We met on a summer night, in a campground high up in the Rockies. We were from opposite coasts, two random particles on separate trajectories: I was headed for a new job, driving across the country and camping to save money; she was returning to Boston after having moved a friend and her truckful of possessions to San Francisco, camping because she wanted to look at the stars.
We drank cheap wine and ate even cheaper grilled hot dogs. Then we walked together under the dark velvet dome studded with crystalline stars like the inside of a geode, brighter than I’d ever seen them, while she explained to me their beauty: each as unique as a diamond, with a different-colored light. I could not remember the last time I’d looked up at the stars.
“I’m going there,” she said.
“You mean Mars?” ?That was the big news back then, the announcement of a mission to Mars. Everyone knew it was a propaganda effort to make America seem great again, a new space race to go along with the new nuclear arms race and the stockpiling of rare Earth elements and zero-day cyber vulnerabilities. The other side had already promised their own Martian base, and we had to mirror their move in this new Great Game.
She shook her head. “What’s the point of jumping onto a reef just a few steps from shore? I mean out there.”
It was not the kind of statement one questioned, so instead of why and how and what are you talking about, I asked her what she hoped to find out there among the stars.
other Suns perhaps
With thir attendant Moons thou wilt descrie
Communicating Male and Femal Light,
Which two great Sexes animate the World,
Stor’d in each Orb perhaps with some that live.
For such vast room in Nature unpossest
By living Soule, desert and desolate,
Onely to shine, yet scarce to contribute
Each Orb a glimps of Light, conveyd so farr
Down to this habitable, which returnes
Light back to them, is obvious to dispute.
“What do they think about? How do they experience the world? I’ve been imagining such stories all my life, but the truth will be stranger and more wonderful than any fairy tale.”
She spoke to me of gravitational lenses and nuclear pulse propulsion, of the Fermi Paradox and the Drake Equation, of Arecibo and Yevpatoria, of Blue Origin and SpaceX.
“Aren’t you afraid?” I asked.
“I almost died before I could begin to remember.”
She told me about her childhood. Her parents were avid sailors who had been lucky enough to retire early. They bought a boat and lived on it, and the boat was her first home. When she was three, her parents decided to sail across the Pacific. Halfway across the ocean, somewhere near the Marshall Islands, the boat sprung a leak. The family tried everything they could to save the vessel, but in the end had to activate the emergency beacon to call for help.
“That was my very first memory. I wobbled on this immense bridge between the sea and the sky, and as it sank into the water and we had to jump off, Mom had me say good-bye.”
By the time they were rescued by a Coast Guard plane, they had been adrift in the water in life vests for almost a full day and night. Sunburned and sickened by the salt water she swallowed, she spent a month in the hospital afterward.
“A lot of people were angry at my parents, saying they were reckless and irresponsible to endanger a child like that. But I’m forever grateful to them. They gave me the greatest gift parents could give to a child: fearlessness. They worked and saved and bought another boat, and we went out to the sea again.”
It was such an alien way of thinking that I didn’t know what to say. She seemed to detect my unease, and, turning to me, smiled.
“I like to think we were carrying on the tradition of the Polynesians who set out across the endless Pacific in their canoes or the Vikings who sailed for America. We have always lived on a boat, you know? That’s what Earth is, a boat in space.”
For a moment, as I listened to her, I felt as if I could step through the distance between us and hear an echo of the world through her ears, see the stars through her eyes: an austere clarity that made my heart leap.
Cheap wine and burned hot dogs, other Suns perhaps, the diamonds in the sky seen from a boat adrift at sea, the fiery clarity of falling in love.
? ? ?
The Tick-Tocks are the only uranium-based life forms known in the universe.
The surface of their planet is an endless vista of bare rock. To human eyes it seems a wasteland, but etched into this surface are elaborate, colorful patterns at an immense scale, each as large as an airport or stadium: curlicues like calligraphy strokes; spirals like the tips of fiddlehead ferns; hyperbolas like the shadows of flashlights against a cave wall; dense, radiating clusters like glowing cities seen from space. From time to time, a plume of superheated steam erupts from the ground like the blow of a whale or the explosion of an ice volcano on Enceladus.
Where are the creatures who left these monumental sketches? These tributes to lives lived and lost, these recordings of joys and sorrows known and forgotten?
You dig beneath the surface. Tunneling into the sandstone deposits over granite bedrock, you find pockets of uranium steeped in water.
In the darkness, the nucleus of a uranium atom spontaneously breaks apart, releasing a few neutrons. The neutrons travel through the vast emptiness of internuclear space like ships bound for strange stars (this is not really an accurate picture, but it’s a romantic image and easy to illustrate). The water molecules, nebula-like, slow down the neutrons until they touch down on another uranium nucleus, a new world.
But the addition of this new neutron makes the nucleus unstable. It oscillates like a ringing alarm clock, breaks apart into two new elemental nuclei and two or three neutrons, new starships bound for distant worlds, to begin the cycle again.
To have a self-sustaining nuclear chain reaction with uranium, you need enough concentration of the right kind of uranium, uranium-235, which breaks apart when it absorbs the free neutrons, and something to slow down the speeding neutrons so that they can be absorbed, and water works well enough. Creation has blessed the world of the Tick-Tocks with both.
The by-products of fission, those fragments split from the uranium atom, fall along a bimodal distribution. Cesium, iodine, xenon, zirconium, molybdenum, technetium . . . like new stars formed from the remnants of a supernova, some last a few hours, others millions of years.
The thoughts and memories of the Tick-Tocks are formed from these glowing jewels in the dark sea. The atoms take the place of neurons, and the neutrons act as neurotransmitters. The moderating medium and neutron poisons act as inhibitors and deflect the flight of neutrons, forming neural pathways through the void. The computation process emerges at the subatomic level, and is manifested in the flight paths of messenger neutrons; the topology, composition, and arrangement of atoms; and the brilliant flashes of fissile explosion and decay.
As the thoughts of the Tick-Tocks grow ever more lively, excited, the water in the pockets of uranium heats up. When the pressure is great enough, a stream of superheated water flows up a crack in the sandstone cap and explodes at the surface in a plume of steam. The grand, intricate, fractal patterns made by the varicolored salt deposits they leave on the surface resemble the ionization trails left by subatomic particles in a bubble chamber.
Eventually, enough of the water will have been boiled away that the fast neutrons can no longer be captured by the uranium atoms to sustain the reaction. The universe sinks into quiescence, and thoughts disappear from this galaxy of atoms. This is how the Tick-Tocks die: with the heat of their own vitality.