Several years ago I was in a department store, frazzled and running late, looking for things I couldn’t find. As I was hastening along an aisle, a woman came toward me. She was quite a bit older than I was, and in a state of substantial disarray. As I drew closer I saw her shirt was wrongly buttoned. I put up a hand to prevent her bumping into me, and she put up a hand as well. I stopped. She stopped. We stared at each other with a kind of pity. And with a sudden rush of mortification, I understood that I was looking at myself in a mirror. Was I that tired and shambolic? Was I that old?

Scrolling through social media this week, it seemed all the world was actually seeking out a version of this experience. The viral app FaceApp uses artificial intelligence to “age” a user’s photo and offer a disorienting glimpse into decades from now. More than a hundred million people have downloaded FaceApp (despite concerns that it was created by Russian developers looking to harvest user data). Everywhere I looked online were images of my friends’ and acquaintances’ future selves.

Simone de Beauvoir observed in “Old Age” that the old tend to say “them” rather than “us. ” The person in the mirror is a shock, wearing the face of someone we never thought we’d become, gazing at us from a future that has arrived before we are ready for it. FaceApp proves that we cannot resist the temptation to peek at our decline, and yet we view these images as speculative fiction, not realized and therefore unreal.

What is it about getting older that I resist or don’t entirely believe? I don’t try to look younger than I am. I don’t disguise my wrinkles (though I do buy anti-aging cream, despite knowing it doesn’t work). Most of the time, I like it that my face is marked by experience. I would never have cosmetic surgery. I’ve long ago gotten used to the fact that my children now walk faster than me, swim faster, think faster. As I grow older, I often experience invisibility as a gift, not an insult. Yet when a young man stands up for me on the train, it still seems like a category error.