For years, Henry Markram has claimed that he can simulate the human brain in a computer within a decade. On 23 January 2013, the European Commission told him to prove it. His ambitious Human Brain Project (HBP) won one of two ceiling-shattering grants from the EC to the tune of a billion euros, ending a two-year contest against several other grandiose projects. Can he now deliver? Is it even possible to build a computer simulation of the most powerful computer in the world—the 1.4-kg cluster of 86 billion neurons that sits inside our skulls?The very idea has many neuroscientists in an uproar, and the HBP’s substantial budget, awarded at a tumultuous