Narcissus was famous in ancient Greek mythology for his obsession with admiring his idol as it was reflected in the water. But the same movement is done every day, for centuries, by all the inhabitants of the civilized world using a magical tool, the mirror.
Ancient civilizations used minerals and metals that could mirror the idol, such as volcanic obsidian glass (Mayans, Aztecs, and Olmecs), copper, brass, iron, tin, silver and gold. Greeks, Egyptians, Persians, Chaldeans, Chaldeans, Mesopotamians, Romans, Etruscans, Indians, Jews, Tibetans, Chinese were reflected in polished bronze and silver sheets.
In 1985 the German Justus von Liebig applied a thin layer of silver to the glass using silver nitrate. This resulted in the mass production of cheap mirrors. Today the most common way of manufacturing mirrors is by ‘liquid deposition’ of silver, nickel or chrome.
In a flat mirror, a parallel beam of light changes direction of motion, but still remains parallel. The images produced by flat mirrors are imaginary and are the size of the real object.
There are also Concave mirrors, where a parallel beam of light converges at a point that is the focus of the mirror. Finally, there are convex mirrors in which a parallel beam of light is deflected, giving the impression that it comes from a point source, which is “behind” the mirror. In practice, concave and convex mirrors do not focus a parallel beam of light at one point, due to spherical aberration.