View Single Post
juanrga
#12
Feb17-12, 09:01 AM
P: 476
Quote Quote by twofish-quant View Post
And I've known extremely brilliant people in one field that were cranks when they were in another one. Roger Penrose is an example. One thing about the author is that he seems to have no experience dealing with objects in which the gravity field makes a considerable contribution to the system, which is not good when you are dealing with black holes. He seems to miss completely the point about polytropes.

He might be brilliant in thermodynamics in other fields, but the arguments that he is giving in that paper seems to be total non-sense.

I may not be an "expert in thermodynamics" but I do know a thing or two about collapsed systems. His arguments make absolutely no sense because in any sort of stellar object, you are moving energy back and forth between the material object and the gravity field, and you can't just take an object and consider only the themodynamic energy. If you want to do your bookkeepping right, you have to consider the energy that is in the gravity field, which he doesn't do.

Since he isn't including the energy in the gravity field, all of his other arguments fall apart. If you include gravity, you get the results in the first section, which he doesn't seem to understand.
It is evident that this kind or argument can be inverted. People as Hawking, experienced in black holes and general relativity, can say nonsense when entering in the field of thermodynamics.

Even if we ignore now that «the energy that is in the gravity field» is not well-defined in general relativity, what you say about thermodynamic energy and gravitation seems to be without any basis.

Already many ordinary textbooks explain how gravitational energy [itex]M\phi[/itex] contributes to thermodynamic energy. Of course, in a BH the situation is more complex and [itex]M\phi[/itex] is not enough, but thermodynamics in presence of gravitation continues to hold and I fail to see your point.