130 Will Robots Inherit the Earth? LIMITS OF HUMAN MEMORY If we want to consider augmenting our brains, we might first ask how much a person knows today. Thomas K. Landauer of Bell Communications Research reviewed many experiments in which people were asked to read text, look at pictures, and listen to words, sentences, short passages of music, and non- sense syllables. [1] They were later tested in various ways to see how much they remembered. In none of these situations were people able to learn, and later remember, more than about 2 bits per second, for any extended period. If you could main- tain that rate for twelve hours every day for 100 years, the total would be about three billion bits – less than what we can store today on a regular 5-inch Compact Disk. In a decade or so, that amount should fit on a single computer chip. Although  these  experiments  do  not  much  resemble  what we do in real life, we do not have any hard evidence that people can learn more quickly. Despite those popular legends about people with ‘photographic memories,’ no one seems to have mastered, word for word, the contents of as few as one hundred books – or of a single major encyclopedia. The com- plete works of Shakespeare come to about 130 million bits. Landauer’s limit implies that a person would need at least four years to memorize them. We have no well-founded estimates of how much information we require to perform skills such as painting or skiing, but I do not see any reason why these activities should not be similarly limited. The brain is believed to contain the order of a hundred tril- lion synapses – which should leave plenty of room for those few billion bits of reproducible memories. Someday though, it should be feasible to build that much storage space into a package as small as a pea, using nanotechnology.