Shadows live in a simple world. They glide effortlessly across any sort of surface, oblivious to the higher dimension of space in which 3-D bodies move, collide and sometimes block the paths of rays of light. Shadows have no idea how important that third dimension is, and how objects in it endow those very shadows with their quasi-physical existence. Indeed, the laws of shadow physics all depend on the third dimension’s presence. And just as the clueless inhabitants of the shadow world require an extra dimension to explain how they exist and interact, reality for humans may also depend on... (p. 26)

Two hundred years later, Charles Darwin’s ideas still live on.

Darwin's life and his contribution to science

At the end of The Matrix trilogy, Neo and Agent Smith are engaged in one final, interminable scene of surreal combat, a surrogate competition for an eternal battle between humans and machines. “It’s pointless to keep fighting,” Agent Smith declares to Neo. “Why do you persist?” “Because I choose to,” Neo replies, just before the computer-generated Smith meets his demise in a cinematic celebration of human free will’s superiority to the programming that enslaves machines. Machines are mindless. The brain is a decider. All very inspiring, except that the brain itself is a... (p. 28)

A century ago, mathematician Hermann Minkowski famously merged space with time, establishing a new foundation for physics; today physicists are rethinking how the two should fit together

In mid-20th century America, two scientists towered over all others in the public mind: Albert Einstein and Robert Oppenheimer. Oppenheimer was the man who built the atomic bomb; Einstein’s theories explained how such a vast release of energy was possible. Both were acclaimed as geniuses of the highest order. Yet they were dissimilar in numerous respects. Einstein was solitary, kind, self-assured and even stubborn; Oppenheimer was gregarious, witty, sometimes sarcastic and cruel, and at some level deeply insecure. Historian Silvan S. Schweber exploits these contrasts to explore the meaning ...