- #1
Question69
- 43
- 7
- TL;DR
- Is energy conserved in GR?
Is energy really not conserved in a constantly expanding universe?
Is energy really not conserved in a constantly expanding Universe?
- Context: High School
- Thread starter Question69
- Start date
Click For Summary
Discussion Overview
The discussion revolves around the conservation of energy in the context of a constantly expanding universe. Participants explore the definitions of "energy" and "conserved," and reference existing literature on the topic.
Discussion Character
- Debate/contested
- Conceptual clarification
Main Points Raised
- Some participants suggest that the conservation of energy is dependent on the definitions of "energy" and "conserved."
- References to Sean Carroll's blog post and a Usenet Physics FAQ article are made as resources for understanding the complexities of energy conservation in an expanding universe.
- One participant expresses skepticism about the conclusions drawn by Sean Carroll, indicating a willingness to question established views.
- There is a suggestion that prior knowledge of the referenced materials should have been mentioned in the original post for clarity.
Areas of Agreement / Disagreement
Participants do not reach a consensus on the conservation of energy in an expanding universe, with multiple views and uncertainties remaining regarding the definitions and implications of energy conservation.
Contextual Notes
Limitations include the ambiguity in the definitions of "energy" and "conserved," as well as the unresolved nature of the discussion regarding the implications of an expanding universe on energy conservation.
- #2
PeterDonis
Mentor
- 49,533
- 25,577
The short answer is, it depends on what you mean by "energy" and what you mean by "conserved". 
Sean Carroll's blog post on the topic is a good place to start:
https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/
Sean Carroll's blog post on the topic is a good place to start:https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/
- #3
PeterDonis
Mentor
- 49,533
- 25,577
Credit where credit is due, this bon mot is not original with me, it comes from this Usenet Physics FAQ article, also worth reading:PeterDonis said:it depends on what you mean by "energy" and what you mean by "conserved".
https://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html
- #4
Question69
- 43
- 7
Oh I've read that already, it was when I first found about it really, I just thought I'd ask you guys because maybe Sean is wrong :)PeterDonis said:The short answer is, it depends on what you mean by "energy" and what you mean by "conserved".
https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/
- #5
PeterDonis
Mentor
- 49,533
- 25,577
Um, no.Question69 said:
- #6
PeterDonis
Mentor
- 49,533
- 25,577
That would have been a good thing to mention in the OP of this thread.Question69 said:
Do you have any further questions on the topic?
- #7
Question69
- 43
- 7
I should have, yes, and no.PeterDonis said:
- #8
PeterDonis
Mentor
- 49,533
- 25,577
I'll take that as "no further questions". Thread closed.Question69 said:
Similar threads
- · Replies 12 ·
High School
Expanding Universe: How Does It Conserve Energy?
- · Replies 21 ·
- · Replies 7 ·
- · Replies 25 ·
- · Replies 17 ·
Undergrad
Dark energy and conservation of energy
- · Replies 4 ·
- · Replies 36 ·
- · Replies 2 ·
- · Replies 17 ·
- · Replies 35 ·