How can a particle be in two places at once? What do wave-particle duality and quantum uncertainty mean? Why did Richard Feynman, who won a Nobel prize for his work on quantum theory, say that "nobody understands quantum mechanics"? Drawing on a long-standing fascination with quantum physics, and decades spent investiagating its history, Gribbin tells its story - from Max Planck's realization at the dawn of the 20th century that light behaves like a stream of particles, to the future possibility of parallel worlds and teleportation.