Significance Of Composition-Dependent Effects In Fifth-Force Searches

Indications of a possible composition-dependent fifth force, based on a reanalysis of the Eotvos experiment, have not been supported by a number of modern experiments. Here, we argue that searching for a composition-dependent fifth force necessarily requires data from experiments in which the acceleration differences of three or more independent pairs of test samples of varying composition are determined. We suggest that a new round of fifth-force experiments is called for, in each of which three or more different pairs of samples are compared. (C) 2021 Elsevier B.V. All rights reserved.