Search for Gravitational Strength Forces Below 1 cm

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Experiments will be conducted to test Newtons law of gravitation atinter-mass separations of less than one centimeter. For separationsbetween one centimeter and one tenth of a millimeter, the experimentswill be sensitive enough to detect gravity and to test for deviationsfrom Newtons inverse-square law. For smaller separations theexperiments could detect proposed new short-range forces stronger thangravity but still many orders of magnitude weaker than other knownforces. The investigators will first complete on-going experiments withan existing room temperature apparatus, and then construct a newcryogenic instrument with greater sensitivity. A planar tungstentorsional oscillator is used as the sensitive force detector. There iscurrently intense interest among theoretical physicists in thepossibility that there may exist new feeble forces at length scalesbelow one centimeter. String theory, which seeks to encompass allknown physics including gravitation, generally predicts light fieldscalled 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 stringtheory.Theorists have also proposed that there may exist several new compactspatial dimensions beyond the usual three, and that gravity is weakbecause it is able to spread out in the extra dimensions. When thenumber of extra dimensions is two, this view leads to large deviationsfrom Newtons law of gravitation at about one millimeter. Experimentalevidence of the predicted deviations would be a dramatic step forwardfor our understanding of fundamental physics.