I: The Map Sphere

The Map Sphere consists of thirteen stellar sails, circular in shape, arranged asymmetrically around the host star. They are easy to miss but look closely and you will see them: specks against the dark, clustered in no more than thirty degrees of arc. They are not really a sphere, this is true. Their total power production is so low you would be forgiven for doubting their function—the crew of the Dabih did, when they followed the Vaba signal to its source and first sighted the Map Sphere. Hours of debate were spent discussing its purpose, hours during which they might have been noticing that each sail’s position is constant with respect to the fixed stars, that each produces enough power to independently keep its station. Dr. Bhatt was the one who finally made the connection—mobile highway signs, that was her analogy, with their little solar panels perched on top.

The rest is obvious, in hindsight, but they didn’t yet have the advantage of having given the thing a name. It took a further two days to arrive at map from first principles: thirteen markers, painstakingly maintaining their position, and what happens if you start at the centre of the star and draw a line through each? Imagine the indrawn breaths, the glances exchanged over navigational charts, when one line after another terminated in the centre of a neighbouring star. In that moment, the crew of the Dabih experienced the nameless emotion of growing ever more certain that you have made the most momentous discovery in history.

Captain Žukov was a perceptive man. In another life he had been a musician, attuned to the subtleties of notes arranged in this pattern and no other. He understood the implications of the Map Sphere. All thirteen markers pointed in the same general direction: the Dabih had found the very edge of a map whose makers had invited outside visitors, who’d put a signpost in their path and urged them inwards, and you would not be begrudged a modicum of caution in following it.

He put it to a vote. The crew, bonded by circumstance and drunk on discovery, responded with one voice.

II: The Home Sphere

The brightest minds on Earth were dreaming of building the Home Sphere. It consists of two circular shells cupping the host star like a child who has caught a tadpole, who is running to show you before the thing dries out. In between, swarms of stellar sails hang suspended by the force of starlight. From a distance it is like looking at the star through a mosquito net. Dimmer, but in its dimness powering the industry of a civilisation.

The brightest minds were dreaming, waking, confronting the harsh reality of materials science and orbital dynamics. On Earth, Dr. Bhatt counted herself among them; now, she had the opportunity to be more than them. She insisted on a survey. She filled drive after drive with data, as thorough an examination as the Dabih and its probes were capable of, every detail a shortcut through years of trial and error. When she returned to Earth, she was sure, the prototypes would be mere months away.

While she worked, Captain Žukov made a survey of the stillness. He considered the second planet out, so squarely in the star’s habitable zone, and wondered at the lack of radio signals. He found the remnants of orbitals and imagined traffic zipping from each to each. In his mind he heard the notes of the alien song that would have played on the occasion of their first meeting. Faced with the reality, he felt not disappointment but sadness. Where had they gone, these makers of miracles? What tragic impulse drove them from their home?

Others among the crew were more prosaic. Better, they reasoned, to be archaeologists than diplomats. You never know what living aliens might be up to. Not that the Dabih had either personnel or expertise for archaeology—and so, Dr. Bhatt’s survey done, there was, paradoxically, nothing left to do in a stellar system full of history.

The Dabih lined up the next point on the map, and Captain Žukov pretended his quarters did not echo with a song he’d never heard.

III: The Giant Sphere

The Giant Sphere is the place where visitors learn the difference between impossibilities. It is built around an old star, growing larger and redder by the million years. Its interlocking plates are opaque, kilometres-thick shells banding the star like manacles. On their outside surfaces, the ruins of cities cover a thousand times the area of Earth.

The shells have been there longer than you can imagine. No one remains to hear the groans of metal slowly stressed where their lowest depths brush the corona of the star. If there are places where other, closer shells have crumbled, where their frames have bent and twisted and fallen into the red giant, you can see no sign of them. One day, nothing will be left but the bones of planets cracked to build the impossible.

Dr. Bhatt understood the impossibility of the Home Sphere. It was impossible in the meaning of one problem after another, one barrier overleaped until none remained. Impossible, in the manner of science, now but not later. The Giant Sphere was impossible in the sense of division by zero. In the moment of first setting her eyes on it, the doctor’s fate was set. It was not scientific curiosity that drove her pursuit of the spheres from this point on, but the awe in awful.

The crew whispered, splintered. Captain Žukov was not the only one among them who heard a song timbred beyond human hearing. Not the only one to look at the rings of debris that once were planets and imagine the refuse of Venus in their place, or of Mercury, or of Mars. Arguments broke out. The aliens were gone, true, and their secrets ripe for the taking: but the aliens were gone, and who wanted to remain and find out what made them so, these people who tamed a red giant, whose works lasted so long that the star swelled around them, was on the verge of the last laugh. It was a disagreement without resolution, because one side saw danger in the same evidence that assured the other of safety.

The vote was closer, this time, but Dr. Bhatt was a persuasive speaker. Humanity had conquered the Earth and the solar system; now, she offered them the universe.

The Dabih flew on.

IVa: The Art Sphere

The Art Sphere is the greatest achievement of the people who built it. Alone among their creations, it forms a complete sphere around its host star—a blue giant, one of a binary, though you can tell only by the faint tint of the light that passes through the shell. The sphere’s surface is tiled like stained glass, to a pattern your brain is always on the edge of recognising. They had meaning once, those patterns. Other than the stars and the sphere, the stellar system is empty, because the Art Sphere has no purpose but beauty. It tames the light of its star, allows a gaze to fall upon its shining surface with no damage to the eyes that cast it. It generates power, but there is nothing in the system to use it, nor was there ever. It exists because it can exist.

The Art Sphere is what broke Captain Žukov. He did not see in it, as Dr. Bhatt did, the progression of civilisation, but of increasingly alien motivations. What art, what beauty, what meaning was worth the bodies of a dozen planets, a million asteroids?

Captain or not, he stuck with democratic principles to the end. He spoke with the crew. One by one he convinced them. The journey would end here.

And meanwhile, Dr. Bhatt turned her attention to the Art Sphere’s companion.

IVb: The Nameless Sphere

The other object in this binary system is a neutron star. Like any X-ray binary, it siphons material from its larger twin. Unlike any other, the accreted gas does not form a disc. Nothing artificial orbits the neutron star, but its gas shell is artificial all the same: mediated by the Art Sphere, shape dictated by the interactions of gravity and starlight and the forces that hold the sphere together.

And if you studied those patterns of gas, the thread linking one star to the other; if your mind had, slowly, been stamped with the influence of a song you did not hear yourself; if you wished to be artist and not beholder; if, in short, you were Dr. Bhatt, you would find in them one last piece of the map.

Dr. Bhatt was not so democratically minded as the captain. While others debated their return journey, she snuck onto the bridge. While they resolved to break the news to her, she plotted the Dabih’s final journey.

It does not take a majority to make the wrong decision. Perhaps one day explorers will find this system and choose, unanimously, to set aside the ambition of caged stars and turn back. It is possible.

We do not think it will happen.

To build what we built took a million years. What civilisation, following our footsteps so carefully, would fail to take a shortcut when presented with one? You who have made it this far, you will not stop shy of the greatest secret.

This is the bet we made: that before those million years were up, you would find our map. Find it, and follow it to our end.

V: The Final Sphere

Do you know the most common object of worship in the universe? The sun.

We use the word advisedly. A sun is the star from which a people spring. A sun is a star, personified. It is a word we have left behind, we who are a people, starified. Do not be afraid—the doctor and the captain are here, waiting for you. We are all here, waiting, we who are mainframes and roiling plasma, we who are a star knowing itself, thinking itself, centring itself, we who are feeding what once we drained.

The tadpole belongs in its pond.

We are the final sphere anyone will ever build. We are the final stellar system stripped of the history written in veins of ore. We are the checks against an empty universe. A thousand civilisations dream of being who we were; and when their dreams lead them here, to our reality, their builders and their miners and their extractors will put down their tools, and in their silence the stars will sing.