My story "The Time Travel Club" is out in the new issue of Asimov's Science Fiction. It's the story of a group of people who get together to share their made-up time travel experiences. And then someone turns up who's built an actual working time machine. To write this tale, I needed to delve into real physics.

In fact, "The Time Travel Club" was one of the most challenging stories to write — because I wanted to deal with the idea of time travel causing spatial displacement. I consulted with Dr. Dave Goldberg, author of io9's "Ask a Physicist" column, and he shot down my initial idea. Then he and I went back and forth for a while, before we were able to come up with an idea for how traveling in time could cause someone (or something) to move through space as well, even if you're supposed to be in the same physical location you started from.

To implement Dr. Dave's solution, I had to do a lot of math. For one crucial part of the story, I even had to do trigonometry, to figure out exactly where an object would wind up after moving at a particular angle for a certain distance. And then Dr. Dave broke my heart — he wrote to me and said that we'd gotten it wrong, and the whole thing would work somewhat differently than he originally thought. I had to go back and do all the math over again.

Meanwhile, I tried hard to come up with an emotional arc for the story that worked with the time travel concept. I went through a lot of different ideas, including one story that I was calling "Radical Feminists With a Time Machine. What Could Go Wrong?" — but in the end, the notion of the Time Travel Club really worked for me. The idea of people who already felt like time travelers, even before they had access to a time machine, felt really powerful to me in the end. And there are one or two parts of this story that I still get choked up reading, every time.

Here's how "The Time Travel Club" begins:

Nobody could decide what should be the first object to travel through time. Malik offered his car keys. Jerboa held up an action figure. But then Lydia suggested her one-year sobriety coin, and it seemed too perfect to pass up. After all, the coin had a unit of time on it, as if it came from a realm where time really was a denomination of currency. And they were about to break the bank of time forever, if this worked.

Lydia handed over the coin, no longer shiny due to endless thumb-worrying. And then she had a small anxiety attack. “Just as long as I get it back,” she said, trying to keep the edge out of her voice.

“You will,” said Madame Alberta with a smile. “This coin, we send a mere one minute into the future. It reappears in precisely the same place from which it disappears.”

Lydia would have been nervous about the first test of the time machine in Madame Alberta’s musty dry laundry room in any case. After all they’d been through to make this happen, the stupid thing had to work. But now, she felt like a piece of herself—a piece she had fought for—was about to vanish, and she would need to have faith. She sucked at having faith.

Madame Alberta took the coin and placed it in the airtight glass cube—six by six by six—that they’d built where the washer/dryer was supposed to be. The balsa-walled laundry room was so crammed with equipment, there was scarcely room for four people to hunch over together. Once the coin was sitting on the floor of the cube, Madame Alberta walked back toward the main piece of equipment, which looked like a million vacuum cleaner hoses attached to a giant slow-cooker.

“I keep thinking about what you were saying before,” Lydia said to Malik, trying to distract herself. “About wanting to stand outside history and see the empires rising and falling from a great height, instead of being swept along by the waves. But what if this power to send things, and people, back and forth across history makes us the masters of reality? What if we can make the waves change direction, or turn back entirely? What then?”

“I chose your group with great care,” said Madame Alberta. “As I have said. You have the wisdom to use this technology properly, all of you.”

Madame Alberta pulled a big lever. A whoosh of purple neon vapor into the glass cube, followed by a “klorrrrrp” sound like someone opening a soda can and burping at the same time—in exactly the way that might suggest they’d had enough soda already—and the coin was gone.

“Wow,” said Malik. His eyebrows went all the way up so his forehead concertina-ed, and his short dreads did a fractal scatter.

“It just vanished,” said Jerboa, bouncing with excitement, floppy hat flopping. “It just . . . It’s on its way.”

Lydia wanted to hold her breath, but there was so little air in here that she was already light-headed. This whole wooden-beamed staircase-flanked basement area felt like a soup of fumes.

Lydia really needed to pee, but she didn’t want to go upstairs and risk missing the sudden reappearance of her coin, which would be newer than everything else in the world by a minute. She held it, swaying and squirming. She looked down at her phone, and there were just about thirty seconds left. She wondered if they should count down. But that was probably too tacky. She really couldn’t breathe at this point, and she was starting to taste candyfloss and everything smelled white.

“Just ten seconds left,” Malik said. And then they did count down, after all. “Nine . . . eight . . . seven . . . six . . . five! Four! Three! Two! ONE!”

They all stopped and stared at the cube, which remained empty. There was no “soda-gas” noise, no sign of an object breaking back into the physical world from some netherspace.

“Um,” said Jerboa. “Did we count down too soon?”

“It is possible my calculations,” said Madame Alberta, waving her hands in distress. Her fake accent was slipping even more than usual. “But no. I mean, I quadruple-checked. They cannot be wrong.”

“Give it a minute or two longer,” said Malik. “I’m sure it’ll turn up.” As if it was a missing sock in the dryer, instead of a coin in the cube that sat where a dryer ought to be.

Read a longer excerpt at the Asimov's site. You can buy the whole issue (for the Kindle) for just \$3.49 right here.