Half a trillion neurons, a hundred trillion synapses. I.B.M. has just announced the world’s grandest simulation of a brain, all running on a collection of ninety-six of the world’s fastest computers. The project is code-named Compass, and its initial goal is to simulate the brain of the macaque monkey (commonly used in laboratory studies of neuroscience). In sheer scale, it’s far more ambitious than anything previously attempted, and it actually has almost ten times as many neurons as a human brain. Science News Daily called it a “cognitive milestone,” and Popular Science said that I.B.M.’s “cognitive computing program… just hit a major high.” Are full-scale simulations of human brains imminent, as some media accounts seem to suggest?