Echo

The structure had been dark for five days when it spoke again.

Not the warm amber of its dimming — not any light at all. The optical array showed nothing. But Mira had left the hydrophone array running because she hadn't been able to bring herself to shut it down, and at 3:47 AM ship time the alert went off.

Not a countdown. Not coordinates. A compressed burst on a frequency so low the division's instruments never registered it — below the threshold Kwan's team had calibrated for, below even the fear frequency Eriksson's team had documented on Svalbard. Not 18 Hz. 3 Hz. A frequency the human body feels as pressure in the sternum, as a weight on the chest.

She worked for six hours to decode it.

What emerged was not a message in the way she'd learned to expect messages. It was a record — the kind you keep not to send but to preserve, the way certain civilizations wrote histories not for an audience but because the act of recording was itself the act of caring.

They had been watching this arm of the galaxy for longer than the arm itself had been stable. Every intelligent species that had arisen here was documented: first emergence, communication development, reach into space, and then — for most of them — an end date. Mira scrolled through the catalog and felt the weight of it accumulate.

Forty-seven species. Forty-three had end dates.

Humanity was entry forty-seven. No end date. But there was a notation beside it that she had to decode separately: a flag, a marker, something that translated roughly as approaching threshold.

She found the entry for the species most similar to humanity — similar trajectory, similar timeline, similar level of development at the point of their flag. They had reached threshold approximately eleven thousand years ago and made a choice. The record noted the choice without judging it.

Seven hundred years after the choice, they were gone. Not gone-away. Gone.

The record was clinical. The beings documented facts. But reading through the notation of a species' complete absence, Mira found the grief from layer five again — the enormous preserved grief she'd heard in the dark — and understood something.

They cared. They had been watching for four billion years and they still cared when something ended.

She filed her own notation in her log: I don't know what threshold is. I don't know what choice that species made. I don't know if we've made it yet.

She looked at the timestamp on humanity's entry.

She looked at the date of the notation beside it.

The flag had been placed two hundred and twelve years ago.

Whatever threshold was, they had already decided humanity was approaching it.

The question she couldn't answer yet was: approaching from which direction?