Infrared a wave and like its quantum particle, the photon. Infrared radiation was discovered in 1800 by astronomer Sir William Herschel, who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer. Slightly more than half of the total energy from the Sun was eventually found to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has a critical effect on Earth's climate. Infrared radiation is emitted or absorbed by molecules when they change their rotational-vibrational movements. It excites vibrational modes
Ultraviolet (Light My Way) dealt with themes of anxiety and despair. Bono has described "Ultraviolet" as "an epic U2 song [but] the key of it left my voice in a conversational place and allowed a different kind of lyric writing." Producer Eno wrote that a combination of opposites within each song was a signature characteristic of "Achtung Baby" and that as part of that, "Ultraviolet" had a "helicopterish melancholy". In "Achtung Baby"s album package, "Ultraviolet" is presented next to a photograph of a crumbling Berlin building that has a Trabant parked in front of it. "Rolling Stone" noted that "Ultraviolet" was one of the