Thursday, November 04, 2010

The physics of mind and the limits of AI

Consider these three recent articles together ...

One ...

Dienekes' Anthropology Blog: Brains to Hand-axes quoting Science Daily

Stone Age humans were only able to develop relatively advanced tools after their brains evolved a greater capacity for complex thought, according to a new study that investigates why it took early humans almost two million years to move from razor-sharp stones to a hand-held stone axe...

Two ...

Gordon's Notes: The new history is deep history

... What did humans do in Georgian caves for 30,000 years? Thirty thousand years of waving and sewing and nothing changes?! They could not have had the same brains we have ...

Three ...

Optimization at the Intersection of Biology and Physics - Natalie Angier - NYTimes.com

... the basic building blocks of human eyesight turn out to be practically perfect... Photoreceptors operate at the outermost boundary allowed by the laws of physics, which means they are as good as they can be, period. Each one is designed to detect and respond to single photons of light — the smallest possible packages in which light comes wrapped...

... Photoreceptors exemplify the principle of optimization, an idea, gaining ever wider traction among researchers, that certain key features of the natural world have been honed by evolution to the highest possible peaks of performance ...  Scientists have identified and mathematically anatomized an array of cases where optimization has left its fastidious mark, among them the superb efficiency with which bacterial cells will close in on a food source; the precision response in a fruit fly embryo to contouring molecules that help distinguish tail from head; and the way a shark can find its prey by measuring micro-fluxes of electricity in the water a tremulous millionth of a volt strong — which, as Douglas Fields observed in Scientific American, is like detecting an electrical field generated by a standard AA battery “with one pole dipped in the Long Island Sound and the other pole in waters of Jacksonville, Fla.”

... Simon Laughlin of Cambridge University has proposed that the brain’s wiring system has been maximally miniaturized, condensed for the sake of speed to the physical edge of signal fidelity.

According to Charles Stevens of the Salk Institute, our brains distinguish noise from signal through redundancy of neurons and a canny averaging of what those neurons have to say...

Photoreceptors are a specialization of brains. Brains have been evolving for a very long time.

Long enough, perhaps, for brains to run up against the constraints of physics.

It's not something most of us have contemplated. It is probably misleading, it might be more true that brains have run up against the constraints of room temperature physics operating on biological systems. Still, it's interesting.

If true, it doesn't mean that an artificial brain couldn't be substantially smarter than the smartest human. It might suggest, however, that it could't be qualitatively smarter. The Ais might think us a bit dull and slow, but they might still want to talk ...

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