Testing Weak-Field Gravity

One of the most important problems in science today is the origin of \dark matter". Much of our understanding of the history and present state of the universe depends upon conjectures about the nature of dark matter. In some sense, our knowledge rests upon a \house of cards" which won't be buttressed until progress is made in identifying what dark matter represents. Most research today is founded upon the belief that dark matter really is matter of some sort. A small minority of astronomers contends that the origin of dark matter lies at least in part in a breakdown of the law of weakeld gravity on scales larger than the solar system. Indeed, the ubiquity of at rotation curves, namely a "disk-halo conspiracy", lends credence to the idea that some weakness in fundamental physics is at the root of dark matter. Perhaps further support for this view comes from the observation that mass-to-light ratios increase with the scale over which they are measured, all the way from star clusters to galactic disks to spheroids to individual galaxies to binary galaxies to galaxy groups to galaxy clusters. On the other hand, gravitational images of background dwarf galaxies generated by galaxy clusters suggest that most of the matter in clusters is not in the form of galaxies, but instead is widely distributed. Indeed, observations at X-ray wavelengths of the intracluster medium suggest that there is an underlying dark medium setting the form of the potential. Given what is at stake, the author feels that it is imperative that more research be directed at evaluating the viability of the law of gravity over large scales. One way may be to to focus upon dwarf spheroidal galaxies. Such galaxies are found in the immediate environment of spirals and ellipticals,