There’s a question going around on Twitter, courtesy of the writer Matt Whitlock: “Without revealing your actual age, what’s something you remember that if you told a younger person they wouldn’t understand?”

This simple query has received, at this date, 18,000 responses. Here is just a tiny selection:

Etcetera. You are welcome to peruse the replies looking for your precise moment in time to be pinned to the screen, wiggling.

It is obvious that most of the relics of earlier eras that stick with people are technological, or at least about the material culture of technology.

It is banal to note that these technological eras are becoming shorter. No one expects today’s social networks or electronics to last as long as AM radio or the internal combustion engine or even three-channel broadcast television. That’s not how products work anymore. Many things are designed for obsolescence and the rest end up there anyway with frightening speed.

Most of the time, this occasions alarm. Everything’s speedin’ up! Future shock, etc.

But there is pleasure, “That’s my shit!” kind of pleasure, in possessing this knowledge of obsolete lived experience. As the technologies we live with exist for less and less time, a more precise psychological archaeology becomes possible. The slices of time that we invoke when we say, “Remember when you could record songs off the radio” or “Remember the sound of a dial-up modem” or “Remember Facebook before News Feed” or “Remember borders on Instagram pictures” become thinner and thinner. A decade becomes a couple years becomes a few months. The combination of your age and life station and technological possibilities fuse into a fixed moment that’s more meaningful than any generational label or simple number. What gives these moments their power is that they mark our time as it is smashed to pieces by market forces and what is sometimes called progress.

And yet you share something real with the other people who understand, like really understand, one of these moments. And no one else can join the club. It can’t be looked up on Wikipedia or gathered from Google or glimpsed in a YouTube video. You can’t buy that experience at Etsy or eBay or even the weirdest vintage place in all of Oakland.

You had to be a body in a place in a culture. You had to be there.