Letter From Discover

The (long and winding) road to reality

Sunday, June 05, 2005

Is physics stuck in a rut? The question might surprise longtime Discover readers, who regularly hear about breakneck advances in fields ranging from engineered materials to atomic teleportation. But spend some time with the esteemed British physicist and mathematician Sir Roger Penrose and you may begin to wonder. In his new book, The Road to Reality, he focuses on the very biggest questions in physics—and there the pace of progress can look agonizingly slow.

Penrose notes that some of the most basic questions about space and time raised by Euclid, Plato, and Aristotle remain unanswered. Three centuries after Isaac Newton, we don’t really know what gravity is. A radical model called string theory is supposed to add clarity by linking gravity and the rest of physics in one tidy set of equations, but that effort is proceeding at a glacial pace. The last demonstrably successful step toward unification was the discovery of the electroweak interaction in the 1960s. Current ideas in string theory seem so abstract that Penrose worries they may be mainly of mathematical interest.

Even one of the most successful theories of the last century is maddeningly incomplete. Back in the 1920s, quantum mechanics provided the first detailed description of the subatomic world. What quantum physics doesn’t answer is perhaps the biggest question of all: Why does reality look the way it does? Instead, the theory has raised a bunch of new questions, showing that subatomic particles can suddenly materialize in places where, according to common sense, they should not be. If anything, the rules of reality look stranger now than they did in the time of Aristotle.

Penrose has spent his career bucking the status quo in science, searching for new approaches to the big questions. He calls his latest book The Road to Reality because he genuinely believes that physics will provide the answers we are looking for—it just needs some fresh ideas to get moving again. He makes his case with such passion that this 1,000-page volume, loaded with equations, is shooting up the best-seller lists. This is a serious science book that is actually meant to be read, not just admired on a shelf.

At age 73, Penrose is full of boundless enthusiasm and would like nothing better than to help spark the next physics revolution. For starters, he thinks he has figured out why the effects of quantum weirdness aren’t evident in our everyday world. In the pages that follow, we examine his novel theory and the grand experiment he has proposed to put it to the test.

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