vertical line represents the flow of time from past to future.” He stopped the line in the middle of the board, drawing a dot and labeling it with an
x
.
“This is the first time
x
. This is where Nagato changed the world that surrounded her, and where the time as it exists in your memory was created.”
Koizumi resumed the movement of the pen, but he did not directly continue the line. Instead it curved to the right, eventually creating a circle that returned to point
x
. The diagram now looked like a morning glory sprout with one leaf plucked off.
“The circle is the history that you remember since December eighteenth. You used the escape program to travel back to the Tanabata four years earlier, then jumped back to the morning of December eighteenth. If Nagato had just been repaired at that moment, everything would have been fine, but that’s not how it went.”
Yeah, because Ryoko Asakura was there. But Asakura wasn’t the only one there. There was also another version of me fromthe future, along with Asahina and Nagato, and we managed to put things right. From my perspective now, it had happened a month ago.
“Indeed. You saved yourself. And that”—Koizumi’s pen started at
x
again, this time drawing a circle that looped to the left—“is this point, from which this world is now continuing. In Suzumiya’s memory as in mine, you fell down the stairs on December eighteenth and were unconscious until the twenty-first. And a month later, you would travel back from this timeline to go save yourself.”
Once he’d finished drawing the circle to the left of the line, Koizumi didn’t stop. He then continued on past the
x
, extending the line up until it reached the top edge of the board, then setting the pen down. Koizumi then took a half step back from the board and regarded me carefully.
I quickly grasped the nature of the diagram. It looked like an eight turned sideways—the symbol for infinity—with a line exactly bisecting the point between the two loops. Point
x
was where all the lines met.
Even I, who’d long proclaimed my cowardice in the face of math and science, gradually began to understand what Koizumi was trying to explain.
The loop on the right was the time in my memory. After a lot of hassle, I’d returned to point
x
and met glasses-Nagato just as she was changing the world, then gotten stabbed by Asakura.
On the other hand, the loop on the left was time of which I had no memory. I’d been stabbed, lost consciousness, been taken to the hospital where I was in a bed for three days until waking up—all within that loop.
And both of those loops had their start at
x
.
“Which means that there are two points
x
,” explained Koizumi. “There’s point
x
, where the world was changed, and… let’s call it
x'
, where the change was undone,” he said, looking contemplatively at his diagram. “Without
x
, there can be no
x'
. So
x
was not erased. You can probably think of them as being superimposed.Yes… one written atop the other. Just as old data is covered up by new data written atop it,
x
, along with the changed world that followed from it, was overwritten by
x'
, but it hasn’t disappeared completely. It’s still there.”
“I do not remotely understand,” I said with nonchalance even as I recalled Asahina the Elder’s words.
An even larger and more complex space-time-quake
, she’d said.
“It’s something like looking at a multilevel circuit board from above. There are points where the circuits appear to cross each other in two dimensions, but when you factor in the third dimension, you see they’re on different levels. Things that appear to occupy the same space in two dimensions differ in depth.”
I rubbed my temples. Koizumi was explaining all this, but I wondered what a time traveler would say. Or an alien.
“There is another possibility. May I explain?”
Given the circumstances, I’d listen to whatever the hell he wanted to say.
“The memory that you
Johnny Shaw, Matthew Funk, Gary Phillips, Christopher Blair, Cameron Ashley