THE EDGE OF KNOWLEDGE

The five greatest mysteries that science has yet to solve.

Theoretical physicist Krauss, the author of Quintessence, A Universe From Nothing, and other acclaimed books of popular science, is not the first to point out that civilizations throughout history have taken for granted that all important questions had been answered. It was only a few centuries ago that thinkers realized their ignorance and launched the scientific revolution, whose most important words were, “I don’t know.” Krauss delivers five long chapters, each addressing unanswered questions in the vast areas of time, space, matter, life, and consciousness. The first three embrace the author’s specialty, so readers might expect an easier ride; however, it’s still dense reading, even without equations. Time seemed simple until Einstein pointed out a few complications that created bizarre but proven phenomena. Time slows as gravity increases until it stops. Its flow depends not just on the motion of an object, but the environment in which it finds itself. Are there places where time itself doesn’t exist? We don’t know. Einstein proved that space and time are equivalent, but we can move back and forth in three dimensions of space and return from whence we came. The fourth dimension seems to force us, tick by tick, into the future. Is it possible to move about in time? Maybe, but probably not. Matter seems straightforward until Krauss reveals that almost all of it (“dark matter”) is invisible and does not consist of familiar atoms. Even stranger, almost all energy (“dark energy”) resides in empty space, corresponds to no matter at all, and is so far a complete mystery. Life seems to contain only two great unknowns—how it began and whether life exists beyond Earth—and consciousness remains a rat’s nest of theories. A steady guide who refuses to dumb it down, Krauss explains our ignorance as simply as he deems necessary, but no simpler.

Science buffs will relish these insights; others will require refresher courses in college physics and biology.