by Cixin Liu
“The lights of New York wash out the stars. The sky’s far brighter than this over DC,” he said.
The Chinese president nodded but said nothing.
The US president went on, “I like looking at the stars, too. In the ever-changing course of history, our profession needs an immovable reference object.”
“That object is an illusion,” the Chinese president said.
“Why do you say that?”
Instead of responding directly, the Chinese president pointed at a cluster of stars that had just come out. “Look, that’s the Southern Cross, and that’s Canis Major.”
The US president smiled. “You’ve proven they’re immovable enough. Ten thousand years ago, primitive man would have seen the same Southern Cross and Canis Major as we do today. They may have even come up with those names.”
“No, Mr. President. In fact, the sky might even have been different just yesterday.” The Chinese president looked up for a third time. He remained calm, but the steel in his eyes made the other two nervous. They looked at the same placid sky they had seen so many times before; nothing seemed wrong. They looked questioningly at the Chinese president.
“The two constellations I just noted should only be visible from the southern hemisphere,” he said without pointing them out or looking upward. He turned thoughtfully toward the horizon.
The secretary general and US president looked questioningly at him.
“We’re looking at the sky from the other side of the Earth,” he said.
The US president yelped, but then restrained himself and said in a voice even lower than before, “You’ve got to be kidding.”
“Look, what’s that?” the secretary general said, pointing at the sky with a hand raised only to eye level so as not to alarm the others.
“The moon, of course,” the US president said after a brief glance overhead. But when the Chinese president slowly shook his head, he looked up a second time and was less certain. At first, the semicircular shape in the sky looked like the moon in first quarter, but it was bluish, as if a scrap of daytime sky had gotten stuck. The US president looked more closely at the blue semicircle. He held out a finger and measured the blue moon against it. “It’s growing.”
The three politicians stared up at the sky, not caring anymore if they’d startle the others. The heads of state in the surrounding seats noticed their movements, and more people looked upward. The orchestra on the outdoor stage abruptly stopped its warm-up.
By now, it was clear that the blue semicircle was not the moon, because its diameter had grown to twice that, and its darkness-shrouded other half was now visible in dim blue. In its brighter half, details could be made out; its surface was not a uniform blue but had patches of brown.
“God! Isn’t that North America?” someone shouted. They were right. You could distinguish the familiar shape of the continent, which lay smack on the border between the light and dark halves. (It may have occurred to someone that was the very same position they occupied.) Then they found Asia, and the Arctic Ocean and the Bering Strait.…
“It’s … Earth!”
The US president drew back his finger. The blue sphere in the sky was now growing at a rate visible without a reference object, and was now at least three times the diameter of the moon. At first, it looked like a balloon rapidly inflating in the sky, but then a shout from the crowd abruptly changed that impression:
“It’s falling!”
The shout provided a reasonable interpretation of the scene before them. Regardless of its accuracy, they immediately had a new sense of what was happening: another Earth was crashing toward them in space! The approaching blue planet now occupied a third of the sky, and surface details could be made out: brown continents covered in mountain wrinkles, cloud coverage looking like unmelted snow, outlined in black from the shadows cast on the ground. There was white at the North Pole, parts of which glittered—ice, rather than clouds. On a blue ocean, a snow-white object spiraled lazily with the delicate beauty of a velvet flower in a blue crystal vase—a newborn hurricane.… But when the huge blue sphere grew to cover half the sky, their perception experienced an almost simultaneous transformation.
“God! We’re falling!”
The feeling of inversion came in an instant. The sphere filling half the sky gave them a feeling of height, or that the ground beneath their feet had vanished and they were now falling toward the other Earth. Its surface was clearer now, and on the dark side, not far from the shadow line, those with keen eyes could see a faint glowing band: the lights of America’s East Coast cities, their own location in New York a somewhat brighter spot within it. The other planet now filled two-thirds of the sky, and it seemed as if the two Earths would collide. There were screams from the crowd, and many of them shut their eyes.
Then all was still. The Earth overhead was no longer falling (or the ground they stood on was no longer falling toward it). The sphere hung motionless covering two-thirds of the sky, bathing the land in its blue glow.
Now sounds of chaos could be heard from the city, but the occupants of the lawn had the strongest nerves on the planet in unstable situations, so they held back their panic at the nightmarish scene and approached it more quietly.
“It’s a hallucination,” the secretary general said.
“Yes,” the Chinese president said. “If it were real, we’d feel the gravity. And this close to the sea, we’d be drowned by the tide.”
“It’s more than just the tides,” the Russian president said. “The two Earths would be torn to pieces by their mutual attraction.”
“The laws of physics don’t permit two Earths to remain motionless,” the Japanese prime minister said, and, turning to the Chinese president, added, “When that Earth first appeared, you were saying that the stars of the southern hemisphere were in the sky above us. Could the two phenomena be connected?” It was a tacit admission of eavesdropping, but they were past caring at this point.
“Perhaps we’re about to find out,” the US president said. He spoke into a mobile phone; the secretary of state, at his elbow, informed the others that he was speaking with the International Space Station. And so they focused their anticipation on the president, who listened attentively to the phone but said only a few words. Silence reigned on the lawn, where in the blue light of that other Earth they looked like a throng of ghosts. After about two minutes, the president set down the phone, climbed onto a chair, and shouted to the expectant crowd:
“It’s simple. A huge mirror has appeared next to the Earth!”
THE MIRROR
There was no way to describe it other than a huge mirror. Its surface perfectly reflected visual light as well as radar with no energy or image loss. Viewed from the right distance, the Earth would look like a stone on a go board ten billion square kilometers in area.
It shouldn’t have been difficult for Endeavor’s astronauts to obtain preliminary data, since an astronomer and a space physicist were on board and had all the necessary equipment available and at their disposal, including the ISS, to conduct observations; however, their momentary panic had nearly sent the orbiter to its doom. The ISS was a fully-equipped observation platform, but its orbit was not conducive to observing an object situated 450 kilometers above the North Pole nearly perpendicular to the Earth’s axis. Endeavor’s orbit sent it over the poles so it could carry out observations of the ozone holes; at a height of 280 kilometers, it was flying right between the Earth and the mirror.
Flying with an Earth on either side was nightmarish, like speeding along a canyon with blue cliffs towering above them. The pilot insisted it was a mirage, like the spatial disorientation he had experienced twice during his three thousand hours in a fighter jet, but the commander was convinced there really were two Earths. He ordered their orbit adjusted to compensate for the gravitational pull of the second one, but the astronomer stopped him in time. Once they got over their initial shock and learned from observations of the shuttle’s orbit that one of the t
wo Earths had no mass, they let out a sigh of relief: if they had made the compensational adjustments, Endeavor would be nothing more than a shooting star over the North Pole.
The astronauts carefully observed the massless Earth. Visual inspection indicated the orbiter was much farther away from it, but its North Pole seemed little different from that of the nearer Earth, if not entirely identical. They saw laser beams emitting from both North Poles, two long, dark red snakes twisting slowly in identical shapes at identical positions. Eventually they discovered one thing that the nearer Earth did not have: an object in flight above the massless Earth. Visually they judged it to be in an orbit roughly three hundred kilometers above its surface, but when they attempted to probe its orbit more precisely using shipboard radar, the radar seemed to bounce back from a solid wall a hundred-odd kilometers away. The massless Earth and the flying object were on the opposite side of that wall. Observing the object through the cockpit window using high-powered binoculars, the commander saw another space shuttle flying in low orbit over the frozen Arctic ice pack like a moth crawling along a blue striped wall. There was a figure behind that shuttle’s cockpit window, looking through binoculars. The commander waved, and the figure waved at the same time.
And so they discovered the mirror.
They altered course to draw closer to the mirror. At a distance of three kilometers, the astronauts could see clearly Endeavor’s reflection six kilometers away, the glow of its aft engines lending it the form of a creeping firefly.
One astronaut took a spacewalk for humanity’s first close encounter with the mirror. Thrusters on the suit spurted streams of white, speeding him across the distance. Carefully, he adjusted the jets to bring himself into position ten meters from the mirror. His reflection was remarkably clear, without any distortion. Since he was in orbit but the mirror was stationary with respect to the Earth, he had a relative speed of ten kilometers per second. He was racing past it, but no motion at all was visible. It was the smoothest, shiniest surface in the universe.
When the astronaut decelerated, his thruster jets had been aimed at the mirror for an extended period, and a white fog of benzene propellant had drifted toward it. During previous space walks, whenever the fog had come into contact with the shuttle or the outside wall of the ISS, it would leave a conspicuous smudge; he imagined it would be the same with the mirror, except that with the high relative velocity, the smudge would be a long stripe, like he used to draw with soap on the bathroom mirror as a child. But he saw nothing. The fog vanished upon contact with the mirror, whose surface remained bright as ever.
The shuttle’s orbital trajectory gave them only a limited amount of time near the mirror, prompting the astronaut to act quickly. In an almost unconscious act the moment the fog disappeared, he took a wrench out of his tool bag and tossed it at the mirror, but once it left his hand, he and the astronauts aboard the shuttle were paralyzed with the realization that the relative velocity between it and the mirror gave it the force of a bomb. In terror they watched the wrench tumble toward the mirror and had a vision of the spiderweb fractures that in just moments would spread like lightning across the surface from the point of impact, and then the enormous mirror shattering into billions of glittering fragments, a sea of silver in the blackness of space.… But when the wrench touched the surface it vanished without a trace, and the mirror remained as smooth as before.
It actually wasn’t hard to see that the mirror was massless, not a physical body, since floating motionless over Earth’s North Pole would be impossible otherwise. (It might be more accurate to state, given their relative sizes, that the Earth was floating in the middle of the mirror.) Rather than a physical entity, the mirror was a field of some sort. Contact with the fog and the wrench proved that.
Delicately manipulating his thrusters and making continual microadjustments of the jets, the astronaut drew within half a meter of the mirror. He stared straight into his reflection, amazed once again at its fidelity: a perfect copy, one perhaps even more finely wrought than the original. He extended a hand toward it until he and his reflected hand were practically touching, separated by less than a centimeter. His earpiece was silent—the commander did not order him to stop—so he pushed forward, and his hand disappeared into the mirror. He and his image were joined at the wrist. There had been no sensation of contact. He retracted his hand and looked at it carefully. The suit glove was perfectly unharmed. No marks whatsoever.
Below the astronaut, the shuttle was gradually drawing away from the mirror and had to constantly run its engines and thrusters to maintain proximity. However, due to its trajectory its drift was accelerating, and before long such adjustments would be impossible. A second encounter would require waiting an entire orbit, but would the mirror still be there? With this in mind, the astronaut made a decision. He switched on his thrusters and headed straight into the mirror.
His reflection loomed large, filling his field of vision with the quicksilver bubble of his helmet’s one-way reflective faceplate. He fought to keep from closing his eyes as his head touched the mirror. At contact he felt nothing, but in that very moment everything vanished before his eyes, replaced by the darkness of space and the familiar Milky Way. He jerked around, and below him was the same view of the galaxy, with one addition: his own reflection receding into the distance, the maneuvering units he and his reflection wore linked by streams of thruster jet fog.
He had crossed the mirror, and the other side of it was a mirror, too.
His earpiece had been chirping with the commander’s voice when he was approaching the mirror, but it had cut out. The mirror blocked radio waves. Worse, the Earth wasn’t visible from this side. Surrounded entirely by stars gave the astronaut the feeling of being isolated in a different world, and he began to panic. He adjusted the jets and arrested his outward motion. He had passed through the first time with his body parallel to the mirror, but now he oriented himself perpendicular, as if diving headfirst into it. Just before contact, he cut his speed. Then the top of his head touched the top of his reflection, and then he passed through and saw with relief the blue Earth below him, and heard the commander’s voice in his ear.
Once his upper torso was through he dropped his drift speed, leaving the remainder of his body on the other side. Then he reversed the direction of his jets and began to back up; fog from the jets on the opposite side of the mirror issued from the surface around him like steam rising from a lake in which he was partially submerged. When the surface reached his nose, he made another startling discovery: The mirror passed through his faceplate and filled the crescent space between it and his face. He looked downward and saw his frightened pupils reflected in the crescent. No doubt the mirror was passing through his entire head, but he felt nothing. He reduced his speed to the absolute minimum, no faster than the tick of a second hand, and advanced millimeter by millimeter until the mirror bisected his pupils and vanished.
Everything was back to normal: Earth’s blue sphere on one side, the glittering Milky Way on the other. But that familiar world persisted only for a second or two. He couldn’t reduce his speed to zero, so before long the mirror was above his eyes, and the Earth vanished, leaving only the Milky Way. Above him, the mirror blocking his view of Earth extending hundreds of thousands of kilometers into the distance. The angle of reflection distorted his view of the stars into a silver halo on the mirror’s surface. He reversed thrusters and drifted back, and the mirror dropped down across his eyes, vanishing momentarily as it passed to reveal both Earth and Milky Way before the galaxy vanished and the halo turned blue on the mirror’s surface. He moved slowly back and forth several times, and as his pupils oscillated on either side, he felt like he was passing across a membrane between two worlds. At last he managed a fairly lengthy pause with the mirror invisible at the center of his pupils. He opened his eyes wide for a glimpse of a line at its position, but he saw nothing.
“The thing’s got no width!” he exclaimed.
“Maybe it�
�s only a few atoms thick, so you just can’t see it. Maybe it approached Earth edgewise and that’s why it arrived undetected.” That was the assessment of the shuttle crew, who were watching the images sent back.
The astonishing thing was that the mirror, perhaps just atoms thick but over a hundred Pacific Oceans in area, was so flat as to be invisible from a parallel vantage point; in classical geometry, it was an ideal plane.
Its absolute flatness explained its absolute smoothness. It was an ideal mirror.
A sense of isolation replaced the astronauts’ shock and fear. The mirror made the universe strange and rendered them a group of newborn babes abandoned in a new, unfathomable world.
Then the mirror spoke.
THE MUSICIAN
“I am a musician,” it said. “I am a musician.”
The pleasing voice resounding through space was audible to all. In an instant, all sleepers on Earth awoke, and all those already awake froze like statues.
The mirror continued, “Below I see a concert whose audience members are capable of representing the planet’s civilization. Do you wish to speak with me?”
The national leaders looked to the secretary general, who was momentarily at a loss for words.
“I have something to say,” the mirror said.
“Can you hear us?” the secretary general ventured.
The mirror answered immediately, “Of course I can. I could distinguish the voice of every bacterium on the world below me, if I wanted to. I perceive things differently from you. I can observe the rotation of every atom simultaneously. My perception encompasses temporal dimensions: I can witness the entire history of a thing all at once. You only see cross sections, but I see all.”
