Why “positronic”?
When I first began writing science fiction stories, the positron had been discovered only six years before as a particle with all the properties of an electron except for an opposite charge. It was the first (and, at that time, still the only) bit of antimatter that had been discovered, and it carried a kind of science-fictional flavor about it.
That meant that if I spoke of “positronic robots” rather than “electronic robots,” I would have something exotic and futuristic instead of something conventional.
—The Word I Invented, 1980
How does the positronic brain work?
[P]ositrons are very evanescent particles, at least in our world. They don’t survive more than a millionth of a second or so before they bump into one of the electrons with which our world is crowded, and then the two annihilate each other.
I had a vision, therefore, of “positronic pathways” along which positrons briefly flashed and disappeared. These pathways were analogous to the neurons of the animal nervous system, and the positrons themselves were analogous to the nerve impulse. The exact nature of the pathways were controlled by positronic potentials, and where certain potentials were set prohibitively high, then certain thoughts or deeds became virtually impossible. It was the balance of such potentials which resulted in the Three Laws.
Of course, it takes a great deal of energy, on the subatomic scale, to produce a positron; and that positron, when it encounters an electron and is annihilated, produces a great deal of energy on the subatomic scale. Where does that positron-producing energy come from and where does the positron-annihilation energy go to?
The answer to that is that I didn’t know and didn’t care. I never referred to the matter. The assumption (which I didn’t bother to state) was that future technology would handle it and that the process would be so familiar that nobody would wonder about it or comment upon it—any more than a contemporary person would worry about what happens in a generating plant when a switch is flicked and a bathroom light goes on.
—The Word I Invented, 1980
What is the positronic brain made of?
When I wrote my first few robot stories in 1939 and 1940, I imagined a “positronic brain” of a spongy type of platinum-iridium alloy. It was platinum-iridium because that is a particularly inert metal and is least likely to undergo chemical changes. It was spongy so that it would offer an enormous surface on which electrical patterns could be formed and un-formed.
—Cybernetic Organism, 1987
Additional sources
The mere fact that I talk about positronic robots and say they are guided by the Three Laws of Robotics has no actual predictive value from the engineering standpoint. Imagine, for instance, a discussion between an interviewer (Q) and myself (A).
Q. 855
What is a positronic robot, sir?
A. One with a positronic brain.
Q. And what is a positronic brain?
A. One in which positronic shifts take the place of the electronic shifts in the living human brain.
Q. But why should positronics be superior to electronics for the purpose?
A. I don’t know.
Q. How do you keep your positrons from combining with electrons and forming a flood of energy that will melt down the robot into a puddle of metal?
A. I haven’t the vaguest notion.
Q. For that matter, how do you translate positronic flows into the “Three Laws of Robotics”?
A. Beats me.
I’m not ashamed of this. In writing my robot stories it is not my intention to describe robot-engineering in detail. It was merely my intention to describe a society in which advanced robots were common and to try to work out possible resulting consequences.
—Future? Tense!, 1965
> It was usually called the “positronic robot” series, because the electric currents in the brains were flows of positrons rather than electrons. I did that just to make the brains sound part of a futuristic technology, but some of the less sophisticated readers thought that this was based on sound science and would ask me to give them additional information on how it worked.
> —[In Memory Yet Green](http://www.isfdb.org/cgi-bin/title.cgi?103248), 1979
> [W]hen in 1939 I began to write robot series, I gave my robots “positronic brains” as a glamorous science fictional variation of the flat and uninspiring “electronic brains.”
> —[Opposite!](http://www. 855