"Lungfish"

a short story by David Brin

Currently published in The River of Time.
Copyright © 1987, by David Brin. All rights reserved. No duplication or resale without permission.

Greeter is right. One of the little humans does seem to be on the track of something. We crippled survivors all listen in as Greeter arranges to tap the tiny Earthship's crude computers, where its Captain stores her speculations.
     Her thoughts are crisp indeed, for a biological creature.
     Still, she is missing many, many pieces to the puzzle....

THE LONELY SKY
by Ursula Fleming

After centuries of wondering, mankind has at last realized an ancient dream. We have discovered proof of civilizations other than our own.
 
In the decade we have been exploring the Outer Belt in earnest, humanity has uncovered artifacts from more than forty different cultures... all represented by robot starships... all apparently long dead.
 
What happened here?
 
And why were all those long-ago visitors robots?
 
Back in the late twentieth century, some scholars had begun to doubt that biological beings could ever adapt well enough to space travel to colonize more than a little corner of the Milky Way. But even if that were so, it would not prevent exploration of the galaxy. Advanced intelligences could send out mechanical representatives, robots better suited to the tedium and dangers of interstellar spaceflight than living beings.
 
After all, a mature, long-lived culture could afford to wait thousands of years for data to return from distant star systems.
 
Even so, the galaxy is a big place. To send a probe to every site of interest could impoverish a civilization.
 
The most efficient way would be to dispatch only a few deluxe robot ships, instead of a giant fleet of cheaper models. Those first probes would investigate nearby stars and planets. Then, after their explorations were done, they would use local resources to make copies of themselves.
 
The legendary John Von Neumann first described the concept. Sophisticated machines, programmed to replicate themselves from raw materials, could launch their "daughters" toward still further stellar systems. There, each probe would make still more duplicates, and so on.
 
Exploration could proceed far faster than if carried out by living beings. And after the first wave there would be no further cost to the home system. From then on information would pour back, year after year, century after century.
 
It sounded so logical. Those twentieth century scholars calculated that the technique could deliver an exploration probe to every star in our galaxy a mere three million years after the first was launched -- an eyeblink compared to the age of the galaxy.
 
But there was a rub! When we humans discovered radio and then spaceflight, no extra-solar probes announced themselves to say hello. There were no messages welcoming us into the civilized sky.
 
At first those twentieth century philosophers thought there could be only one explanation....

Let us re-create the logic of those philosophers of the last century, in an imagined conversation.
 
 
"We will certainly build robot scouts someday. Colonization aside, any truly curious race could hardly resist the temptation to send out mechanical emissaries, to say 'hello' to strangers out there and report back what they find. The first crude probes to leave our solar system -- the Voyagers and Pioneers -- demonstrated this basic desire. They carried simple messages meant to be deciphered by other beings long after the authors were dust.
 
"Anyone out there enough like us to be interesting would certainly do the same.
 
"And yet, if self-reproducing probes are the most efficient way to explore, why haven't any already said hello to us? It must mean that nobody before us ever attained the capability to send them!
 
"We can only conclude that we are the first curious, gregarious, technically competent species in the history of the Milky Way."
 
 
The logic was so compelling that most people gave up on the idea of contact, especially when radio searches turned up nothing but star static.
 
Then humanity spread out beyond Mars and the Inner Belt, and we stumbled onto the Devastation.

The story is still sketchy, but we can already begin to guess some of what happened out here, long before mankind was a glimmer on the horizon.
 
Long ago the first "Von Neumann type" interstellar probe arrived in our solar system. It came to explore and perhaps report back across the empty light-years. That earliest emissary found no intelligent life here, so it proceeded to its second task.
 
It mined an asteroid and sent newly made duplicates of itself onward to other stars. The original then remained behind to watch and wait, patient against the day when something interesting might happen in this little corner of space.
 
As the epochs passed new probes arrived, representatives of other civilizations. Once their own replicas had been launched, the newcomers joined a small but growing community of mechanical ambassadors to this backwater system -- waiting for it to evolve somebody to say hello to.

We have found a few of these early probes, remnants of a lost age of innocence in the galaxy.
 
More precisely, we have found their blasted remains.
 
Perhaps one day the innocent star emissaries sensed some new entity enter the solar system. Did they move to greet it, eager for gossip to share? Like those twentieth century thinkers, perhaps they believed that replicant probes would have to be benign.
 
But things had changed. The age of innocence was over. The galaxy had grown up; it had become nasty.
 
The wreckage we are finding now -- whose salvage drives our new industrial revolution -- was left by an unfathomable war that stretched across vast times, and was fought by entities to whom biological life was a nearly forgotten oddity.