What do Einstein's theory of relativity, string theory, and lots of other mind-bending—and space-bending—revelations of modern physics have in common? None of them could have been discovered until scientists and mathematicians recognized an uncomfortable truth—that there was a reason the world's greatest mathematical minds had failed to prove Euclid's fifth postulate after more than two thousand years of effort: the postulate, which defines the nature of parallel lines and space, was untrue.
In The Fifth Postulate, acclaimed science writer Jason Socrates Bardi tells the perplexing tale of what happened when, in the early 1800s, three great mathematicians, working independently, came to the same profound conclusion. Not only was the postulate unprovable, but discarding it opened an entire new universe of non-Euclidian geometry, in which the recognition that space is curved solved scores of previously insolvable problems and laid the groundwork for a host of new discoveries to come. Which of these brilliant thinkers would claim credit for this momentous discovery? None of them.

Why would the reigning genius of his day hide his manuscripts and barely mention their conclusions and back away in horror from what was arguably the greatest logical insight in the history of science? Why would the respected head of a European university face confusion and ridicule when trying to publish the same discovery? And why would a promising young army engineer find the secret and then retire, trying not to think about it anymore?

This bizarre true story of reluctant discovery recounts the little-known tale of the strangely parallel, triumphant, and tragic lives of János Bolyai, Carl Friedrich Gauss, and Nikolai Lobachevsky. It examines a world of science in which the objective quest for new truth is inhibited by blind adherence to an old, unproven postulate—mainly because of fear that, if it were untrue, everything that was known about geometry, nature, and the universe itself would have to change.

Even more surprising is the story of an eighteenth-century priest who, in an attempt to illustrate the absurdity of a world without the fifth postulate, stumbled upon and described non-Euclidian geometry without ever having understood the importance of what he had found. You'll also meet the mathematician who spent much of his life searching for a proof to the postulate, only to discover that his close friend Gauss had discarded it years before but had never told him.

Packed with fascinating anecdotes and insights, as well as crystal-clear explanations of complex mathematical concepts, The Fifth Postulate is compelling reading for anyone interested in the history of science and mathematics and the politics of discovery. It is also a chilling cautionary tale about the fragility of truth whose lessons are as pertinent today as they were two centuries ago.

**About the Author**

**Jason Socrates Bardi**, author of *The Calculus Wars*, holds master's degrees in both science writing and molecular biophysics from Johns Hopkins University.