Wavenumber Wavenumber In the physical sciences, the wavenumber (also wave number or repetency) is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance. Whereas temporal frequency can be thought of as the number of waves per unit time, wavenumber is the number of waves per unit distance. In multidimensional systems, the wavenumber is the magnitude of the wave vector. The space of wave vectors is called reciprocal space. Wave numbers and wave vectors play an essential role in optics and the physics of wave scattering, such as X-ray diffraction, neutron diffraction, and elementary
What a Time to Be Alive debuted at number one on the US "Billboard" 200, with 375,000 album-equivalent units; it sold 334,000 copies in its first week, with the remainder of its unit count representing the album's streaming activity and track sales during the tracking week. It became both Drake and Future's second albums to chart at number one on the "Billboard" 200 in 2015 ("If You're Reading This It's Too Late" and "DS2", respectively). In its second week it sold 65,000 copies. As of January 27, 2016, "What a Time to Be Alive" has sold 519,000 copies in the United States. The album was certified