The flimsy QMart bag in my right hand holds a gallon bag of popcorn (dinner), a KitKat bar (breakfast) and 80 tabs of aspirin (every four hours without fail). I’ve dragged myself home after too long at the lab, and taped up for me on my apartment door is a torn-out sheet of spiral notebook paper along with a capless blue BiC. In my own horribad handwriting, the note says:

Dear Me — It’s Me, You. I’m You, but from the future. Unfortunately We can’t meet (for kaboom reasons) but written notes work. Write back (ACTUALLY write, ON PAPER), go look in the bathroom, I’ll leave an answer there. OK? OK, go. — Me

There are three obvious possibilities here: hallucination, prank or … no way. Unless?

I feel a little silly about it but I do swap the groceries to my other hand so I can take the pen and write: Hi?

In the bathroom there’s a new note taped to the mirror, in my handwriting again:

Dear Me — Cool, ‘Hi?’ Is officially the text of the first cross-temporal communication ever performed by humans. We have really stepped up to this momentous occasion, five stars. Anyway. Darts tonight. — The Other One

I check for hidden cameras, of course, but if this were a prank that would imply that someone cared. Facts not in evidence.

I rip the paper off the mirror, flip it over and scrawl across the back why are you writing to me??? Where’s a good place for a reply? I’ll try the sock drawer.

Dear Me — I’m not sure actually? But I did it the first time around and I’m not super into breaking causality. Don’t forget to memorize these notes btw, wouldn’t want to screw up the universe. — Still Here (So Far)

Read more science fiction from Nature Futures

I shrug on my coat because clearly it’s time to go back to work. There’s another note in the pocket, reminding me again about what must be some historically important darts. Maybe I want Me to crack time travel at a specific date in the future that’s not tonight, so I’m trying to keep Me away from the lab?

There’s no one left in the workroom, so the lights are out until the motion detector picks me up and wheezily forces the overheads to wake up and do their jobs. The tempo-travel prototype I’ve been banging my head against is back in the corner, near the 110 A socket that’s the only one we have, and my first step is to check that no one’s messed with it. No one has besides Me, who decided to leave a new note inside about darts.

I power up the prototype and the first thing I try is sending a note back in time and to the bathroom. I write Is this working yet? but when I go to the unisex the only note I see is one that says DARTS!?!!!!! so I think that’s from the other guy. I check my watch. He really wants Me to go to this thing. Or maybe He wants Me to blow Him off for the sake of the work, which is my go-to move when people harass me. This is why I’m single.

I know, though, that I’m either hallucinating or close to a breakthrough. There is approximately zero point zero zero chance that I am budging from this lab. So I sit next to the machine, back propped against the concrete, laptop propped on my knees, and I think. I take data. I tinker.

It must be hours later when I shake myself awake. There’s a bit of a drool situation on my shoulder and there’s a message on my belly from Me. This one just says You’re an idiot.

I head back to the bathroom to wash up and there’s a new note waiting for me, propped against the mirror.

Dear Me — Just so You know, You were supposed to meet a girl tonight. Devi. She’s cool. — Darts Champ WITH a Girlfriend, aka Not You

Who could possibly be thinking about girls at a time like this?? Other-Me is cracked. I crumple up his note and move to throw it in the trash …

Wait.

I un-crumple the note.

How does Future-Me know about this girl Devi? I didn’t go. We didn’t meet.