"And what of all that, Bander?"
"The flow of heat from hotter to colder, which must take place by the second law of thermodynamics, can be used to do work."
"In theory, yes, but sunlight is dilute, the heat of the planetary surface is even more dilute, and the rate at which heat escapes from the interior makes that the most dilute of all. The amount of heat-flow that can be harnessed would probably not be enough to lift a pebble."
"It depends on the device you use for the purpose," said Bander. "Our own tool was developed over a period of thousands of years and it is nothing less than a portion of our brain."
Bander lifted the hair on either side of its head, exposing that portion of its skull behind its ears. It turned its head this way and that, and behind each ear was a bulge the size and shape of the blunt end of a hen's egg.
"That portion of my brain, and its absence in you, is what makes the difference between a Solarian and you."
48.
TREVIZE glanced now and then at Bliss's face, which seemed entirely concentrated on Bander. Trevize had grown quite certain he knew what was going on.
Bander, despite its paean to freedom, found this unique opportunity irresistible. There was no way it could speak to robots on a basis of intellectual equality, and certainly not to animals. To speak to its fellow-Solarians would be, to it, unpleasant, and what communication there must be would be forced, and never spontaneous.
As for Trevize, Bliss, and Pelorat, they might be half-human to Bander, and it might regard them as no more an infringement on its liberty than a robot or a goat would be-but they were its intellectual equals (or near equals) and the chance to speak to them was a unique luxury it had never experienced before.
No wonder, Trevize thought, it was indulging itself in this way. And Bliss (Trevize was doubly sure) was encouraging this, just pushing Bander's mind ever so gently in order to urge it to do what it very much wanted to do in any case.
Bliss, presumably, was working on the supposition that if Bander spoke enough, it might tell them something useful concerning Earth. That made sense to Trevize, so that even if he had not been truly curious about the subject under discussion, he would nevertheless have endeavored to continue the conversation.
"What do those brain-lobes do?" Trevize asked.
Bander said, "They are transducers. They are activated by the flow of heat and they convert the heat-flow into mechanical energy."
"I cannot believe that. The flow of heat is insufficient."
"Little half-human, you do not think. If there were many Solarians crowded together, each trying to make use of the flow of heat, then, yes, the supply would be insufficient. I, however, have over forty thousand square kilometers that are mine, mine alone. I can collect heat-flow from any quantity of those square kilometers with no one to dispute me, so the quantity is sufficient. Do you see?"
"Is it that simple to collect heat-flow over a wide area? The mere act of concentration takes a great deal of energy."
"Perhaps, but I am not aware of it. My transducer-lobes are constantly concentrating heat-flow so that as work is needed, work is done. When I drew your weapons into the air, a particular volume of the sunlit atmosphere lost some of its excess heat to a volume of the shaded area, so that I was using solar energy for the purpose. Instead of using mechanical or electronic devices to bring that about, however, I used a neuronic device." It touched one of the transducer-lobes gently. "It does it quickly, efficiently, constantly-and effortlessly."
"Unbelievable," muttered Pelorat.
"Not at all unbelievable," said Bander. "Consider the delicacy of the eye and ear, and how they can turn small quantities of photons and air vibrations into information. That would seem unbelievable if you had never come across it before. The transducer-lobes are no more unbelievable, and would not be so to you, were they not unfamiliar."
Trevize said, "What do you do with these constantly operating transducerlobes?"
"We run our world," said Bander. "Every robot on this vast estate obtains its energy from me; or, rather, from natural heat-flow. Whether a robot is adjusting a contact, or felling a tree, the energy is derived from mental transduction-my mental transduction."
"And if you are asleep?"
"The process of transduction continues waking or sleeping, little half-human," said Bander. "Do you cease breathing when you sleep? Does your heart stop beating? At night, my robots continue working at the cost of cooling Solaria's interior a bit. The change is immeasurably small on a global scale and there are only twelve hundred of us, so that all the energy we use does not appreciably shorten our sun's life or drain the world's internal heat."
"Has it occurred to you that you might use it as a weapon?"
Bander stared at Trevize as though he were something peculiarly incomprehensible. "I suppose by that," he said, "you mean that Solaria might confront other worlds with energy weapons based on transduction? Why should we? Even if we could beat their energy weapons based on other principles-which is anything but certain-what would we gain? The control of other worlds? What do we want with other worlds when we have an ideal world of our own? Do we want to establish our domination over half-humans and use them in forced labor? We have our robots that are far better than half-humans for the purpose. We have everything. We want nothing-except to be left to ourselves. See here-I'll tell you another story."
"Go ahead," said Trevize.
"Twenty thousand years ago when the half-creatures of Earth began to swarm into space and we ourselves withdrew underground, the other Spacer worlds were determined to oppose the new Earth-settlers. So they struck at Earth."