  Realists developed causal theories of reference to account for continuity of reference for terms like ‘atom’ or ‘electron’, even though the theories about atoms and electrons have undergone significant changes. The difference with the terms ‘ether’ and ‘caloric’ is that they are no longer used in modern science. However, as C.L. Hardin and Alexander Rosenberg (1982) argue, the causal theory of reference may be used to defend the claim that terms like ‘ether’ referred to whatever causes the phenomena responsible for the terms' introduction. This is criticized by Laudan (1984) as making the reference of theoretical terms a trivial matter, since as long as some phenomena prompt the introduction of a term it will automatically successfully refer to whatever is the relevant cause (or causes). Furthermore, this theory radically disconnects what a theorist is talking about from what she thinks she is talking about. For example, Aristotle or Newton could be said to be referring to geodesic motion in a curved spacetime when, respectively, they talked about the natural motion of material objects, and the fall of a body under the effect of the gravitational force.