Deciphering the Christoffel Symbol and Potential in Shutz's Relativity Book"

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Discussion Overview

The discussion revolves around the Christoffel symbol for the potential \(\phi\) as presented in Schutz's relativity book, particularly focusing on the expression \(\Gamma^0_{00}= \frac{\phi,_0}{1+2\phi}\) and its approximation as \(\Gamma^0_{00}= \phi,_0 + 0( \phi^2)\). Participants are exploring the mathematical reasoning behind this approximation, including Taylor expansion and the implications of the condition \(|\phi| << 1\).

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant expresses confusion regarding the quadratic term \(0( \phi^2)\) in the approximation of the Christoffel symbol and mentions attempts to use Taylor expansion without success.
  • Another participant asks for clarification on the specific edition of Schutz's book and the page number where the equation is found, indicating a need for context in the discussion.
  • A later reply provides a mathematical manipulation of the expression, suggesting that the second-order terms are negligible under the condition \(|\phi| << 1\) and that \(\phi\) varies smoothly.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the interpretation of the quadratic term in the context of the Christoffel symbol. The discussion remains unresolved regarding the clarity of the approximation and the application of Taylor expansion.

Contextual Notes

There are limitations in the discussion related to the assumptions made about the smoothness of \(\phi\) and the treatment of higher-order terms in the Taylor expansion, which are not fully explored or resolved.

alejandrito29
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Hello,

i have learning the boock of Shutz , and i not understand why the Christoffel symbol for the potential
[tex]\phi[/tex] with [tex]|\phi |<<1[/tex] .

[tex]\Gamma^0_{00}= \frac{\phi,_0}{1+2\phi}[/tex] is written as

[tex]\Gamma^0_{00}= \phi,_0 + 0( \phi^2)[/tex]

I don't see the quadratic term [tex]0( \phi^2)[/tex] . I tried with Taylor, but i don't understand
 
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alejandrito29 said:
Hello,

i have learning the boock of Shutz , and i not understand why the Christoffel symbol for the potential
[tex]\phi[/tex] with [tex]|\phi |<<1[/tex] .

[tex]\Gamma^0_{00}= \frac{\phi,_0}{1+2\phi}[/tex] is written as

[tex]\Gamma^0_{00}= \phi,_0 + 0( \phi^2)[/tex]

I don't see the quadratic term [tex]0( \phi^2)[/tex] . I tried with Taylor, but i don't understand

Which edition of Schutz do you have, the first or second? What page is it on?
 
Popper said:
Which edition of Schutz do you have, the first or second? What page is it on?

pg 186, equation 7.13

i know the firtz edition
 
##\frac{\partial _{t}\phi}{1 + 2\phi}\simeq \partial _{t}\phi(1 - 2\phi) = \partial _{t}\phi - \partial _{t}(\phi^{2})##. ##|\phi| << 1## and ##\phi## varies smoothly so the derivatives of the second order terms should also be negligible.
 

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