Black hole mass as function proper time

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Hi there.

1. The problem statement
I am asked to write the equations which give us the mass of a black hole as function the proper time.

Homework Equations



The Schwarzschild metrics is given by
$$ ds^2=-(1- \frac{2GM}{r})dt^2+(1-\frac{2GM}{r})^{-1}dr^2+ r^2(d\theta^2+ \sin^2(\theta) d\phi^2) $$


The Attempt at a Solution


The proper time [itex]\tau[/itex] is related to the metrics by the eq.[itex]ds^2=-d\tau ^2[/itex] hence I need to calculate the following expression [itex]\Delta\tau= - \int \sqrt{ds^2}[/itex] in order to get the proper time, and finally i have to solve for M, (the mass)

Am I right? , any idea?

Thanks
 
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.Yes, your approach is correct. Solving for M in the Schwarzschild metrics equation will give you the mass of a black hole as a function of proper time.