What if gravity wasn't geometry—would conservation laws still hold?

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Discussion Overview

The discussion revolves around the implications of gravity not being a geometric phenomenon, specifically questioning what conservation laws might be violated if gravity were treated as a force instead. Participants explore the relationship between gravity, geometry, and conservation laws within various frameworks, including classical physics and quantum gravity.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants question what conservation laws would be broken if gravity were not considered a geometric property, suggesting that this could lead to inconsistencies in other laws of physics.
  • Others reference Noether's Theorem, discussing its implications for the relationship between space and time and the necessity of geometry in physical theories.
  • There are claims that the equivalence principle in geometric theories explains the equality of inertial and gravitational mass, raising questions about the consequences of treating gravity as a force.
  • Some participants express uncertainty about the specific models that would apply if gravity were not geometric, indicating that without a defined model, the questions posed may not be answerable.
  • One participant notes that the invariance in Noether's theorem and the invariance in general relativity are different, suggesting a nuanced understanding of conservation laws in classical physics.
  • There is a mention of "Point of View Invariance" and its potential implications for conservation of energy, though this is met with skepticism and calls for clarification.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of gravity not being geometry. Multiple competing views are presented regarding the relationship between gravity, geometry, and conservation laws, with ongoing questions and uncertainties remaining unresolved.

Contextual Notes

Limitations include a lack of specific models to reference when discussing gravity as a force versus geometry, as well as varying interpretations of Noether's Theorem and its applications across different physical frameworks.

mieral
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If gravity was not geometry.. what conservation law(s) would be broken?
For example.. if gravity was a force.. would other laws of physics be broken?

But gravity as geometry may not be complete answer because it has to be made compatible with quantum. Its quite puzzling.
 
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mieral said:
If gravity was not geometry.. what conservation law(s) would be broken?
You are asking "if the laws of physics did not apply then what would the laws of physics say about <insert nonsense of your choice>".
 
I heard of the Noether Theorem.. thought there was a necessary requirement why space has to be bind to time as geometry.

If not.. maybe the source code of the universe is geometry to the core.

Ok.. please transfer this thread to the Beyond the Standard Model as we are digging up some connections. Thanks
 
I'm not a moderator so I can't move the thread but I can tell you that "beyond the standard model" does NOT mean "stuff that conflicts with known science".
 
phinds said:
I'm not a moderator so I can't move the thread but I can tell you that "beyond the standard model" does NOT mean "stuff that conflicts with known science".

Beyond the standard model is Quantum Gravity. I thought why gravity was geometry had a reason.. wasn't it to make symmetry of space and time. Is this the only reason why gravity was geometry? But then geometry has to satisfy quantum and geometry can't be all it. That is why I think this topic is more appropriate for beyond the standard model.
 
mieral said:
If gravity was not geometry.. what conservation law(s) would be broken?
For example.. if gravity was a force.. would other laws of physics be broken?
Geometric theories follow the equivalence principle and explain the equality of inertial and gravitational mass.
 
mieral said:
If gravity was not geometry.. what conservation law(s) would be broken?
For example.. if gravity was a force.. would other laws of physics be broken?

In classical/non-relativistic physics, where gravity is a force, what conservation laws are broken and what other laws of physics are broken?
 
martinbn said:
In classical/non-relativistic physics, where gravity is a force, what conservation laws are broken and what other laws of physics are broken?

Beats me. What?
 
You are asking the question "if gravity is not geometry but a force what conservation laws and other laws of physics are broken", you tell us why you expect that any laws will be broken? For example what conservation laws do you think are broken in classical physics?
 
  • #10
martinbn said:
You are asking the question "if gravity is not geometry but a force what conservation laws and other laws of physics are broken", you tell us why you expect that any laws will be broken? For example what conservation laws do you think are broken in classical physics?

I remember reading it's Point of View Invariance. The rest I don't remember. But so what if point of view invariance is lost.. maybe conservation of energy? I forgot that's why I'm asking.
 
  • #11
mieral said:
I remember reading it's Point of View Invariance. The rest I don't remember. But so what if point of view invariance is lost.. maybe conservation of energy? I forgot that's why I'm asking.

I think I see what your confusion might be. The invariance in Noether's theorem and the invariance in general relativity are different. It is actually the other way around than what is implied in your question. In classical physics you do have the invariance that gives you conservation of energy, but not every spacetime has it.
 
  • #12
mieral said:
If gravity was not geometry.. what conservation law(s) would be broken?
For example.. if gravity was a force.. would other laws of physics be broken?

These questions are not answerable because you have not told us what specific model you want to use. "If gravity was not geometry" just tells us what model not to use (the usual spacetime geometry model of GR). It doesn't tell us what model to use.

"If gravity was a force" could be interpreted as saying "use Newtonian mechanics", but we already know what Newtonian mechanics predicts and which of those predictions don't match reality. If there is some other model that says gravity is a force, you'll need to tell us what it is.

mieral said:
I heard of the Noether Theorem.. thought there was a necessary requirement why space has to be bind to time as geometry.

No, it isn't. The reason we use spacetime geometry in relativity is that it works: the theory we build on that model matches reality. But there are plenty of other possible theories that are consistent with Noether's Theorem. You can formulate Noether's Theorem in Newtonian physics.

mieral said:
I remember reading it's Point of View Invariance.

If you mean the principle of relativity, this is not limited to GR either. Newtonian mechanics has a principle of relativity.

In the absence of a specific question that can be answered, this thread is closed.
 

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