Invented by Albert Michelson in the late 19th century, interferometers are powerful tools developed to make incredibly small measurements. These investigative devices are called interferometers because they work by merging two or more sources of light to create an interference pattern, which can be measured and analyzed. Interferometers are so powerful that some have even been designed to measure a distance of 1/10,000th of a proton. The ability to take such small measurements is useful in fields such as astronomy, seismology, fiber optics, and quantum mechanics.