# Short story about aliens sending messages to Earth and prime math being key to decoding

I read this short story probably in the 2000s, but I don’t know how old it was then.

Story beats I remember:

• Aliens decided it was too much work to actually travel, so they just beamed messages to other planets.
• We receive a message and are struggling to decode it.
• There is the usual math stuff that is universal and easy to figure out. Like symbols for adding and equals and digits and primeness.
• Then the message introduced a statement like “1 @ prime” — and this turned out to mean “maybe” because a civilization could reasonably define 1 as prime or not.
• From this small beginning of a subjective word, the message was able to finally escape the dry world of math.
• The message was a DNA sequence and instructions to make an alien clone. This was how the aliens “traveled” to other planets.
• The humans that decoded the message built an alien and raised it and story ended happily.

I’ve always loved that maybe-prime jump from math to more interesting topics. But I have never been able to remember the name of the story.

• You've put "1 @ prime" into quote marks. Is this intended to be a direct quote that you recall from the book? Commented Nov 12, 2023 at 13:04
• Hi, welcome to SF&F. Did you read this in a magazine or an anthology (or online)? Commented Nov 12, 2023 at 13:04
• Primes being used in decoding is common in sci-fi... and in reality. See for example the Arecibo Message. Commented Nov 12, 2023 at 21:53
• Valorum, no sorry that was not meant to be a direct quote, just an example — there was some sort of alien symbol for “maybe” between the symbols for “1” and “prime”. Good question! Commented Nov 13, 2023 at 14:09

It isn't a short story, but the idea that 1 perhaps is prime is part of decoding the alien message in Robert J. Sawyer's novel Rollback (2007).

"You're right. It is a debatable point. One is definitely an odd-ball as primes go. And two — well, it’s not an odd-ball; it's an even-ball. That is, it's the only even prime number. You could just as arbitrarily define the set of primes as all odd numbers that have precisely two whole-number factors. If you did it that way, then two isn't a prime."

"Ah."

"See? That's what they're conveying. Delta is a symbol that means, I think, 'It's a matter of opinion.' Neither answer is wrong; it's just a matter of personal preference, see?"

The novel also matches the part about the aliens sending the information required to clone bodies for certain individuals to meet other intelligent races:

"It's a — a blueprint, I guess you could call it."

"You mean for a spaceship? Like in Contact?"

"No. Not for a spaceship." She looked briefly at Gunter, then back at Don. "For a Dracon."

"What?"

"The bulk of the message is the Dracon genome, and related biochemical information."

He frowned. "Well, um, I guess that'll be fascinating to study."

"We're not supposed to study it," Sarah said. "Or at least, that's not all we're supposed to do."

"What then?"

"We're supposed to" — she paused, presumably seeking a word — "to actualize it."

"Sorry?"

"The message," she said, "also includes instructions for making an artificial womb and an incubator."

Don felt his eyebrows going up. "You mean they want us to grow one of them?"

"That's right."

The book ends with Don and his new wife Lenore raising two Dracon children alongside their own children.

It's not a short story, though, it's a complete novel. It was, however, serialized in Analog in 2006, so that might be confusing you.

• You're very welcome Commented Nov 12, 2023 at 14:02
• That must be it! Memory is fickle and it must have been a full novel. Thank you so much! Commented Nov 13, 2023 at 14:11