- #31
Freeman Dyson
- 213
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I know spacetime is something but I am wondering what that something is. is it only the gravitational field? is the geometry of spacetime, gravity?
Dark Energy & the Law of Thermodynamics
- Context: Graduate
- Thread starter S.Vasojevic
- Start date
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- Tags
- Dark energy Energy
Click For Summary
Discussion Overview
The discussion revolves around the relationship between dark energy, the expansion of the universe, and the implications for the laws of thermodynamics, particularly the first law. Participants explore whether galaxies are receding due to a force or simply because space itself is expanding, and the potential consequences of this on gravitational potential energy and energy conservation.
Discussion Character
- Debate/contested
- Conceptual clarification
- Exploratory
Main Points Raised
- Some participants propose that galaxies are moving apart not due to a force overcoming gravity, but because more space is being added between them.
- Others argue that the movement of galaxies is a result of their previous motion and that the acceleration of their recession is due to a force, potentially attributed to dark energy, which is not fully understood.
- A later reply questions how to measure the difference between expanding space and motion through non-expanding space, suggesting that on small scales, these concepts may be indistinguishable.
- One participant asserts that if the expansion of space leads to a gain in gravitational potential energy without the expenditure of other energy forms, it could violate the first law of thermodynamics.
- Another participant counters that the energy associated with the expansion comes from kinetic energy and that the universe behaves as if it has negative pressure, which allows for energy gain without violating conservation principles.
- Some participants express uncertainty about the implications of dark energy and the nature of energy conservation in an expanding universe, noting that energy conservation may only hold locally rather than globally.
- There is a discussion about whether the universe is creating space as it expands and how this relates to the concepts of cosmological redshift and the nature of motion in the universe.
Areas of Agreement / Disagreement
Participants do not reach a consensus, as multiple competing views remain regarding the nature of the expansion of the universe, the role of dark energy, and the implications for thermodynamic laws.
Contextual Notes
Participants acknowledge limitations in understanding the mechanisms behind dark energy and the implications for energy conservation, as well as the challenges in defining and measuring concepts related to space expansion.
Who May Find This Useful
This discussion may be of interest to individuals exploring modern cosmology, particularly those curious about the implications of dark energy, the expansion of the universe, and the foundational principles of thermodynamics in this context.
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