The incandescent light bulb is a specimen of extreme thermal tension, a vessel designed to maintain a precarious equilibrium between brilliance and dissolution. At its heart lies the tungsten filament, a metal chosen for its singular ability to withstand the violence of Joule heating. Operating at temperatures typically reaching $2500^\circ\text{C}$—well below its melting point of $3422^\circ\text{C}$—the filament exists in a state of constant, microscopic evaporation.
To prevent the immediate oxidation of the tungsten, the filament is enclosed in a glass envelope that is either evacuated of air or filled with an inert gas, such as argon or nitrogen. This gas serves a dual purpose: it retards the evaporation of the tungsten and provides a thermal buffer. However, the process of "blackening" is an inevitable biological-like aging of the specimen. As tungsten atoms evaporate from the filament, they are carried by convection currents and deposited on the cooler interior surface of the glass. This dark, metallic film is a mineral record of the bulb's own consumption, a slow sedimentation of the light-source upon its own skin.
The somatic failure of the bulb is usually binary: the filament reaches a point of "notching"—where a local variation in diameter creates a hot spot that accelerates evaporation—and snaps. The result is a sudden cessation of light and the transformation of the object from a tool of illumination into a piece of waste. In some cases, the glass envelope itself fails, allowing oxygen to rush in and instantly convert the white-hot tungsten into an aerosol of brown tungsten oxides ($\text{WO}_3$), a final, colorful gasp of chemical reaction.
The afterlife of the incandescent bulb is characterized by a profound lack of economic incentive. Unlike the copper-rich landline telephone or the zinc-heavy battery, the bulb contains only a minuscule amount of tungsten and a fragile shell of soda-lime glass. Because the cost of separating the tungsten filament from the glass and the aluminum base exceeds the value of the recovered materials, the vast majority of bulbs bypass the recycling stream entirely.
In the landfill, the bulb's afterlife is one of fragmentation. The glass envelope, under the pressure of overlying waste, shatters into iridescent shards. The tungsten filament, now a cold, brittle wire, persists as a microscopic metallic ghost among the rubble. The bulb, which once pushed back the darkness of the human night, ends its existence as a transparent, jagged ruin, contributing to the sterile, glassy strata of the Anthropocene.