Solution strategy for linearized gravity problem

[Paul Colby]

That is a good thing, because we are not interested in all null paths.

Isn't a photon trajectory a null path?

Yes, I agree these solve (*), but why is it important that you've found exactly one solution that don't interest us?

Because what I found isn't a geodesic but is a solution to (*). So (*) isn't a complete specification of the geodesic problem statement.

Can you propose some strategy that will work?

yes, solve the geodesic problem for the metric you've been given then transform the answer to the $M$ is in motion frame?

 

[Jonsson]

yes, solve the geodesic problem for the metric you've been given then transform the answer to the $M$ is in motion frame?

Thanks. I found the deflection angle is $\frac{4GM}{b}$. How do you say I transform this quantity back?