Dark energy and conservation of energy

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Discussion Overview

The discussion centers on the relationship between dark energy and the conservation of energy within the framework of general relativity (GR). Participants explore whether different types of dark energy, such as the cosmological constant and quintessence, affect the conservation of energy, particularly in an expanding universe.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants reference Sean Carroll's article suggesting that dark energy does not violate conservation of energy, depending on the definition of energy used.
  • Others assert that energy is not globally conserved in any universe, with local conservation of stress-energy being a key principle in GR.
  • A participant questions whether the type of dark energy influences the conservation of energy, referencing differing opinions on energy conservation in an expanding universe.
  • Concerns are raised about the lack of specific references when discussing varying viewpoints on energy conservation, emphasizing the need for clarity in definitions.
  • John Baez's perspective is introduced, indicating that the conservation of energy in GR may depend on the acceptance of pseudotensors, prompting further inquiry into the implications of dark energy types.

Areas of Agreement / Disagreement

Participants express differing views on the conservation of energy in the context of dark energy and GR, with no consensus reached on whether the type of dark energy affects this conservation.

Contextual Notes

The discussion highlights the complexity of energy conservation in GR, noting that definitions and interpretations play a significant role in the analysis. There are unresolved aspects regarding the implications of different types of dark energy on energy conservation.

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TL;DR
Conservation of energy and different types of dark energy
According to this Sean Carroll article, “https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/
And other threads in here, depending on your definition of energy, dark energy does not violate conservation of energy, my questions is if this is true regardless of the type of dark energy (e.g cosmological constant, quintessence, etc.)

some threads that discussed this topic.
https://www.physicsforums.com/threads/does-spacetime-absorb-energy-in-general-relativity.1013951/


https://www.physicsforums.com/threa...n-in-general-relativity.1060029/#post-7061167
 
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Even in a universe without dark energy, energy is not conserved globally. Stress-energy is always locally conserved in GR.

Edit: Also, referring to ”some threads” is unhelpful. Please provide specific examples or we have no way of knowing what you are referring to.
 
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Orodruin said:
Even in a universe without dark energy, energy is not conserved globally. Stress-energy is always locally conserved in GR.

Edit: Also, referring to ”some threads” is unhelpful. Please provide specific examples or we have no way of knowing what you are referring to.
yes I understand that but like Sean Carrol points out in his article. there are some people who prefer to say that energy is conserved in an expanding universe. My question was if the type of dark energy used changes anything.
 
OCD said:
there are some people who prefer to say that energy is conserved in an expanding universe.
Without a better reference that "some people" there is just no way that we can answer your question sensibly.

One of the things that you will have gotten from that Sean Carroll piece (which is just scratching the surface of a very complex problem) is that in GR conservation of energy is complicated enough that when someone is taking about it the first step is to be clear on exactly what they mean by "conservation of energy".
 
Nugatory said:
Without a better reference that "some people" there is just no way that we can answer your question sensibly. One of the things that you will have gotten from that Sean Carroll piece (which is just scratching the surface of a very complex problem) is that in GR conservation of energy is complicated enough that when someone is taking about it the first step is to be clear on exactly what they mean by "conservation of energy".
Okay for example john baez in https://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html says that it depends on your definition of energy to determine whether or not is conserved in GR, more specifically he says that if you accept pseudotensors energy is conserved in GR, does the type of dark energy changes anything here?
 

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