Einstein (III)

“ Strong (Einstein) Equivalence Principle” (assumes WEP): all gravitational effects are (globally) replaced by the metric of a curved, 4-dimension space-time… General Relativity is based on WEP

WEP Þ UFF: should bodies of different composition fall with different accelerations, the elevator and the test mass inside it would generally fall with different accelerations and the observer would be able to tell that he is close to the surface of the Earth and not in an accelerated frame in empty space. In this sense the Equivalence Principle expresses the very essence of General Relativity and as such it deserves to be tested as accurately as possible.