|MadSci Network: Physics|
The most convenient form for the second law of thermodynamics (to answer your question) is: "In an ADIABATICALY ISOLATED thermodynamical system the entropy will increase in any real (irreversible) process". From this, it is obvious that the second law doesn't say anything about the evolution of open system, as is a gas cloud in space. We notice, as you did, that for the process of condensation of cosmic gas into a star the entropy decreases. We also know that: T*dS = dQ, and T>0 Therefore, it must be that energy is radiated as heat. This effect can be observed. The same line of reasoning could also be used to show that matter falling into a black hole would emit energy as termic radiation. This is a way of detecting black holes. Also, see the answer to question 907687350.Ph
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