This article explores the iconic double-slit experiment, from Thomas Young’s original interference pattern to modern single-electron versions. It explains how firing particles one by one still builds a wave-like pattern, and how measurement collapses this duality—revealing the quantum observer effect and the strange role of consciousness in physics.

This article examines Albert Einstein’s 1905 explanation of the photoelectric effect, which proved light consists of quantized particles—photons. It describes the failure of classical wave theory, Einstein’s revolutionary equation, and how this discovery earned him a Nobel Prize while establishing particle duality as a physical reality, not a mathematical trick.