What does the following statement mean and why is it true?
The Weak Equivalence Principle (WEP) implies that in general curved space-time there is no privileged coordinate system.
I have looked up the WEP -- as far as I can see, it is more or less the Universality of free fall (?) My (probably totally missing the point) interpretation of the statement is that in general curved space-time, you can't do away with the Gravitational Field everywhere simultaneously... But like I said, I am probably barking up the wrong tree here. Grateful if someone could explain!
Context: This was to justify the use of tensor calculus in GR.