Chapter One: Dessert Before Dinner
"I have noticed even people who claim everything is predestined, and that we can do nothing to change it, look before they cross the road."
It was a mundane home, even by Muggle standards—the lawn was tended, if carelessly, and there was a garage, even if nobody could quite recall a car emerging from it. The man living there was friendly, on the rare occasions he spoke to the neighbors. It had been noted (but not with any particular interest) when his girlfriend moved in a few months prior. And if anyone noticed that the house wasn't connected to the Muggle power grid, nobody had said anything.
It was a mundane home that Alan walked up to in the brisk evening air, whistling a soft tune to match the soft light of the street lamps. It was a mundane home, at least on the outside.
"How was your day, mein Schatz?" Ava's voice wafted from the dining room. Her English was flawless, but she addressed Alan in German sometimes. It reminded her of when they had first met at Scarab Academy—he in Talamh House and she in Lasair—and the two would sit in the library, documenting the slight peculiarities in her spellcasting that resulted from pronouncing incantations with a German accent. Even then, science had drawn the two together.
"Excellent." Alan shed his coat and his reserved personality as he entered the room, "I've finally worked out the subtleties of timeline-splitting, and you won't believe what I found out." He picked his way over chocolate frog wrappers and crumpled blueprints on his way to the table, where Ava slouched in a rolling chair. She had clearly been absorbed in another one of her programming projects, for her laptop displayed many lines of the MagicJava language she'd developed, and there was a scorched ring on the table where an automated Protego had contained the disastrous results of a compiler error.
(Alan had learned some rudimentary coding from his girlfriend, but was still more comfortable crafting new spells and enchantments with his hands, in the familiar rune circles that Ava called an "abhorrent affront to visual programming languages." Understandably, she handled most of the complex spell construction.)
"Reading Hawking again?" Ava asked as Alan set his book down on the table. He planted a kiss on her forehead and sat down next to her.
"Yep," he affirmed, "Although that Fletcher bloke called him trash earlier today."
Ava shook her head, "Hawking's sexism gets to me, but trash is a bit harsh."
"Somehow, I doubt Fletcher was thinking along those lines," Alan chuckled, "It would have taken me ages to get so far without this book, though."
Ava's glance held an implicit question. Alan put off his own curiosity about her work and stood up again.
"All right," he said, "I'll demonstrate, then I'll tell you about my day."
Alan set a mental timer; Ava started recording with a few keystrokes. "In one minute, I'm going to travel thirty seconds back in time, which gives me half a minute to explain this. Once my future self appears, he will cast either red or green sparks. I will take note of this, and when it's my turn to travel back, my sparks will be the opposite color of his."
Ava nodded. "Which will split the timeline in two, creating one reality with green sparks and one with red. Haven't we agreed not to split the timeline?"
"Yes, but the split isn't as permanent as we thought before."
Vworp.
Alan's doppelgänger stumbled out of the future, met his own eyes—always an unnerving experience—and switched places with him. He snapped his fingers, and sparks flew. As the colors faded and the previous Alan prepared to jump to the past, his slightly older self raised his eyebrows in Ava's general direction.
"Now, my love… what colour were those sparks?"
"Red, of course." Her brow furrowed. "N- no, green, perhaps. I'm not sure. Both seem right. They were a distinct colour, I recall that much." A pause. "Does this mean what I think it does?"
"Oh yes," Alan replied, "The timeline splits, but it merges again if the two parallel realities are similar enough. Apparently the different memories held in your mind aren't sufficient to keep the two timelines apart. So when they merge, you get both sets of memories. And it's happened to you before, right? Just like it's happened to me, and everyone else. I suspect that this implies time travel is more common than we thought."
Ava leaned forward; her blue eyes were bright with curiosity. "How different can the timelines be before they can't merge anymore?"
"A few degrees centigrade, a centimeter or so of movement—more if the the moving object is of uniform material, and much more if it's a liquid or gas. I haven't figured out any more than that, but I suspect that you're clever enough to craft a spell that will facilitate the merging."
Ava bit her lip thoughtfully, glancing at her laptop, then looked back at her boyfriend. "In your demonstration, though… an event can't cause itself, so you must have gone back at some point without seeing any sparks or future-self. Why don't we remember that?"
"I believe it works like a probability distribution," Alan replied, "On my first time, no future self appeared, but I went back anyway and cast green sparks. But I don't remember doing so at all, because that was just one instance, compared to infinite instances where I did see my future self come back. The time loop iterates over and over again, burying the initial conditions that spawned it."
"So if you only cast green sparks every fourth time instead of every other time, we would remember the red ones more strongly?"
"Precisely."
"And a merging is just a split in reverse, so if you traveled back from now, the timeline would split from your perspective and you'd be seeing red sparks in one and green in the other."
"I suspect so, but if I tried confirming it by experiment I couldn't remember."
"Try drawing the memories from your mind with magic, then examining them?"
"Brilliant."
"And if you then made a permanent change in the past, like… like shifting the table over a foot, but only if you saw red sparks… then…"
"Depends. If seeing my second future-self caused me to not go back a second time, then the whole demonstration, dual timelines and all, would would split once more, but in the other split, the red and green timelines wouldn't re-merge, so there would be three parallel timelines… and if I went back anyway, despite seeing him, then that time loop would overwrite the original one and result in only two."
Ava sat in silence for several seconds.
"I think," she said slowly, "that if we are to embroil ourselves in any time travel shenanigans, then I will practice summoning graph paper."
• • • • • • • •
It wasn't until they were eating dinner that Ava brought it up—it had troubled her since Alan's demonstration, but she didn't want to put a damper on the discovery.
"I'm glad that you figured this out," she said in between bites of corn, "But you really shouldn't have risked splitting the timeline before you knew what would happen."
Alan, reclining in his chair, shook his head. "I was hesitant, but there was no other way. Besides, I tried it on a patch of air first. Nothing that would cause the timelines to be any different. But tell me," and he leaned forward in anticipation, "How's your side of the project coming?"
"Ach, it's so close," she said, "But there's no way for me to reliably gather position data on the extraterrestrial bodies."
"Wait, is that all?"
Ava frowned. "It's a big problem, mein Schatz. My computer lacks the power to-"
"No no, I realize that. It's just that the Muggles have been collecting a fair bit of data themselves. We could even pull some from the future."
"And it's stored on the internet somewhere?"
"Yes, I can give you a few sites to start from after dinner."
Ava pushed away her plate, scourgifying the half-eaten meal. "Dinner's over. What are the sites?" Alan noticed her familiar expression; he thought it looked like lightning was dancing behind her eyes.
He scribbled down a few URLs. "Can MagicJava get data from the Muggle internet?"
"I'm almost offended that you even have to ask that," she grinned, "I'll pull it from as far into the future as I can go without the Muggles changing protocols on me. Should be a few decades at least."
"Perfect." He smiled as she grabbed a keyboard from where it hung on the wall and started writing code. He could feel her peculiar brand of magic on his skin. It felt different from normal spellcasting—more like a powerful magical artifact at work, but with layers and layers of complexity that left his magic-sense tingling.
Alan took his time finishing his dinner, as Ava surrounded herself with more and more virtual displays. She typed a few commands on her keyboard, and prodded six dots seemingly at random. The displays grew fuzzy, flickered, and collapsed to a small point of light.
Alan looked up questioningly. "Did it work?" he whispered. Ava held up a finger, staring intently at what could have been a lumos suspended in midair.
The point of light burst into a host of figures, interlocking circles and lines that shot through the air; they resolved themselves one by one into stars and planets, galaxies and black holes, nebulae and supernovae and everything in between.
Ava, lit by billions of revolving points of data, let out an excited "Ha!" that turned into a full-blown bout of laughter, and Alan was reminded that she was descended from the man upon which Mary Shelley had based her famous mad scientist. His own face was frozen in wonder; only his eyes darted back and forth from the beauty of his lover's mirth to the beauty of the data surrounding her.
With a wave of Ava's hand, the room was lit only by the ceiling light once more. The couple locked eyes, both rather breathless, and it was Alan that got the first words out.
"Wow," he said.
"Yeah."
"You have the data now?"
"Yeah."
Neither one of them was quite sure what to say after that. The last puzzle piece had been handed to them, they needed only to place it and the universe would be theirs to explore. But there was a nagging feeling, some massive object seen out of the corner of the mind's eye… Ava managed to put it into words first.
"With great power comes great responsibility," she murmured, "Alan, are we obliged to be heroes now? Will we feel guilty forever because we haven't helped everyone we could help?"
Alan ran his hands through his long hair, pondering. The moon was faintly visible through the thin curtains, and it now seemed close enough to touch. The mantelpiece clock turned future into present and present into past with every tick.
"No," Alan finally replied, his voice quiet and hesitant, but calm, "Every time we remember something two disparate ways, or whenever you and a friend remember the same event as drastically different… that's strong evidence that there are already time travelers altering history all around us, saving people, fighting evil… and they're braver people than us, I'm sure. Being that kind of hero is hard, but it does come naturally to some people… not us, though. We're scientists, and that's a whole different type of heroism. Perhaps, some day, we can be the wise old couple for some worthy hero, and we should definitely help out wherever we can, but… no, I don't think we're obligated."
Ava nodded, reassured but still somber, and asked the final question—the question that had been on her mind all throughout this evening of many questions.
"Where do we go first?"
The words hovered in the air like a snitch, shining yet elusive.
Alan shrugged. "I can't possibly answer that, and neither can you. Let's let the program choose a random life-supporting planet for us. I'm sure we'll find plenty of fascinating things wherever we go."
Another nod, slow and thoughtful this time.
"I'm going to need one of those Muggle energy drinks for this one."
• • • • • • • •
The taptaptap of keys was quiet, but it filled the otherwise silent bedroom. Ava liked the sound, liked the tactile response; it was the only reason she still used a physical laptop for her otherwise ethereal programming. She smiled to herself, relishing the warmth of Alan's sleeping figure nestled against her side. The clock read 2:00. Soft moonlight and the glow of the screen lent a diffused aura to the room.
Magic was in the air.