“The truth here”, the professor says with a raised chin and the smugness of surety, “is that travelling backwards through time is simply impossible”.
I raise my hand.
“Even putting aside all the theory we’ve just discussed”, the professor continues, sweeping a glance across the room, “if travel to the past really were possible, we very likely should have observed it by now”. He returns his gaze to the middle of the lecture hall, right where I’m sitting.
“That probably sounds like a ridiculous argument to some of you”, he says, “perhaps future humans have unlocked the power of time travel, but simply choose not to use it in obvious ways”.
“Professor”, I call out, trying to get his attention.
“Maybe they’re aware of the dangers of time travel, and so are careful to only use it in subtle ways that are undetectable to us”, he goes on without a pause, “after all, they, like many of us, must have seen Back to the Future”. He smiles as a wave of chuckles passes through the lecture hall.
“Excuse me, Professor”, I try again, wagging my raised hand.
“As much as I enjoy sci-fi tropes”, he says without so much as a nod in my direction, “if humanity really does figure out the physics and engineering of time travel, I think it’s likely we would be able to calculate the outcomes of meddling with the timeline”.
I stand up.
“Surely, we would find ways to travel back and interact with our past selves to influence history for the better”.
He’s facing another side of the lecture hall now, so I start making my way to the nearest aisle.
“At the very least, it seems like we would travel back to let our past selves know that it is indeed possible”.
He’s looking in my direction but still not acknowledging me. I start towards the stage he’s lecturing from.
“We can actually run a simple experiment right now to test this!”, he exclaims with a wry smile. “Some days from now, I will circulate open invitations for future time travelers to come here, to this moment in this lecture, and reveal themselves to prove me wrong”.
I start up the stairs to the stage.
“So, if any of you in this lecture hall is a time traveler, show yourself now!” he exclaims.
I walk over and tap him on the shoulder.
“Anyone?”. He makes a show of sweeping across the room with a hand over his forehead.
“Professor!”, I say, trying to yank his shoulder to spin him around.
He does not turn, or even notice.
“There you have it”, he says triumphantly, “proof that there are no time travelers”.
“Not exactly”, I sigh as I watch him walk smugly back to the center of the podium.
“It’s just that you can’t seem to perceive us, no matter how hard we try”.
The professor continues his lecture uninterrupted, just as he always has.