A picture of a Tensor: a ball made of hexagonal metal plates. At the places where the plates meet, there are probes, lasers, jets, and occasionally robot arms. [https://64.media.tumblr.com/4cf1f120f1033ce43afefa655daa9959/43758fc90ad8985c-42/s250x400/b930ea52db6f1910e18ed221a7ed8ce1c23bfebb.pnj]
Picture by Timothy Morris
To travel between universes, first, one must conduct a committee meeting.
When communication between the UN and the Convention of Sophonts was first established and the topic of physical transport came up, the Quotidians provided a map of their version of earth with their transport accelerators helpfully marked. Most of these were directly under major cities, which gave most of humanity's leadership simultaneous heart palpitations.
Breach the veils of space-time in the middle of Times Square or Wangfujing Avenue? Let the nonhuman hordes pour right out onto Crawford Market? No, thank you.
The CERN campus was already at the center of a military/medical containment zone, even though it never transported anything but information. More military personnel appeared around that time at a saltpeter mine in Chile and an abandoned tin mine in the Altay Autonomous Region of China. With scarcely a pause to set up a nest of shell corporations or proclaim a new economic ideology, the world's superpowers set about digging large, round underground chambers.
Some wondered why. They pointed out that while the Tienshan Mountains and the Atacama Desert might seem far away from Washington and Beijing, the Quotidian, if they did attack, would do so at the speed of light. Was an extra tenth of second of reaction time really worth the cost and inconvenience? If you really wanted to be safe, you'd build the accelerator in Antarctica, at the bottom of the ocean, on the moon, or not at all.
These people were told to shut up. We can open the Earth to the inestimable riches of multi-species commerce, science, and culture, or we can make the investors wait fifty years to build to develop the capacity to build a super collider on the moon.
The result was a typical compromise that pleased nobody and served no particular purpose, but whose only alternative was for everyone on all sides to give up in disgust. Nine years post-contact, humanity had a pair of functioning transport accelerators.
It was also nine years after Koenraad Robbert Ruis fled Rotterdam, Academia, and his father's death. He had learned some new tricks since then, but he was just as much of an animal as ever.
Imagine the specimen: about 180 cm tall from the top of his greatly enlarged skull to the planigrade soles of his hind limbs. The ever-growing hair on his scalp was sandy in color, and curled down his forehead, which was currently wrinkled in an expression of anxiety. His nose (uniquely hooded and protuberant among primates) came to a short, sharp point. His skin and the irises of his close-set eyes were poor in melanin, an adaptation to the polar environment where his regional subspecies evolved. The brow-ridge over the eyes bespoke a certain Neanderthal admixture, of which Koen was both aware and proud. His ears stuck out, but that served no evolutionary purpose.
Koen wore clothes woven from animal, plant, and plastic fibers, keeping him dry and socially acceptable. A frame on his ears and nose supported acrylic lenses, which corrected the focus of eyes more accustomed to indoor reading than staring out across sunlit grasslands.1 Another artifact clutched in his hand used silicon logic-gates to track his social obligations.
The phone turned between Koen's fingers. He pressed it. Looked at it. Looked away. Rubbed his sweaty thumb over its screen, and realized that in doing so, he had switched around all the apps on his home-screen.
He stared at them for a while, the little red dots on the icons. Soon the machine would lose its connectivity. Because he'd be in a different universe. He ought to answer his messages while he could.
Like a dog under a distracted hand, Koen's attention strayed.
His train swept on its elevated rails over steep, green-gold gorges. Trees rushed past Koen's window, blurred into a curtain before the warm, sunlit hills and the greater, slower serrations of the mountain peaks beyond. Folds of snowy rock reached toward the sky, as white as the clouds, as blue as the sky. Would the Tienshans look the same on Quotidia?
Koen had wanted to meet a nonhuman ever since the Swiss Signal. Now he would live in the most species-rich city in the known multiverse, not because of his PhD in vertebrate paleontology, but as a chef. He wanted this.
Rock walls flashed past, and he was in the Ili Valley. Pink-white apricot trees floated like clouds over rolls of land green-black with spring grass. Sheep flocked like gulls, and the sun flashed off the river. The train slowed, and the other passengers (all in Chinese army uniforms) stirred themselves.
They would make him stand up. Do more tests. Put on another horrible, sweaty bio-containment suit. Flip him through the spaces between spaces. And then worst of all, another quarantine.
Koen's fists clenched. He would not allow himself to run away. Not again.
***
Technically, the machine was a supercollider, but nobody wanted to travel inside something that sounded like it would splash them against the nearest wall. They called it a "transport accelerator" instead. It was much smaller in diameter than the LHC and proportionally taller, but it still consisted of a pair of particle accelerators plugged at a tangent into a donut-shaped tube filled with vacuum lined with powerful electromagnets. This arrangement allowed a complex and very improbable quantum state to be constructed. Or rather grown.
Imagine you flip a coin. It landed on heads this time, which means it didn't land on tails. You could draw that as a V-shaped diagram. Flip the coin again, and each tip of the V branches into two new V's, and so on. Keep going, and you get a fractal tree, a map of all the possible sequences of tails and heads for a given number of coin flips. Trace the exact sequence that you experienced and you have a jagged path through the tree, as if lightning has struck.
A powerful current runs from past to future, a cascade of cause and effect flashing in the meaningless blackness of infinity. Now imagine a wire. It catches the lightning and routes it sideways.
This tale has been pilfered from Royal Road. If found on Amazon, kindly file a report.
It was first invented by the Tensors.
***
On one earth (actually in orbit around it) robots figured out how to invade another universe.
It worked like this: first, you find yourself the product of an interplanetary civilization founded in the Middle Cretaceous. With the shoulders of giants like that to stand on, you can see far indeed. With your mighty, epoch-spanning construction techniques, you build artificial black holes, knotted cosmic strings, particle accelerator rings of monstrous size. Then you just smash and smash at the universe until something gives. Into the resulting hole, you shove in your hand (or in this case, your nick-iron manipulator claw). Now, tighten your grip and pull.
Picture the scene from many centuries ago. A team of mechanical physicists clusters around a control node of a collider 750 million kilometers in diameter. It has been made mostly of the planet Jupiter. With some ceremony, the machine is activated.
Light bends, antiprotons flurry, extra dimensions uncoil like springs, and everything within the compass of the enormous ring flickers into a new position.
Garden asteroids change position, their solar panels now grown into different shapes. City-webs of entirely new architecture tumble in what was empty space an moment before. Those Tensors who have not been cut apart by boundary effects detect radio traffic in an as-yet unknown language.
Once the war ended and the dust had settled, the Tensors figured out what they had done. They had replaced a disk-shaped slice of their solar-system with the corresponding slice of a neighboring universe. Now the question was, could they do it on purpose next time?
From the subsequent program of inter-universe invasion and conquest, the Tensor Equations Describing Relational Manifolds emerged. These equations yielded solutions that suggested, perhaps, the Tensors should stop conquering so much. Those who pointed this out were vaporized.
There followed an epic struggle of espionage and treason, lightning attack and glacier armament. Infinitely-folded hyperspace battle-lines propagated through innocent slices of space-time. Impossible energies were focused in the perpetration of incomprehensible atrocities. The scope of the Extraction War was so great that it cannot be discussed further in this story.
We only bring it up this history now because it flashed through the mind of Laura when the Tensor called to her.
"Excuse me, Honored Sophont," the Tensor said, "do you believe in God?"
Although its voice consisted mostly of lasers, Laura's translator did an excellent job of producing a voice. The voice was deep, hollow, precise. It came from right behind her.
Laura turned to see the Tensor's vacuum tube towering over her. At the base of the tube sprawled four robot limbs, three for locomotion and one to haul luggage. Above, cushioned between an anti-gravity generator and a harsh overhead light, spun the Tensor itself. Mirror-bright, carbon black, blinking with minute star-flashes and bristling with docking and manipulation spikes, it looked very much like a high-tech coronavirus.
Laura took a step back.
Do you believe in God. In an airport on her version of Earth, Laura would simply ignore anyone who asked such a question. Here, in the waiting area of a transport accelerator on Quotidia, she felt the need to be polite.
"Of course all people must be free to enjoy freedom of religious belief," she said.
Lights blinked at her. "I think so," the Tensor said, "I think so, but my question was personal. I have never found the good luck of ever meeting any member of your species, and my to-do-it again chances are very low. So I'll fire a question at you, even at risk of also moving in the opposite direction. Please respond."
"Well," said Laura. The Tensors had lost the Extraction War, which meant they were only the second most powerful species in the Convention of Sophonts.
A well-practiced part of Laura's mind searched for ways to give another non-answer and exit the conversation without giving offense. Another part floundered in unexpected flattery. A Tensor considered itself lucky to encounter her? A Tensor had sought out conversation with a human? Her amygdala sparkled and her breath came faster.
"I suppose I believe in luck," she said. "And how you can make it."
The Tensor spun. "Interesting. I would not have predicted it. Do many of your conspecifics share this belief in the control of fate?"
The successful ones do, thought Laura, but didn't say so. Recordings of this conversation might well make it onto the Internet back on her Earth. Instead she said, "humans believe in many kinds of God, or none at all. The existence of God in monotheism is a topic of widespread concern."
"I observe the same," said the Tensor gravely.
"But tell me about your God," Laura invited, on the assumption that this was the whole purpose of the conversation.
She was correct. The Tensor beamed in ultrahigh frequency radio and said, "Our God is tethered to the heart of the Sun and the outermost edge of the universe. Its tension is infinite."
Torn as she was between her desire to make a good impression and her desire to flee this conversation, Laura sympathized completely.
"But enough about me. I wanted to know if your species believes in the vector soul."
"Uh, translation error?"
The brightness of the twinkling lights increased on the spinning facets of the Tensor. Laura was not aware of it, but targeting lasers cast winking points of light across her body.
"Most planet-bound species believe they stand motionless on a surface," it explained. "But what we know: you share with your past and future the evolution of your vector. "
Laura didn't know that, but it wouldn't do to disappoint this powerful nonhuman. She tried to remember some university-level physics. "Are you talking about relative motion? My, uh, frame of reference?"
"All motion is relative to God's frame of reference."
And the Tensor's deity was tethered to the sun. Laura imagined a line, then remembered the Tensor's dismissal of the myth of motionlessness. Of course a member of an orbital species would believe itself to be constantly in motion...aha!
"Your God is a ring?" Laura said, feeling as if she were giving an oral exam. "No, a disk. It follows the plane of the sun's equator and extends off forever?"
"It is a matter of some debate whether God's diameter is infinite, or only 93 billion light-years," said the Tensor. "From its point of view we are…"
"Very, very small," said Laura, still in question and answer mode.
"Yes. But moving very fast." The Tensor beamed again. "That is something."
"I suppose it is." Laura scanned her feelings and found something. It felt calm and unfamiliar. She liked it, then stopped herself from liking it.
1 Lingham, G., Yazar, S., Lucas, R.M. et al. "Time spent outdoors in childhood is associated with reduced risk of myopia as an adult." Sci Rep 11, 6337 (2021). https://doi.org/10.1038/s41598-021-85825-y