Testing the Equivalence Principle on Earth and in space

“Free“ test cylinders not possible…

Test cylinders cannot be free falling: must be suspended because of inevitable tidal effects if initial conditions differ by Dr (release error)

STEP & mSCOPE test cylinders centered actively (physical equilibrium centring not sufficient); GG test cylinders centered by physical equilibrium):

Blaser (CQG, 2001): “In the clever concept of GG, the CM of the two masses confined by super-critical rotation actually exactly follow the orbits of figure 1”