Our brain is quite an ingenious machine, I knew that already. But through an article in the Scientific American, written by Ferris Jabr (“Does thinking hard really burn more calories?“), I found out how incredibly efficient it is. Our brain uses about 20% of our energy when we are physically more or less at rest. This means that if a body uses 1,300 calories on a lazy day, the brain consumes 260 of these calories. This might sound like a lot, knowing that our brain weighs only about 1.4 kilograms, which comes down to 2% of our body weight, but it’s actually very, very little. The article explains that 1,300 calories per day equals 63 watts, which means that our brain consumes one fifth of that; 12.6 watts. And that is the equivalent of a compact fluorescent bulb.
If a body uses 1,300 calories on a lazy day, the brain consumes 260 of these calories
The article continues to explain that IBM’s Watson, the super computer that beat Jeoperdy! winners Brad Rutter and Ken Jennings in 2011, used 90 IBM Power 750 servers, equalling 1000 watts in total. Watson was programmed for a relatively narrow task; choose what question is being asked, when we present you three answers. To do this better than a (very knowledgeable) human being, it had to be able to process 500 gigabytes, the equivalent of a million books per second. That sounds like a lot, but while this computer is a master at scanning knowledge and understands language reasonably well, it can’t fulfil any other creative tasks, such as filtering sensory stimuli, making visual perceptions and decisions, imagining, etc. This means that energy-wise our brain is still by far the most efficient computer on this planet. And that it will still take a while before the computer outpowers the brain and, on top of that, will burn its energy as efficiently.