Mareks J. Posted December 9, 2015 Share Posted December 9, 2015 How hot can be pure energy? Link to comment Share on other sites More sharing options...
andrewcellini Posted December 9, 2015 Share Posted December 9, 2015 energy is a property not a substance. Link to comment Share on other sites More sharing options...
Phi for All Posted December 9, 2015 Share Posted December 9, 2015 energy is a property not a substance. ... so there can never be pure energy (sorry, I wasn't sure that was clear). You can't separate the energy from the object it's a property of. 1 Link to comment Share on other sites More sharing options...
DevilSolution Posted December 9, 2015 Share Posted December 9, 2015 I imagine that supernova's are quite hot. Obviously not energy persay but its disperses plenty of it very quickly. Link to comment Share on other sites More sharing options...
swansont Posted December 9, 2015 Share Posted December 9, 2015 Hot is a property or condition. Heat is energy being transferred owing to a temperature difference. Link to comment Share on other sites More sharing options...
MigL Posted December 9, 2015 Share Posted December 9, 2015 Energy can be expressed as a temperature. Link to comment Share on other sites More sharing options...
swansont Posted December 9, 2015 Share Posted December 9, 2015 Energy can be expressed as a temperature. No, not really. Temperature tells you something about energy - average vibrational KE - but the reverse isn't true. Link to comment Share on other sites More sharing options...
MigL Posted December 10, 2015 Share Posted December 10, 2015 So why can't I express the energy of a particle by its equivalent temperature ? Its done all the time, in colliders as well as descriptions of the early universe. Please elaborate Swansont. Link to comment Share on other sites More sharing options...
ajb Posted December 10, 2015 Share Posted December 10, 2015 So why can't I express the energy of a particle by its equivalent temperature ? You can always use Boltzmann's constant to go between the units of energy and temperature. However, one would have to take care and it may not be possible to understand the 'temperature' as the temperature as understood in the kinetic theory of gases. Link to comment Share on other sites More sharing options...
studiot Posted December 10, 2015 Share Posted December 10, 2015 MigL Energy can be expressed as a temperature. Sometimes yes but only indirectly. Consider first my shed wall. Today it is 300oK inside and outside the shed. The wall temperature is 300oK Tonight the same wall, inside and outside temperatures will be 285oK. The wall hasn't changed its KE or its PE but it has lost some heat content. So in that sense the temperature is an indication (measure even) of the energy of the wall. But consider a different wall separating a furnace at 3000oK from the outside at 300oK. This wall contains cooling pipes and much coolant flows through these, carrying away energy and maintaining the wall temperature. In this case the wall temperature is not a measure of energy and perhaps not even a good indicator. The mass flow and difference in temperature between inlet and outlet of the coolant is however. Link to comment Share on other sites More sharing options...
DrP Posted December 10, 2015 Share Posted December 10, 2015 Don't think you need the 'degree' symbol with Kelvin Studiot.. it's just 0K or 273K Link to comment Share on other sites More sharing options...
swansont Posted December 10, 2015 Share Posted December 10, 2015 So why can't I express the energy of a particle by its equivalent temperature ? Its done all the time, in colliders as well as descriptions of the early universe. Please elaborate Swansont. A 1 kg ball moving with a speed of 1 m/s has half a Joule of translational KE. But it doesn't have a temperature based on that rolling. kT for that energy is about 10^22 K. Temperature assumes an ensemble of particles that have reached a steady state and exhibit a Maxwell-Boltzmann distribution of speeds. The description of colliders assumes that you had such an ensemble, because in the early universe you did. You would need to assume you had billions of 1 kg balls, elastically colliding , with an average speed of 1 m/s to assign a temperature to that. Link to comment Share on other sites More sharing options...
MigL Posted December 11, 2015 Share Posted December 11, 2015 I see. I'm taking a narrow view ( from kinetic theory ) and trying to apply it generally ( where it doesn't necessarily work ). Thank you, gentlemen. Link to comment Share on other sites More sharing options...
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