Another way of thinking about how efficient the brain is: By the article’s numbers, about 5.5 million TPU hours were required to train the machine to play as well as a Go champion.

A Go champion might have trained for 8 hours a day, for 15 years (age 5 to 20). That is about 40 000 hours.

In other words, machines required 137 times longer to learn the game, and at twice the power consumption! There is still a lot of room for improvement.

>KataGo's latest run used about 29 GPUs, rather than thousands (like AlphaZero and ELF), first reached superhuman levels on that hardware in perhaps just three to six days, and reached strength similar to ELF in about 14 days. With minor adjustments and a few more GPUs, starting around 40 days it roughly began to match or surpass Leela Zero in some tests with different configurations, time controls, and hardware. And finally after about four months of training time, the current run may be wrapping up fairly soon, but we hope to be able to continue it or begin another run in the future.