A Possible Limit to Gravitation

On Possible Modifications of Gravitation in the (sub)millimeter Range

I discuss possible modifications of gravitation at short distances in string theories with large internal dimensions and low string scale. The modifications are due to the change of Newton’s law in the presence of (sub)millimeter-size transverse dimensions, or due to the existence of light scalars with masses as small as 10 eV, related to the mechanism of supersymmetry breaking, mediating new Y...

Lower limit to the scale of an effective quantum theory of gravitation.

An effective quantum theory of gravitation in which gravity weakens at energies higher than approximately 10(-3) eV is one way to accommodate the apparent smallness of the cosmological constant. Such a theory predicts departures from the Newtonian inverse-square force law on distances below approximately 0.05 mm. However, it is shown that this modification also leads to changes in the long-rang...

Lower Limit to The Scale of an Effective Theory of Gravitation

Is it possible to train patients to limit weight bearing on a lower extremity?

Orthopedic patients are often instructed on how much weight to bear on an injured or postoperative extremity. Although specific weight-bearing instructions are given to a majority of lower-extremity orthopedic patients, the ability of patients to comply with these instructions is questioned in the medical literature. This study compared the effectiveness of new forms of clinical interventions d...

Action-at-a-Distance and Local Action in Gravitation: Discussion and Possible Solution of the Dilemma

The problem of the character of gravitation is approached by discussing three main possible modes of action from the historical, theoretical and empirical standpoints. The “Newtonian” mode of action-at-a-distance (AAAD)—in which Newton himself did not believe—is followed through three centuries, though the aim is not historical accuracy. This approach includes several Webertype theories of velo...