Resource Letter ETC-1: extraterrestrial civilization.

This Resource Letter provides a guide to the literature about intelligent life beyond the human sphere of exploration. It offers a starting point for professionals and academics interested in participating in the debate about the existence of other technological civilizations or in the search for extraterrestrial intelligence (SETI). It can also serve as a reference for teaching. This Letter is not intended as an exhaustive bibliography, but several extensive bibliographies have been cited. The letter E after an item indicates elementary, nontechnical material of general interest to persons becoming informed in the field. Intermediate level material, of a somewhat more specialized nature, is indicated by the Letter I. The annotation A indicates advanced, technical material. An asterisk (*) precedes items to be included in an accompanying Reprint Book.

Polarization nearness variation in an anisotropically absorbing medium.

Azzam and Bashara have shown that a general, anisotropically absorbing, and retarding medium can be represented by a generalized form of the Jones matrix, whose first eigenstate is the polarization ellipse least attenuated by the medium, and whose second eigenstate (or eigenpolarization) is the one most absorbed. It is often convenient to represent a polarized beam incident to and departing from a medium as being in a state which is a linear combination of the two eigenstates. Successive slabs of the same material bring this state into ever greater Nearness to the low absorption eigenpolarization. An expression is developed to determine Nearness as a function of the optical depths of the two eigenstates and the state of the incident light.