Expanding universe and thermodynamics

Click For Summary

Discussion Overview

The discussion centers on the implications of the expanding universe on bound systems, such as atoms and solar systems, and whether this expansion leads to energy release within these systems. Participants explore the relationship between cosmic expansion and local interactions, questioning how energy conservation is affected by these dynamics.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants propose that if space is expanding, there should be energy released as matter "falls in" to maintain relationships within bound systems.
  • Others argue that the expansion of the universe does not affect bound systems like atoms and solar systems, asserting that local interactions prevent any observable changes.
  • A participant questions the implications of expanding space on small scales, suggesting that potential energy should convert to kinetic energy to maintain structure.
  • Some participants clarify that the effects of dark energy are negligible on small scales, comparing it to an ant pushing on a house, which has no significant impact.
  • There is a discussion about the complexities of general relativity and how energy conservation principles differ from classical mechanics in the context of cosmic expansion.
  • One participant suggests that even if the effects of expansion are minuscule, they could still lead to energy transfers within bound systems over time.
  • Another participant emphasizes that the expansion of space is a general relativity effect and that it complicates the understanding of energy dynamics in bound systems.

Areas of Agreement / Disagreement

Participants do not reach consensus on whether the expansion of space affects bound systems or if energy is released as a result. Multiple competing views remain regarding the implications of cosmic expansion on local structures.

Contextual Notes

The discussion highlights limitations in understanding how expansion interacts with gravitationally bound systems and the challenges in reconciling different models of the universe.

  • #31
PeterDonis said:
That's because the thermodynamic budgetry you are used to is based on an underlying assumption of time translation invariance (which someone mentioned in a previous post). The expansion of the universe breaks time translation invariance; that means the thermodynamic budgetry you learned no longer holds in the form you learned it. There are ways of constructing a modified budgetry, but it still has limitations.

This article by Sean Carroll is worth reading in this connection:

http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/
Excellent link, PeterDonis. Directly addresses the question.
 

Similar threads

Undergrad How would the laws of thermodynamics change in a contracting universe?
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad Density fluctuations in a homogeneous linearly expanding universe?
  • · Replies 7 ·
Replies
7
Views
3K
High School Estimates — True Size of the Universe?
  • · Replies 33 ·
2
Replies
33
Views
7K
Graduate Our universe as an expanding sponge that is constantly falling.
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad Is Expansion of Space Affecting Gravitational and Nuclear Forces?
  • · Replies 24 ·
Replies
24
Views
3K
Graduate On the origin and the evolution of information in the Universe
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Why isn't everything expanding in an expanding universe?
  • · Replies 51 ·
2
Replies
51
Views
6K
Undergrad Is energy conserved during the formation of local systems?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Can a Homogeneous Universe Avoid a Big Crunch?
  • · Replies 28 ·
Replies
28
Views
3K
Undergrad More extended equilibrium configurations due to dark energy?
  • · Replies 19 ·
Replies
19
Views
3K