  Scalar fields have had a long and controversial life in gravity theories,
having progressed through many deaths and resurrections. The first scientific
gravity theory, Newton's, was that of a scalar potential field, so it was
natural for Einstein and others to consider the possibility of incorporating
gravity into special relativity as a scalar theory. This effort, though
fruitless in its original intent, nevertheless was useful in leading the way to
Einstein's general relativity, a purely two-tensor field theory. However, a
universally coupled scalar field again appeared, both in the context of Dirac's
large number hypothesis and in five dimensional unified field theories as
studied by Fierz, Jordan, and others. While later experimentation seems to
indicate that if such a scalar exists its influence on solar system size
interactions is negligible, other reincarnations have been proposed under the
guise of dilatons in string theory and inflatons in cosmology. This paper
presents a brief overview of this history.
