Is this equation I made correct?

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Discussion Overview

The discussion revolves around the validity of an equation proposed by a participant to describe gravitational length contractions using coordinates. The scope includes theoretical considerations in General Relativity and the implications of using a background coordinate system.

Discussion Character

  • Technical explanation, Debate/contested

Main Points Raised

  • One participant presents an equation for gravitational length contraction, attempting to express it in terms of coordinates.
  • Another participant identifies a "fatal flaw" in the proposed equation, suggesting that it assumes a background coordinate system.
  • A request for clarification is made regarding the use of a background coordinate system.
  • A further explanation is provided, stating that in General Relativity, coordinate systems are only valid locally due to the curvature of space-time, which complicates the mapping of a single coordinate system across the entire space-time.
  • It is noted that gravitational length contraction is an observer effect, implying that different observers may perceive different lengths, which challenges the use of a coordinate system to describe these effects.
  • A reference to Sten Odenwald's discussion is provided for further reading on the topic.

Areas of Agreement / Disagreement

Participants express disagreement regarding the validity of the proposed equation and the assumptions made about coordinate systems in General Relativity. The discussion remains unresolved as differing viewpoints are presented without consensus.

Contextual Notes

The discussion highlights limitations related to the assumptions of coordinate systems in General Relativity and the nature of gravitational length contraction as an observer-dependent phenomenon.

zeromodz
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I wanted to make an equation that shows gravitational length contractions by using coordinates instead of a final length.

L^2 = X^2 + Y^2 + Z^2
L = √(X^2 + Y^2 + Z^2)


L = Lo * √(1 - 2GM / RC^2) (Gravitational length contraction)
L = √(X^2 + Y^2 + Z^2) * √(1 - 2GM / RC^2)
L = √(X^2 + Y^2 + Z^2 - (2GMX^2)/XC^2 - (2GMY^2/YC^2) - (2GMZ^2/ZC^2))
L = √(X^2 + Y^2 + Z^2 - (2GMX/C^2) - (2GMY/C^2) - (2GMZ/C^2))


L = √(X^2 + Y^2 + Z^2 -2GM(X + Y + Z) / C^2) <--------Final equation.

What do you think?
 
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The fatal flaw is you have assumed a background coordinate system.
 
Chronos said:
The fatal flaw is you have assumed a background coordinate system.

Could you please elaborate? Why can't I use a background coordinate system?
 
zeromodz said:
Could you please elaborate? Why can't I use a background coordinate system?
In General Relativity, coordinate systems are only valid locally. Curvature makes it so that you simply can't map any single coordinate system onto a whole space-time without running into problems.

To see why curvature does this, you can take the Earth as an example. If you start doing your calculations using the normal longitude/latitude coordinates we use on the surface of the Earth, you'll find that your calculations go haywire at the poles (because at the poles, every longitude maps onto just one point).

So we simply cannot take coordinates as being fundamental. Rather, coordinates are simply numbers we write down to describe some local region of space-time.

Finally, there's the issue that gravitational length contraction is an observer effect. Different observers will, in principle, see very different lengths. But a coordinate system isn't necessarily describing what anyone observer sees.
 

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