Clif's Book World

This book reads much as if it was based on notes taken during an all night bull session with leading scientists. It's sort of a travelogue by a journalist reporting on his itinerant interviews with the leading minds in astrophysics and the earth sciences.  Along the way we learn about science and also a bit about the personalities of those doing the science. 

Beyond their personal stories and concerns about reduced funding for scientific research, the reader is exposed to “a portrait of our planet revealing how the earth came to life and how someday it will die. It is also a chronicle of an unfolding scientific revolution zooming in on the ardent search for other earths around other stars. Most of all however it is a meditation on humanity’s uncertain legacy.”

The "five billion" referred to by the title is the estimated length of time life can exist on earth (i.e. from first appearance of single cell life to final destruction by a dying sun).   We are currently at four and a half billion on that timeline, so we're closer to the end than the beginning. If we manage to survive the other threats to life on earth (e.g. asteroids and nuclear bombs), sometime in the next half billion years we'll need to decide whether to meekly accept our fate or search for other planets to colonize.

Topics covered in this book vary widely, some not related in obvious ways to astrophysics or life on earth. (Come to think of it, what's not related to life on earth?) 

The following is a rough log of some of the subjects addressed:

- The search for extraterrestrial intelligence (SETI).

- The probabilities of extra-terrestrial life (longevity of intelligent life is most important variable, and difficult to estimate, in determining likelihood of intelligent life existing concurrently within the same galaxy.)

- Recent success in finding planets around other stars (exoplanets).

- Using radial-velocity spectroscopy (measuring the wobble) or the transit of planets in front of their stars to calculate number size and orbit size of exoplanets.

- Description of fierce competition between astronomers to find planets (even claims of stealing information).

- Stories told about past efforts to observe the transit of Venus.

- Calculation of the monetary value of a world (the reality of limited resources makes this analysis necessary to help in making decisions regarding where to invest research money)

- Description of the geologic history of the earth

- Description the the history of life on earth

- Description of what we know about history of earth’s atmosphere, temperatures and probable cause of future global warming

- Description of geologic history of Marcellus shale formation in northeastern USA.

- Story of the history of science from ancient Greeks to modern days.

- Explanation of the carbon/silicate interaction in the Archean atmosphere to prevent runaway greenhouse effect like that on Venus. 

- History of rocket science and the demise of NASA's future space exploration plans.

- Possible strategies of using technology to reduce expensive rocket launch costs.

- Biographic sketch of Sara Seager, MIT Professor of Physics and Planetary Science.

Wikipedia article with latest exoplanet count:

Exoplanet http://en.wikipedia.org/wiki/Extrasol...
(1056 planets in 802 planetary systems including 175 multiple planetary systems as of 20 December 2013).

The question is raised near the end of the book, "Just how many transiting Jupiters do we need?" This raises the possibility that once we confirm the existence of thousands of planets the whole field of exoplanet research may experience a dot-com bubble sort of collapse as people lose interest. Another suggestion is that we need to encourage the Chinese to begin discovering earthlike exoplanets (and naming them Chinese names) so we'll be motivated to not be outdone by them.