Positronic Brain - Background

Background

Asimov remained vague about the technical details except to assert that the brain's substructure was formed from an alloy of platinum and iridium. It was stated to be very vulnerable to radiation, and apparently a type of volatile memory (since robots in storage required a power source keeping their brains "alive"). The focus of Asimov's stories was directed more towards the software of robots (such as the Three Laws of Robotics) than the hardware in which it was implemented, although it is stated in his stories that to create a positronic brain without the Three Laws it would have been necessary to spend years redesigning the brain itself.

Within his stories of robotics on Earth and their development by U.S. Robots, Asimov's positronic brain became less of a plot device, and more of a technological item worthy of study.

A positronic brain cannot ordinarily be built without incorporating the Three Laws; any modification thereof would drastically modify robot behavior. Behavioral dilemmas resulting from conflicting potentials set by inexperienced and/or malicious users of the robot for the Three Laws make up the bulk of Asimov's stories concerning robots. They are resolved by applying the science of logic and psychology together with mathematics, the supreme solution finder being Dr. Susan Calvin, Chief Robopsychologist of U.S. Robots.

The Three Laws are also a bottleneck in terms of brain sophistication. Very complex brains designed to handle world economy interpret the First Law in expanded sense to include humanity as opposed to a single human; in Asimov's later works like Robots and Empire this is referred to as the "Zeroth Law". At least one brain constructed as a calculating machine as opposed to being robot control circuits are designed to have a flexible, childlike personality so that it was able to pursue difficult problems without the Three Laws inhibiting it completely. Specialized brains created for overseeing world economics were stated to have no personality at all.

Under specific conditions, the Three Laws can be obviated, with the modification of the actual robotic design.

• Robots which are of low enough value can have the Third Law deleted; they do not have to protect themselves from harm, and the brain size can be reduced by half.
• Robots that do not require orders from a human being may have the Second Law deleted, and therefore require smaller brains again, providing they do not require the Third Law.
• Robots that are disposable, cannot receive orders from a human being and are not able to harm a human, will not require even the First Law. The sophistication of positronic circuitry renders a brain so small that it could comfortably fit within the skull of an insect.

Robots of the aforementioned last type directly parallel contemporary industrial robotics practice, though real-life robots do contain safety sensors and systems, in a concern for human safety (a weak form of the First Law; the robot is a safe tool to use, but has no "judgment", which is implicit in Asimov's own stories).

Several robot stories have been written by other authors following Asimov's death. For example, in Roger MacBride Allen's Caliban trilogy, a Spacer roboticist called Gubber Anshaw invents the gravitonic brain. It offers speed and capacity improvements over traditional positronic designs, but the strong influence of tradition make robotics labs reject Anshaw's work. Only one roboticist, Fredda Leving, chooses to adopt gravitonics, because it offers her a blank slate on which she could explore alternatives to the Three Laws. Because they are not dependent upon centuries of earlier research, gravitonic brains can be programmed with the standard Laws, variations of the Laws, or even empty pathways which specify no Laws at all.