He recognized the tidy, economical lettering as his own, but had no memory whatsoever of writing those words, or any of those on the dozens of pages that followed.

“I’ve got to stop,” he said aloud. “The condition I’m in, I can’t be trusted not to screw things up.”

He listened to the words carefully, and decided that they made sense. Wearily, he wrapped up the head in aluminum foil and placed it in the refrigerator, ejecting a month-old carton of grapefruit juice and a six-pack of Diet Pepsis to make room for it. He didn’t have a padlock, but a little rummaging came up with a long orange extension cord, which he wrapped around the refrigerator several times. With a Magic Marker he wrote, Danger!!! Botulism experiment in progress—DO NOT OPEN!!! on a sheet of paper, and taped it to the door.

Now he could go home.

But now that the head—the impossible, glorious head—was no longer in front of him soaking up his every thought, he was faced with the problem of its existence.

Where had it come from? What could possibly explain such a miracle? How could such a thing exist?

Time travel? No.

He’d read a physics paper once, purporting to demonstrate the theoretical possibility of time travel. It required the construction of an extremely long, large, and dense cylinder massing as much as the Milky Way Galaxy, and rotating at half the speed of light. But even if such a monster could be built—and it couldn’t—it would still be of dubious utility. An object shot past its surface at exactly the right angle would indeed travel into either the past or the future, depending on whether it was traveling with the cylinder’s rotation or against it. But how far it would go, there was no predicting. And a quick jaunt to the Mesozoic was out of the question—nothing could travel to a time before the cylinder was created or after its destruction.