Wednesday, June 27, 2007

Limits to understanding: evolved circuits, the genetic code, and the mind

DI has a fascinating review of recent research on hardware evolution. The implications are obviously relevant to a recent article in The Economist on the multidimensional/network encoding of genetic information (see also NYT on encoding meaning in topology), and on attempts to understand cognition.
Damn Interesting - On the Origin of Circuits

...Dr. Thompson peered inside his perfect offspring to gain insight into its methods, but what he found inside was baffling. The plucky chip was utilizing only thirty-seven of its one hundred logic gates, and most of them were arranged in a curious collection of feedback loops. Five individual logic cells were functionally disconnected from the rest– with no pathways that would allow them to influence the output– yet when the researcher disabled any one of them the chip lost its ability to discriminate the tones. Furthermore, the final program did not work reliably when it was loaded onto other FPGAs of the same type.

It seems that evolution had not merely selected the best code for the task, it had also advocated those programs which took advantage of the electromagnetic quirks of that specific microchip environment. The five separate logic cells were clearly crucial to the chip's operation, but they were interacting with the main circuitry through some unorthodox method– most likely via the subtle magnetic fields that are created when electrons flow through circuitry, an effect known as magnetic flux. There was also evidence that the circuit was not relying solely on the transistors' absolute ON and OFF positions like a typical chip; it was capitalizing upon analogue shades of gray along with the digital black and white...
I've written before about my teenage experience with modeling the evolved and emergent pneumatic braking system of a 20th century freight train. Evolved systems are characteristically very hard for an evolved mind to interpret. Meaning can be encoded in a baroque and illogical fashion, expressed across multiple continuous and undefined "surfaces" of representation. It may be fundamentally impossible for a mind to truly "understand" it's mechanisms, even if we are able ultimately to create another mind on a much more "reasoned" substrate.

If we eventually discover that the world of physics is fundamentally more like an evolved than a designed system, then we shall mourn the lost innocence of ambitious comprehension ...

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