- #1

- 4,809

- 31

## Homework Statement

An observer atop a tower of 10m on Earth sends a signal towards the base of the tower every second according to his clock. The gravitational field corresponds to the metric.

[tex]d\tau^2=(1+zg)dt^2+\frac{1}{1+zg}(dx^2+dy^2+dz^2)[/tex]

(where g~10m/s²)

An observer on the ground receives the signals on what interval?

## Homework Equations

## The Attempt at a Solution

Since the signals are sent at the same place (x=0,y=0,z=10), the metric atop the tower for these events is

[tex]d\tau^2=(1+10g)dt^2[/tex]

But what is dt, what is dtau exactly? How do they relate to the 1 second interval? Is dtau supposed to be the same for both observer or something?