From Wikipedia, the free encyclopedia

A positronic brain is a fictional technological device, originally conceived by science fiction writer Isaac Asimov. Its role is to serve as a central computer for a robot, and, in some unspecified way, to provide it with a form of consciousness recognizable to humans. When Asimov wrote his first robot stories in 1939/1940, the positron was a newly discovered particle and so the buzz word positronic, coined by analogy with electronic, added a contemporary gloss of popular science to the concept.

Contents 1 Background 2 Appearances in Science Ficiton 2.1 Doctor Who 2.2 Star Trek 2.3 The Time Machine (2002 film) 2.4 Once Upon a Time... Space 2.5 Perry Rhodan 2.6 I, Robot, 2004 Film 2.7 Bicentennial Man 3 References 4 See also 5 External links

Asimov remained vague about the technical details except to assert that the brain's substructure was formed from an alloy of platinum and iridium. Asimov relied on the reader's knowledge of the capacity of positrons and electrons to be formed in pairs and to annihilate each other, in order to convey the impression that such pair creation and destruction could serve as a metaphor for the evanescence of thought. 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.

Within his stories of robotics on Earth and their development by U.S. Robots and Mechanical Men Ltd., Asimov's positronic brain became less of a plot device, and more of a technological item worthy of study. Over time, a number of different characteristics became apparent: The brain could not function without the Three Laws of Robotics, which were not only required to be present in the brain for the brain to function, but 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. Their resolution is 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.

Another feature of positronic robots is that their brains are designed in a set of sequential coordinate systems, which while not wholly generalized, are specific enough to designate the intended function of each robot under consideration. Where the second letter of the designation would be a specific code for a coordinate pattern, RB robots tend to be heavy labor models, ZZ series for special application in extreme environments, JN models are optimized for open-ended 'intuitive' correlation of non-discrete variables, TN and NDR for housework (though RB models can also be suitably modified for household duties), AL and LN for space mining, EZ models for book galley editing, and NS for high-energy system building in space. Experimental models such as the JG series were designed for performing correlative judgments with limited data, but had the flaw of being selective enough to violate human rights despite adhering to the Three Laws at their highest level.

The Three Laws are also a bottleneck in terms of brain sophistication. Very complex brains designed to handle world economy have to have a First Law expanded to include humanity as opposed to a single human. Brains which are constructed as calculating machines as opposed to being robot control circuits are designed to have a flexible, child-like personality so that they are able to pursue difficult problems without the Three Laws inhibiting them completely. 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 then require smaller brains again, providing they do not require the Third Law. And Robots that are disposable, cannot receive orders from a human being and are not able to harm a human, require a positronic brain so small that it could comfortably fit within the skull of an insect.

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 invented the gravitonic brain. It offered speed and capacity improvements over traditional positronic designs, but the strong influence of tradition made robotics labs reject Anshaw's work. Only one roboticist, Fredda Leving, chose to adopt gravitonics, because it offered her a blank slate on which she could explore alternatives to the Three Laws. Because they were not dependent upon centuries of earlier research, gravitonic brains could be programmed with the standard Laws, variations of the Laws, or even empty pathways which specify no Laws at all.

In the The Power of the Daleks, a fourth series episode of the British sci-fi program Doctor Who, the Doctor, played by Patrick Troughton, awakens from his first regeneration and eventually faces one of his old nemeses, the Daleks — a race of armed robotic tank shells with violent organic brains. The humans in the episode, who had found disabled Daleks and who are examining them, discover that, upon activation, the daleks have fantastic powers of computation, prompting a scientist to comment "what sort of positronic brain must this device possess." Lulled into complacency by the obsequiousness of the Dalek under study, the humans are unprepared for a relentless attempt at conquest by the restored dalek specimens. While the scientist in question commented on a positronic brain, the Daleks are actually organic life-forms that were encased in robotic shells, and thus do not possess the purported positronic brain. They were created through genetic manipulation of the Kaled race by its chief scientist, Davros, to create a new species to win a millennium-long war against their rivals, the Thaals, on their home world Skaro. The Daleks evolved into a species completely devoid of emotion and most of the five senses, but also completely rational and committed to the belief that they were superior to all other life, and therefore committed to their conquest. The Daleks suffer from no Asimovian legal limitations and continue to plague humanity, the Doctor and all other creatures throughout the entire series.

The fictional characters Lieutenant Commander Data, his "mother" Julianna Soong Tainer, and his brothers Lore and B-4 from the Star Trek series The Next Generation, are androids equipped with positronic brains. In one episode Data creates an offspring named Lal with a similar but somewhat more sophisticated brain. After a short time she displays promising advances in emotion and other human behaviors that Data has not been able to master, but later dies of a "rapid positronic cascade failure" shortly after she is told that Starfleet wants to separate her from Data. In the episode Datalore, Lieutenant Natasha Yar refers to the positronic brain as Asimov's dream. The episode "Brothers" depicts an unnumbered quantity of androids (and/or android parts) that preceded both Lore and Data. These are assumed to also possess positronic brains in some form or fashion with each being an improvement over the last.

None of these androids are constrained by Asimov's robot laws, although Data's actions are restricted by ethical programming provided by his creator, Dr. Noonien Soong since Lore displays an apparent lack of ethics early on in his development.

Vox, the holographic artificially intelligent librarian (played by Orlando Jones), utilizes a photonic brain in the year 2030. Presumable a photonic brain replaces the use of electrons with the use of photons, as the positronic brain uses positrons in place of electrons.

This animated sci-fi series features the character of the positronic brain android Métro

In the German science fiction series Perry Rhodan, positronic brains (German: Positroniken) are the main computer technology (for quite a time they were replaced by the more powerful Syntronics, but those stopped working due to the increased Hyperimpedance). The most powerful positronic is called NATHAN and covers large parts of the earth's moon. Many of the larger computers (including NATHAN) as well as the race of Posbis combine a biological component with the positronic brain, giving them sentience and creativity.

The robots in the 2004 film I, Robot also had positronic brains. Sonny, one of the main characters from the film, had two separate positronic brains working in unison (The second being a positronic "heart"), which meant he had choices open to him the other standard robots in the film did not. He also had the possibility of being able to develop emotion and ignore the Three Laws of Robotics.

Additionally, there was a colossal positronic brain, VIKI, that played a prominent role in the story.

The robots in the 1999 film Bicentennial Man (based on one of Asimov's stories) also had positronic brains, including the main character Andrew, an NDR series robot that started to experience human characteristics such as creativity. Only when Andrew allows his positronic brain to "decay", thereby willfully abandoning his immortality, is he declared a human being. This event takes place on the two-hundredth anniversary of his creation, hence the title.

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (June 2006)

• Transmog

• Positronic brain article at Memory Alpha, a Star Trek wiki