Gregory Powell and Mike Donovan have been despatched to Mercury to resurrect an abandoned mine. On arrival they discover that the ‘photo-cell banks’ that protect the mining base from the glaring sun are shot and they’ll need selenium to get them running. Fortunately there are naturally occurring open pools of it dotted around the planet surface nearby, so Donovan sends their robot – SPD-1, or Speedy – out to get some.
Of course, Speedy doesn’t come back, and the reason is a conflict between the Second and Third Laws of Robotics.
1. A robot may not injure a human or, through inaction allow a human to come to harm.2. A robot must obey the orders given it by human beings except where such orders would conflict with the First Law.3. A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.
I’ve always admired the elegant hierarchy that Asimov built into the rules. It’s actually a pretty good code to live by: don’t hurt anyone, help people out if you can do it without hurting someone else and look after yourself as long it doesn’t mean being selfish or hurting someone. It’s also an excellent way to create puzzles that protagonists have find their way out of.
The problem in this case is a bit inelegant as it relies on Speedy having had the intensity of the Third Law dialled up because of the hostile Mercurial environment. There’s a volcanic vent or something near the selenium pool he’s been sent to that will damage him if he gets too close. At the same time, he’s trying to obey the orders he’s been given in accordance with the Second Law. He ends up running in circles around the pool. Donovan and Powell figure it out between them:
‘You see how it works, don’t you? There’s some sort of danger centring on the selenium pool. It increases as he approaches, and a certain distance from it Rule 3 potential, unusually high to start with, exactly balances the Rule 2 potential, unusually low to start with.’Donovan rose to his feet. ‘And it strikes an equilibrium. I see. Rule 3 drives him back, Rule 2 drives him forward -’‘So he follows a circle around the selenium pool, staying on the locus of all points of potential equilibrium.’
For some reason it’s also made Speedy act as if he’s drunk. I suppose Donovan’s explanation of this reflects Asimov’s idea of what artificial intelligence would look like: ‘At potential equilibrium, half the positronic paths in his brain are out of kilter. I’m not a robot specialist, but that seems obvious. Probably he’s lost control of just those parts of his voluntary mechanism that a human drunk has. Ve-e-ery pretty.’
The robot reels around singing airs from Gilbert & Sullivan operas. Interestingly this is one of the things my Mum does after a few wines. I wonder if robots go on benders where they ask humans to give them orders that get them rolling equillibriumed?
The Donovan and Powell try a neat chemical trick to break the robot our of its fugue, allowing Asimov to show off his knowledge of chemistry and the Mercurial environment. He does thrillingly with both, and its this jolly-chaps-being-clever-about-science feeling that makes the story so appealing.
Asimov is one of those writers who’s often criticised for his slight characterisation, and there’s not much counter-evidence here. Donovan and Powell are introduced in the framing text that precedes the story. Susan Calvin reminisces to a journalist ‘I’d advise you to look up Gregory Powell. He and Mike Donovan handled our most difficult cases in the teens and twenties.’
I can’t say I was always able to tell them apart, although we do get a few heavy-handed references to Donovan’s red hair. Powell is the one who comes up with the final desperate plan and risks his life to save them both, but it’s clear that Donovan would have done the same thing. Even though the characters aren’t the focus, the vacuity of the characterisation does suck a a bit of life out of the story. Hard to to really feel much more than a kind of vague agitation at the possible death of these likeable but ultimately undistinguished men.
They’re going to be in a few of the stories, I think, so we’ll see if they develop at all.