It took me a while to remember: The question he’d latched onto so long ago, on a starry night in the Smokies. The Fermi paradox. “Then hand them over peacefully, buddy. No questions asked.”
Remember how you said there might be a big roadblock somewhere?
“The Great Filter. That’s what we call it.”
Like, maybe there’s a Great Filter right at the beginning, when molecules turn into living things. Or it might be when you first evolve a cell, or when cells learn to come together. Or maybe the first brain.
“Lots of bottlenecks.”
I was just thinking. We’ve been looking and listening for sixty years.
“The absence of evidence is not the evidence of absence.”
I know. But maybe the Great Filter isn’t behind us. Maybe it’s ahead of us.
And maybe we were just now hitting it. Wild, violent, and godlike consciousness, lots and lots of consciousness, exponential and exploding consciousness, leveraged up by machines and multiplied by the billions: power too precarious to last long.
Because otherwise . . . How old did you say the universe is?
“Fourteen billion years.”
Because otherwise, they’d be here. All over. Right?
His hands waved in every direction. They froze when something primordial signed the air. Robbie saw them first, still mere specks: a family of sandhill cranes, three of them, flying southward in loose formation toward winter quarters that the young one had not yet seen. They were late leaving. But the whole autumn was weeks late, as late as next spring would be early to arrive.
They drew near along a liquid thread. Their wings, gray shawls trimmed in black, arched and fell. The long dark tips of their primary feathers flexed like spectral fingers. They flew outstretched, an arrow from beak to claws. And in the middle, between the slender necks and legs, came a bulge of body that seemed too bulky to get airborne, even with all the pumping of those great wings.
The sound came again, and Robbie grabbed my arm. First one, then another, then all three birds unspooled a chilling chord. They came so close we could see the splashes of red across the bulbs of their heads.
Dinosaurs, Dad.
The birds passed over us. Robbie held still and watched them wing away to nothing. He seemed frightened and small, unsure how he got here on the edge of woods, water, and sky. At last his fingers loosened their grip on my wrist. How would we ever know aliens? We can’t even know birds.
WE SAW SIMILIS FROM A LONG WAY AWAY. It was a ball of perfect indigo, glinting with the light of the nearby star it captured.
What’s that? my son asked. People must have made that.
“It’s a solar cell.”
A solar cell that covers the whole planet? Crazy!
We made a few rotations around the globe, confirming him. Similis was a world trying to capture every photon of energy that fell on it.
That’s suicide, Dad. If they hog all the energy, how do they grow their food?
“Maybe food is something else, on Similis.”
We went for a look, down to the planet’s surface. It was as dark as Nithar, but much colder, and silent aside from a steady background hum, which we followed. There were lakes and oceans, all frozen under thick ice. We passed underneath scattered, blasted snags that must have been thick forests once. There were fields of nothing, and grassless pastures of slag and rock. The roads were abandoned, the towns and cities empty. But no sign of destruction or violence. Everything had fallen into decay slowly, on its own. The world looked as if all the residents had walked out and been taken into the sky. But the sky was covered in solar panels, pumping out electrons at full tilt.
We followed the hum down into a valley. There we found the only buildings still intact, a vast industrial barracks guarded and repaired by ever-vigilant robots. Great conduits of cabling channeled all the energy captured by the solar shell into the sprawling complex.
Who built this?
“The inhabitants of Similis.”
What is it?
“It’s a computer server farm.”
What happened to everyone, Dad? Where did the people go?
“They’re all inside.”
My son frowned and tried to picture: a building of circuitry, infinitely bigger on the inside than on the outside. Rich, unlimited, endless, and inventive civilizations—millennia of hope and fear and adventure and desire—dying and resurrecting, saving and reloading, going on forever, until the power failed.
FOR HIS TENTH BIRTHDAY, the boy who once could not be roused in the morning without wailing like a howler monkey brought me breakfast in bed: fruit compote, toast, and pecan cheese, all artfully arranged on a platter accompanied by a painted bouquet of mums.