Heat flows from the hot end toward the cool end following Fourier's law of conduction, while the rod also loses heat to the surrounding air along its whole length (Newton's law of cooling). The balance between these two effects is why the temperature falls off roughly exponentially with distance rather than staying constant — higher conductivity pushes heat further before it can escape, flattening and extending the gradient; lower conductivity keeps the heat concentrated near the source, producing a steep drop-off. The simulation runs about 1,500× faster than real time so the effect is visible within seconds; the underlying physics and relative timing between materials is accurate.