"Okay," I said.

"Ah, but it's not okay! See, if you ask people to indicate exactly when they decided to do something, they report that the idea occurred to them about 350 milliseconds before the motor act begins. A guy named Benjamin Libet proved that ages ago."

"But — but that must be a measurement error," I said. "I mean, you're talking about milliseconds."

"No, not really. The difference between 550 milliseconds and 350 milliseconds is a fifth of a second: that's quite a significant amount of time, and easy enough to measure accurately. This basic test has been replicated over again over again since the 1980s, and the data are rock solid."

"But that doesn't make sense. You're saying—"

"I'm saying that what our intuition tells us the sequence of events should be, and what the sequence actually is, don't agree. Intuitively, we think the sequence must be: first, you decide to shake hands with your old friend Bob; second, your brain, in response to that decision, begins sending signals to your arm that it wants to shake hands; and third, your arm starts to swing up for the handshake. Right? But what really happens is this: first, your brain starts sending signals to shake hands; second, you consciously decide to shake hands with your old friend; and third, your arm starts to swing up. The brain has started down the road to shaking hands before you have consciously made any decision. Your conscious brain takes ownership of the action, and fools itself into thinking it started the action, but really it's just a spectator, watching what your body is doing."

"So you are saying there's no free will."

"Not quite. Our conscious minds have the free will to veto the action. See? The action begins 550 milliseconds prior to the first physical movement. Two hundred milliseconds later, the action that's already been started comes to the attention of your conscious self — and your conscious self has 350 milliseconds to put on the brakes before anything happens. The conscious brain doesn't initiate so-called voluntary acts, although it can step in and stop them."

"Really?" I said.

Porter nodded his long face vigorously. "Absolutely. Everybody's experienced this, if you stop and think about it: you're lying in bed, quite mellow, and you look over at the clock, and you think to yourself, I really should get up, it's time to get up, I've got to go to work. You may think this a half-dozen times or more, and then, suddenly, you are getting up — the action has begun, without you being consciously aware that you've finally, really made the decision to get out of bed.

And that's because you haven't consciously made that decision; your unconscious has made it for you. It — not the conscious you — has concluded once and for all that it really is time to get out of bed."

"But I didn't have this problem when I was biological."

"No, that's right. And that was because of the slow speed of chemical reactions. But your new body and your new brain operate at electrical, not chemical, speeds, and the veto mechanism sometimes comes into play too late to do what it's supposed to do. But, as I said, I can make a few adjustments. Forgive me, but I'm going to have to pull back the skin on your head, and open up your skull…"

Finally, it was time to go back home. And when I got to the house in North York, I couldn't wait to see my lovable old Irish setter. "Clamhead!" I called out, as I came through the front door. "Here, girl! I'm home!"

Clamhead came bounding down the stairs, but stopped short when she saw me. I'd expected her to leap up and kiss my face, but that didn't happen. Indeed, she lowered her forelegs, lay her ears flat, reared up her hind legs, and barked menacingly at me.

"Clamhead, it's me!" I said. "It's just me."

The dog barked again, and then growled.

"Clammy, it's just me, honest!"

The growl became a snarl. The front door was still open and I thought about making a run for it. But no, damn it, no. This was my house.

"Come on, girl, it's just me. It's just Jake."

Clamhead leapt. I managed a half-step backward, but she slapped her paws against my chest, and barked loudly, over and over and over again.

"Clammy, Clammy!" I said. "Sit, girl! Sit!"

I'd never known Clamhead to bite anyone, but she bit me. I was wearing a short-sleeve shirt; she closed her jaws on my naked forearm and yanked backward, tearing out a ragged piece of plastiskin, revealing fiber-optic nerves, bungee-cord muscles, and a blue metal armature within. She fell back on her haunches, and sniffed at the piece of plastic, then turned tail, and bounded away up the stairs, whimpering.

My heart wasn't beating fast — because I had no heart. My breathing wasn't ragged — because I did not breathe. My eyes weren't stinging — because I could not cry. I just stood there, letting time pass, shaking my head slowly left and right, feeling rejected and alone.

The spider-shaped moonship landed next to a small cluster of mirrored domes, near the crater Aristarchus. After three days of zero-g, having any weight at all felt oppressive. But, really, it was a gentle tug, only one-sixth of what was normal on Earth.

The Immortex staffer had been wise to warn us: the moonbase here was utilitarian at best — it felt like the inside of a submarine. Sadly, we had to spend three days here, going through decontamination procedures. With hundreds of potential points of departure from Earth, and only one possible lunar arrival point, it made sense that the elaborate decontamination facilities were up here, not down there.

This had been the first permanent base established on the moon. It had originally been built by the Chinese, and a lot of the signage was still in that language, but it was now administered by a multinational consortium. Its official name was LS

One — Lunar Settlement One — but in honor of the arriving immigrants, someone had erected a big sign that said "LS Island," a pun it took me a few moments to get.

And I was indeed an immigrant: this world, this airless, dusty sphere, was going to be my home for the rest of my life — however long that might be. Of course, here on the moon, the vessels in my brain would be subject to less stress, so perhaps I'd last longer than I would have had I stayed down on Earth.

Perhaps. In any event, the doctors at High Eden would know precisely what to do if I had an … incident. The advance directive I'd sworn out was a contract, and contracts must be honored.

"All Immortex passengers," said a voice over an intercom, "please report to decontamination."

I headed down the corridor with a bounce that I didn't feel in my step.

I am a Mindscan, an uploaded consciousness, a transferred personality, and yet, despite having fewer external indicators of my internal mental state, I am still very much corporeal.

For centuries, humans have claimed to have out-of-body experiences. But what is the mind divorced from the body? What would a recording of my brain patterns be without a body to give them form?

I've always pooh-poohed the notion of out-of-body experiences, of the idea that you can look down upon your own body from above. After all, what are you looking with? Surely not your eyes — they're part of your body. Could an incorporeal entity sense anything? Photons need to be arrested to be detected; they have to hit something — the back of the eye to be seen as light, the skin to be felt as heat. A disembodied spirit could not see.

And, even if it did somehow detect things, no one ever claimed to have anything but normal vision when out of their body. They see the world around them as they always have before, just from a different angle. They don't see infrared; they don't see ultraviolet — vision without eyes seems exactly the same as vision with eyes. And yet if eyes are not really necessary for sight, why does plucking them out — or even just covering them — always, without fail, result in a loss of vision? And if it's just a coincidence that out-of-body perceptions happen to resemble what eyes see, why do color-blind people, like I was, never report a world of hues previously unknown to them when they have out-of-body experiences?