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Aug7-10, 03:36 PM
P: 665
Quote Quote by Petr Mugver View Post

[tex](d\tau)^2=dx^\mu dx_\mu[/tex]

is the proper time of the particle, that you can write

Just a minor error: Following the Riemannian line-element for a general spacetime, this must have been

[tex](cd\tau)^2=dx^\mu dx_\mu[/tex]

because the LHS is just the square of the differential of proper length, [tex]ds^2.[/tex]