On weaker forces than gravity

The limits on hypothetical new interactions with a range accessible to detection by laboratory and geophysical experiments are briefly reviewed, and the limits at larger distances imposed by a rich body of astronomical observations are elaborated on. The systematic deviations correlated with baryon number that have recently been unearthed from the data of Eoetvoes' classical experiment, can bravely but consistently be interpreted as a new force whose range is narrowly bracketed somewhere in between Mercury's distance to the Sun and our distance to the moon. This hypothetical long-range interaction would be five and a half orders of magnitude weaker than gravity. The new force would make like bodies attract, and would therefore not constitute an elegant explanation of why protons have not been seen to decay. (orig.)