Search for Gravitational Strength Forces Below 1 cm

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Experiments will be conducted to test Newtons law of gravitation at inter-mass separations of less than one centimeter. For separations between one centimeter and one tenth of a millimeter, the experiments will be sensitive enough to detect gravity and to test for deviations from Newtons inverse-square law. For smaller separations the experiments could detect proposed new short-range forces stronger than gravity but still many orders of magnitude weaker than other known forces. The investigators will first complete on-going experiments with an existing room temperature apparatus, and then construct a new cryogenic instrument with greater sensitivity. A planar tungsten torsional oscillator is used as the sensitive force detector. There is currently intense interest among theoretical physicists in the possibility that there may exist new feeble forces at length scales below one centimeter. String theory, which seeks to encompass all known physics including gravitation, generally predicts light fields called moduli. When these acquire mass through certain mechanisms, they may mediate forces with a range of about one millimeter. Detecting such forces would provide dramatic evidence for string theory. Theorists have also proposed that there may exist several new compact spatial dimensions beyond the usual three, and that gravity is weak because it is able to spread out in the extra dimensions. When the number of extra dimensions is two, this view leads to large deviations from Newtons law of gravitation at about one millimeter. Experimental evidence of the predicted deviations would be a dramatic step forward for our understanding of fundamental physics.