Schwarzschild Metric Question again

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SUMMARY

The Schwarzschild Metric is valid for radial distances R greater than 2M, where R represents the radial coordinate and M denotes the mass of the gravitating body. The discussion clarifies that R and M can be expressed in compatible units, particularly when using Planck units, where both the gravitational constant G and the speed of light c are normalized to 1. It is emphasized that R=2M is a coordinate singularity rather than a physical one, and there are extensions of the Schwarzschild solution applicable for R less than 2M.

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

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