Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit. It is defined as the bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture; the diffracting object or aperture becomes a secondary source of the propagating wave. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1660. In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wave-front as a collection of individual spherical wavelets; the characteristic banding pattern is most pronounced when a wave from a coherent source encounters a slit/aperture, comparable in size to its wavelength, as shown in the inserted image. This is due to the addition, or interference, of different points on the wave-front that travel by paths of different lengths to the registering surface.

However, if there are multiple spaced openings, a complex pattern of varying intensity can result. These effects occur when a light wave travels through a medium with a varying refractive index, or when a sound wave travels through a medium with varying acoustic impedance – all waves diffract, including gravitational waves, water waves, other electromagnetic waves such as X-rays and radio waves. Furthermore, quantum mechanics demonstrates that matter possesses wave-like properties, hence, undergoes diffraction. Diffraction and interference are related and are nearly – if not – identical in meaning. Richard Feynman observes that "diffraction" tends to be used when referring to many wave sources, "interference" when only a few are considered; the effects of diffraction are seen in everyday life. The most striking examples of diffraction are those; this principle can be extended to engineer a grating with a structure such that it will produce any diffraction pattern desired. Diffraction in the atmosphere by small particles can cause a bright ring to be visible around a bright light source like the sun or the moon.

A shadow of a solid object, using light from a compact source, shows small fringes near its edges. The speckle pattern, observed when laser light falls on an optically rough surface is a diffraction phenomenon; when deli meat appears to be iridescent, diffraction off the meat fibers. All these effects are a consequence of the fact. Diffraction can occur with any kind of wave. Ocean waves diffract around other obstacles. Sound waves can diffract around objects, why one can still hear someone calling when hiding behind a tree. Diffraction can be a concern in some technical applications; the effects of diffraction of light were first observed and characterized by Francesco Maria Grimaldi, who coined the term diffraction, from the Latin diffringere,'to break into pieces', referring to light breaking up into different directions. The results of Grimaldi's observations were published posthumously in 1665. Isaac Newton attributed them to inflexion of light rays. James Gregory observed the diffraction patterns caused by a bird feather, the first diffraction grating to be discovered.

Thomas Young performed a celebrated experiment in 1803 demonstrating interference from two spaced slits. Explaining his results by interference of the waves emanating from the two different slits, he deduced that light must propagate as waves. Augustin-Jean Fresnel did more definitive studies and calculations of diffraction, made public in 1815 and 1818, thereby gave great support to the wave theory of light, advanced by Christiaan Huygens and reinvigorated by Young, against Newton's particle theory. In classical physics diffraction arises because of the way; the propagation of a wave can be visualized by considering every particle of the transmitted medium on a wavefront as a point source for a secondary spherical wave. The wave displacement at any subsequent point is the sum of these secondary waves; when waves are added together, their sum is determined by the relative phases as well as the amplitudes of the individual waves so that the summed amplitude of the waves can have any value between zero and the sum of the individual amplitudes.

Hence, diffraction patterns have a series of maxima and minima. In the modern quantum mechanical understanding of light propagation through a slit every photon has what is known as a wavefunction which describes its path from the emitter through the slit to the screen; the wavefunction — the path the photon will take — is determined by the physical surroundings such as slit geometry, screen distance and initial conditions when the photon is created. In important experiments the existence of the photon's wavefunction was demonstrated. In the quantum approach the diffraction pattern is created by the distribution of paths, the observation of light and dark bands is the presence or absence of photons in these areas; the quantum approach has so

Nathan D. Larson is a perennial candidate for public office in the U. S. state of Virginia. He served 14 months in prison for the felony of threatening President George W. Bush's life, he has advocated curtailing women's rights and decriminalizing child sexual abuse and incest, is a white supremacist. An accountant, Larson has a degree from George Mason University, where he was a cannabis reform activist. In November 2008, Larson ran for Congress in the 1st congressional district of Virginia, as an anarcho-capitalist, he received less than 2% of the vote. In 2009, he pleaded guilty to sending a letter in December 2008 to the United States Secret Service threatening to kill the President, was sentenced to 16 months' imprisonment and three years' supervised release. In March 2017 he described the letter as "an act of civil disobedience"; as a convicted felon, Larson was barred from seeking state office in Virginia, until Governor Terry McAuliffe restored voting and candidacy rights to thousands of felons in 2016.

The following year he stood as an independent candidate for the Virginia House of Delegates in the 31st district, again receiving less than 2% of the vote. His candidacy was discussed in the 2017 campaign for the state governorship, with the Republican nominee, Ed Gillespie, using it to criticize McAuliffe's action. Larson was expelled from the Virginia branch of the Libertarian Party early that year. In 2018, he ran as a "quasi-neoreactionary libertarian" for election to Congress from the 10th congressional district of Virginia, before withdrawing in August. In his 2008 candidacy for Congress, as an anarcho-capitalist, Larson advocated doing away with government at all levels, saying: "All government functions could be better performed by the private sector". Endorsed by the Libertarian Party of Virginia, he stated in its newsletter that the primary aim of his candidacy was introducing libertarian ideas. In 2017, as a self-described "red pill Libertarian", his platform for election to the Virginia House included legalizing child pornography and polygyny, eliminating state funding for girls' and women's education, repealing the 19th Amendment to the U.

S. Constitution, which gave women the vote, his 2018 online political manifesto, taken down, advocates "benevolent white supremacy" and names Adolf Hitler as a "white supremacist hero". It calls for free trade, "putting an end to U. S. involvement in foreign wars arising from our country's alliance with Israel", drug legalization, "suicide rights", protection of gun ownership rights, legalization of child pornography and incest, repeal of the 1994 Violence Against Women Act. Regarding women he states: "We need to switch to a system that classifies women as property of their fathers and of their husbands". After withdrawing his candidacy in August 2018, he offered his endorsement to Democrat Jennifer Wexton, giving as one of his reasons that the Republican incumbent, Barbara Comstock, "continually takes the side of career women". On white supremacy, he says that whites are superior to other races because of "our cultural creativeness, our willingness to invest in the long term rather than living for today, our conscientious desire to do the right thing if it requires heroic self-sacrifice for the good of society", must resist Jews' attempts to "attain complete supremacy" in the U.

S. which would lead to their "destroy what made this country worth living in". Larson created internet chat rooms for self-identified "incels" and for pedophiles, suiped.org and incelocalypse.today, wrote posts on the sites endorsing child rape and describing himself as a "hebephilic rapist". Both sites were removed by the hosting company in late May 2018 after a complaint by the website Babe.net. He told The Huffington Post in response to a question about whether he is a pedophile or writes about it online, "It's a mix of both... When people go over the top there’s a grain of truth to what they say." He described the term as "vague" and described men being attracted to underage girls as "normal". In August 2010 he wrote to the federal prosecutor describing the mental health treatment he had received after his conviction as "a complete waste of taxpayer money" since he did not have a mental illness, announced that he would violate the terms of his release from prison: "If you happen to hear the distinctive sound of gunfire of a Solothurn S-18/100 20 mm Anti-Tank Cannon emanating from my backyard, as cardboard cutouts of statist federal politicians, federal judges, federal prosecutors, federal agents become riddled with large, ragged bullet holes, please know, that there is nothing amiss.

Larson is from lives in Catlett, Virginia, as of June 2018 with his parents. He admitted to raping his ex-spouse, transgender and committed suicide after the birth of their daughter. In November 2015 a jury in Colorado denied him custody of the girl, he announced the following month that he would seek legal termination of his parental rights, he has remarried. "Nathan Larson for Congress campaign manifesto". 2018. Archived from the original. Kim Lacapria. "FACT CHECK: Is Congressional Candidate Nathan Larson an Admitted Pedophile?". Snopes.com. Retrieved 26 January 2019. Nathan Larson at Ba

Foxy was a late'70s Latin dance/disco group from Hialeah, Florida. The group consisted of singer and guitarist Ish "Angel" Ledesma, percussionist Richard "Richie" Puente, keyboardist Charlie Murciano, bass guitarist Arnold Paseiro, drummer Joe Galdo, co-lead vocalist Gary Ortiz. Shortly after the first album was issued, Ortiz was replaced by Carlo Driggs, who contributed vocals/percussion and shared songwriting credits on Foxy's second album, Get Off. Foxy's biggest hit was "Get Off" in 1978, which peaked at #9 on the Billboard Hot 100 and #1 on the Soul chart for two weeks; the song was a Dutch Number-One smash hit single. It was their only release from the 1978 album Get Off, released in 1978. In early 1979, the band were in Criteria Studios, where they played on the backing track of ABBA's song "Voulez-Vous", the only time ABBA recorded outside of Sweden. Driggs left shortly before Foxy's third album was recorded, was not replaced; the group's third album Hot Numbers was released in 1979. The first single, "Hot Number" peaked at #21 on the Billboard Hot 100, #4 on the Soul chart in 1979.

Keyboardist Charlie Murciano departed the band in 1979, the group, now a quartet, issued one final album Party Boys before breaking up in 1980. Ish Ledesma formed the groups Oxo in 1983 and Company B in 1986, the latter with his wife Lori L. her sister Lezlee Livrano, Susan Johnson. In addition to his involvement and writing credits with Foxy, Carlo Driggs was the lead singer of Kracker, which released three albums. Driggs was the lead singer of Paul Revere & the Raiders for over 20 years. Driggs died in Miami, Florida on May 31, 2017 of a sudden massive heart attack after playing with his band at home at age 67. Puente, who died on July 18, 2004 at age 51, was the son of the famous bandleader Tito Puente. A news report on the website allaboutjazz.com said Richard Puente "was hospitalized after suffering from viral encephoplopathy due to a prior brain injury, the result of a mugging over 10 years ago. Since his release from the hospital, Richie had been nonverbal, confined to a bed and wheelchair and relegated to tube feeding.

He resided at home with his 95-year-old grandmother and his mother, Ida Carlini."