Technical Comparison of Human Brains and Artificial Processors – No Direct Lead

potentials, which limits their spacing to a few 10s per second. It is probably no accident that the “frame rate,” at which we can distinguish that movies are actually a sequence of stills, is about 40 per second. Thus, electronic processing is close to a billion times faster. e Size: The linear dimension of a typical neuron is about 10 microns. Molecular dimensions, which set a practical limit, are about 10,000 times smaller, and artificial processing units are approaching that scale. Smallness makes communication more efficient. e Stability: Whereas human memory 1s essentially continuous (analog), artificial memory can incorporate discrete (digital) features. Whereas analog quantities can erode, digital quantities can be stored, refreshed, and maintained with complete accuracy. e Duty Cycle: Human brains grow tired with effort. They need time off to take nourishment and to sleep. They carry the burden of aging. Most profoundly: They die. e Modularity (open architecture): Because artificial information processors can support precisely defined digital interfaces, they can readily assimilate new modules. Thus, if we want a computer to “see” ultraviolet or infrared or “hear” ultrasound, we can feed the output from an appropriate sensor directly into its “nervous system.” The architecture of brains is much more closed and opaque, and the human immune system actively resists implants. e Quantum readiness: One case of modularity deserves special mention, because of its long-term potential. Recently physicists and information scientists have come to appreciate that the principles of quantum mechanics support new computing principles, which can empower qualitatively new forms of information processing and (plausibly) new levels of intelligence. But these possibilities rely on aspects of quantum behavior which are quite delicate and seem especially unsuitable for interfacing with the warm, wet, messy enviroment of human brains. Evidently, as platforms for intelligence, human brains are far from optimal. Still, although versatile housekeeping robots or mechanical soldiers would find ready, lucrative markets, at present there is no machine that approaches the kind of general-purpose human intelligence those applications would require. Despite their relative weakness on many fronts, human brains have some big advantages over their artificial competitors. Let me mention five: e Three-dimensionality: Although, as noted, the linear dimensions of existing artificial processing units are vastly smaller than those of brains, the procedure by which they’re made—centered on lithography (basically, etching)—is essentially two-dimensional. That is revealed visibly in the geometry of computer boards and chips. Of course, one can stack boards, but the spacing between layers is much larger, and communication much less efficient, than within layers. Brains make better use of all three dimensions. e Self-repair: Human brains can recover from, or work around, many kinds of injuries or errors. Computers often must be repaired or rebooted externally. 59 HOUSE_OVERSIGHT_016279