Based on highly accurate optical interferometry and fundamental quantum calculations, researchers in the US are developing an improved definition of the SI unit for pressure that will consign the ...

A property of a material that changes the speed of light, computed as the ratio of the speed of light in a vacuum to the speed of light through the material. When light travels at an angle between two ...

The Brix scale, derived from the refractive index of a solution at 20 degrees Celsius (68 Fahrenheit), is widely known. Originally, it was established by determining the weight percentage of sucrose ...