But the crucial ability was, as always, killing. So the logic of evolution has pressed the radio eye into service. With oxygen at a premium, chasing down prey could easily exhaust an EM’s energy reserves, making it vulnerable. Far better to fry a target and approach it cautiously. The radio eye could probe, identify, and kill—and then probe again, listening for telltale signs that the targets nervous system had gone out of business. All this, without coming close enough to risk the prey’s claws or horns or hooves. So with evolution’s marvelous economy, the eye did everything; seeing, talking, killing, even cooking. And the mind behind the eye struggled to improve perception, resolution, accuracy. The eye and the mind must have evolved together, perhaps in a bootstrapping loop like the hand/mind link in man.
Nigel, they’re drifting your way.
“As I expected,” he mutters to himself.
What? What’s that? Look, if you have something in mind, Nigel, I would just as soon not have Bob jumping down our throats about—
“Quite. Worry not, friend Daffler. I’m simply here to see what I can see.”
There will be plenty of guys down here in an hour. You tell them what to look for and—
“I’m not quite sure myself.”
Pebbles rattle against his plates and the land heaves beneath him, an orange flare burst through the shrouding dust, and Nigel sees the descending streams of orange again, bigger now, spilling down the burnished rock faces hundreds of meters above.
Jeez, it’s picking up again. That western face might slip down any moment, I’d say.
“Geology’s not your department, Daffler. You’re the comm man. I’m the jack-of-all-trades.”
Well, yes, but simple—
“Nothing down here is simple. Mind the EMs, eh? They’re having a go.”
What? Oh, I see. They’re heading toward you. Straight for that flank of the ridge.
“Right. You can scarcely ask me to maneuver around them, not since Bob’s warned us off close contact until the big team arrives.”
Uh, yes. But—
“Closing down now, if you don’t mind. I want to be sure I’m not seen.”
Uh-huh, Daffler grunts suspiciously, but his carrier falls silent.
Nigel is alone in the sleeting amber light as the low murmur of the mountain comes to him through his treads and he listens intently to the muted sputters and chiming beeps that make up the EM conversations and songs and continual probings, the microwave scattering through the canyons and washes of this bleak land. He thumbs on the radio map sent down from Lancer and studies the gathering dots that shamble toward him.
A small animal scurries by, frightened, and Nigel marvels that the little thing—eyeless, pea-brained—can sniff the EMs at this range, and know enough to flee.
The EM body itself may serve as a big antenna, the bones acting as low-conductivity pickups, so that to the EM there is a vague sense of smaller beings approaching. Otherwise they would be vulnerable to parasites and ingenious throat-slitters, who could mount them and be invisible. But somehow the whole-body antenna must “see” small predators so the EMs can fry them, step on them, pluck them off. Perhaps under selection pressure the brain had developed some aperture synthesis technique, like the widely separated radio antennas on Earth that have an “eye” the effective size of their separation. And did their spines serve as tuning coils?
Nigel clanks into a narrow gully as the EM specks approach. He wants his performance to be beyond criticism by Bob and the rest, to seem a perfectly responsible pattern in view of the EM movements, and so he draws back into the gully, toward an outcropping of blue-green rock.
A burst of orange throws shadows before him. He pauses at the mottled blue-green place, puzzled, remembering, but the second flash blinds him and then comes a crashing, stones shower him, a rough roar makes him peer upward where the mountain belches clouds and flames, long streams of lava now pouring from the sagging mouth of the fresh crater, huge jets of steam gushing forth into the banks of dust, the moisture clearing the air before it, the sulfur oxides now falling into the valley beyond, where they will feed the scrub plants and weak little animals, the bottom of the food chain which the EMs tap, and have been tapping for a vast long time now, though how long the geologists cannot say, with the crust of Isis always churning and destroying all evidence of the past.
Nigel turns back to the mottling, curious, reaches down—and suddenly sees the EM, sluggish but steady, legs jerking, coming dead toward him. The big head is fixed directly at him and Nigel hopes his radio blanket looks to the EM like a boring, typical rock. He inches backward, shuts down all carrier waves, braces—
But the EM halts, ignoring Nigel, head swiveling, and cants itself, settling downward, thrusting the lumpy black knobs in its abdomen, lowering itself until they make contact with the blue-green veins in the rock.
Its waxy skin ripples, it settles farther, the glazed blue of its skin begins to pulse with other colors, as soft purples seep from the abdomen, and Nigel reminds himself that in the Ra light this purple is in a fact a green, a biochem flag of a porphyrin derivative, but the colors wash away the thought as magentas and hard yellows and sprays of red curl across the body of the EM, flowing as boom the volcano above rips light through the hovering sheets of fine dust, a stream of lava splits the rock face fifty meters away with a sudden lance of orange, and the EM trembles, trembles, tilts lower, seems to shake with a kind of lust and hunger, not noticing the second and then a third large shape that emerge from the slow, spattering rain that now begins to fall, fat dollops of moist sulfur oxides, drops that streak the approaching, lurching shapes as they lower themselves in turn to the outcropping, ponderous, their mircrowaves filling and merging with a new and stronger weave, the scattershot clicks and barks of radio-shifting as the ground surges and a crashing explosion high up the mountain pours light into the gully, the EMs signal now, flowing into song, their boxlike heads tilting, scanning, a steady note emerging now as Nigel recognizes the long, low tone that is from the old Earth-side radio show.
They are joining together to point at the sky and send the slow mournful impulse that will wed with the other millions of EMs and stretch across the light-years toward the Earth, a mere dot in the sky that so long ago seemed to speak to these time-weary creatures.
A shower of bright orange blossoms at the abdomen of each EM. Sparks cut the air. Nigel backs away.
A crackling fills his pickups and the EM fugue grows, the huge bodies rocking slightly as the air cracks and snaps with energy, dancing singing joy forever, brimming, flying, the lava crashing over the ridge, prickly heat pours from it, and Nigel sees suddenly how the EMs live for this moment, the single time when they have enough swelling, filling life to burst forth and claw up at the sky that holds a speck of hope and promise, some possibility beyond the smothering sameness of their twilight rusting world.
They seek the volcanoes for food, not for warmth. The lava flows down thousands of meters of mountainside, a hot metallic conductor falling in the strong magnetic field of Isis, cutting the magnetic field lines and generating currents, electric fields, a vast circuit that cannot close easily because the rock around the lava is inert, a poor conductor, and so the electrical current builds as the lava flows, cutting across more field lines, gathering energy until it strikes a seam of metal-rich ore and suddenly the circuit can close, it is shorted, the vast currents run through the blue-green rock layers, seeking a return channel to the top of the mountain, to complete the loop, blind current following Faraday’s remorseless law.