GR explanation of Newtonian Phenomena

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Discussion Overview

The discussion revolves around the explanation of gravitational phenomena from a general relativity perspective, particularly focusing on the nature of falling objects and the interpretation of acceleration in relation to gravity. The scope includes theoretical considerations and conceptual clarifications regarding general relativity and Newtonian mechanics.

Discussion Character

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

Main Points Raised

  • Some participants inquire how a general relativist would explain why an object falls towards the Earth.
  • One participant suggests that the apple follows a geodesic path through space-time, referencing the principle of extremal aging.
  • Another participant argues that the question of whether the apple falls or the Earth accelerates towards the apple is irrelevant in general relativity, as either viewpoint can be used.
  • A different viewpoint emphasizes that science describes rather than explains, suggesting that the interpretation of acceleration is coordinate dependent.
  • One participant notes that once a coordinate system is chosen, it can be stated whose coordinates represent an accelerating object, specifically mentioning 3-acceleration and the zero 4-acceleration of both the Earth and the apple.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of gravitational phenomena and the nature of scientific explanation. There is no consensus on the best way to frame the discussion, and multiple competing perspectives remain.

Contextual Notes

The discussion includes unresolved questions about the implications of coordinate systems in general relativity and the nature of scientific explanation versus description.

aachenmann
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1. How would a general relativist explain why an object falls towards the earth?

2. Is it correct to say that it is not the apple that falls towards the Earth but it is the Earth that accelerates towards the apple? Why is this ok to say?
 
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The apple follows a geodesic path through space-time. One way o describing the mathematical characteristics of this path is to say that it satisfies the principle of extremal aging.

see for instance http://www.bun.kyoto-u.ac.jp/~suchii/extrem.aging.html
http://www.eftaylor.com/pub/chapter2.pdf

and look for past PF posts with this keyword.

2) The question is really irrelevant in GR - it doesn't matter which viewpoint you use.
 
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aachenmann said:
1. How would a general relativist explain why an object falls towards the earth?
Science does not explain, it describes. To say that it explains leads one into a logical circle.
2. Is it correct to say that it is not the apple that falls towards the Earth but it is the Earth that accelerates towards the apple? Why is this ok to say?
What accelerates is actually doing the acceleration is a coordinate dependent statement. Once you choose a coordinate system you can state whose coordinates in that system represents an accelerating object. Here I speak of 3-acceleration since the 4-acceleration of each object, i.e. Earth and apple, is zero.

Pete
 
Since the OP is no longer with us, there seems no point in keeping this thread open.
 

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