seminario Prof. Fischbach - july 6

                       FRASCATI SEMINAR
         Thursday July 6 - at 15.00 - Auditorio Bruno Touschek

            E. FISCHBACH - Purdue University



         The ongoing attempts to unify the known fundamental forces have
      led to the suggestion that there may exist new gravity-like forces
      in nature. These would arise from the exchange of new light bosonic
      quanta among the constituents of ordinary matter and would produce
      apparent deviations from the predictions of Newtonian gravity. The
      suggestion of such a  "fifth force" in 1986  helped to stimulate a
      large number of new experiments to search for weak long-range forces.
      This talk will review both the theoretical motivation for such new
      forces and the experimental results that have been obtained to date.
         More recently newer string-inspired theories have suggested the
      presence of additional macroscopic forces acting over sub-millimeter
      distances. Detecting such forces presents special challenges - both
      theoretical and experimental - for reasons that I will discuss.


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