Invisibility? Time travel? "Physics of the Impossible" says it may not be far-fetched

"Physics of the Impossible"

by Michio Kaku

Doubleday, 327 pp., $26.95

In "Through the Looking Glass," the White Queen scolded Alice for mental laziness and boasted of believing "six impossible things before breakfast." In his dizzying new survey of science's furthest frontiers, "Physics of the Impossible," Michio Kaku asks readers not to completely discount them.

Kaku deals with such far-fetched ideas as invisibility and teleportation in a completely scientific manner. He divides impossibility into three classes: Class 1 for concepts our present technology can't make manifest, but which don't actually violate any known physical laws; Class 2 for concepts beyond our technology that also challenge our interpretation of those laws; Class 3 for concepts that outright defy known physical laws and would demand huge changes in our understanding of how the universe works.

Surprisingly, the third section is the shortest. Only two of Kaku's topics are impossible in this sense. Perpetual-motion machines and precognition, the staple of storefront psychics, come much closer to true impossibility than constructs familiar to us through cinematic special-effects, namely Class 2's time travel, faster-than-light spaceships, and parallel universes.

The bulk of this book is taken up by enticingly possible impossibilities such as force fields, machine- and extraterrestrial intelligence, and telepathy. A physics professor at City University of New York, Kaku is also a respected popularizer of scientific theory, and he does a great job here of making concrete the heady abstractions necessary to our grasp of the physics behind these ideas. Writing about "antiuniverses," for instance, Kaku describes "charge-reversed" universes, which would be full of antielectrons and antiprotons, and potentially of antipeople living on antiplanets. "Parity-reversed" universes, he explains, would exist as mirror images of our own, substituting right for left and left for right. But the only sort of anti-universe allowed by physics combines these two kinds with a third: the "time-reversed" universe, in which "fried eggs jump off the dinner plate, reform on the frying pan, and then jump back into the egg, sealing the cracks." Dealing as he does in these pages with science-fictional concepts, Kaku often refers to genre books and films ranging from Mark Twain's "A Connecticut Yankee in King Arthur's Court" to "Terminator 3." Aside from his puzzling omission of Robert A. Heinlein's classic "All You Zombies" among stories illustrating the paradoxes of time travel, Kaku's choices seem knowledgeable.

But it's always clear that his interest in the impossible encompasses more than recreational reading. And his careful footnotes cite research in these areas by scores of other scientists — superstars such as Einstein and Stephen Hawking as well as less well-known figures such as cosmic-wormhole expert Matthew Visser of Washington University. More gently than the White Queen, Kaku encourages us to take seriously ideas the world's great intellects consider crazy, reminding us that these same powerful minds sometimes wonder whether such way-out theories and models of the universe are crazy enough to be true.

Nisi Shawl reviews science-fiction for

The Seattle Times. Her book "Filter House"

will be published in June by Aqueduct Press.