The Role of Gravity in Determining Physics at High as Well as Low Energies

It is noted that in the context of a supersymmetric preonic approach to unification, gravity, though weak, can play an essential role in determining some crucial aspects of low-energy physics. These include: (i) SUSY-breaking, (ii) electroweak symmetry-breaking, and (iii) generation of masses of quarks and leptons, all of which would vanish if we turn off gravity. Such a role of gravity has its roots in the Witten index theorem which would forbid SUSY-breaking, within the class of theories under consideration, in the absence of gravity.