I have been thinking about light — specifically, the light that existed during November 1990. Not metaphorical light. Not cultural or emotional light. I mean actual electromagnetic radiation: photons produced by lamps, television screens, streetlights, fires, and the countless other sources that illuminated the world thirty-five years ago.

That light did not wait for permission to leave. The moment it came into existence — whether as a radio broadcast, a reflection from a window at dusk, or a stray photon escaping into the night sky — it departed at the universe's maximum permitted speed. There was no hesitation, no gradual release. Light moves at light speed. It always does. The photons from November 1990 began their journey instantly, and they have not stopped since.

I find myself returning to this fact because of what it implies about distance. Roughly thirty-five years have passed since that month. Light travels at approximately 300,000 kilometres per second — a velocity so extreme that it crosses the distance from Earth to the Moon in just over a second. Therefore, in thirty-five years, light covers approximately thirty-five light-years. The photons that escaped Earth in November 1990 now lie somewhere in that region of interstellar space, far beyond the planets, far beyond the Sun's gravitational influence, already among distant stars.

The geometry of this expansion matters. Light from a point source does not travel in a beam or a trail. It radiates outward in all directions simultaneously, forming an expanding spherical shell. Every photon that escapes Earth joins this shell, contributing to its surface as it races outward. The shell from November 1990 is therefore not a streak across space but a vast, thinning sphere — centered on Earth, expanding at light speed, its edge now brushing regions of the galaxy where no human technology has ever reached.

I keep thinking about the nested structure this creates. Earth does not emit light once and then fall silent. It shines continuously, leaking energy into the cosmos every moment. Each instant produces a new shell, layered inside the older ones like rings in a tree or ripples on a dark pond. November 1990 is only one layer in this endless expansion, but it is a complete one — fixed in time, permanently embedded in space. Inside it lie the shells of December 1990, January 1991, and every month since. Outside it lie the shells of October 1990 and all the years before, stretching back to the first artificial lights and beyond, to the natural emissions of the planet itself.

The scale of this structure defies ordinary imagination. By now, the shell from November 1990 has passed through regions containing dozens of star systems. It has crossed distances that would take our fastest spacecraft tens of thousands of years to traverse. And it continues to expand, adding another light-year of radius with every passing year. The shell will never stop. It will never turn back. It will thin as it spreads — the energy distributed across an ever-larger surface — but it will not cease to exist.

However, I must acknowledge what this light actually contains. Most of the photons produced in November 1990 never escaped at all. The vast majority were absorbed almost immediately — by air, by water, by walls and furniture, by skin and leaves and countless other surfaces. Those photons lived short lives and ended close to home, their energy converted to heat and dissipated. Only a small fraction slipped free into space, and even that fraction carried limited information. Radio and television signals, yes. Reflected sunlight, certainly. The faint glow of cities at night. But nothing like a detailed record of human activity. The escaping light is a trace, not a transcript.

Additionally, detectability diminishes with distance. The energy that seemed bright on Earth becomes vanishingly faint when spread across a sphere thirty-five light-years in radius. Any hypothetical observer in a distant star system would need instruments of extraordinary sensitivity to detect Earth's emissions at all, let alone decode them. The light is there — it exists as a physical reality — but it approaches the threshold of meaninglessness. A signal so weak that no plausible receiver could extract information from it differs little, in practical terms, from no signal at all.

I find this simultaneously humbling and strangely moving. The light of November 1990 carries a fragile imprint of Earth as it was then — its technologies, its nights and days, its quiet leakage of signal and glow. That imprint travels outward through dust, through darkness, through regions where no one is listening and no one may ever listen. It moves on regardless. The light does not require an audience. It does not slow when it encounters emptiness. It simply continues, because that is what light does.

I sometimes imagine what that shell contains, at least in principle. The radio broadcasts of that month. The television signals. The last traces of analogue transmission before digital encoding changed everything. The faint reflections of streetlights and headlamps. The glow of windows on November evenings. All of it now impossibly distant, thinned to near-invisibility, but still physically present in the universe. The shell is an expanding echo of a specific moment when the world was younger and I was younger within it.

The past tense matters here. I am not describing something that is happening. I am describing something that already happened, long ago. The light of November 1990 is not leaving Earth now. It left. It has been gone for decades. The departure occurred before I understood what departure meant, before I thought to wonder where the photons go when they slip past the atmosphere and enter the void. By the time I became curious about such things, the shell had already crossed distances I could not meaningfully comprehend.

As a result, I carry a strange awareness when I think about that month. It is finished in one sense — concluded, historical, safely in the past. However, it is also ongoing in another sense. The light continues outward. The shell expands. Something from November 1990 is still in motion, still traveling, still adding distance with every passing second. I do not know how to reconcile these two truths. The month is over. The light is not.

This is what I keep returning to: the persistence of departure. The light did not hesitate. It did not linger. It left instantly, and it has been leaving ever since — an ever-expanding wave front carrying traces of a world that no longer exists in the form it had then. I cannot retrieve that light. I cannot even detect it. But I know it is there, somewhere in the dark between the stars, moving outward at the speed of causality itself.

The light of November 1990 is still, inexorably, on its way.