Can MOND type hypotheses be tested in a free fall laboratory environment
The extremely small accelerations of objects required for the the onset of modified Newtonian dynamics, or MOND, makes testing the hypothesis in conventional terrestrial laboratories virtually impossible. This is due to the large background acceleration of Earth, which is transmitted to the acceleration of test objects within an apparatus. We show however, that it may be possible to test MOND-type hypotheses with experiments using a conventional apparatus capable of tracking very small accelerations of its components, but performed in locally inertial frames such as artificial satellites and other freely falling laboratories. For example, experiments involving an optical interferometer or a torsion balance in these laboratories would show nonlinear dynamics, and displacement amplitudes larger than expected. These experiments may also be able to test potential violations of the strong equivalence principle by MOND and to distinguish between its two possible interpretations (modified inertia and modified gravity). The asymptotic flatness of galaxy rotation curves in spiral galaxies and the related apparent mass discrepancy according to Newtonian dynamics led to the proposal of dark matter [1]. Dark matter has also been inferred from observations of apparent magnitudes of Type Ia supernovae at large redshifts within the standard FreedmanRobertson-Walker cosmological paradigm and could account for as much as about 28% of the mass-energy density of the observable Universe [2]. Although several dark matter candidates have been proposed, including weakly interacting massive particles, axions etc., none has been directly observed so far. Another proposal known as modified Newtonian dynamics (MOND) postulates the modification of the law of gravity to a µ(a/a0) = GM r 2 , (1)