/sci/ - Science & Math

>>15216919

>>14766291
it's obvious you don't know what you're talking about. you caught me in an educational mood, so lucky for you, i won't simply insult you. you can start with here
https://physics.stackexchange.com/questions/2625/what-is-the-difference-between-thermodynamics-and-statistical-mechanics
thermodynamics is the older and more mature analysis of equilibria states, and is far more reaching in its descriptions of temperature. statistical mechanics attempts to derive thermodynamic principles (e.g. equilibrium states) from microscopic assumptions. however you cannot derive the laws of thermodynamics from statistical mechanics, and that's a problem. rather, what you do is assume the laws of thermodynamics are valid, and then patch up your model of statistical mechanics with it.

in a nutshell, thermodynamics is more fundamental (and is why we continue to say the laws of thermodynamics and not the laws of statistical mechanics). entropy was defined in terms of thermodynamics, and that's precisely what the second law talks about regarding entropy (and not the statistical mechanics version utilizing microstates). heat engines of all types use thermodynamics in their construction, and not statistical mechanics.

now, what actually is entropy? for that you need a historical understanding. when the laws of thermodynamics were being discovered, the thermodynamic temperature was defined as a scale to track equilibrium conditions. this thermodynamic temperature is distinct from statistical mechanics and cannot be derived from statistical mechanics (it's often called Theta). see e.g.
https://en.wikipedia.org/wiki/Thermodynamic_temperature

really, entropy just boils down to a thermodynamically scaled energy (thermodynamics is the study of scales, at its heart). turns out this scaled energy was useful in thermodynamics and was given a name of entropy (etymologically almost identical to energy in meaning). much like energy, only changes in entropy are physically meaningful.

>>14566545