1. Einstein showed that light travels in bundles called quanta, which are at
the heart of the light-emitting diode. When electrons in a semiconductor-based diode move from one side to another, they shift to a less excited state, releasing energy in the form of photons. Channel these, and you get a bright, long-lasting light source.

2. In 1917 Einstein demonstrated that when a photon comes into contact with an atom, it can trigger a chain-reaction release of additional photons from