It's about power:
This projection overlooks the dark, hot underbelly of Moore’s law: power consumption per chip, which has also exploded since 1985. By 2025, the memory of an artificial brain would use nearly a gigawatt of power, the amount currently consumed by all of Washington, D.C. So brute-force escalation of current computer technology would give us an artificial brain that is far too costly to operate.and emotions:
Compare this with your brain, which uses about 12 watts, an amount that supports not only memory but all your thought processes. This is less than the energy consumed by a typical refrigerator light, and half the typical needs of a laptop computer. Cutting power consumption by half while increasing computing power many times over is a pretty challenging design standard. As smart as we are, in this sense we are all dim bulbs.
Still, engineers could learn a thing or two from brain strategies. For example, even the most advanced computers have difficulty telling a dog from a cat, something that can be done at a glance by a toddler — or a cat. We use emotions, the brain’s steersman, to assign value to our experiences and to future possibilities, often allowing us to evaluate potential outcomes efficiently and rapidly when information is uncertain. In general, we bring an extraordinary amount of background information to bear on seemingly simple tasks, allowing us to make inferences that are difficult for machines.Sarah Conners the world over can breath a sigh of relief.