Quantum theory is the bedrock of contemporary physics and the basis of understanding matter in its tiniest dimensions and the vast universe as a whole. But for many, the theory remains an impenetrable enigma. Now, two physicists seek to remedy this situation by both drawing on their scientific expertise and their talent for communicating science to the general reader. In this lucid, informative book, designed for the curious, they make the seemingly daunting subject of quantum physics accessible, appealing, and exciting. Their story is partly historical, covering the many "Eureka" moments when great scientists-Max Planck, Albert Einstein, Niels Bohr, Werner Heisenberg, Erwin Schrödinger, and others-struggled to come to grips with the bizarre realities that quantum research revealed.