shing light at it (2:48). Such outside sources stimulate the atoms within the material, thereby causing light energy to be released in an orderly fashion. The energy is then amplified when it bounces back and forth between the two mirrors within the laser. Some of the amplified light energy passes out through the mirror that is less reflective. This results in a powerful beam of light which can be easily controlled and thus applied to a variety of important uses. In the field of industry, laser beams are used for cutting and welding large pieces of metal. In medicine, tiny lasers are often used for delicate surgical procedures. In the world of entertainment, lasers are used for light shows as well as in such home entertainment systems as video laser discs or audio compact discs. Lasers are also important in such things as supermarket scanners, computer printers, and telephone communications systems. In addition to these examples, there are many, many other potential applications for lasers in today's society.
Although lasers were not developed until the 1950's, the idea for them dates back to the early twentieth century and the work of Albert Einstein. In 1917, Einstein wrote a paper in which he described the concept of stimulated emission. In discussing spontaneous emission, he noted that there was another way in which light energy could be derived. Thus, Einstein claimed that "a number of electrons can be 'kicked' from higher to lower states rather than allowed to fall normally" (3:24). By stimulating the emission of light energy, it would be possible to control that energy as well as to increase its power. However, despite Einstein's remarkable d
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