Gravitation as curvature of space vs field theory

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Discussion Overview

The discussion revolves around the reconciliation of two perspectives on gravitation: one that describes it as the curvature of space due to the presence of matter, and another that conceptualizes it as a field acting through hypothetical particles known as gravitons. The scope includes theoretical considerations and the implications of general relativity and quantum mechanics.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants propose that gravitation can be understood as both curvature of space and as a field mediated by gravitons, questioning how these views can be reconciled.
  • One participant notes that the gravitational field is not currently described as being composed of gravitons in mainstream physics, suggesting that the geometric aspects of general relativity may not be taken literally.
  • Another participant suggests that a potential reconciliation might come from an undiscovered quantum theory of gravity, referencing other discussions on the topic.
  • A comparison is drawn to electromagnetism, which is described in both classical and quantum terms, raising the question of whether a similar reconciliation is possible for gravitation.
  • It is noted that gravity, as described by general relativity, is unique in that it involves curved spacetime, unlike the other forces that are part of the Standard Model of particle physics.
  • One participant emphasizes the need for a theory of quantum gravity to address the differences between general relativity and the Standard Model, highlighting the background independence of general relativity.

Areas of Agreement / Disagreement

Participants express differing views on the reconciliation of gravitational theories, with no consensus reached on how to integrate the concepts of curvature and field theory. Multiple competing perspectives remain present in the discussion.

Contextual Notes

Participants acknowledge the limitations of current theories and the unresolved nature of a quantum theory of gravity, which may be necessary to fully understand the relationship between the curvature of spacetime and the concept of gravitational fields.

rudolfbaer
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Gravitation is described on one hand as curvature of space in the presence of matter.
It is also described as a field acting through gravitons on matter. How can the two views be reconciled?
 
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The gravitational field is not described as being composed of gravitons in any mainstream physical theory at present.

In the spirit of Weinberg, it might also be worth considering the viewpoint that the geometric aspects of general relativity are not to be taken especially literally -- it is a mathematical theory that describes the gravitational interaction in a language that happens to be geometric. In the same vein, electromagnetism can also be understood as a geometric theory (where the vector potential arises as a quantity associated with the geometry of the internal U(1) group space), but that doesn't stop us from also associating the vector potential with photons in field theory.
 
rudolfbaer said:
Gravitation is described on one hand as curvature of space in the presence of matter.
It is also described as a field acting through gravitons on matter. How can the two views be reconciled?

Through an (as yet undiscovered) quantum theory of gravity. You'll find a number of threads in the relativity and quantum mechanics sections - for example https://www.physicsforums.com/showthread.php?t=689165
 
rudolfbaer said:
Gravitation is described on one hand as curvature of space in the presence of matter.
It is also described as a field acting through gravitons on matter. How can the two views be reconciled?

Compare to this question: Electromagnetism is described on one hand in terms of classical electric and magnetic fields. It is also described as a (quantum) field acting through (virtual and real) photons on matter. How can the two views be reconciled?
 
Gravity viewed as curvature of spacetime is general relativity; unlike the other 'forces',
gravity is not part of the Standard Model of particle physics.


Gravity in general relativity is curved spacetime; In quantum mechanics particles are the carriers for the electromagnetic, strong and weak forces...so the hypothetical idea of a particle for gravity is called the gravitron. It's never been detected, maybe because it is so weak. But gravity seems especially unique: it curves spacetime.

http://en.wikipedia.org/wiki/Gravitons

general relativity

...does not allow any particular space-time background to be singled out as the "true" space-time background, general relativity is said to be background independent. In contrast, the Standard Model is not background independent, with Minkowski space enjoying a special status as the fixed background space-time. A theory of quantum gravity is needed in order to reconcile these differences.
 
thanks to all, I will have to "digest" this.
 
Don't forget the salt
 

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