- #1
binbagsss
- 1,254
- 11
Homework Statement
Question attached
My method was going to be:
set ##r=R## and solve for ##n(R)##
set ##r=2GM## and solve for ##n(2GM)##
I was then going to integrate proper time ##s## over these values of ##r##:
##\int\limits^{n=cos^{-1}(\frac{4GM}{R}-1)}_{n=cos^{-1}(1)=0} s(n) dn ###
whereas the solution, all you have to do is plug in these values ##n(r)## and ##n(2GM)## into ##s=s(n)##, equation (2).
Is it wrong to integrate or would I get the same answer?
Is the reason that you can plug in and don't need to integrate due to the fact that the lagrangian, is invariant under reparameterisation, or does it have nothing to do with this??:
i.e:
##s=\sqrt{L}=\sqrt{g_{uv}\frac{dx^u}{dn}\frac{dx^v}{dn}} dn##, ##n## the parameter
Homework Equations
see above
The Attempt at a Solution
see above[/B]