Robert Kirshner's book, `The Extravagant Universe: Exploding Stars, Dark Energy and the Accelerating Cosmos', is another in a series of interesting texts on cosmology written essentially for those who are science-illiterate, or at least only somewhat informed, and who wish to know some of the key insights and discoveries of our time regarding astronomy. Particularly at the end of this text, where Kirshner explains the importance of this kind of scientific research (why would the government or private agencies want to spend money on research that has little if anything to do with addressing the desires of humanity, encapsulated by Kirshner, as wanting to `rich, safe and immortal'?) for the average person - it is not just for intellectual fancy or whim, but the long-term implications of understanding the universe can affect our lives in ways we can't even contemplate today.
Kirshner's narrative looks at many of the key discoveries, controversies, and personalities of the field of astrophysics, theoretical physics and cosmology in the twentieth century. Kirshner lays the groundwork not with Einstein (as so many texts do) but rather goes behind Einstein to the earlier work of Gauss and Riemann, with mathematics that, at the time, would not have been considered useful in the ways Einstein's general relativity made it. Kirshner looks at observation (Hubble Telescope, observations of background radiation through various methods, etc.) as well as theoretical conjectures to show the strand of thinking from the early universal constructs to present day theories.
Kirshner traces the history of recent astronomy and cosmology through researchers in history such as Einstein and Hubble as well as persons he knows personally and professionally at work in the field today. Particularly in the last half-to-third of the book, where Kirshner brings in this personal level of acquaintance with the people involved, the science comes alive in a very human way. Kirshner is good at showing the limitations, as well - sometimes you just get lucky, or your gifts complement others. With regard to Hubble and Hale, for example, Kirshner recounts the evidence that they did not really understand Einstein's general relativity or the mathematics of his cosmological thinking; nonetheless, they continued their observational researches, and when Hubble discovered the expansion of the universe, Kirshner states that you don't have to know all of the mathematical and technical details involved in science, but rather `you just have to face in the right direction and go forward' with those things that you can do!
Some of the key concepts Kirshner develops include the life-cycle of stars, the overall shape and structure of the universe, the idea of dark matter/dark energy that has gone unknown for so long, and the ideas of reaching back to the origins of the universe and drawing conclusions for the acceleration of the universal expansion. Kirshner does not develop the areas of planetary science or solar-system type ideas in this text except very peripherally - this is a book for grand topics on a cosmic scale indeed.
The book is very readable and accessible to any with an advanced high-school or undergraduate beginning ability in science. How could it not be, given an author whose mis-spent youth watching `Rocky and Bullwinkle' cartoons is confessed in the endnotes? There are technical terms, and (gasp!) even a few equations thrown in here and there, but understanding the narrative is not dependent upon being able to process the equations. There are colour plates in the centre, with other black-and-white photographs and images throughout. In keeping with the non-technical nature of the text, endnotes are kept to a minimum, and recommended readings are few.
An interesting text, and a very good subject.
