Find Null Geodesics with affine parameter

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The discussion revolves around finding null geodesics using an affine parameter with a specific metric. The user is attempting to solve a homework problem but encounters a discrepancy in the sign of the solution for t. There are issues with broken image links, hindering others from providing assistance. The user is encouraged to re-upload the images for better clarity and support. The focus remains on deriving the correct expressions for null geodesics from the given initial conditions.
myra2016
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Homework Statement


The metric is given by
https://dl.dropboxusercontent.com/u/86990331/metric12334.jpg
H is constant; s is an affine parameter, and so r(0)=t(0)=0.

Apologise in advance because I'm not very good with LaTex. So I used Word for equations, and upload handwritten attempt at solution :smile:

Homework Equations


Need to show that the null geodesics from r=0, t=0 are given by
https://dl.dropboxusercontent.com/u/86990331/metricquestion.jpg

The Attempt at a Solution


I get the required t but the sign is different.
https://dl.dropboxusercontent.com/u/86990331/metricattemptatsolution.jpg
 
Last edited by a moderator:
Hello, please attempt to re-upload the images, currently the links appear to be broken and may very well be the reason no one can help.
 

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