These stories are set in or include some kind of alternate reality—parallel worlds or universes, or other dimensions, or alternate histories.
“Infinite Assassin” by Greg Egan
The narrator is surprisingly stable across parallel worlds. The Company recruited him to go into the whirlpool when reality starts shuffling. This is caused by a rare reaction to a drug called “S”. Most of its users are concentrated in ghettos. The narrator gets sent to one such place, Leightown, to deal with the latest anomaly. He’s dressed to blend in and dropped off by helicopter close by.
This is the first story in the preview of Axiomatic. (Select Kindle first then Preview)
“Technical Error” by Arthur C. Clarke
Richard Nelson is making a routine temperature check on the liquid helium. It’s in range; the insulation is working. He’s in the pit of the generator, the first one to use superconductivity. The load on the power network has been steadily rising. Lights, cookers and heaters are being turned on all over the city, and an observatory powers up its magnets’ coils due to an unexpected astronomical event. The strain reaches its peak as Nelson reaches the center of the pit.
This is the ninth story in the preview of The Collected Stories of Arthur C. Clarke. (57% into preview)
“Moon Six” by Stephen Baxter
Bado is on the Cape Canaveral beach, holding his Moon rocks and tools. It’s different—no launch complexes, no Kennedy Space Center and an unfamiliar Moon. He’s wearing his Moon gear and has no money. In another reality, Bado is on the Moon with Slade, exploring Wildwood Crater. Their mission is to retrieve some pieces of the Surveyor and bring them home.
This is the first story in the preview of Other Worlds Than These. (12% into preview)
“A Brief Guide to Other Histories” by Paul McAuley
The narrator’s platoon went through the Turing gate to another America. There are recognizable elements in this New York—buildings, taxis and various landmarks. This world is every bit as real as their own. It was taken over by a rogue General who made himself President-for-Life. The narrator’s reality offered assistance in the civil war against this tyrant. Now, they’re dealing with guerilla fighters.
This is the second story in the preview of Other Worlds Than These. (66% into preview)
The following story is also in the Other Worlds anthology.
“An Empty House With Many Doors” by Michael Swanwick
A man drinks while cleaning up his house. He takes out the garbage and gets his food. He thinks of Katherine, but is also forgetting what she looks like. He goes out for a walk, making his way among all the people. Suddenly, he sees something that, apparently, no one else can see.
“Probably Still the Chosen One” by Kelly Barnhill
Eleven-year-old Corrina has just returned from a year-long stay in Nibiru. She learned to use a sword and shield, and various survival skills. The High Priest will return for her in a week when he has the circlet. He instructs her to stay near the Portal under the cupboard by the sink. Corrina wonders how her mother will react to her long absence.
This story can be read in the preview of The Best Science Fiction and Fantasy of the Year: Volume 12. (46% into preview)
“Into Darkness” by Greg Egan
John is awakened by a buzzer and sees that it’s red—it’s not a drill. He quickly gets ready. He steps outside just as the police car pulls up. They’re headed for The Intake, a large sphere that usually appears over populated regions. It’s believed to be a wormhole that has come unstuck. He’s a Runner, a rescue worker, who enters The Intake to help people caught inside, where some of the usual laws of physics don’t apply.
Some of this story can be read in the preview of The Best of Greg Egan. (74% into Kindle preview)
“Professor Future Vs. the Titan of Sirens” by Jim Gotaas
Professor Future is incognito, taking a temporary break in the past. He’s in a disco, dancing and singing while also performing some complicated calculations in his head. He receives a warning message of an emergency in his own time that only he can deal with. Almost immediately, he’s back in his lab in high-Earth orbit. An old rival, Galactopus, who’s been relegated to a pocket-universe, is threatening again.
This story can be read in the preview of Space: 1975: Space Opera Stories. (45% into preview)
“Left to Right” by Isaac Asimov
Robert L. Forward, a research physicist, is explaining his new invention. It has a spinning ring of particles moving near the speed of light. Anything passing through the opening should experience a change in parity—a reversal of some sort. To effectively test it, he needs to use matter that is highly organized.
Read “Left to Right”
“—And He Built a Crooked House” by Robert A. Heinlein
Quintus Teal, an architect, expounds on what a house really is, to his friend Bailey. He’s disappointed in his colleagues’ ordinary take on house design. He sees a house as a living, dynamic, changing thing. When Bailey dismisses the ranting with a comparison to the fourth dimension, it gives Teal an idea.
“A Subway Named Möbius” by A. J. Deutsch
The Boylston shuttle ties together all seven train lines on four levels. One day, train #86 disappears, but it’s not noticed right away. An engineer makes a connection to the recent reports of missing persons. An investigation identifies about 350 missing people, in addition to the train. A mathematician has a theory about a node—a singularity.
“The Wall of Darkness” by Arthur C. Clarke
Shervane’s planet has extremes of heat and cold on each side. The people live in the narrow belt between. He’s at the age to travel East and visit his other countrymen for a year of learning. Before he went, his father took him deep into the cold part of the planet, the Shadow Land, to show him something. They climbed a small hill. His father pointed to the horizon, to something difficult to see. Shervane became obsessed with what he saw.
“The Destiny of Milton Gomrath” by Alexie Panshin
Milton Gomrath is a garbage collector with aspirations for something better. He’s an orphan. He likes to imagine that a long lost relative will come into his life and elevate him.
“Inside” by Carol Carr
A young woman has lived in a house for six months, and believes she’s been reborn there. Although she lives in it, she has a vague sense that the house can’t really exist. At first, it was just a bedroom. It has gradually been growing—rooms, hallways, furniture and more.
“Living Space” by Isaac Asimov
Clarence Rimbro owns Earth—one of them. There are infinite Earths that support the population of one trillion humans. Getting to the original Earth is easy. He drives through it on the way home from work. Some people still choose to live there. One day, his wife, Sandra, tells him she heard a noise. This is highly unusual, so Clarence looks into it.