The Persistence of Memory

The eleventh episode of Cosmos dealt the human brain, how we remember things, and much more. Dr. Sagan started out by explaining the significance of the children's game twenty questions, and describing just how much information could be determined with twenty carefully chosen questions. He then went on to speak about non-human intelligence and focused primarily on whales, whale songs, etc. to make his points. This in turn led to a discussion of genes, the fact that this they are the site of the non-learned intelligence, what is stored in them, and the complexity of the information. According to the show amoeba DNA is comprised of about forty million bits, while human DNA is on the order of five billion bits.

Following the discussion on genes the topic shifted to the human brain itself, and therefore the learned intelligence. Estimates show that the human brain has on the order of one hundred billion neurones, and something like one hundred trillion connections. Dr. Sagan went on to compare the city (in this case New York) to the brain to show how the development of the brain is somewhat like how a city develops over the centuries (starts small & simple, and builds towards the big and complex). However he points out that unlike the city the brain is very much into redundancy.

The next topic to be discussed was what happened when we needed more memory than we had the ability to store inside our heads. In other words the written work, printing, books, and libraries. He pointed out that printing started in China with block printing sometime between the second and sixth centuries, but that it took another thousand years before it caught on in Europe. Before it came to Europe there was some ten thousand books in all of Europe (all handwritten), but then in a span of fifty years there was over ten million books, and knowledge was available to all.



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