Ultraviolet divergence short distances. The name comes from the earliest example of such a divergence, the "ultraviolet catastrophe" first encountered in understanding blackbody radiation. According to classical physics at the end of the nineteenth century, the quantity of radiation in the form of light released at any specific wavelength should increase with decreasing wavelength—in particular, there should be considerably more ultraviolet light released from a blackbody radiator than infrared light. Measurements showed the opposite, with maximal energy released at intermediate wavelengths, suggesting a failure of classical mechanics. This problem eventually led to the development of quantum mechanics. The successful resolution of the
Ultraviolet (Light My Way) it. "Ultraviolet" played a featured role during the encores of the group's 1992–1993 Zoo TV Tour, 2009–2011 U2 360° Tour, and the Joshua Tree Tour 2017. "Ultraviolet (Light My Way)" began as two different demos, one variously called "Ultraviolet" and "69" (which eventually evolved into the B-side "Lady with the Spinning Head") and an alternately arranged demo called "Light My Way". Over the course of the recording sessions, U2 added various overdubs to the song, but producer Brian Eno believed these additions negatively impacted the track. Eno aided the group in editing down the song, and he explained his assistance