Is gravity both a force and not a force?

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Discussion Overview

The discussion revolves around the nature of gravity, specifically whether it can be considered both a force and not a force, exploring this concept through various theoretical frameworks including Newtonian gravity and general relativity. Participants examine the implications of these models in different contexts, such as engineering and cosmology.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants suggest that gravity can be viewed as a force in certain contexts (e.g., Newtonian mechanics for smaller masses) while being described as a curvature of spacetime in general relativity for larger masses.
  • Others argue that the definition of a force is contingent on how one interprets acceleration and the equivalence principle, leading to differing views on whether gravity qualifies as a force.
  • A participant mentions that Newton's model is sufficient for practical applications like civil engineering, while general relativity is more accurate for cosmological scales.
  • Some contributions highlight that both Newtonian and relativistic models have their own limits of validity, and neither can be considered universally applicable.
  • There is a mention of gravitational time dilation as an effect that challenges the notion of gravity being simply a force, suggesting that additional considerations are necessary to fully understand gravity's nature.
  • One participant introduces the idea of gravity existing in a superposition of being a force and not being a force, indicating a complex and nuanced understanding of the topic.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of gravity, with no consensus reached. Some agree on the utility of different models in varying contexts, while others contest the definitions and implications of gravity as a force.

Contextual Notes

Participants note that both Newtonian and general relativistic models have limitations, and the discussion reflects ongoing debates about the foundational understanding of gravity, including the potential implications of quantum gravity.

  • #31
jbriggs444 said:
In science, if you can never detect it, you can safely ignore it and let Occam's razor cut it away.

I was trying to point out a conceptual inconsistency in Newtonian mechanics. Had Einstein ignored it, we would not have general relativity today.

Demystifier said:
Before dealing with gravity and general relativity, one should ask and answer an analogous question in Newtonian mechanics: Is inertial force a force or not a force? After answering that one, the gravity case is conceptually much easier.

Yes, that's what I meant with 'forces' causing 'relative acceleration'.
 

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