Uryson (The Lebedev Physics Institute of Russian Academy of Sciences) explores the possibility that ultra high energy cosmic rays are extragalactic in origin and their sources are astrophysical objects. The slim book presents a model of cosmic ray acceleration in low luminosity Seyfert nuclei and asserts that detected ultra high energy protons are either nuclei fragments or have been accelerated in blue lacerate objects. Annotation ©2010 Book News, Inc., Portland, OR (booknews.com)