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This question is boggling me for some time. We know that heat can be transferred from matter to matter and heat is nothing more than tiny atoms vibration intensity (correct me if I'm wrong). But space is a vacuum, and so arises the question: Can you heat vacuum? :)) How can it be that earth loses it's heat to space itself?

Thanks

Davita
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Earth can lose heat to space through radiation.

The earth behaves roughly as a blackbody and so radiates electromagnetic radiation into space at a rate of roughly 120 PW.

alemi
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  • I suspected that. But that's another solution that's boggling me :D I'll ask it here if you don't mind. As far as I know radiation has no mass, and according to Einstein's famous equation, mass=energy. So how come that if radiation has no mass, it is carrying energy (heat)? Thanks again :) – Davita Aug 01 '14 at 00:01
  • @Davita See this question – alemi Aug 01 '14 at 00:03
  • Thanks. Tobias states that "the energy of a photon is proportional to its frequency.". He also wrote a formula E=pc=hc/λ=hν. Now I'm not sure what "h" stands for, but as he says, "v" is frequency. What I don't understand is that, if a mass of a single photon is 0, how do we get a positive number when multipliyng over a constant factor of "h" (which I have no idea what it is :D ) – Davita Aug 01 '14 at 00:12
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    @Davita: $h$ = Planck's constant. – Kyle Kanos Aug 01 '14 at 00:14
  • I mean, frequency is an inverse distance between light waves, the higher the frequency the more photons we get and vice versa, but how a multiplication of 0s can yield a positive number (which is it's energy)? Sorry for my broken English, not a native speaker here :) – Davita Aug 01 '14 at 00:15
  • BTW, just curious, 230 PW stands for Peta Watt or Pico watt? :)) - Dumob question I know, it's just picowatt seems to me unrealistic small number, but petawatt 2 big :)) – Davita Aug 01 '14 at 00:22
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    @Davita PetaWatt, or $10^{15}$ W – alemi Aug 01 '14 at 00:28
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    @Davita A photon has 0 rest mass ($m=0$), but $E=mc^2$ and $E=pc$ are both simplifications; the latter applies when $m=0$. The full formula is $E = \sqrt{m^2c^4 + p^2c^2}$. When we say a photon is a "massless" particle, we mean that it has no rest mass, not that it has no mass-energy at all. – Tim S. Aug 01 '14 at 02:31
  • @Tim thanks Tim. You mean that when in motion, photon has a mass because it is carrying energy? – Davita Aug 01 '14 at 02:40
  • @Davita: Not quite (though it's technically just a point of view). You could view it as the photon acquiring mass or you could also view it as the photon having equivalent mass of the amount of energy it carries. It's just human interpretation. The equations are the same since mass=energy. – slebetman Aug 01 '14 at 03:42
  • @slebetman damn, I hate multiple correct answers... :)) thanks, a bit more clear now :) – Davita Aug 01 '14 at 04:31