So, to begin with, we wondered, how do you send a message to the past? We studied on it. We consulted various oracles...




We were still unsure how to go about it. So we went to see a dimensional ghost to consult with him (his name is Harry).



Still unsure, we asked some friends how they would send a message to the past. N said, "I'd use air, by burning the message, or maybe the ocean--throwing it in; or I guess maybe I could bury it."



She seemed to be taking an elemental approach. Next I asked A. She said, "I'd send an airplane back in time." How? we asked. "By a portal." So, you'd have to find a portal? N asked. A nodded, "Or make one. You could be born with the ability to make one, you'd do this," here she gestured emphatically:



"--and make a portal."

These were good answers, but we weren't born with the portal-making ability and still felt we hadn't found our path.

Then I went to see a movie (the cat stayed home). The Alamo Drafthouse, I realized, is all about the past.



Movies, in fact, are always, by definition, a visit to something past, even when they're about the future. Aha! The movie theater is (in fact) a temple of the past, real, imagined, and, otherwise (whatever that might be).

So, while waiting for the movie to begin (and while a bit of strange film from the past was played as pre-show) I wrote a message to the past, as embodied by film and honored at the Alamo Drafthouse.
 

Sorry it's blurry; but it seems appropriate for a message about to travel into the past.

I left it where all the people of alien invasion movies past could see it, and be reassured that they had not died (or panicked and run screaming, anyway) in vain.