How can you create a geodesic path using the metric and initial velocity?

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Discussion Overview

The discussion revolves around the creation of a geodesic path using a specified metric and initial velocity for an object approaching Earth. It touches on theoretical aspects of general relativity, particularly in the context of Minkowski space and the absence of gravitational forces.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant presents a scenario involving a small object approaching Earth, providing its initial position and velocity, along with the relevant metric and curvature tensors.
  • The participant queries how to derive a geodesic path from the given metric and initial velocity, suggesting the use of incremental steps.
  • Another participant shares a link to a resource on solving geodesic equations, indicating a potential method for further exploration.
  • A participant expresses concern about the clarity of their initial post, acknowledging the lack of external gravitational forces in Minkowski space.
  • One participant mentions a numerical solution they developed for the Schwarzschild metric, indicating a willingness to share results once their technical issues are resolved.

Areas of Agreement / Disagreement

There is no consensus on how to create the geodesic path, and multiple approaches and perspectives are presented without resolution.

Contextual Notes

The discussion includes unresolved technical details regarding the application of metrics and the implications of curvature tensors, as well as the potential for numerical solutions that have not been fully explored or validated.

Jack3145
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Let's say there is a small object heading towards Earth (it will burn up). It is first observed at:
[tex]x^{\\mu}=[x^{1},x^{2},x^{2},x^{4}]=[x_{0},y_{0},z_{0},t_{0}][/tex]
with a velocity:
[tex]V_{v}=[v_{1},v_{2},v_{3},v_{4}][/tex]

The metric is:
[tex]ds^{2} = dx^{2} + dy^{2} + dz^{2} -c^{2}*dt^{2}[/tex]
[tex]g_{\\mu\\v} = \\left(\\begin{array}{cccc}<BR>1 & 0 & 0 & 0\\\\<BR>0 & 1 & 0 & 0\\\\<Br>0 & 0 & 1 & 0\\\\<BR>\\\\<BR>0 & 0 & 0 & 1<BR>\\end{array})\\right[/tex]

Affinity is:
[tex]\\Gamma^{\\rho}{\\mu\\v} = 0[/tex]

Riemann Curvature tensor is:
[tex]R^{\\rho}{\\mu\\v\\sigma} = 0[/tex]

Ricci Tensor is:
[tex]R{\\mu\\sigma} = 0[/tex]

My Question is how do you make a geodesic path from the metric and initial velocity?

[tex]V_{v} = x^{\\mu}*g_{\\mu\\v}[/tex] and make incremental steps?
 
Last edited:
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Sorry for the abomination. I know that Minkowski Space has no external gravitational forces acting on it.
 
You can still edit post #1. Looks like you need to remove a lot of \ symbols.
 
You indicated an interest in a numerical solution. I did a Scilab solution for the Schwarzschild metric. Unfortunately I compressed the file using bz2 on Linux and my present (vista) decoder has a problem. If you are interested I will have my Linux machine back up in two weeks or perhaps somebody else will separate out the parts; the mash-up is probably my fault.
I never checked the compression or enhanced the program since nobody ever responded to my scilab post.
Some orbits are shown in the eps file at:
http://www.plaidheron.com/ray/temp/
drdth_f-example.eps
Ray
 
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