Caroline McCarthy chose exactly the right picture for the occasion. I posted the tweet with an ID of 5,000,000,000—not necessarily the five-billionth tweet, but I’ll take the zeroes however I can get ‘em—and it’s got me thinking about counting schemes.

Think of the total arbitrariness of something like the year 2000—and how even understanding that arbitrariness didn’t make it feel less momentous. How totally unmomentous it really was in retrospect. The senseless power of round-number birthdays—I’m turning 30 this December! Thirty what? Units of orbital wisdom?

That, in turn, makes me think—and I’ve linked to this several times before—of Matt Webb’s sublime personal light cone calculator. He describes it succinctly:

From the moment of my birth, light [that I could have influenced] has been expanding around the Earth and light [which could influence me, from an increasing distance of origin] reaching it—this ever-growing sphere of potential causality is my light cone.

I’ve been subscribed to my personal light cone RSS feed for a few years now, and I always enjoy seeing that the photons bounced back by our planet on December 19, 1979 have reached a new star. They just passed—literally just yesterday—Beta Comae Berenices.

Even beyond its obvious sci-fi appeal, I appreciate the light cone’s non-annual nature. Progress doesn’t come at an even pace. Another thing Matt Webb and his colleagues at BERG do is give evocative code-names to big, chunky phases of their collective life, marked by expansion or shifting focus. The phase they’re in now, they’ve dubbed the Escalante. How cool is that?

Personal epochs are infinitely preferable to preexisting schemes. This NYT feature about life phases is charming and well-designed, but let it not go unsaid: It’s also totally oppressive. I know, I know, it’s tongue-in-cheek, but even so. These things sneak in.

We measure everything these days by, er, measuring. It’s all clocks and counters. Even things that don’t function as clocks or counters are ticking away inside. My printer is ticking away inside. This blog is ticking away inside.

Contrast it all to my little virtual athan, which I’ve still got running. That’s another way of subdividing time, but it seems to me it’s a more sensitive one. Rather than, you know, very scientifically count the seconds and then celebrate something arbitrary—OMG 12:34:56 P.M.!!—we come up with something arbitrary to start with and then lay it over the day. More sensitive, and more honest.

What would life be like without a clock? I mean, really diligently clock-free. Would you be more or less tuned into the subjective experience of time? That is, when you’re really jamming, really flowing in a Csíkszentmihályi-ian sense—without a clock to look up to and go “What the…! Five hours have passed,” is the experience still remarkable? Or does it just feel normal? Maybe the sun just steps in as a substitute timepiece—“Heavens, ’tis dusk already!”—and it’s impossible to be truly clock-free, at least as long as you’re still on this planet, and still have a window.

This is all to say, think about what, and how, you count.

Kappa-1 Ceti, here I come.