Schwarzschild Metric Question...again

[franznietzsche]

The Schwarzschild Metric is only valid for R>2M, What are the units used here? Obviously R and M should have incompatible units...so how can any comparison of this type be made?

[DW]

Originally posted by franznietzsche
The Schwarzschild Metric is only valid for R>2M,

We can only externally check its validity down to that limit, but that does not mean that it is only valid down to that limit.

What are the units used here? Obviously R and M should have incompatible units...so how can any comparison of this type be made?

In Plank units among other systems c = 1 and G = 1. So 2GM/c^2 = 2M. Specifically which system was used was up to whoever the author was.

[Stingray]

There are extensions of the Schwarzchild solution for R<2M in other coordinates. R=2M is only a coordinate singularity, not a physical one.