The Hummingbird Boy

Short sci-fiction

“Time travel is infinitely more complex than one might think, at a quick glance,” he said, raising his voice so the back of the lecture hall could hear him. Half the room were on their phones, the others half asleep. “You might think of it as simply reversing ‘time’ as an entity, but you’re not. You’d have to reverse every single object, every single process. Every single molecule. And you’d have to do it step by step, across every change that has ever happened across hundreds of thousands of milliseconds.”

No one was really listening. It was late in the semester, a cold, wet day and too early in the morning for any concentration from a collection of uninspiring, mid-league undergraduates. But he continued, more for himself than out of any hope for them. “So let’s say you calculated all the changes you needed to go back a single minute. What would need to be undone? The sunlight in this room? The shadows cast? The synapses in your brain that make you aware of the present? The messages you’ve just sent to half your friends around the world? The oxygen you’ve just exhaled as carbon dioxide? Some of them could be undone, yes. But in order? Quickly? Globally? Across the universe? What if a hummingbird just burst through the window unexpectedly? Would you have just created a slightly different reality-”

“You could probably do it through an algorithm,” a young man said suddenly, causing the room to shuffle uncomfortably at his engagement. “You know, get an AI system to mass calculate what has happened, and then develop the technology to reverse it. You’d have to start really small though. Like an ant or something.”

“Good!” he said, scrawling the words ‘start small’ on the blackboard. “Now we’re talking. So with an ant- what would the algorithm need to do? What would it need to be able to detect to understand the connection between time (T) and change (Delta-V, f, I, F,J, etc)?”