test person was accidentally exposed to vacuum in a NASA vacuum chamber. The victim lost consciousness after 14 seconds but survived without permanent damages. His last recall was boiling water at the tongue.
  4. Oct 6, 2012 #3
    thanks alot, but than again.. there's also radiation heating the body, radiation from other bodies that went trough the same process 0-10000000000000... years ago. But I am guessing that this intergalatic radiation might have very little value relative to the heat lost, so one could talk about the temperature of space as the average energy included in radiation per cubic meter.
  5. Oct 6, 2012 #4


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    Last time I checked it was about 2.7 K, or -270.5°C, give or take. It depends on how close to a star is the point of interest.
  6. Oct 6, 2012 #5
    So, that would be the temperature you are heated give or take distance from stars. But you could say you gain 2,7 k while you loose a certain amount of head trough emitting radiation. Materials absorb heat ad varying rate, couldn't space be looked at as the same? It must have a relatively low amount of absorbance since compared to being at 2,7 k you'd loose heat slower than liquid nytrogen at 2,7 k.. is there any constant that tells about this?
  7. Oct 6, 2012 #6


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    Melting Point of Nitrogen: 63.15 K (-210.00°C or -346.00°F).

    Melting Point of Hydrogen: 14.009985 K (-259.14 °C, -434.45203 °F)

    The only thing liquid at 2.7 K is He, and that is assuming there is some gravity field to keep it liquid.

    Out in space, there is a dearth of matter, that is matter in the normal or familiar sense.

    Far away from stars or gaseous clouds, it's cold, i.e., not a lot of enthalpy.


    There are regions that are a bit warmer - http://www.ism.ucalgary.ca/Star_Formation/ISM.html

    In a vacuum far away from a star or any significant mass, temperature as we experience it, is rather irrelevant.
  8. Oct 6, 2012 #7
    yeah it's beautiful... from any matter it's kind of like a single wavefunction... it spreads endlessly from it's starting point, so a human would radiate until frozen, than maybe the atoms would have half lives until there was nothing left but some sort of waves, potential energy reaching it's lowest and entropy winning... hahah now I'm just wandering off
  9. Oct 6, 2012 #8

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    Don't base your understanding of science on science fiction movies. The science is inevitably bad. In the best it is only bad. In most it is very, very bad. Watch them for the special effects, maybe for the story. But never the science.

    Exposure to space for a short period of time (less than a minute or so) isn't going to have lasting effects so long as you don't try to hold your breath. Exposure to space will not make you explode, it won't make your blood boil, and it won't freeze you to death. You will die, but it will be lack of oxygen that kills you. This will happen long before your body cools down by any significant amount.
  10. Oct 7, 2012 #9

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    The beauty of science fiction movies is that it makes one wonder.
    It's triggered me countless times to find out how the science really works.
    Often enough I found that an SF story or movie made really good points.

    Freezing to a human statue (after having died from lack of oxygen) seems about right to me.
    And with an oxygen supply, one would probably freeze to death.

    Btw, true vacuum does not exist.
    Vacuum does contain atoms, just very few of them.
    Last edited: Oct 7, 2012
  11. Oct 7, 2012 #10


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    Out of interest would there be significant damage to the lungs, eyes and ears due to pressure change?
  12. Oct 7, 2012 #11

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    Seems to me that if you don't keep your eyes closed, your eyes will pop out.
    But afterward, you can probably push them back in again with no permanent damage.

    I think 1 bar of pressure difference is not enough to make your eardrums rupture, but it will be really uncomfortable.
    The skin of your ears will be damaged by inflation, but that may heal.

    Exposure of the fragile lung tissue to vacuum sounds really unhealthy and will probably cause lasting damage.
    So I believe you should hold at least part of your breath.
    I'm wondering why DH said you shouldn't hold your breath.

    Edit: Just looking up some references:
    It seems that holding your breath may cause lung rupture due to the difference in pressure.
    In particular the wiki article says that a rough estimate is that after 90 seconds of exposure, the body will not be able to recover.
    The article has references on humans and animals that have been exposed to space.
    Last edited: Oct 7, 2012
  13. Oct 28, 2013 #12
    I don't think this is the case, Here is why:
    A normal person consumes about 9 MJ per day.
    The heat released is around 900 J per second.
    So, you'd run through your 9 MJ in just 10000 seconds, less than 3 hours.
    But, people frequently spend more energy than this exercising, 200 Watts is not an inconceivable amount of power for someone to spend.

    Also, they are extremely unlikely to be floating naked, if they wear clothing, it is perfectly safe for it to get below 0 C, if they wear a coat, it is reasonable that it could get colder than -40 C while they are perfectly fine.

    Even wearing a coat, the person now only has to contend with a few hundred watts of heat lost.
    Or... Wearing an unpowered spacesuit, it would be totally fine for it to reach arbitrarily low temperatures.

    And finally, even if you can't maintain the energy, human statues have 5.5 MJ less than normal people, meaning that it would take a long time for someone to freeze to that point.

    My best guess would be around 8 hours deep-space survivability with nothing more than a star trek uniform and pressurized device over all orifices.
  14. Oct 28, 2013 #13


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    You keep reviving old threads; you may want to check dates in the future.
  15. Oct 29, 2013 #14


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    I think unprotected exposure to space would be fatal in much less than a minute. Think of it like being in a hyperbaric chamber on earth at two atmospheres that abruptly loses containment, and the external temperature is only a few degrees kelvin.
  16. Oct 30, 2013 #15
    Plus three Russian cosmonauts died from decompression. People do die of ebullism and asphyxiation way before hypothermia. the op is right.

    you woud freeze after a while of course.
    Last edited by a moderator: Oct 31, 2013
  17. Oct 30, 2013 #16
    Yeah thanks, I found out in 2012 when this thread was posted.
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