BOOK REVIEW
Billions and Billions: Excerpts from Majestic Universe and Unfolding Our Universe
The Helix Nebula, in the constellation Aquarius, is the closest planetary nebula to us, at a distance of 450 light-years. Its central star, a very hot white dwarf, ionizes an inner shell of oxygen which appears green, and an outer, pinkish shell of hydrogen.
Majestic Universe: Views from Here to Infinity
Serge Brunier
Cambridge, $39.95
A useful analogy is to imagine space-time to be represented by an elastic sheet. In the absence of matter, space-time is like a flat sheet; a lightweight ball set rolling across such a sheet would move in a straight line. If a weight were placed on the sheet, it would cause an indentation that would deflect the ball from its straight-line path; a heavier weight (representing a greater mass) would cause a larger and deep indentation, causing greater deflection of the ball. Given the right velocity, a ball could remain "in orbit" within the indentation; similarly, a planet remains in its orbit within the curved space-time surrounding the sun.
Unfolding Our Universe
Iain Nicolson
Cambridge, $39.95
About once a month at Sigma Xi headquarters, we liven up the lunch hour with an American Scientist Pizza Lunch talk. In these informal lectures, scientists describe new research to nonscientists. The series is light on jargon but heavy on solid science. Each Pizza Lunch offers an in-depth look at its subject, whether it's bedbugs or the smart grid. Click below to read about and download these talks -- and to subscribe!
