Gradually, water seeps back into the mines, trickling through seams in the sandstone and cracks in the granite. When enough water has filled the husk of the past, a random decaying atom will release the neutron that will start the chain reaction again, ushering forth a florescence of new ideas and new beliefs, a new generation of life lit from the embers of the old.
Some have disputed the notion that the Tick-Tocks can think. How can they be said to be thinking, the skeptics ask, when the flight of neutrons are determined by the laws of physics with a soup?on of quantum randomness? Where is their free will? Where is their self-determination? Meanwhile, the electrochemical reactor piles in the skeptics’ brains hum along, following the laws of physics with an indistinguishable rigor.
Like tides, the Tick-Tock nuclear reactions operate in pulses. Cycle after cycle, each generation discovers the world anew. The ancients leave no wisdom for the future, and the young do not look to the past. They live for one season and one season alone.
Yet, on the surface of the planet, in those etched, fantastic rock paintings, is a palimpsest of their rise and fall, the exhalations of empires. The chronicles of the Tick-Tocks are left for other intelligences in the cosmos to interpret.
As the Tick-Tocks flourish, they also deplete the concentration of uranium-235. Each generation consumes some of the nonrenewable resources of their universe, leaving less for future generations and beckoning closer the day when a sustained chain reaction will no longer be possible. Like a clock winding down inexorably, the world of the Tick-Tocks will then sink into an eternal, cold silence.
? ? ?
Your mother’s excitement was palpable.
“Can you call a Realtor?” she asked. “I’ll get started on liquidating our stocks. We don’t need to save anymore. Your mother is going to go on that cruise she’s always wanted.”
“When did we win the lottery?” I asked.
She handed me a stack of paper. LENS Program Orientation.
I flipped through it. . . . ?Your application essay is among the most extraordinary entries we’ve received . . . pending a physical examination and psychological evaluation . . . limited to the immediate family . . .
“What is this?”
Her face fell as she realized that I truly did not understand.
Radio waves attenuated rapidly in the vastness of space, she explained. If anyone is shouting into the void in the orbs around those distant stars, they would not be heard except by their closest neighbors. A civilization would have to harness the energy of an entire star to broadcast a message that could traverse interstellar distances—and how often would that happen? Look at Earth: we’d barely managed to survive one Cold War before another started. Long before we get to the point of harnessing the energy of the Sun, our children will be either wading through a postapocalyptic flooded landscape or shivering in a nuclear winter, back in another Stone Age.
“But there is a way to cheat, a way for even a primitive civilization like ours to catch faint whispers from across the galaxy and perhaps even answer back.”
The Sun’s gravity bends the light and radio waves from distant stars around it. This is one of the most important results from general relativity.
Suppose some other world out there in our galaxy, not much more advanced than ours, sent out a message with the most powerful antenna they could construct. By the time those emissions reached us, the electromagnetic waves would be so faint as to be undetectable. We’d have to turn the entire Solar System into a parabolic dish to capture it.
But as those radio waves grazed the surface of the Sun, the gravity of the star would bend them slightly, much as a lens bends rays of light. Those slightly bent beams from around the rim of the sun would converge at some distance beyond.
“Just as rays of sunlight could be focused by a magnifying glass into a spot on the ground.”
The gain of an antenna placed at the focal point of the sun’s gravitational lens would be enormous, close to ten billion times in certain frequency ranges, and orders of magnitude more in others. Even a twelve-meter inflatable dish would be able to detect transmissions from the other end of the galaxy. And if others in the galaxy were also clever enough to harness the gravitational lenses of their own suns, we would be able to talk to them as well—though the exchange would more resemble monologues delivered across the lifetimes of stars than a conversation, messages set adrift in bottles bound for distant shores, from one long-dead generation to generations yet unborn.
This spot, as it turns out, is about 550 AU from the Sun, almost fourteen times the distance of Pluto. The Sun’s light would take just over three days to reach it, but at our present level of technology, it would take more than a century for a spacecraft.
Why send people? Why now?
“Because by the time an automated probe reached the focal point, we don’t know if anyone will still be here. Will the human race survive even another century? No, we must send people so that they can be there to listen, and perhaps talk back.
“I’m going, and I’d like you to come with me.”
? ? ?
The Thereals live within the hulls of great starships.
Their species, sensing the catastrophe of a world-ending disaster, commissioned the construction of escape arks for a small percentage of their world’s population. Almost all of the refugees were children, for the Thereals loved their young as much as any other species.
Years before their star went supernova, the arks were launched in various directions at possible new home worlds. The ships began to accelerate, and the children settled down to learning from machine tutors and the few adults on board, trying to carry on the traditions of a dying world.
Only when the last of the adults were about to die aboard each ship did they reveal the truth to the children: the ships were not equipped with means for deceleration. They would accelerate forever, asymptotically approaching the speed of light, until the ships ran out of fuel and coasted along at the final cruising speed, toward the end of the universe.
Within their frame of reference, time would pass normally. But outside the ship, the rest of the universe would be hurtling along to its ultimate doom against the tide of entropy. To an outside observer, time seemed to stop in the ships.
Plucked out of the stream of time, the children would grow a few years older, but not much more. They would die only when the universe ended. This was the only way to ensure their safety, the adults explained, an asymptotic approach to triumphing over death. They would never have their own children; they would never have to mourn; they would never have to fear, to plan, to make impossible choices in sacrifice. They would be the last Thereals alive and possibly the last intelligent beings in the universe.
All parents make choices for their children. Almost always they think it’s for the best.
? ? ?
All along, I had thought I could change her. I had thought she would want to stay because of me, because of our child. I had loved her because she was different; I also thought she would transform out of love.
“Love has many forms,” she said. “This is mine.”