Friday, May 24, 2013

Review of The Information: A History, A Theory, A Flood by James Gleick

In the bargain bin I picked up a copy of The Information: A History, A Theory, A Flood by James Gleick, which is a history of communication and information, for some light reading.

Did you know that "telegraph" originally referred to a system of conveying information by means of visual signals, using towers with pivoting shutters, also known as a semaphore line, Napoleonic semaphore, or optical telegraph? It was invented in France in the 1790s and used throughout the world until the advent of the electrical telegraph.

Telegraph Hill in San Francisco was where a semaphore tower was built in 1849 in order to signal the rest of the city what kind of ships were entering the Golden Gate, and therefore predict what kind of cargoes would be carried and what would happen to local prices for those goods. It was the high frequency trading of its day!

Also, France banned unauthorized optical telegraphy in 1837 because a monopoly on the swift spread of information was a tool of state power.

Other tidbit: the "ban" is a logarithmic unit which measures information or entropy: "a change in a weight of evidence of 1 deciban (i.e., a change in an odds ratio from evens to about 5:4) is about as finely as humans can reasonably be expected to quantify their degree of belief in a hypothesis".


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