Given the dominance of dark energy and dark matter, and even the mystery of why so much ordinary matter has survived to today, physicists joke that we live in the dark ages. But these mysteries are precisely what make this an exciting time for anyone investigating the cosmos." (Chapter 1, p. 9)
-- narrator (1 - The Clandestine Dark Matter Society paragraph 4-5)

Importance: Lisa Randall strives throughout the book to connect even the most sophisticated scientific concepts to the general reader in a way that's easily understood. She also tries to present her findings in a way that indicates their relative importance. Here she indicates that the study of dark matter and energy is nothing less than the future of physics.

Errant comets or asteroids can both be a source of meteoroids. The trajectories of distant comets are difficult to predict, but sufficiently large asteroids can be detected well before they arrive. In October 2008 scientists announced they had found an asteroid that would...
-- Narrator (chapter 9 paragraph 1)