Getting a new perspective; Michio Kaku was inspired by watching fish in a pond

Credit: Chris Callas/COSMOS

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Understanding other worlds came naturally to him. Perhaps it was an inevitable consequence of being the child of Japanese Americans. His parents, though born in California, spent World War II behind barbed wire, guarded by people with machine guns: incarcerated by their own country as enemy aliens. Afterwards his father worked as a gardener, his mother a maid: two of the few jobs that were available to Japanese Americans. Kaku grew up poor, but one of the family treats was to visit the Japanese Tea Garden in San Francisco's Golden Gate Park. It turned out to be the place of a childhood epiphany. Wondering in the way that only a child does, Kaku looked at the carp swimming in a weedy pond and imagined how they would not be able to conceive of other worlds. "A carp engineer would believe that was all there is; but a carp physicist would see the ripples on the surface and start thinking about unseen dimensions," Kaku told me, laying the first of many lashes on his token engineer.

Kaku's curiosity and penchant for unearthly thinking were largely misunderstood, a large part of the reason why today he has become a light unto others. "When I was a teenager and asked questions, eyes would glaze over - I didn't want others to go through the trials of fire."

But his teenage curiosity did pay off. "Because my parents were poor, I knew from a very early age that I would have to be self-reliant. Hence, in high school, I built a 2.3 million electron volt atom smasher, which helped me to get into Harvard. My parents did not understand at all what I was doing, but they realised it was important, and helped in any way they could. The atom smasher used up 22 miles [35km] of cooper wire, which my parents and I wound on the high-school football field over Christmas vacation."

The atom smasher consistently blew the fuses at his parents' home. But it also impressed atomic scientist Edward Teller, who arranged a scholarship at Harvard University for the young Kaku.

Early on, college life proved quite prosaic for Kaku. It involved learning the bread and butter of physics - most tediously having to memorise Maxwell's eight hideous mathematical equations that describe electromagnetic fields. But the physics course kept the best till last. In the advanced class, Kaku experienced an epiphany to rival that of the carp in the tea garden. "We physicists have the greatest mind-blowing coming of age; its an existential shock."

What Kaku learned was that Maxwell's eight lines of equations, could be reduced to one. The shock was that this equation magically rose out of Einstein's gravity equations if you added a fifth dimension! (that is, a fourth spatial dimension: we are used to three spatial dimensions and one of time). "That's the difference between engineers and physicists: engineers are happy with Maxwell's original equations; they think 'how horrible but how useful'." Physicists, however, are looking for the underlying elegant logic of the universe. And according to proponents of string theory that logic is: physical laws become simpler in higher dimensions.

The five dimensional transformation of Maxwell's equations is not controversial: it works. Indeed mathematicians often operate in extra dimensions. Where the controversy lies is whether these mathematical abstractions have any counterpart in the real world. String theory physicists believe they do; not just in five dimensions - but in 11!