The Extravagant Universe

One of the world's leading astronomers, Robert Kirshner, takes readers inside a lively research team on the quest that led them to an extraordinary cosmological discovery: the expansion of the universe is accelerating under the influence of a dark energy that makes space itself expand. In addition to sharing the story of this exciting discovery, Kirshner also brings the science up-to-date in a new epilogue. He explains how the idea of an accelerating universe--once a daring interpretation of sketchy data--is now the standard assumption in cosmology today.

This measurement of dark energy--a quality of space itself that causes cosmic acceleration--points to a gaping hole in our understanding of fundamental physics. In 1917, Einstein proposed the "cosmological constant" to explain a static universe. When observations proved that the universe was expanding, he cast this early form of dark energy aside. But recent observations described first-hand in this book show that the cosmological constant--or something just like it--dominates the universe's mass and energy budget and determines its fate and shape.

Warned by Einstein's blunder, and contradicted by the initial results of a competing research team, Kirshner and his colleagues were reluctant to accept their own result. But, convinced by evidence built on their hard-earned understanding of exploding stars, they announced their conclusion that the universe is accelerating in February 1998. Other lines of inquiry and parallel supernova research now support a new synthesis of a cosmos dominated by dark energy but also containing several forms of dark matter. We live in an extravagant universe with a surprising number of essential ingredients: the real universe we measure is not the simplest one we could imagine.

This book invites any reader to share in the excitement of a remarkable adventure of discovery.

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.

The first half of the book is essentially a crash course in the basics of cosmology, with many anecdotes and background from earlier research since Einstein or even before. Kirshner's witty style keeps this section entertaining even for those familiar with the information. He compares several distance indicators, such as Cepheid variables, redshifts, and supernovae. We learn how supernovae can be used to measure distances to remote galaxies due to their incredible brightness. We also become familiar with the pitfalls of using supernovae as standard candles, because there are a few different types.

Then the author gets into the real purpose of his book: to describe his research team's methods, results, and road to success with the press. The subtitle of the book is somewhat misleading; it should have been something like "The Story of the High-Z Supernova Search Team". Though the information wasn't presented in quite the way I was expecting, Kirshner gets the job done. He patiently educates the layman reader in many aspects of astronomy and cosmology. Towards the end it becomes a race between two supernova search teams using different methods. Though I found this yarn interesting, I would have preferred a general discourse to the narrative presented here.

Overall, this book is probably one of the most well-written and absorbing reads on this specific subject. Science and astronomy buffs should enjoy it greatly.