Morse Signal · You Are Not Alone

21:47. On the twelfth floor of No. 12 Residential Tower on the Seventh Ring Road, the light in one window began to flash. That building is about 400 metres from Qiu Che's home in a straight line; he lives on the nineteenth floor, and his line of sight runs level with the height of the twelfth.

The flashing had a pattern, and it matched none of the fixed frequencies in this city — the warning lights on public buildings run at a fixed frequency, the advertising projection boards run at a fixed frequency, the emergency lighting runs at a fixed frequency too. The one in the window went short, short, long, pause, long, short, long, pause.

A Skylink search for "light signal ancient communication method" returned one entry in 0.6 seconds: Morse code, developed in the mid-19th century, formally retired from global public communication systems after 2030, now used only in historical preservation, military backup and among amateur radio enthusiasts.

Recording with Skylink uploads to the cloud automatically, and the window across the way would draw an anomalous surveillance request within about 5 minutes. So the tools left were paper, pencil and eyes. A short flash marked as "·", a long one as "—", a pause as "/", and 20 minutes filled three complete cycles.

The first reading came out wrong — the starting point had been taken from the middle of a cycle, and what it read was WORRY followed by NOT ALONE, which would not join up. He waited for the next round, fixed on the longest pause, and counted again from where the message truly began:

DON'T WORRY. NOT ALONE.

Seventeen letters. Skyvault did not translate this string of signals for him.

With a small flashlight bought at a stationery shop, he sent back the same short, short, short. The other side returned the same three, and then the light turned steady, not flashing, not going out. 3 minutes later ten windows on that floor lost power at once, and 3 seconds after that they came back at a brightness and colour temperature exactly matching every other floor. From the first time the flashlight lit to the moment that floor was synchronized: 3 minutes 12 seconds.

The next morning he pulled the curtain open a crack and counted three windows to the left and three windows to the right: grey-white curtains, no light leaking at the edges, and nowhere on that floor a single window left holding any trace of being out of step.