Tosco said, “Have you checked that you’re not saturating the light paper’s response? Outside a limited range of intensities, that coating just flattens any variation in brightness.”
“We’ve checked,” Carlo replied tersely. Amanda added, “Everything’s been calibrated so it lies within a suitable exposure range. We won’t get the original light curve back, but any distortion should be comparable to the natural range of variation in the signal.” If the brain itself didn’t send out identical sequences for the same action every time, the flesh ought to be as forgiving with this artificial version as it needed to be with the biological messages it received every day.
The inverter gave a soft thud as its tension arm detected the end of the spool, halting the drive. Amanda retrieved the duplicate tape and rewound it slowly so Carlo could scrutinize it. The darkest paper in the original recording had protected the second strip from the lamplight in the inverter, allowing it to remain almost translucent, while the most translucent parts of the original—those exposed to the weakest signal from the probe—would have offered far less protection, allowing the duplicate to darken almost to opacity.
Carlo could see no sudden shifts in the tone of the paper that would indicate a surge or deficit of the sensitizing gas, and no stretches of flattened contrast that would imply that they’d saturated the coating. Light recording was a finicky art, but their experience was beginning to pay off.
“What do you think?” Amanda must have reached her own conclusion, but she kept her voice neutral. If Carlo wanted to declare the tape unusable—giving him an excuse to back out of the experiment—that was up to him.
“It’s fine,” he declared. As he spoke, he felt his left forearm twitch in dissent: a needle of hardstone driven through his wrist wasn’t fine at all, and every scrag of his flesh knew that there was a stranger incursion yet to come.
Amanda loaded the duplicate tape into the light player, running the leader through onto the receiving spool. She gently tugged the connecting arm from the left-hand probe out of its socket in the light recorder and swung it around toward the new machine. When it was in place, there was one more adjustment to make: she reached down and took hold of the probe itself, and turned the ring attached to the mirror at the bottom of the needle. Before, it had faced back up along his arm, to catch some of the light arriving from his brain. Now it was angled toward that light’s destination, down the motor pathway into his hand.
“Why doesn’t he just use a vole?” one of Tosco’s students whispered to another.
“That needle’s too big.”
“So why not make it smaller?”
“Be quiet, or you’ll be playing vole next time.”
Carlo said, “A smaller needle wouldn’t capture enough light. We’ll need to develop more sensitive paper before we can shrink the probes.”
“Are you ready?” Amanda asked him. She’d wound the player’s spring and lit the lamp while he’d been distracted by the students.
Carlo started to relax his left arm—doing his best to surrender control, to prepare himself not to fight what was coming—but then he felt the slight change in muscle tone threaten to shift the probe. He didn’t really need to disown the whole limb, though, so long as he could hold back the urge to intervene when the ghost of his earlier self started taking liberties with his body.
“I’m ready,” he replied.
Amanda engaged the drive on the player. Carlo gazed down his arm at his finger, which was moving without his bidding.
Cold nausea churned through his gut and esophagus, loosening food tubules from mouth to anus; he fought it and managed to hold onto his breakfast. There was nothing painful in the sensations coming from his finger—but a part of his brain was insisting that some kind of parasite had invaded the flesh, and its alarming twitches could only presage the likelihood of it burrowing even deeper. As he struggled to understand precisely where this revulsion was coming from—focusing his attention on the stretching of the skin, the tension in the muscles, the disposition of the joints—he couldn’t identify any one thing he hadn’t felt when he’d performed the same movements willingly. But he couldn’t separate that raw sensation from the context and declare that it was as innocent as before. Flesh that moved of its own accord simply could not be treated with equanimity.
When the playback stopped, Carlo shuddered with relief. The illusory parasite lingered for a moment, a fat dead thing trapped under his skin, but when he crooked his finger a few times it vanished. He realized that he hadn’t had the presence of mind to check his movements against the original script; he looked to Amanda for her verdict.
“The mimicry was pretty close,” she said. “A few gestures were dropped or ambiguous, but most were repeated accurately.”
Some of the onlookers offered congratulatory cheers. Carlo felt drained, but as his nausea faded he managed a chirp of satisfaction. As primitive and unpleasant as the whole demonstration had been, it had established an important principle. All the more so if they could repeat it with one more twist.
Amanda had already started rewinding the tape. “Give me a lapse or two,” he told her.
“You don’t have to do the second stage today,” she replied.
“I’m not wasting that spike in my wrist.” Carlo turned from her and saw Tosco watching him in silence, then he shifted his gaze slightly and addressed the man’s students. “You can mark this day as the birth of a new field,” he proclaimed. “The light recorder will revolutionize the study of the brain’s signals—and light puppetry will be the best way to compare those signals in different species.” Once they refined the equipment, they could replay the instructions from one vole’s brain in a distant cousin’s body and see which parts of the signal were interpreted the same way in both species. Not every nuance would be the same, but flesh was flesh, it all shared a common ancestor. With time and patience, they could take this language apart and uncover all its subtleties, as surely as scholars of ancient writing had decoded old engravings by their own process of comparison.
He nodded to Amanda to proceed. She uncoupled the connecting arm from the first probe, and swung it over toward his right hand. Carlo resisted the urge to pluck the needle out of his left wrist immediately; sometimes the extraction went horribly wrong, and he didn’t want to vocalize that much pain in front of an audience.
With the player connected to the right-hand probe, Carlo spent a moment preparing himself. It hadn’t been so bad the first time, and now he knew exactly what to expect. His gut had settled, he wouldn’t disgrace himself.
“I’m ready,” he said.
Amanda engaged the drive.
The finger they’d targeted with the probe remained motionless. “What?” Frustrated, Carlo moved his forearm slightly, just enough to feel the bite of stone against his flesh. Suddenly his whole right hand sprung to life: all six fingers flexing and waggling, turning and twitching, wriggling like worms with their heads in a trap.
With one word he could have had the signal shut off, but Carlo wanted to see this final stage play out; even with the probe misaligned it could tell them something useful. His sense of violation was more acute than before, but he could tolerate it for a couple of lapses. He glanced at Amanda; she was diligently observing his contortions, trying to judge how well they conformed to the script. Carlo could only be sure of one detaiclass="underline" some of his fingers were moving differently than others, so they couldn’t all be doing the right thing.