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Fifth Force

PTB-Kolloquium

I review certain theoretical frameworks that predict existence of gravity-competing forces at macroscopic distances, which can be experimentally tested.

Such are the frameworks with large extra dimensions as well as the frameworks that give rise to time-dependent constant of nature, such as, for example a time-dependent fine structure constant. Such theories are severely restricted by the experimental observations.

We discuss some experimental prospects that involve both earth-based as well as extra terrestrial measurements.