# Schwarzschild metric

1. Jan 28, 2015

### TimeRip496

How do you obtain this equation M=Gm/c^2. What does M stand for? Is is newton law at infinity? Again what is this newton law at infinity?

2. Jan 28, 2015

### Staff: Mentor

M is just the mass of the black hole using units in which G and c are both equal to one.

We don't have to make this substitution but if we don't we'll be schlepping factors of G and c around everywhere in our equations, and they're complicated enough already.

3. Jan 28, 2015

### TimeRip496

Do you mind telling me a source for such derivation? Cause all the Internet gives is just the derivation of the schwarzschild radius.

4. Jan 28, 2015

### Staff: Mentor

It's just a conversion factor from mass units to length units; $Gm / c^2$ converts the mass $m$ to an equivalent length. The Schwarzschild radius corresponding to $m$ is just twice that equivalent length.