Does gravity defy the 2nd Law?

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SUMMARY

This discussion centers on the relationship between gravity, thermodynamics, and the Second Law of Thermodynamics, specifically regarding whether gravity can defy this law. Participants conclude that gravity does not defy the Second Law, as the formation of a star from a diffuse gas cloud involves energy loss through radiation, which increases the overall entropy of the system. The conversation also emphasizes the importance of considering phase space over spatial volume when discussing entropy changes during gravitational collapse.

PREREQUISITES
  • Understanding of the Second Law of Thermodynamics
  • Familiarity with concepts of entropy and phase space
  • Basic knowledge of gravitational collapse and star formation
  • Awareness of thermodynamic equilibrium and energy transfer
NEXT STEPS
  • Research the implications of the Second Law of Thermodynamics in astrophysics
  • Study the concept of Jeans instability in gas clouds
  • Explore the relationship between temperature, entropy, and phase space
  • Investigate the processes involved in star formation and energy radiation
USEFUL FOR

Astrophysicists, thermodynamicists, and students of physics seeking to deepen their understanding of entropy, gravitational collapse, and the fundamental laws governing star formation.

  • #31
Perhaps an image is worth more than 100 words. This is my intuitive picture

Gravity and 2nd Law.JPG
 
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  • #32
Gerinski said:
I never stated that the cloud of gas could or could not radiate, that came only in some of the answers such as Anorlunda's.
You are the one who put it in the container, from which it can't radiate.
Personally, even now I do not see why such a gravitationally coalescing cloud of gas could not radiate to its immediate environment in the rest of the container.
What "rest of the container? Isn't it filled completely with a gas?

How does your scenario apply to the real universe? Why are we even talking about it? What game are we playing here?
 
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  • #33
Gerinski said:
I never stated that the cloud of gas could or could not radiate
Gerinski said:
Because of the impossibility to radiate

In general, if you are going to do that, it's best to do it somewhere where your previous messages are not stored.

And I'm done here.
 
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  • #34
The answer was given by @Demystifier in post #6: the wrong assumption is that entropy has been reduced.

Time to close the thread. Thanks to all that participated.
 
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