“Yes,” she said. “See, Mom, the thing is, it’s one thing to simulate a brain. It’s another thing to talk to it. We forget this because our brains are hooked up to bodies with handy peripherals like tongues that can speak and fingers that can type. As long as those work, you can always get some idea of what’s going on in a brain. But a brain in a box doesn’t have those. Which is probably another reason that no one has tried this yet.”

“Namely, that there’s no point in doing it if you can’t get meaningful information out.”

“Yeah, it’s like hooking an EEG up to a patient in a coma,” Sophia said.

“That is a useful analogy.”

“The EEG is a legit scientific instrument. It’s definitely telling you something about brain activity. No question about it. But you can stand there all day looking at the strip of paper coming out of the EEG, staring at the wiggles, and still not have the faintest idea whether anything useful is actually going on inside of that brain. Whether the person is conscious. What they’re thinking.”

“And here the EEG is an analogy for what exactly?” C-plus asked. He knew, of course. He was prompting her.

“The burn rate. The cost. The monetary cost of running the simulation. When a lot of neurons are engaged and a lot of signals are being passed over the connectome, the quantum processors at Hole in the Wall are busy, and so the system charges us more money, and draws it down from the account. I can log on and watch the balance in the account declining. Sometimes it declines fast, sometimes slow. If I draw a graph of the burn rate, it looks like this.” She peeled the top sheet off the pad to expose a new page and slashed out a long horizontal axis that presumably represented time. A shorter vertical axis was burn rate. Starting at their origin, she began to draw a line across the page, wiggling the pen randomly up and down. “At first, a lot of what looks like noise. Activity comes and goes in surges. I tried running some statistical packages against it but it’s pretty close to just chaos. But then later we start to see some periodicity emerge.” She began ticking the pen up, down, up, down, in a steady rhythm. “Like a heartbeat. Just for a little while. Then back to random.” More pen shaking. She was approaching the edge of the paper. “Just within the past week, though, it really settled down.” She slowed the pen’s progress and marked out a neat, regular series of ramps, each ramp ending with a sudden drop toward zero. The last of them went off the page. Having run out of paper, she flipped the pad around and held it up so that Enoch and C-plus could see her handiwork.