Knowing she should close up shop and get some sleep, Alison closed her browser. There was another window behind it, showing a scrolling page of…text? Code? Instinctively she went to close it. However, another window had opened up within it, and another within that, like a digital Russian doll. She went cold and hit the trip switch on her internet connection, for what little good it would do. There was a third nested window now, with even smaller text running rapidly in weird, random conglomerations of ASCII pixels. It was as though her computer was possessed and trying to enunciate demonic language.

Convulsively, she yanked the power cable. Her heart began to hammer as the screen stayed lit, impossibly, even as the lights on the computer hard drive died. The distorted characters inhabiting the inner window were speeding up exponentially. In the slower code in the outer windows she began to catch snippets: names, dates, coordinates.

A large slice of her psyche was denying that any of this was happening, preferring to believe this was a tiredness-induced hallucination—or even the introduction of some neural agent into her system. The rest of her, concerned with gathering intel no matter how impossible, fumbled her phone out. She started taking photos of the screen with shaking hands.

Forty seconds later, the screen died at last. When she booted the machine up in safe mode, it worked perfectly. Then came a thorough scan, a search through the memory, attempts to look over recent histories…but there was no evidence that anything untoward had happened. Only the photos on her phone stood as mute testimony.

She put her head in her hands, breathing heavily. It wasn’t that it had happened; it was that it had happened again.

Interlude: The Philosophers

Excerpt from Other Edens: Speculative Evolution and Intelligence by Professor Ruth Emerson of the University of California

What if—bear with me—a civilization of gigantic immortal spacefaring trilobites didn’t evolve? I know, it seems hardly credible, but imagine, if you will.

Our own timeline shared the events of the trilobites’ time until it didn’t. Until that point in a shared Cambrian where the arthropods sealed their eternal dominance in their version of history. Whereas in our timeline the plucky vertebrate descendants survived and prospered, and went on to…

But it’s not time to tell that story yet. For here’s another divergence point, budding away and writing its own timeline. This is another Earth we never knew, which gave rise to something that could know itself. And there will be others, each sharing a history with ours right up to the point it doesn’t—diverging from our history one after another, each one the “real” Earth to the things that evolve in it.

In this Earth’s timeline, sentient trilobites didn’t evolve. Their kin exist, certainly, and they will persist here for longer than in our world, but they are not masters of the world.