If gravity is not a force, what is holding us down?

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Discussion Overview

The discussion revolves around the nature of gravity, specifically whether it is a force or a result of the curvature of spacetime. Participants explore theoretical implications, conceptual understandings, and analogies related to gravity's effects on objects and their motion, with a focus on general relativity and its interpretations.

Discussion Character

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

Main Points Raised

  • Some participants propose that gravity is not a force but rather a contraction or curvature of space.
  • Others argue that gravity is a curvature of spacetime, emphasizing that objects travel along geodesics rather than in straight lines unless acted upon by a force.
  • A participant describes the analogy of two people walking north on a curved Earth, suggesting that their paths converge due to curvature, similar to how gravity affects objects.
  • Another viewpoint suggests that the ground pushes us upwards rather than gravity holding us down, with the surface of the Earth continually accelerating upwards.
  • Some participants express difficulty in understanding the concept of geodesics and how they relate to the sensation of falling and stopping upon hitting the ground.
  • There is a mention of the distinction between gravitational forces and electromagnetic forces, with some arguing that the discussion about gravity being a force is largely semantic.
  • One participant introduces a more complex view, suggesting that gravity could be interpreted through gauge theory, relating it to the geometry of spacetime.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of gravity, with no consensus reached on whether it should be classified as a force or a geometric effect of spacetime curvature.

Contextual Notes

Some participants highlight the complexity of understanding curved spacetime and its implications for gravitational effects, noting that the equivalence between inertial forces and gravitational effects is context-dependent and may not be universally applicable.

  • #61
paradisePhysicist said:
On a more serious note though, I think the movie will be easier to visualize since its already visual. On the other hand, the book may be so well written that it is easy to visualize also.
Understanding is the goal. A visual understanding is not.
 
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  • #62
As someone not familiar with the math's I find Vsauce's youtube video below very informational for those trying to get a grasp on why no forces are involved. I would recommend you watch it all though for a quick snippet check out timeframe 16:15 - 17:25, this demonstrates how straight paths come together on a curved surface. Possibly continue watch through to 20:40.

 

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