Futurists have long talked about the day when computers become as powerful and versatile as the human brain. A recent simulation shows that day is not exactly imminent. In one of the most accurate simulations of the human brain to date, a Japanese supercomputer modeled one second of one percent of human brain activity, a task that took 40 minutes, according to The Telegraph.

The simulation was carried out by Japan’s K computer, the world’s fourth most powerful supercomputer, and replicated a network consisting of 1.73 billion neurons. There have been larger simulations before, although they took longer. IBM’s SyNAPSE, for example, modeled 530 billion neurons in late 2012, as Popular Science pointed out in April of last year. That’s more than the total number of neurons in a human’s brain, which is about 86 billion neurons on average. That project took several hours.