Self-gravitating systems and MOND

[JCTthatsME]

I have been studying self-gravitating systems and their unusual property of negative heat capacity. This makes me wonder how far such a thermodynamic description can be extended.

Does the concept of self-gravitation apply only to bound stellar systems, or could it also be applicable at the galactic scale?

In particular, is there any relation (or contrast) between this thermodynamic perspective and the MOND approach to flat galactic rotation curves?

Could it be said that the 'reach' of a self-gravitating system naturally ends where MOND-type effects begin?

 

[renormalize]

In particular, is there any relation (or contrast) between this thermodynamic perspective and the MOND approach to flat galactic rotation curves?

Are you familiar with the connection between MOND and thermodynamics that is inherent in Entropic (or Emergent) Gravity? (See https://en.wikipedia.org/wiki/Entropic_gravity.)

 

[JCTthatsME]

Yes, I am familiar with Verlinde’s work on entropic gravity, which actually motivated my interest in this topic. However, I have not seen a direct discussion of negative heat capacity (C < 0) in connection with MOND there. That is exactly the link I am trying to understand better.

 

[JCTthatsME]

I have been working for some time on a formulation of MOND based on negative heat capacity (C < 0).
However, I am not aware of studies where C < 0 has been explicitly discussed in this context. Are there references that formulate MOND or entropic gravity directly in terms of negative heat capacity, and to what extent is this approach comparable to established formulations? I am specifically looking for literature or exchange opportunities in order to align my ideas with known work.

 

[renormalize]

Are there references that formulate MOND or entropic gravity directly in terms of negative heat capacity, and to what extent is this approach comparable to established formulations? I am specifically looking for literature or exchange opportunities in order to align my ideas with known work.

As far as I can tell, to date there are no credible papers published on this specific topic. However, if you google "negative heat capacity mond gravity" you can easily find an unpublished e-print that claims to consider this. But such a source is unsuitable for discussion here on Physics Forums.

 

[JCTthatsME]

I understand that Physics Forums does not allow discussion of personal theories or unpublished sources. My question is: am I allowed to raise a topic if I base it exclusively on peer-reviewed publications, while summarizing the connections in my own words?

For example, if I want to discuss negative heat capacity in self-gravitating systems and its possible relation to gravitational dynamics, but only cite established papers from the literature (without referencing unpublished e-prints), would such a discussion be acceptable?

 

[renormalize]

For example, if I want to discuss negative heat capacity in self-gravitating systems and its possible relation to gravitational dynamics, but only cite established papers from the literature (without referencing unpublished e-prints), would such a discussion be acceptable?

The mentors can correct me, but my understanding is: yes, this is exactly what PF is intended to do. So I say have at it!

 

[JCTthatsME]

I would like to discuss an approach based on negative heat capacity and Tolman's relation for stationary spacetime.

Since I am not sure how to correctly insert mathematical formulas here in the forum, I will make the approach available as a PDF file.

Result: For stationary spacetimes with a timelike Killing field, the gravitational redshift and the field strength can be described by a single gravitothermal potential θ:=lnTgrav (Tolman temperature)

[Moderator's note: attachment deleted]

 

[renormalize]

I would like to discuss an approach based on negative heat capacity and Tolman's relation for stationary spacetime.

I am confused as to the relevance of your attachment. The words "heat capacity" appear nowhere.

 

[JCTthatsME]

In self-gravitating systems it is well known that the heat capacity can become negative [cite Lynden-Bell/Antonov]. This motivates introducing a gravitational temperature field, since standard thermodynamics does not apply directly. I therefore define a gravitothermal potential .

 

[berkeman]

Thread is closed temporarily for Moderation.

 

[PeterDonis]

I understand that Physics Forums does not allow discussion of personal theories or unpublished sources.

That's correct. And yet your post #8 does exactly that, as you confirm in your post #10. Therefore, this thread will remain closed.