Laser
A laser is a device that emits coherent light through stimulated emission of radiation. The word itself is an acronym: Light Amplification by Stimulated Emission of Radiation. Unlike ordinary light sources, lasers produce beams where all photons travel in the same direction with aligned waves, creating extraordinary intensity and precision.
Lasers work by exciting atoms or molecules to higher Energy states, then triggering them to release that energy in sync. A mirror system bounces light back and forth, amplifying the effect until a focused beam escapes. The result: light so concentrated it can cut steel, so pure it enables quantum experiments, so precise it measures displacement to fractions of a wavelength.
Since their invention in 1960, lasers have become indispensable. They read barcodes and data storage, perform surgery with minimal damage, enable telecommunications across continents via fiber optics, and probe the cosmos in multimessenger astronomy. Industrial lasers cut, weld, and engrave; research lasers unlock secrets of matter and time.