AUTHOR'S NOTE: In mathematics, science and engineering, a "delta" (symbolized by the Greek letter Δ) is used to identify a divergence, such as differential temperature or pressure (ΔT or ΔP) between environmental states or process streams, that allows monitoring of variable conditions. Here I'm using it in a slightly more esoteric way with similar intent. … Continue reading A Past-and-Present “Differential Life” Spread: Exploring The Gap Between “Then” and “Now”