Dark as Day

When she came to the very end of the signal, with its termination as a repeated pattern of the fourteen-bit stop sequence, Milly at once went back to the begi

Something she had brought with her from Argus Station, more important than clothing or personal effects, was her own suite of processing programs. She had no illusions that they were better than anyone else’s; what she was sure was that they were different. Also, they were hers, and she knew them inside-out.

She began her analysis. It was similar to what she had attempted months ago, with one crucial difference: she could now build on everything established or conjectured by the Puzzle Network group. The start-stop coding sequence was known. She was sure of the integers. Perhaps most important of all, she knew that what she was dealing with was a signal. Puzzles always become easier when you know that a solution exists.

The section that she clipped out for inspection was only a small section of the whole, roughly a hundred million digits out of twenty-one billion. You could eat that up very quickly with images, but she had deliberately avoided low-entropy data runs. What she hoped to find was “text” — whatever that term might mean to an alien mind. It was too early in the game to hope for keys to an actual language.

After the first few minutes, Milly entered the twilight zone. Her mind became a place where symbols took on their own life and formed their own relationships. The signal contained dozens of these, short and well-defined strings that had been identified by other workers as common repeat patterns, but were not yet understood as to meaning. Sometimes the unknown strings appeared close to known integers, sometimes they coupled only to other unknowns. At this stage of understanding, the “knowns” lay within a great quagmire of uncertainties. The trick — if a trick existed — was to stand on a firm starting-point, something you definitely understood, then discover a sequence that allowed you to scramble out along it to reach another point of understanding.

Milly worked on, oblivious to where she was or how long she had been sitting there, until she found her attention returning, again and again, to a sequence containing only a few tens of thousands of digits. She had culled it piece by piece from the sea of a hundred million bits, without knowing at a conscious level what she accepted and what she rejected.

What made these samples different from any random selections? They seemed like a meaningless mixture. The pattern, if it could be called a pattern, comprised sets of small integers, always separated from each other by a repeated string. That string always contained the same twenty binary digits, and it could indicate an actual number but more likely stood for a symbol of some kind. Milly gave it a name. Call it the 20-bit “co

Milly substituted the word “co

On the face of it, she didn’t have much. Here was eight-co

Signifying?

Milly concentrated until the numbers and words swam and wandered and wobbled in front of her eyes. Pattern recognition was what humans did well, better than any computer so far built.

There had to be a pattern, right?

Right! So recognize it!

The display sneered back at her, Right! If you can!

Milly closed her eyes, took a deep breath, and sat motionless for a long time. At the conscious level, she seemed to be drifting from thought to random thought. But when she opened her eyes she was changing the word “co

The section she had been looking at became: 8 — 6 — 8, 8 — 7 — 8, 1 — 8 — 1, 1,1 — –6 — –1,1. If anything, that was more confusing than before.

And then, suddenly, it was not confusing at all. Milly shivered and rubbed her eyes. How dense could you get? Before she started, she had told herself the order in which a rational being would try to construct meaningful messages: mathematics, then physics, then chemistry. When that was done, you could consider interpreting biology and language.

Mathematics they had, at least at the level of the integers. It might be months or years before they advanced to complex variables and algebraic topology and the theory of continuous groups, but you did not need all those for a start on other subjects.

In physics and chemistry, what was the most obvious and fundamental information a message might offer? The periodic table was a basic building block, invariant across the universe. Hydrogen came first, helium second, lithium third, and so on right up through all the stable elements. Carbon was sixth, nitrogen seventh, oxygen eighth, and you had absolutely no choice in those assignments.

So now:

8 — 6 — 8: carbon dioxide, complete with the symbol for a chemical bond.

8 — 7 — 8: nitrous oxide.

1 — 8 — 1: hydrogen-oxygen-hydrogen — water. If you were a human, you would have placed that first. Did it occur more frequently than the other symbols? Milly would have to go back and check.

And 1,1 — –6 — –1,1? The dash was a clumsy notation for a two-or three-dimensional bond, but the reader was presumed to be intelligent. This one was methane, CH4, carbon with single bonds to four hydrogen atoms. Maybe the 2-D or 3-D representation would be found elsewhere in the signal, but meanwhile this would suffice. Sca

It wasn’t a great discovery, maybe it was just one small step up the mountain of understanding involved in deciphering an alien message. But it was her step, one that no one else had ever taken. Milly didn’t just want to post it on the Puzzle Network displays. She wanted to tell somebody, shout it to the world before her brain burst and the information was lost.

She stood up quickly, swayed, and grabbed the edge of the console. She came close to blacking out and had to drop back into her seat to save herself.

As dizziness receded she glanced over to see what time it was. Well past midnight. At once she knew what was happening. It was her old problem. She had sat alone in her cubicle, oblivious to everything but the displays and her own thoughts, for more than half a day. Now that she was again aware of her body, her mouth was dry and her throat felt as though it could not swallow. She needed a drink, and she needed to go to the bathroom — and both those things took priority over the table of the elements.

She stood up, more carefully this time, and eased her way to the cubicle door and out into the corridor. She did not know where the bathroom was, but instinct told her that there must be one close to a conference room. She moved slowly along the corridor to the end, supporting herself with a hand on the wall and glad now that all the doors were closed.