Speed of light can be calculated, "often with less than 5% error". Interferometry is another method to find the wavelength of electromagnetic radiation for determining the speed of light. A coherent beam of light (e.g. from a laser), with a known frequency ("f"), is split to follow two paths and then recombined. By adjusting the path length while observing the interference pattern and carefully measuring the change in path length, the wavelength of the light ("λ") can be determined. The speed of light is then calculated using the equation "c" = "λf". Before the advent of laser technology, coherent radio sources were used
Max Planck Institute for the Science of Light Max Planck Institute for the Science of Light The Max Planck Institute for the Science of Light (MPL) performs basic research in optical metrology, optical communication, new optical materials, plasmonics and nanophotonics and optical applications in biology and medicine. It is part of the Max Planck Society and was founded on January 1, 2009 in Erlangen near Nuremberg. The Institute is based on the Max Planck Research Group "Optics, Information and Photonics", which was founded in 2004 at the University of Erlangen-Nuremberg, as a precursor. The institute currently comprises five divisions. The institute currently is organized in five divisions, each