What Is Relativity?

It is commonly assumed that if the Sun suddenly turned into a black hole, it would suck Earth and the rest of the planets into oblivion. Yet, as prominent author and astrophysicist Jeffrey Bennett points out, black holes don't suck. With that simple idea in mind, Bennett begins an entertaining introduction to Einstein's theories of relativity, describing the amazing phenomena readers would actually experience if they took a trip to a black hole.

The theory of relativity reveals the speed of light as the cosmic speed limit, the mind-bending ideas of time dilation and curvature of spacetime, and what may be the most famous equation in history: E = mc2. Indeed, the theory of relativity shapes much of our modern understanding of the universe. It is not "just a theory"—every major prediction of relativity has been tested to exquisite precision, and its practical applications include the Global Positioning System (GPS). Amply illustrated and written in clear, accessible prose, Bennett's book proves anyone can grasp the basics of Einstein's ideas. His intuitive, nonmathematical approach gives a wide audience its first real taste of how relativity works and why it is so important to science and the way we view ourselves as human beings.

Jeffrey Bennett, winner of the 2013 American Institute of Physics Science Communication Award, holds a BA in biophysics from the University of California, San Diego, and an MS and PhD in astrophysics from the University of Colorado, Boulder. He is the lead author of several best-selling textbooks in astronomy, astrobiology, mathematics, and statistics and has written numerous award-winning books for the general public and children.

Bennett... has written an entertaining, brilliant introduction to Einstein's ideas... that is impressively understandable.

... [P]erhaps the best homage that anyone can pay to [Einstein] for such a groundbreaking contribution to physics in particular and science in general.

A sober, comprehensible account of what every intelligent layman should know about space and time.

For in its relatively few pages, Bennett explains relativity to ordinary readers... An impressively accessible distillation of epoch-making science.

...Bennett's fun book shows readers what relativity means, and what it reveals about our universe.

Seth Shostak, Senior Astronomer, SETI Institute:
I have read lots of introductions to relativity, but none is as clear and compelling as this one. For anyone who is keen to grasp the fundamentally simple yet non-intuitive ideas of both special and general relativity, Jeffrey Bennett's book is the way to go. Impressively understandable and interesting.

David J. Helfand, President, American Astronomical Society, and President and Vice Chancellor, Quest University Canada:
Since it first appeared more than a decade ago, I have used Cosmic Perspectives by Jeffrey Bennett and his colleagues in no small part because of the excellence of its chapters on relativity. It is wonderful to now have a stand-alone volume in which his lucid, explanatory text and figures are coupled with a thoughtful commentary on why relativity is important in constructing our scientific and personal views of space and time.

Alberto Nicolis, Columbia University:
What Is Relativity? is a well-written and uniquely readable book that beautifully serves as an introduction to special and general relativity. Jeffrey Bennett carefully avoids bombastic statements and 'spectacularization' of the subject, sticking with well-established facts and presenting them in a clear and compelling manner.