Recognizing they are entering a relatively unexplored area, they abandon old terms like "astrobiology" or "extraterrestrial life" to suggest a new, all encompassing term – xenobiology.  They condemn outright the narrow views expressed by some scientists, notably Peter Ward and Donald Brownlee in "Rare Earth."  Cohen and Stewart argue that limiting life to DNA-based forms is far too restrictive.  Different environments are capable of producing life in ways "we can’t even imagine."  Magnetic fields in suns or neutron stars, silicon-based chemistry, unusual energy uses are all part of the panorama nature has in its recipes in making life start.  Our localized experience is too limited, they argue, and we should look further with more open minds.

Those who have attempted a more open view have traditionally been limited to writers of speculative fiction.  Cohen and Stewart sprinkle the text with examples of this genre, accompanied by an analysis of what is right or wrong with the ET life presented.  "Science fiction" might just as easily be labelled "fictional science" in the eyes of these authors.  Too little attention has been given to environmental complexity by the legions of writers seeking to entertain readers with simple plots and much action.  Among that phalanx, however, there are some writers who strive to bring reality to the fictional worlds they create.  Jack Cohen has been called into the story-building process as a consultant by several authors.  The result, once the dust had settled, was SF with a reality check.  The authors give accounts of some of these efforts and the resulting books should be sought out and compared to those less favoured by the authors of this book.  

Jack&Ian [as they style themselves] have provided a rich trove of ideas for nearly everyone.  Scientists can gain fresh areas of research to consider, while fiction readers may find a whole new list of interesting readings.  The book isn’t footnoted, but there is a divided bibliography of "Popular Xenoscience Reading" and "Technical Xenoscience Reading" at the end.  If you fail to find new concepts to consider here, you haven’t tried.