Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be perceived by the human eye. Visible light is defined as having wavelengths in the range of 400–700 nanometers, or 4.00 × 10−7 to 7.00 × 10−7 m, between the infrared and the ultraviolet. This wavelength means a frequency range of 430–750 terahertz; the main source of light on Earth is the Sun. Sunlight provides the energy that green plants use to create sugars in the form of starches, which release energy into the living things that digest them; this process of photosynthesis provides all the energy used by living things. Another important source of light for humans has been fire, from ancient campfires to modern kerosene lamps. With the development of electric lights and power systems, electric lighting has replaced firelight; some species of animals generate their own light, a process called bioluminescence. For example, fireflies use light to locate mates, vampire squids use it to hide themselves from prey.
The primary properties of visible light are intensity, propagation direction, frequency or wavelength spectrum, polarization, while its speed in a vacuum, 299,792,458 meters per second, is one of the fundamental constants of nature. Visible light, as with all types of electromagnetic radiation, is experimentally found to always move at this speed in a vacuum. In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays and radio waves are light. Like all types of EM radiation, visible light propagates as waves. However, the energy imparted by the waves is absorbed at single locations the way particles are absorbed; the absorbed energy of the EM waves is called a photon, represents the quanta of light. When a wave of light is transformed and absorbed as a photon, the energy of the wave collapses to a single location, this location is where the photon "arrives." This is. This dual wave-like and particle-like nature of light is known as the wave–particle duality.
The study of light, known as optics, is an important research area in modern physics. EM radiation, or EMR, is classified by wavelength into radio waves, infrared, the visible spectrum that we perceive as light, ultraviolet, X-rays, gamma rays; the behavior of EMR depends on its wavelength. Higher frequencies have shorter wavelengths, lower frequencies have longer wavelengths; when EMR interacts with single atoms and molecules, its behavior depends on the amount of energy per quantum it carries. EMR in the visible light region consists of quanta that are at the lower end of the energies that are capable of causing electronic excitation within molecules, which leads to changes in the bonding or chemistry of the molecule. At the lower end of the visible light spectrum, EMR becomes invisible to humans because its photons no longer have enough individual energy to cause a lasting molecular change in the visual molecule retinal in the human retina, which change triggers the sensation of vision. There exist animals that are sensitive to various types of infrared, but not by means of quantum-absorption.
Infrared sensing in snakes depends on a kind of natural thermal imaging, in which tiny packets of cellular water are raised in temperature by the infrared radiation. EMR in this range causes molecular vibration and heating effects, how these animals detect it. Above the range of visible light, ultraviolet light becomes invisible to humans because it is absorbed by the cornea below 360 nm and the internal lens below 400 nm. Furthermore, the rods and cones located in the retina of the human eye cannot detect the short ultraviolet wavelengths and are in fact damaged by ultraviolet. Many animals with eyes that do not require lenses are able to detect ultraviolet, by quantum photon-absorption mechanisms, in much the same chemical way that humans detect visible light. Various sources define visible light as narrowly as 420–680 nm to as broadly as 380–800 nm. Under ideal laboratory conditions, people can see infrared up to at least 1050 nm. Plant growth is affected by the color spectrum of light, a process known as photomorphogenesis.
The speed of light in a vacuum is defined to be 299,792,458 m/s. The fixed value of the speed of light in SI units results from the fact that the meter is now defined in terms of the speed of light. All forms of electromagnetic radiation move at this same speed in vacuum. Different physicists have attempted to measure the speed of light throughout history. Galileo attempted to measure the speed of light in the seventeenth century. An early experiment to measure the speed of light was conducted by Ole Rømer, a Danish physicist, in 1676. Using a telescope, Rømer observed one of its moons, Io. Noting discrepancies in the apparent period of Io's orbit, he calculated that light takes about 22 minutes to traverse the diameter of Earth's orbit. However, its size was not known at that time. If Rømer had known the diameter of the Earth's orbit, he would have calculated a speed of 227,000,000 m/s. Another more accurate measurement of the speed of light was performed in Europe by Hippolyte Fizeau in 1849. Fizeau directed a beam of light at a mirror several kilometers away.
A rotating cog wheel was placed in the pat
Fly Me Courageous is the fourth studio album by the hard rock/Southern rock band Drivin' N' Cryin', released on January 8, 1991 by Island Records. The album is the band's most commercially successful release, in part due to the title track striking a patriotic chord in the United States during the start of the Persian Gulf War. In 1995, Fly Me Courageous was certified gold. Andy Johns was slotted to produce of the album, as the band was impressed by his work with Rod Stewart and Cinderella. However, Johns fell ill. Fly Me Courageous was released during the outbreak of the Persian Gulf War. In turn, the album's title track was interpreted as a pro-war song. "Fly Me Courageous" reached #15 on the Modern Rock Tracks chart. Drivin' N Cryin's guitarist Kevn Kinney said of the song's success: In addition to the title track, "Build a Fire" enjoyed some commercial success, reaching #15 on the Hot Mainstream Rock Tracks chart and receiving regular rotation on MTV. Tom Demalon of Allmusic called Fly Me Courageous Drivin' N Cryin's "finest moment, both commercially and artistically."
Entertainment Weekly's Bob Mack wrote of the album: "Stabs at pop and last-ditch efforts to dazzle are too little, too late, but so, their impulse to integrate influences rather than pick a niche is refreshing". Both reviewers noted the influence of R. E. M. on the album's sound. All tracks are written by Drivin' N' Cryin'; the following people contributed to Fly Me Courageous: Buren Fowler – guitar Kevn Kinney – guitar, vocals Tim Nielsen – bass guitar, backing vocals Jeff Sullivan – drums, percussion George Marino – mastering Tim "Super Glue" Ray – assistant engineering Geoff Workman – engineering, production MacDougal Blues, a 1990 Kevn Kinney solo album that features members of Drivin"n Cryin' Fly Me Courageous page on Drivin' N Cryin's official website
Charles Hawkins was a Seaman in the Union Navy during the American Civil War, where he was awarded the Civil War Congressional Medal of Honor. Hawkins was born depending on the source, in Scotland, he lived in Portsmouth, New Hampshire, enlisted in the Union Navy from New Hampshire. He served on board as one of a volunteer crew of a powderboat, he was given his Medal of Honor on December 23, 1864, when his boat exploded on that date near Fort Fisher. His boat was towed in by USS Wilderness to prevent detection by the enemy, less than two hours after boarding the boat, the explosion took place, the following day fires were observed still burning at the forts. Hawkins was awarded his Medal of Honor on December 31, 1864, he died on February 1908, in Rhode Island. He was buried in Saint Mary Cemetery in Rhode Island. Charles Hawkins at Find a Grave