title: History of gunpowder

text: The arquebus is considered to be the first portable "shoulder" arms firearm. Arquebuses were used as early as 1472 by the Spanish and Portuguese at Zamora. Likewise, the Castilians used arquebuses as well in 1476. In 1496 Philip Monch of the Palatinate composed an illustrated "Buch der Strynt un(d) Buchsse(n)" on guns and "harquebuses." The Mamluks in particular were conservatively against the incorporation of gunpowder weapons. When faced with cannons and arquebuses wielded by the Ottomans they criticized them thus, "God curse the man who invented them, and God curse the man who fires on Muslims with them." Insults were also levied against the Ottomans for having "brought with you this contrivance artfully devised by the Christians of Europe when they were incapable of meeting the Muslim armies on the battlefield." Similarly, musketeers and musket-wielding infantrymen were despised in society by the feudal knights, even until the time of "Don Quixote" author Miguel de Cervantes (1547–1616). Eventually the Mamluks under Qaitbay were ordered in 1489 to train in the use of al-bunduq al-rasas (arquebuses). However, in 1514 an Ottoman army of 12,000 soldiers wielding arquebuses still managed to rout a much larger Mamluk force. The arquebus had become a common infantry weapon by the 16th century due to its relative cheapness – a helmet, breastplate and pike cost about three and a quarter ducats while an arquebus only a little over one ducat. Another advantage of arquebuses over other equipment and weapons was its short training period. While a bow potentially took years to master, an effective arquebusier could be trained in just two weeks. According to a 1571 report by Vincentio d'Alessandri, Persian arms including arquebuses "were superior and better tempered than those of any other nation."


title: History of gunpowder

text: In the early 1500s a larger arquebus known as the musket appeared. The heavy musket, while being rather awkward to handle, requiring a fork rest to fire properly, had the advantage of being able to penetrate the best armor within a range of 180 meters, regular armor at 365 meters, and an unarmed man at 548 meters. However, both the musket and arquebus were effectively limited to a range of only 90 to 185 meters regardless of armor since they were incredibly inaccurate. According to some sources, a smoothbore musket was completely incapable of hitting a man sized target past the 73-meter mark. While rifled guns did exist at this time in the form of grooves cut into the interior of a barrel, these were considered specialist weapons and limited in number. In some aspects this made the smoothbore musket an inferior weapon compared to the bow. The average Mamluk archer for example was capable of hitting targets only 68 meters far away but could keep up a pace of six to eight shots per minute. In comparison, sixteenth-century matchlocks fired off one shot every several minutes, and much less when taking into consideration misfires and malfunctions which occurred up to half the time. This is not to say that firearms of the 16th century were inferior to the bow and arrow, for it could better penetrate armor and required less training, but the disadvantages of the musket were very real, and it would not be until the 1590s that archers were for the most part phased out of "European" warfare. This was possibly a consequence of the increased effectiveness of musket warfare due to the rise of volley fire in Europe as first applied by the Dutch. At this time gunners in European armies reached as high as 40 percent of infantry forces.


title: History of gunpowder

text: As the virtues of the musket became apparent it was quickly adopted throughout Eurasia so that by 1560 even in China generals were giving praise to the new weapon. Qi Jiguang, a noted partisan of the musket, gave a eulogy on the effectiveness of the gun in 1560:


title: History of gunpowder

text: Other East Asian powers such as Đại Việt also adopted the matchlock musket in quick order. Đại Việt in particular was considered by the Ming to have produced the most advanced matchlocks in the world during the 17th century, surpassing even Ottoman, Japanese, and European firearms. European observers of the Trịnh–Nguyễn War also corroborated with the Ming in the proficiency of matchlock making by the Vietnamese. The Vietnamese matchlock was said to have been able to pierce several layers of iron armour, kill two to five men in one shot, yet also fire quietly for a weapon of its caliber.


title: History of gunpowder

text: The Gunpowder Empires generally refer to the Islamic Ottoman, Safavid and Mughal empires. The phrase was first coined by Marshall Hodgson in the title of Book 5 ("The Second Flowering: The Empires of Gunpowder Times") of his highly influential three-volume work, "The Venture of Islam" (1974).


title: History of gunpowder

text: Hogdson applied the term "gunpowder empire" to three Islamic political entities he identified as separate from the unstable, geographically limited confederations of Turkic clans that prevailed in post-Mongol times. He called them "military patronage states of the Later Middle Period," which possessed three defining characteristics: first, a legitimization of independent dynastic law; second, the conception of the whole state as a single military force; third, the attempt to explain all economic and high cultural resources as appanages of the chief military families. Connecting these empires were their traditions which grew "out of Mongol notions of greatness," but "[s]uch notions could fully mature and create stable bureaucratic empires only after gunpowder weapons and their specialized technology attained a primary place in military life."


title: History of gunpowder

text: William H. McNeill further expanded on the concept of gunpowder empires by arguing that such states "were able to monopolize the new artillery, central authorities were able to unite larger territories into new, or newly consolidated, empires."


title: History of gunpowder

text: In 2011 Douglas E. Streusand criticized the Hodgson-McNeill Gunpowder-Empire hypothesis, calling it into disfavor as a neither "adequate [n]or accurate" explanation, although the term remains in use. The main problem he saw with the Hodgson-McNeill theory is that the acquisition of firearms does not seem to have preceded the initial acquisition of territory constituting the imperial critical mass of any of the three early modern Islamic empires, except in the case of the Mughals. Moreover, it seems that the commitment to military autocratic rule pre-dated the acquisition of gunpowder weapons in all three cases.


title: History of gunpowder

text: Whether or not gunpowder was inherently linked to the existence of any of these three empires, it cannot be questioned that each of the three acquired artillery and firearms early in their history and made such weapons an integral part of their military tactics.


title: History of gunpowder

text: It's not certain when the Ottomans started using firearms, however it's argued that they had been using cannons since the Battles of Kosovo (1389) and Nukap (1396) and most certainly by the 1420s. Some argue that field guns only entered service shortly after the Battle of Varna (1444) and more certainly used in the Second Battle of Kosovo (1448). Firearms, (especially grenades) were used in the 1683 siege of Vienna The arquebus reached them around 1425.


title: History of gunpowder

text: In India, guns made of bronze were recovered from Calicut (1504) and Diu (1533). By the 17th century, Indians were manufacturing a diverse variety of firearms; large guns in particular, became visible in Tanjore, Dacca, Bijapur and Murshidabad. Gujarāt supplied Europe saltpeter for use in gunpowder warfare during the 17th century. Bengal and Mālwa participated in saltpeter production. The Dutch, French, Portuguese, and English used Chāpra as a center of saltpeter refining.


title: History of gunpowder

text: Fathullah Shirazi (c. 1582), who worked for Akbar the Great as a mechanical engineer, developed an early multi gun shot. Shirazi's rapid-firing gun had multiple gun barrels that fired hand cannons loaded with gunpowder.


title: History of gunpowder

text: Mysorean rockets were an Indian military weapon, the first iron-cased rockets successfully deployed for military use. The Mysorean army, under Hyder Ali and his son Tipu Sultan, used the rockets effectively against the British East India Company during the 1780s and 1790s.


title: History of gunpowder

text: The Indian war rockets were formidable weapons before such rockets were used in Europe. They had bam-boo rods, a rocket-body lashed to the rod, and iron points. They were directed at the target and fired by lighting the fuse, but the trajectory was rather erratic. The use of mines and counter-mines with explosive charges of gunpowder is mentioned for the times of Akbar and Jahāngir.


title: History of gunpowder

text: Gunpowder was used for hydraulic engineering in China by 1541. Gunpowder blasting followed by dredging of the detritus was a technique which Chen Mu employed to improve the Grand Canal at the waterway where it crossed the Yellow River. In Europe, gunpowder was used in the construction of the Canal du Midi in Southern France. It was completed in 1681 and linked the Mediterranean sea with the Atlantic with 240 km of canal and 100 locks. Another noteworthy consumer of black powder was the Erie canal in New York, which was 585 km long and took eight years to complete, starting in 1817.


title: History of gunpowder

text: Before gunpowder was applied to civil engineering, there were two ways to break up large rocks, by hard labor or by heating with large fires followed by rapid quenching. The earliest record for the use of gunpowder in mines comes from Hungary in 1627. It was introduced to Britain in 1638 by German miners, after which records are numerous. Until the invention of the safety fuse by William Bickford in 1831, the practice was extremely dangerous. Another reason for danger were the dense fumes given off and the risk of igniting flammable gas when used in coal mines.


title: History of gunpowder

text: Gunpowder was also extensively used in railway construction. At first railways followed the contours of the land, or crossed low ground by means of bridges and viaducts, but later railways made extensive use of cuttings and tunnels. One 2400-ft stretch of the 5.4 mi Box Tunnel on the Great Western Railway line between London and Bristol consumed a ton of gunpowder per week for over two years. The 12.9 km long Mont Cenis Tunnel was completed in 13 years starting in 1857 but, even with black powder, progress was only 25 cm a day until the invention of pneumatic drills sped up the work.


title: History of gunpowder

text: During the American Revolutionary War, a number of caves were mined for saltpeter to make gunpowder when supplies from Europe were embargoed. Abigail Adams reputedly also made gunpowder at her family farm in Massachusetts.


title: History of gunpowder

text: During the American Civil War, British India was the main source for saltpeter for the manufacture of gunpowder for the Union armies. This supply was threatened by the British government during the Trent Affair, when Union naval forces stopped a British ship, the RMS Trent, and removed two Confederate diplomats. The British government responded in part by halting all exports of saltpeter to the United States, threatening their gunpowder manufacturing resources. Shortly thereafter, the situation was resolved and the Confederate diplomats were released.


title: History of gunpowder

text: The Union Navy blockaded the southern Confederate States, which reduced the amount of gunpowder that could be imported from overseas. The Confederate Nitre and Mining Bureau was formed to produce gunpowder for the army and the navy from domestic resources. Nitre is the English spelling of "Niter". While carbon and sulfur were readily available throughout the south, potassium nitrate was often produced from the Calcium nitrate found in cave dirt, tobacco barn floors and barn stalls other places. A number of caves were mined, and the men and boys who worked in the caves were called "peter monkey", somewhat in imitation of the naval term "powder monkey" that was used for the boys who brought up charges of gunpowder on gunboats.


title: History of gunpowder

text: On 13 November 1862, the Confederate government advertised in the Charleston Daily Courier for 20 or 30 "able bodied Negro men" to work in the new nitre beds at Ashley Ferry, S.C. The nitre beds were large rectangles of rotted manure and straw, moistened weekly with urine, "dung water", and liquid from privies, cesspools and drains, and turned over regularly. The process was designed to yield saltpeter, an ingredient of gunpowder, which the Confederate army needed during the Civil War. The South was so desperate for saltpeter for gunpowder that one Alabama official reportedly placed a newspaper ad asking that the contents of chamber pots be saved for collection. In the winter of 1863, scores of enslaved people were set to work extracting it from a huge cave in Barstow County, Ga., where they labored by torchlight in grim conditions, hauling out and processing the so-called "peter dirt". In South Carolina, in April 1864, the Confederate government hired 31 enslaved people to work at the Ashley Ferry Nitre Works.


title: History of gunpowder

text: The latter half of the 19th century saw the invention of nitroglycerin, nitrocellulose and smokeless powders which soon replaced traditional gunpowder in most civil and military applications.


title: Michelson–Morley experiment

text: The Michelson–Morley experiment was an attempt to detect the existence of the luminiferous aether, a supposed medium permeating space that was thought to be the carrier of light waves. The experiment was performed between April and July 1887 by American physicists Albert A. Michelson and Edward W. Morley at what is now Case Western Reserve University in Cleveland, Ohio, and published in November of the same year.


title: Michelson–Morley experiment

text: The experiment compared the speed of light in perpendicular directions in an attempt to detect the relative motion of matter through the stationary luminiferous aether ("aether wind"). The result was negative, in that Michelson and Morley found no significant difference between the speed of light in the direction of movement through the presumed aether, and the speed at right angles. This result is generally considered to be the first strong evidence against the then-prevalent aether theory, as well as initiating a line of research that eventually led to special relativity, which rules out a stationary aether. Of this experiment, Albert Einstein wrote, "If the Michelson–Morley experiment had not brought us into serious embarrassment, no one would have regarded the relativity theory as a (halfway) redemption."


title: Michelson–Morley experiment

text: Michelson–Morley type experiments have been repeated many times with steadily increasing sensitivity. These include experiments from 1902 to 1905, and a series of experiments in the 1920s. More recently, in 2009, optical resonator experiments confirmed the absence of any aether wind at the 10 level. Together with the Ives–Stilwell and Kennedy–Thorndike experiments, Michelson–Morley type experiments form one of the fundamental tests of special relativity.


title: Michelson–Morley experiment

text: Physics theories of the 19th century assumed that just as surface water waves must have a supporting substance, i.e., a "medium", to move across (in this case water), and audible sound requires a medium to transmit its wave motions (such as air or water), so light must also require a medium, the "luminiferous aether", to transmit its wave motions. Because light can travel through a vacuum, it was assumed that even a vacuum must be filled with aether. Because the speed of light is so great, and because material bodies pass through the "aether" without obvious friction or drag, it was assumed to have a highly unusual combination of properties. Designing experiments to investigate these properties was a high priority of 19th-century physics.


title: Michelson–Morley experiment

text: Earth orbits around the Sun at a speed of around , or . The Earth is in motion, so two main possibilities were considered: (1) The aether is stationary and only partially dragged by Earth (proposed by Augustin-Jean Fresnel in 1818), or (2) the aether is completely dragged by Earth and thus shares its motion at Earth's surface (proposed by Sir George Stokes, 1st Baronet in 1844). In addition, James Clerk Maxwell (1865) recognized the electromagnetic nature of light and developed what are now called Maxwell's equations, but these equations were still interpreted as describing the motion of waves through an aether, whose state of motion was unknown. Eventually, Fresnel's idea of an (almost) stationary aether was preferred because it appeared to be confirmed by the Fizeau experiment (1851) and the aberration of star light.


title: Michelson–Morley experiment

text: According to the stationary and the partially dragged aether hypotheses, Earth and the aether are in relative motion, implying that a so-called "aether wind" (Fig. 2) should exist. Although it would be possible, in theory, for the Earth's motion to match that of the aether at one moment in time, it was not possible for the Earth to remain at rest with respect to the aether at all times, because of the variation in both the direction and the speed of the motion. At any given point on the Earth's surface, the magnitude and direction of the wind would vary with time of day and season. By analyzing the return speed of light in different directions at various different times, it was thought to be possible to measure the motion of the Earth relative to the aether. The expected relative difference in the measured speed of light was quite small, given that the velocity of the Earth in its orbit around the Sun has a magnitude of about one hundredth of one percent of the speed of light.


title: Michelson–Morley experiment

text: During the mid-19th century, measurements of aether wind effects of first order, i.e., effects proportional to "v"/"c" ("v" being Earth's velocity, "c" the speed of light) were thought to be possible, but no direct measurement of the speed of light was possible with the accuracy required. For instance, the Fizeau–Foucault apparatus could measure the speed of light to perhaps 5% accuracy, which was quite inadequate for measuring directly a first-order 0.01% change in the speed of light. A number of physicists therefore attempted to make measurements of indirect first-order effects not of the speed of light itself, but of variations in the speed of light (see First order aether-drift experiments). The Hoek experiment, for example, was intended to detect interferometric fringe shifts due to speed differences of oppositely propagating light waves through water at rest. The results of such experiments were all negative. This could be explained by using Fresnel's dragging coefficient, according to which the aether and thus light are partially dragged by moving matter. Partial aether-dragging would thwart attempts to measure any first order change in the speed of light. As pointed out by Maxwell (1878), only experimental arrangements capable of measuring second order effects would have any hope of detecting aether drift, i.e., effects proportional to "v"/"c". Existing experimental setups, however, were not sensitive enough to measure effects of that size.


title: Michelson–Morley experiment

text: Michelson had a solution to the problem of how to construct a device sufficiently accurate to detect aether flow. In 1877, while teaching at his alma mater, the United States Naval Academy in Annapolis, Michelson conducted his first known light speed experiments as a part of a classroom demonstration. In 1881, he left active U.S. Naval service while in Germany concluding his studies. In that year, Michelson used a prototype experimental device to make several more measurements.


title: Michelson–Morley experiment

text: The device he designed, later known as a Michelson interferometer, sent yellow light from a sodium flame (for alignment), or white light (for the actual observations), through a half-silvered mirror that was used to split it into two beams traveling at right angles to one another. After leaving the splitter, the beams traveled out to the ends of long arms where they were reflected back into the middle by small mirrors. They then recombined on the far side of the splitter in an eyepiece, producing a pattern of constructive and destructive interference whose transverse displacement would depend on the relative time it takes light to transit the longitudinal "vs." the transverse arms. If the Earth is traveling through an aether medium, a light beam traveling parallel to the flow of that aether will take longer to reflect back and forth than would a beam traveling perpendicular to the aether, because the increase in elapsed time from traveling against the aether wind is more than the time saved by traveling with the aether wind. Michelson expected that the Earth's motion would produce a fringe shift equal to 0.04 fringes—that is, of the separation between areas of the same intensity. He did not observe the expected shift; the greatest average deviation that he measured (in the northwest direction) was only 0.018 fringes; most of his measurements were much less. His conclusion was that Fresnel's hypothesis of a stationary aether with partial aether dragging would have to be rejected, and thus he confirmed Stokes' hypothesis of complete aether dragging.


title: Michelson–Morley experiment

text: However, Alfred Potier (and later Hendrik Lorentz) pointed out to Michelson that he had made an error of calculation, and that the expected fringe shift should have been only 0.02 fringes. Michelson's apparatus was subject to experimental errors far too large to say anything conclusive about the aether wind. Definitive measurement of the aether wind would require an experiment with greater accuracy and better controls than the original. Nevertheless, the prototype was successful in demonstrating that the basic method was feasible.


title: Michelson–Morley experiment

text: In 1885, Michelson began a collaboration with Edward Morley, spending considerable time and money to confirm with higher accuracy Fizeau's 1851 experiment on Fresnel's drag coefficient, to improve on Michelson's 1881 experiment, and to establish the wavelength of light as a standard of length. At this time Michelson was professor of physics at the Case School of Applied Science, and Morley was professor of chemistry at Western Reserve University (WRU), which shared a campus with the Case School on the eastern edge of Cleveland. Michelson suffered a nervous breakdown in September 1885, from which he recovered by October 1885. Morley ascribed this breakdown to the intense work of Michelson during the preparation of the experiments. In 1886, Michelson and Morley successfully confirmed Fresnel's drag coefficient – this result was also considered as a confirmation of the stationary aether concept.


title: Michelson–Morley experiment

text: This result strengthened their hope of finding the aether wind. Michelson and Morley created an improved version of the Michelson experiment with more than enough accuracy to detect this hypothetical effect. The experiment was performed in several periods of concentrated observations between April and July 1887, in the basement of Adelbert Dormitory of WRU (later renamed Pierce Hall, demolished in 1962).


title: Michelson–Morley experiment

text: As shown in Fig. 5, the light was repeatedly reflected back and forth along the arms of the interferometer, increasing the path length to . At this length, the drift would be about 0.4 fringes. To make that easily detectable, the apparatus was assembled in a closed room in the basement of the heavy stone dormitory, eliminating most thermal and vibrational effects. Vibrations were further reduced by building the apparatus on top of a large block of sandstone (Fig. 1), about a foot thick and square, which was then floated in a circular trough of mercury. They estimated that effects of about 0.01 fringe would be detectable.


title: Michelson–Morley experiment

text: Michelson and Morley and other early experimentalists using interferometric techniques in an attempt to measure the properties of the luminiferous aether, used (partially) monochromatic light only for initially setting up their equipment, always switching to white light for the actual measurements. The reason is that measurements were recorded visually. Purely monochromatic light would result in a uniform fringe pattern. Lacking modern means of environmental temperature control, experimentalists struggled with continual fringe drift even when the interferometer was set up in a basement. Because the fringes would occasionally disappear due to vibrations caused by passing horse traffic, distant thunderstorms and the like, an observer could easily "get lost" when the fringes returned to visibility. The advantages of white light, which produced a distinctive colored fringe pattern, far outweighed the difficulties of aligning the apparatus due to its low coherence length. As Dayton Miller wrote, "White light fringes were chosen for the observations because they consist of a small group of fringes having a central, sharply defined black fringe which forms a permanent zero reference mark for all readings." Use of partially monochromatic light (yellow sodium light) during initial alignment enabled the researchers to locate the position of equal path length, more or less easily, before switching to white light.


title: Michelson–Morley experiment

text: The mercury trough allowed the device to turn with close to zero friction, so that once having given the sandstone block a single push it would slowly rotate through the entire range of possible angles to the "aether wind," while measurements were continuously observed by looking through the eyepiece. The hypothesis of aether drift implies that because one of the arms would inevitably turn into the direction of the wind at the same time that another arm was turning perpendicularly to the wind, an effect should be noticeable even over a period of minutes.


title: Michelson–Morley experiment

text: The expectation was that the effect would be graphable as a sine wave with two peaks and two troughs per rotation of the device. This result could have been expected because during each full rotation, each arm would be parallel to the wind twice (facing into and away from the wind giving identical readings) and perpendicular to the wind twice. Additionally, due to the Earth's rotation, the wind would be expected to show periodic changes in direction and magnitude during the course of a sidereal day.


title: Michelson–Morley experiment

text: Because of the motion of the Earth around the Sun, the measured data were also expected to show annual variations.


title: Michelson–Morley experiment

text: After all this thought and preparation, the experiment became what has been called the most famous failed experiment in history. Instead of providing insight into the properties of the aether, Michelson and Morley's article in the "American Journal of Science" reported the measurement to be as small as one-fortieth of the expected displacement (Fig. 7), but "since the displacement is proportional to the square of the velocity" they concluded that the measured velocity was "probably less than one-sixth" of the expected velocity of the Earth's motion in orbit and "certainly less than one-fourth." Although this small "velocity" was measured, it was considered far too small to be used as evidence of speed relative to the aether, and it was understood to be within the range of an experimental error that would allow the speed to actually be zero. For instance, Michelson wrote about the "decidedly negative result" in a letter to Lord Rayleigh in August 1887:


title: Michelson–Morley experiment

text: From the standpoint of the then current aether models, the experimental results were conflicting. The Fizeau experiment and its 1886 repetition by Michelson and Morley apparently confirmed the stationary aether with partial aether dragging, and refuted complete aether dragging. On the other hand, the much more precise Michelson–Morley experiment (1887) apparently confirmed complete aether dragging and refuted the stationary aether. In addition, the Michelson–Morley null result was further substantiated by the null results of other second-order experiments of different kind, namely the Trouton–Noble experiment (1903) and the experiments of Rayleigh and Brace (1902–1904). These problems and their solution led to the development of the Lorentz transformation and special relativity.


title: Michelson–Morley experiment

text: After the "failed" experiment Michelson and Morley ceased their aether drift measurements and started to use their newly developed technique to establish the wavelength of light as a standard of length.


title: Michelson–Morley experiment

text: The beam travel time in the longitudinal direction can be derived as follows: Light is sent from the source and propagates with the speed of light formula_1 in the aether. It passes through the half-silvered mirror at the origin at formula_2. The reflecting mirror is at that moment at distance formula_3 (the length of the interferometer arm) and is moving with velocity formula_4. The beam hits the mirror at time formula_5 and thus travels the distance formula_6. At this time, the mirror has traveled the distance formula_7. Thus formula_8 and consequently the travel time formula_9. The same consideration applies to the backward journey, with the sign of formula_4 reversed, resulting in formula_11 and formula_12. The total travel time formula_13 is:


title: Michelson–Morley experiment

text: Michelson obtained this expression correctly in 1881, however, in transverse direction he obtained the incorrect expression


title: Michelson–Morley experiment

text: because he overlooked the increased path length in the rest frame of the aether. This was corrected by Alfred Potier (1882) and Hendrik Lorentz (1886). The derivation in the transverse direction can be given as follows (analogous to the derivation of time dilation using a light clock): The beam is propagating at the speed of light formula_1 and hits the mirror at time formula_17, traveling the distance formula_18. At the same time, the mirror has traveled the distance formula_19 in the "x" direction. So in order to hit the mirror, the travel path of the beam is formula_3 in the "y" direction (assuming equal-length arms) and formula_19 in the "x" direction. This inclined travel path follows from the transformation from the interferometer rest frame to the aether rest frame. Therefore, the Pythagorean theorem gives the actual beam travel distance of formula_22. Thus formula_23 and consequently the travel time formula_24, which is the same for the backward journey. The total travel time formula_25 is:


title: Michelson–Morley experiment

text: Path difference is denoted by Δλ because the beams are out of phase by a some number of wavelengths (λ). To visualise this, consider taking the two beam paths along the longitudinal and transverse plane, and lying them straight (an animation of this is shown at minute 11:00, The Mechanical Universe, episode 41). One path will be longer than the other, this distance is Δλ. Alternatively, consider the rearrangement of the speed of light formula formula_29 .


title: Michelson–Morley experiment

text: If the relation formula_30 is true (if the velocity of the aether is small relative to the speed of light), then the expression can be simplified using a first order binomial expansion;


title: Michelson–Morley experiment

text: It can be seen from this derivation that aether wind manifests as a path difference. This derivation is true if the experiment is orientated by any factor of 90° with respect to the aether wind. If the path difference is a full number of wavelengths, constructive interference is observed (central fringe will be white). If the path difference is a full number of wavelengths plus one half, deconstructive interference is observed (central fringe will be black).


title: Michelson–Morley experiment

text: To prove the existence of the aether, Michaelson and Morley sought to find the "fringe shift". The idea was simple, the fringes of the interference pattern should shift when rotating it by 90° as the two beams have exchanged roles. To find the fringe shift, subtract the path difference in first orientation by the path difference in the second, then divide by the wavelength, λ, of light;


title: Michelson–Morley experiment

text: Note the difference between Δλ, which is some number of wavelengths, and λ which is a single wavelength. As can be seen by this relation, fringe shift n is a unitless quantity.


title: Michelson–Morley experiment

text: Since "L" ≈ 11 meters and λ≈500 nanometers, the expected fringe shift was "n" ≈ 0.44. The negative result led Michelson to the conclusion that there is no measurable aether drift. However, he never accepted this on a personal level, and the negative result haunted him for the rest of his life (Source; The Mechanical Universe, episode 41).


title: Michelson–Morley experiment

text: If the same situation is described from the view of an observer co-moving with the interferometer, then the effect of aether wind is similar to the effect experienced by a swimmer, who tries to move with velocity formula_1 against a river flowing with velocity formula_4.


title: Michelson–Morley experiment

text: In the longitudinal direction the swimmer first moves upstream, so his velocity is diminished due to the river flow to formula_38. On his way back moving downstream, his velocity is increased to formula_39. This gives the beam travel times formula_5 and formula_41 as mentioned above.


title: Michelson–Morley experiment

text: In the transverse direction, the swimmer has to compensate for the river flow by moving at a certain angle against the flow direction, in order to sustain his exact transverse direction of motion and to reach the other side of the river at the correct location. This diminishes his speed to formula_42, and gives the beam travel time formula_17 as mentioned above.


title: Michelson–Morley experiment

text: The classical analysis predicted a relative phase shift between the longitudinal and transverse beams which in Michelson and Morley's apparatus should have been readily measurable. What is not often appreciated (since there was no means of measuring it), is that motion through the hypothetical aether should also have caused the two beams to diverge as they emerged from the interferometer by about 10 radians.


title: Michelson–Morley experiment

text: For an apparatus in motion, the classical analysis requires that the beam-splitting mirror be slightly offset from an exact 45° if the longitudinal and transverse beams are to emerge from the apparatus exactly superimposed. In the relativistic analysis, Lorentz-contraction of the beam splitter in the direction of motion causes it to become more perpendicular by precisely the amount necessary to compensate for the angle discrepancy of the two beams.


title: Michelson–Morley experiment

text: A first step to explaining the Michelson and Morley experiment's null result was found in the FitzGerald–Lorentz contraction hypothesis, now simply called length contraction or Lorentz contraction, first proposed by George FitzGerald (1889) and Hendrik Lorentz (1892). According to this law all objects physically contract by formula_44 along the line of motion (originally thought to be relative to the aether), formula_45 being the Lorentz factor. This hypothesis was partly motivated by Oliver Heaviside's discovery in 1888 that electrostatic fields are contracting in the line of motion. But since there was no reason at that time to assume that binding forces in matter are of electric origin, length contraction of matter in motion with respect to the aether was considered an Ad hoc hypothesis.


title: Michelson–Morley experiment

text: If length contraction of formula_3 is inserted into the above formula for formula_47, then the light propagation time in the longitudinal direction becomes equal to that in the transverse direction:


title: Michelson–Morley experiment

text: However, length contraction is only a special case of the more general relation, according to which the transverse length is larger than the longitudinal length by the ratio formula_49. This can be achieved in many ways. If formula_50 is the moving longitudinal length and formula_51 the moving transverse length, formula_52 being the rest lengths, then it is given:


title: Michelson–Morley experiment

text: formula_54 can be arbitrarily chosen, so there are infinitely many combinations to explain the Michelson–Morley null result. For instance, if formula_55 the relativistic value of length contraction of formula_50 occurs, but if formula_57 then no length contraction but an elongation of formula_51 occurs. This hypothesis was later extended by Joseph Larmor (1897), Lorentz (1904) and Henri Poincaré (1905), who developed the complete Lorentz transformation including time dilation in order to explain the Trouton–Noble experiment, the Experiments of Rayleigh and Brace, and Kaufmann's experiments. It has the form


title: Michelson–Morley experiment

text: It remained to define the value of formula_54, which was shown by Lorentz (1904) to be unity. In general, Poincaré (1905) demonstrated that only formula_55 allows this transformation to form a group, so it is the only choice compatible with the principle of relativity, "i.e.," making the stationary aether undetectable. Given this, length contraction and time dilation obtain their exact relativistic values.


title: Michelson–Morley experiment

text: Albert Einstein formulated the theory of special relativity by 1905, deriving the Lorentz transformation and thus length contraction and time dilation from the relativity postulate and the constancy of the speed of light, thus removing the "ad hoc" character from the contraction hypothesis. Einstein emphasized the kinematic foundation of the theory and the modification of the notion of space and time, with the stationary aether no longer playing any role in his theory. He also pointed out the group character of the transformation. Einstein was motivated by Maxwell's theory of electromagnetism (in the form as it was given by Lorentz in 1895) and the lack of evidence for the luminiferous aether.


title: Michelson–Morley experiment

text: This allows a more elegant and intuitive explanation of the Michelson–Morley null result. In a comoving frame the null result is self-evident, since the apparatus can be considered as at rest in accordance with the relativity principle, thus the beam travel times are the same. In a frame relative to which the apparatus is moving, the same reasoning applies as described above in "Length contraction and Lorentz transformation", except the word "aether" has to be replaced by "non-comoving inertial frame". Einstein wrote in 1916:


title: Michelson–Morley experiment

text: The extent to which the null result of the Michelson–Morley experiment influenced Einstein is disputed. Alluding to some statements of Einstein, many historians argue that it played no significant role in his path to special relativity, while other statements of Einstein probably suggest that he was influenced by it. In any case, the null result of the Michelson–Morley experiment helped the notion of the constancy of the speed of light gain widespread and rapid acceptance.


title: Michelson–Morley experiment

text: It was later shown by Howard Percy Robertson (1949) and others (see Robertson–Mansouri–Sexl test theory), that it is possible to derive the Lorentz transformation entirely from the combination of three experiments. First, the Michelson–Morley experiment showed that the speed of light is independent of the "orientation" of the apparatus, establishing the relationship between longitudinal (β) and transverse (δ) lengths. Then in 1932, Roy Kennedy and Edward Thorndike modified the Michelson–Morley experiment by making the path lengths of the split beam unequal, with one arm being very short. The Kennedy–Thorndike experiment took place for many months as the Earth moved around the sun. Their negative result showed that the speed of light is independent of the "velocity" of the apparatus in different inertial frames. In addition it established that besides length changes, corresponding time changes must also occur, i.e., it established the relationship between longitudinal lengths (β) and time changes (α). So both experiments do not provide the individual values of these quantities. This uncertainty corresponds to the undefined factor formula_54 as described above. It was clear due to theoretical reasons (the group character of the Lorentz transformation as required by the relativity principle) that the individual values of length contraction and time dilation must assume their exact relativistic form. But a direct measurement of one of these quantities was still desirable to confirm the theoretical results. This was achieved by the Ives–Stilwell experiment (1938), measuring α in accordance with time dilation. Combining this value for α with the Kennedy–Thorndike null result shows that "β" must assume the value of relativistic length contraction. Combining "β" with the Michelson–Morley null result shows that "δ" must be zero. Therefore, the Lorentz transformation with formula_55 is an unavoidable consequence of the combination of these three experiments.


title: Michelson–Morley experiment

text: Special relativity is generally considered the solution to all negative aether drift (or isotropy of the speed of light) measurements, including the Michelson–Morley null result. Many high precision measurements have been conducted as tests of special relativity and modern searches for Lorentz violation in the photon, electron, nucleon, or neutrino sector, all of them confirming relativity.


title: Michelson–Morley experiment

text: As mentioned above, Michelson initially believed that his experiment would confirm Stokes' theory, according to which the aether was fully dragged in the vicinity of the earth (see Aether drag hypothesis). However, complete aether drag contradicts the observed aberration of light and was contradicted by other experiments as well. In addition, Lorentz showed in 1886 that Stokes's attempt to explain aberration is contradictory.


title: Michelson–Morley experiment

text: Furthermore, the assumption that the aether is not carried in the vicinity, but only "within" matter, was very problematic as shown by the Hammar experiment (1935). Hammar directed one leg of his interferometer through a heavy metal pipe plugged with lead. If aether were dragged by mass, it was theorized that the mass of the sealed metal pipe would have been enough to cause a visible effect. Once again, no effect was seen, so aether-drag theories are considered to be disproven.


title: Michelson–Morley experiment

text: Walther Ritz's emission theory (or ballistic theory) was also consistent with the results of the experiment, not requiring aether. The theory postulates that light has always the same velocity in respect to the source. However de Sitter noted that emitter theory predicted several optical effects that were not seen in observations of binary stars in which the light from the two stars could be measured in a spectrometer. If emission theory were correct, the light from the stars should experience unusual fringe shifting due to the velocity of the stars being added to the speed of the light, but no such effect could be seen. It was later shown by J. G. Fox that the original de Sitter experiments were flawed due to extinction, but in 1977 Brecher observed X-rays from binary star systems with similar null results. Furthermore, Filippas and Fox (1964) conducted terrestrial particle accelerator tests specifically designed to address Fox's earlier "extinction" objection, the results being inconsistent with source dependence of the speed of light.


title: Michelson–Morley experiment

text: Although Michelson and Morley went on to different experiments after their first publication in 1887, both remained active in the field. Other versions of the experiment were carried out with increasing sophistication. Morley was not convinced of his own results, and went on to conduct additional experiments with Dayton Miller from 1902 to 1904. Again, the result was negative within the margins of error.


title: Michelson–Morley experiment

text: Miller worked on increasingly larger interferometers, culminating in one with a (effective) arm length that he tried at various sites, including on top of a mountain at the Mount Wilson Observatory. To avoid the possibility of the aether wind being blocked by solid walls, his mountaintop observations used a special shed with thin walls, mainly of canvas. From noisy, irregular data, he consistently extracted a small positive signal that varied with each rotation of the device, with the sidereal day, and on a yearly basis. His measurements in the 1920s amounted to approximately instead of the nearly expected from the Earth's orbital motion alone. He remained convinced this was due to partial entrainment or aether dragging, though he did not attempt a detailed explanation. He ignored critiques demonstrating the inconsistency of his results and the refutation by the Hammar experiment. Miller's findings were considered important at the time, and were discussed by Michelson, Lorentz and others at a meeting reported in 1928. There was general agreement that more experimentation was needed to check Miller's results. Miller later built a non-magnetic device to eliminate magnetostriction, while Michelson built one of non-expanding Invar to eliminate any remaining thermal effects. Other experimenters from around the world increased accuracy, eliminated possible side effects, or both. So far, no one has been able to replicate Miller's results, and modern experimental accuracies have ruled them out. Roberts (2006) has pointed out that the primitive data reduction techniques used by Miller and other early experimenters, including Michelson and Morley, were capable of "creating" apparent periodic signals even when none existed in the actual data. After reanalyzing Miller's original data using modern techniques of quantitative error analysis, Roberts found Miller's apparent signals to be statistically insignificant.


title: Michelson–Morley experiment

text: Using a special optical arrangement involving a 1/20 wave step in one mirror, Roy J. Kennedy (1926) and K.K. Illingworth (1927) (Fig. 8) converted the task of detecting fringe shifts from the relatively insensitive one of estimating their lateral displacements to the considerably more sensitive task of adjusting the light intensity on both sides of a sharp boundary for equal luminance. If they observed unequal illumination on either side of the step, such as in Fig. 8e, they would add or remove calibrated weights from the interferometer until both sides of the step were once again evenly illuminated, as in Fig. 8d. The number of weights added or removed provided a measure of the fringe shift. Different observers could detect changes as little as 1/300 to 1/1500 of a fringe. Kennedy also carried out an experiment at Mount Wilson, finding only about 1/10 the drift measured by Miller and no seasonal effects.


title: Michelson–Morley experiment

text: In 1930, Georg Joos conducted an experiment using an automated interferometer with arms forged from pressed quartz having a very low coefficient of thermal expansion, that took continuous photographic strip recordings of the fringes through dozens of revolutions of the apparatus. Displacements of 1/1000 of a fringe could be measured on the photographic plates. No periodic fringe displacements were found, placing an upper limit to the aether wind of .


title: Michelson–Morley experiment

text: In the table below, the expected values are related to the relative speed between Earth and Sun of . With respect to the speed of the solar system around the galactic center of about , or the speed of the solar system relative to the CMB rest frame of about , the null results of those experiments are even more obvious.


title: Michelson–Morley experiment

text: Optical tests of the isotropy of the speed of light became commonplace. New technologies, including the use of lasers and masers, have significantly improved measurement precision. (In the following table, only Essen (1955), Jaseja (1964), and Shamir/Fox (1969) are experiments of Michelson–Morley type, "i.e.," comparing two perpendicular beams. The other optical experiments employed different methods.)


title: Michelson–Morley experiment

text: During the early 21st century, there has been a resurgence in interest in performing precise Michelson–Morley type experiments using lasers, masers, cryogenic optical resonators, etc. This is in large part due to predictions of quantum gravity that suggest that special relativity may be violated at scales accessible to experimental study. The first of these highly accurate experiments was conducted by Brillet & Hall (1979), in which they analyzed a laser frequency stabilized to a resonance of a rotating optical Fabry–Pérot cavity. They set a limit on the anisotropy of the speed of light resulting from the Earth's motions of Δ"c"/"c" ≈ 10, where Δ"c" is the difference between the speed of light in the "x"- and "y"-directions.


title: Michelson–Morley experiment

text: As of 2015, optical and microwave resonator experiments have improved this limit to Δ"c"/"c" ≈ 10. In some of them, the devices were rotated or remained stationary, and some were combined with the Kennedy–Thorndike experiment. In particular, Earth's direction and velocity (ca. ) relative to the CMB rest frame are ordinarily used as references in these searches for anisotropies.


title: Michelson–Morley experiment

text: Examples of other experiments not based on the Michelson–Morley principle, i.e., non-optical isotropy tests achieving an even higher level of precision, are Clock comparison or Hughes–Drever experiments. In Drever's 1961 experiment, Li nuclei in the ground state, which has total angular momentum "J" = 3/2, were split into four equally spaced levels by a magnetic field. Each transition between a pair of adjacent levels should emit a photon of equal frequency, resulting in a single, sharp spectral line. However, since the nuclear wave functions for different "M" have different orientations in space relative to the magnetic field, any orientation dependence, whether from an aether wind or from a dependence on the large-scale distribution of mass in space (see Mach's principle), would perturb the energy spacings between the four levels, resulting in an anomalous broadening or splitting of the line. No such broadening was observed. Modern repeats of this kind of experiment have provided some of the most accurate confirmations of the principle of Lorentz invariance.


title: Tom Collins

text: The Tom Collins is a Collins cocktail made from gin, lemon juice, sugar, and carbonated water. First memorialized in writing in 1876 by Jerry Thomas, "the father of American mixology", this "gin and sparkling lemonade" drink is typically served in a Collins glass over ice. A non-alcoholic "Collins mix" mixer is produced, enjoyed by some as a soft drink.


title: Tom Collins

text: The earliest publication of any Collins, as well as any Fizz recipe, are both located in the same book, Harry Johnson's 1882 "New and Improved Bartender’s Manual or How to Mix Drinks of the Present Style". The book includes a Tom Collins calling for Old Tom gin and a John Collins calling for Holland Gin, most likely what is known as Genièvre.


title: Tom Collins

text: Cocktail historian David Wondrich stated that there are several other earlier mentions of this version of the drink and that it does bear a striking resemblance to the gin punches served at London clubs like the Garrick in the first half of the 19th century.


title: Tom Collins

text: Clearly unaware of the drink's actual origins, in August 1891, British physician Sir Morell Mackenzie wrote an article in the influential 19th century magazine "Fortnightly Review" claiming that England was the originating country for the Tom Collins cocktail and a person named John Collins was its creator. In the article, Mackenzie quoted an old song called "John Collins." However, the British weekly magazine "Punch" immediately disparaged Mackenzie's efforts, noting in August 1891 that the title of the song actually was "Jim Collins" and that Mackenzie otherwise inaccurately quoted and characterized the song.


title: Tom Collins

text: Confusion over the cocktail's origins continued as American writer Charles Montgomery Skinner noted in 1898 that the Tom Collins had made its way to the "American Bars" in England, France, and Germany, where the American invention stimulated curiosity in Europe and served as a reflection of American art.


title: Tom Collins

text: As time passed, interest in the Tom Collins diminished and its origins became lost. Early on during the 1920s Prohibition in the United States, the American journalist and student of American English H. L. Mencken said:The origin of the ... Tom-Collins ... remains to be established; the historians of alcoholism, like the philologists, have neglected them. But the essentially American character of [this and other drinks] is obvious, despite the fact that a number have gone over into English. The English, in naming their drinks, commonly display a far more limited imagination. Seeking a name, for example, for a mixture of whiskey and soda- water, the best they could achieve was whiskey-and-soda. The Americans, introduced to the same drink, at once gave it the far more original name of high-ball.


title: Tom Collins

text: A drink known as a John Collins has existed since the 1860s at the very least and is believed to have originated with a headwaiter of that name who worked at Limmer's Old House in Conduit Street in Mayfair, which was a popular London hotel and coffee house around 1790–1817.


title: Tom Collins

text: Drinks historian David Wondrich has speculated that the original recipe that was introduced to New York in the 1850s would have been very similar to the gin punches that are known to have been served at fashionable London clubs such as the Garrick during the first half of the 19th century. He states that these would have been along the lines of "gin, lemon juice, chilled soda water, and maraschino liqueur".


title: Tom Collins

text: The specific call for Old Tom gin in the 1869 recipe is a likely cause for the subsequent name change to "Tom Collins" in Jerry Thomas's 1876 recipe. Earlier versions of the gin punch are likely to have used Hollands instead.


title: Tom Collins

text: Some confusion regarding the origin of the drink and the cause for its change of name has arisen in the past due to the following:


title: Tom Collins

text: In 1874, people in New York, Pennsylvania, and elsewhere in the United States would start a conversation with "Have you seen Tom Collins?" After the listener predictably reacts by explaining that they did not know a Tom Collins, the speaker would assert that Tom Collins was talking about the listener to others and that Tom Collins was "just around the corner", "in a [local] bar", or somewhere else near. The conversation about the nonexistent Tom Collins was a proven hoax of exposure. In The Great Tom Collins hoax of 1874, as it became known, the speaker would encourage the listener to act foolishly by reacting to patent nonsense that the hoaxer deliberately presents as reality. In particular, the speaker desired the listener to become agitated at the idea of someone talking about them to others such that the listener would rush off to find the purportedly nearby Tom Collins. Similar to the New York Zoo hoax of 1874, several newspapers propagated the very successful practical joke by printing stories containing false sightings of Tom Collins. The 1874 hoax quickly gained such notoriety that several 1874 music hall songs memorialized the event (copies of which now are in the U.S. Library of Congress).


title: Tom Collins

text: The first published Tom Collins recipe appears to have been in Harry Johnson's 1882 book, "New and Improved Bartender’s Manual or How to Mix Drinks of the Present Style". This book contains a recipe for two Collins drinks, the John Collins and the Tom Collins. The John Collins calls for Holland Gin, which is most likely what is also known as Genièvre, but the recipe for the Tom Collins in this book is as follows:


title: Tom Collins

text: In the 1884 book, "The Modern Bartender’s Guide" by O. H. Byron there is a drink called a "John Collins' Gin" where he calls simply for gin with no specifications of which gin, lemon juice, sugar, and filled with soda. That book also has a "Tom Collins' Brandy", which consists of brandy, lemon juice, gum syrup and Maraschino liqueur, and filled with soda water built in the glass over ice. This book also lists a recipe for a, "Tom Collins Gin and Whiskey", with the only instructions of, "Are concocted in the same manner as a Brandy receipt, substituting their respective liquors".


title: Tom Collins

text: In another 1884 book, "Scientific Barkeeping" by E.N. Cook & Co, you can also find a John Collins and a Tom Collins, with the John Collins calling for Holland Gin and the Tom Collins calling for Whiskey.


title: Tom Collins

text: There is a recipe for the Tom Collins in the 1887 posthumous edition of Jerry Thomas' "Bar-Tender's Guide." Since New York based Thomas would have known about the widespread hoax and the contents of his 1876 published book were developed during or right after The Great Tom Collins hoax of 1874, it was believed by George Sinclair that the hoax event was the most plausible source of the name for the Tom Collins cocktail. Classified under the heading "Collins" with similarly named whisky and brandy drinks, Jerry Thomas' Tom Collins Gin instructed:


title: Tom Collins

text: Shake up well and strain into a large bar-glass. Fill up the glass with plain soda water and drink while it is lively.


title: Tom Collins

text: This was distinguished from the Gin Fizz cocktail in that the 3 dashes of lemon juice in the Gin Fizz was "fizzed" with carbonated water to essentially form a "Gin and Sodawater" whereas the considerably more "juice of a small lemon" in the Tom Collins essentially formed a "Gin and Sparkling Lemonade" when sweetened with the gum syrup. The type of gin used by Thomas was not specified in his 1887 book, but was most likely Old Tom if that was responsible for the change in the drink's name.


title: Tom Collins

text: By 1878, the Tom Collins was being served in the bar rooms of New York City and elsewhere. Identified as among 'the favorite drinks which are in demand everywhere' in an advertisement for the 1878 edition of "The Modern Bartender's Guide" by O. H. Byron, both Tom Collins gin and whiskey and Tom Collins brandy were considered fancy drinks. In the 1891 book, "The Flowing Bowl: When and what to Drink," author William Schmidt listed the Tom Collins as including:


title: Tom Collins

text:
The 1986 "The Book of Cocktails" provides a modern take on Thomas' 1876 recipe for this long drink:John (or Tom) Collins (1986)
ice cubes
2 oz. [6 cL] dry gin
2 oz. [6 cL] lemon juice
1 teaspoon sugar (gomme) syrup
soda water
slice of lemon
1 colored cherry
Place ample ice in large glass. Add gin, lemon juice and syrup. Top up with soda water and stir well. Serve with lemon slice, cherry and a straw.


title: Tom Collins

text: A simple Summer Collins is a two-ingredient cocktail consisting only of equal parts gin and lemonade, served over ice with an optional fruit garnish. The vodka Collins uses vodka in place of gin. The South Side uses limeade in place of lemonade and adds mint. A Rum Collins uses light rum in place of gin.


title: Tom Collins

text: The Juan Collins is a Collins cocktail made from tequila, lime juice, sugar or some other sweetening agent, and club soda. It is a variation of the original Tom Collins, first memorialized in writing in 1876 by "the father of American mixology" Jerry Thomas. This drink typically is served in a Collins glass over ice.


title: Black-eyed children

text: Black-eyed children or black-eyed kids are an American contemporary legend of paranormal creatures that resemble children between ages 6 and 16, with pale skin and black eyes, who are reportedly seen hitchhiking or begging, or are encountered on doorsteps of residential homes.


title: Black-eyed children

text: While tabloid coverage of these creatures has claimed that tales of black-eyed children have existed since the 1980s, most sources indicate that the legend originated from 1996 postings written by Texas reporter Brian Bethel on a "ghost-related mailing list," relating two alleged encounters with "black-eyed kids." Bethel describes encountering two such children in Abilene, Texas in 1996, and claims that a second person had a similar, unrelated encounter in Portland, Oregon. Bethel's stories have become regarded as classic examples of creepypasta, and gained such popularity that he published a FAQ "just to keep up with demand for more info about the new urban legend." In 2012, Brian Bethel told his story on reality TV series "Monsters and Mysteries in America". He wrote a follow-up article for the Abilene Reporter News, describing his experience and maintaining his belief that it was legitimate.


title: Black-eyed children

text: In 2012, the horror film "Black Eyed Kids" was produced with Kickstarter funding, its director commenting that the creepy children were "an urban legend that's been floating around on the Internet for years now, I always thought it was fascinating." A 2013 episode of MSN's "Weekly Strange" that featured reports of black eyed children is thought to have helped spread the legend on the internet.


title: Black-eyed children

text: During one week in September 2014, the British tabloid "Daily Star" ran three sensationalistic front-page stories about alleged sightings of black-eyed children, connected to the sale of a supposedly haunted pub in Staffordshire. The paper claimed a "shock rise in sightings around the world". Alleged sightings are taken seriously by ghost hunters, some of whom believe black eyed children to be extraterrestrials, vampires, or ghosts.


title: Black-eyed children

text: Science writer Sharon A. Hill was unable to find any documentation of black-eyed child encounters, concluding that the tales are passed on as "friend of a friend" ghost stories. Hill considers the legend to resemble "typical spooky folklore stories" such as the phantom black dog, where the subject is not supernatural, and there may never have been an actual original encounter. Snopes rates tales of black-eyed children as a legend, and cites an Inquisitr article that advised readers to "(f)ile black eyed children under the same heading as “bigfoot.” Believe it if you like, but realize that there is no evidence of their existence, just subjective testimony that ranges from reasonable to suspiciously fame-whoring".


title: Mr. Mayor

text: Mr. Mayor is an American sitcom television series created by Tina Fey and Robert Carlock for NBC. The series stars Ted Danson, Bobby Moynihan, Holly Hunter, Vella Lovell, Mike Cabellon, and Kyla Kenedy and premiered on January 7, 2021. In March 2021, the series was renewed for a second season. A holiday special episode aired on December 15, 2021, and the second season premiered on March 15, 2022. In May 2022, the series was canceled after two seasons.


title: Mr. Mayor

text: Neil Bremer (Ted Danson) is a wealthy businessman who runs for mayor of Los Angeles "for all the wrong reasons." Once he wins he has to figure out what he stands for, gain the respect of his staff, and connect with his teenage daughter, all while controlling the coyote population."


title: Mr. Mayor

text: On July 18, 2019, it was reported that NBC had given a 13-episode straight-to-series order to an untitled Tina Fey and Robert Carlock comedy starring Ted Danson, who is set to play a wealthy businessman running for mayor of Los Angeles. Originally meant to be a spin-off/continuation of Fey's series "30 Rock", the series was to star Alec Baldwin reprising his "30 Rock" role of Jack Donaghy, following his political career in New York City. After around a year of negotiations, Baldwin dropped out of the project and was replaced with Danson. Danson refused to move from Los Angeles to New York, so the series was rewritten to take place there.


title: Mr. Mayor

text: On May 11, 2020, it was announced that the series would be called "Mr. Mayor". The series would be executive produced by Tina Fey, Jeff Richmond, Robert Carlock and David Miner. Production companies involved with the series include Little Stranger, Bevel Gears, 3 Arts Entertainment and Universal Television. A first-look tease of the series was included as an end tag on the Peacock stream of "" uploaded on July 16, 2020. The first season began airing on NBC on January 7, 2021, and concluded after nine episodes on February 25, 2021. On March 22, 2021, the series was renewed for a second season. On May 12, 2022, NBC canceled the series after two seasons, causing the show to end on a cliffhanger.


title: Mr. Mayor

text: In 2019", Deadline" reported Bobby Moynihan had joined the cast as Jayden and later that Holly Hunter had also joined the cast as Arpi. In early 2020 Vella Lovell joined the cast as Mikaela, Mike Cabellon joined the cast as Tommy, and Kyla Kenedy joined the cast as Orly Bremer.


title: Mr. Mayor

text: On March 12, 2020, Universal Television suspended the production of the series amid the emergence of COVID-19 in the United States. Filming for the first season commenced shortly after, but was put on hold once again on December 14, 2020, after several crew members tested positive for COVID-19. The following day, it was reported that production would be suspended for the rest of 2020 and was scheduled to resume in January 2021. However, filming for the first season did not resume and the season was cut four episodes short due to the pandemic.


title: Mr. Mayor

text: The first season of the show premiered on NBC with two episodes on January 7, 2021. In July 2020, an end tag of ""30 Rock": A One Time Special" on its post-broadcast stream on Peacock included a teaser trailer of the series and later that year in November 2020, a trailer was released. The nine-episode season concluded with the episode "#PalmTreeReform" on February 25, 2021. The series was acquired by Citytv in Canada. A holiday special episode titled "Mr. Mayor's Magical L.A. Christmas" aired on December 15, 2021, as the second season premiere, ahead of the second season time slot premiere which is March 15, 2022.


title: Mr. Mayor

text: On Rotten Tomatoes, the series holds an approval rating of 44% based on 32 reviews, with an average rating of 4.79/10. The website's critics consensus reads, ""Mr. Mayor" first term suffers from a lack of specificity, leading to broad jokes and wayward plots—still, a reliably winsome Ted Danson and a silly sensibility may be enough for some viewers." On Metacritic, it has a weighted average score of 53 out of 100, based on 22 reviews, indicating "mixed or average reviews". LaToya Ferguson of The A.V. Club gave the fifth and sixth episodes better grades mentioning the lack of Orly in them, noting "these past two episodes have solidified just how superfluous the Orly character and the family sitcom aspect of the series really are."


title: A Horse with No Name

text: "A Horse with No Name" is a song by the folk rock band America, written by Dewey Bunnell. It was the band's first and most successful single, released in late 1971 in Europe and early 1972 in the United States, that topped the charts in Canada, Finland, and the United States. It was certified gold by the Recording Industry Association of America.


title: A Horse with No Name

text: America's self-titled debut album was released initially in Europe, without "A Horse with No Name", and achieved only moderate success. Originally called "Desert Song", "Horse" was written while the band was staying at the home of studio musician Arthur Brown, near Puddletown, Dorset, England. The first two demos were recorded there by Jeff Dexter and Dennis Elliott, which were intended to capture the sensation of the hot, dry desert that had been depicted in a Salvador Dalí painting, and in a picture by M. C. Escher which featured a horse. Writer Dewey Bunnell also says he remembered his childhood travels through the Arizona and New Mexico desert when his family lived at Vandenberg Air Force Base. Bunnell has explained that "A Horse with No Name" was "a metaphor for a vehicle to get away from life's confusion into a quiet, peaceful place".


title: A Horse with No Name

text: Trying to find a song that would be popular in both the United States and Europe, Warner Brothers was reluctant to release Gerry Beckley's "I Need You" ballad as the first single from "America". The label asked the band if it had any other material, then arranged for America to record four more songs at Morgan Studios, in Willesden, London. "A Horse with No Name" was released as the featured song on a three-track single in the UK, Ireland, France, Italy and the Netherlands in late 1971. On the release, "A Horse with No Name" shared the A-side with "Everyone I Meet Is from California"; "Sandman" featured on the B-side. However, its early-1972 two-track US release did not include "Sandman", with "Everyone I Meet Is from California" appearing on the B-side.


title: A Horse with No Name

text: "A Horse with No Name" was recorded in E minor with acoustic guitars, bass guitar, drum kit, and bongo drums. The only other chord is a D, fretted on the low E and G strings, second fret. A 12-string guitar plays an added F♯ (second fret, high E string) on the back beat of the Em. A noted feature of the song is the driving bass line with a hammer-hook in each chorus. A "waterfall"-type solo completes the arrangement. Produced by Ian Samwell on the day of final recording at Morgan Studios, when at first the group thought it was too corny and took some convincing to actually play it. Gerry Beckley has explained in "Acoustic Guitar" magazine (March 2007) that the correct tuning for the guitar is D E D G B D, low to high. The chord pattern that repeats throughout the entire song is: 202002 (Em), then 020202 and 000202. The tuning is unique to this song; they did not use it on any other America song.


title: A Horse with No Name

text: Despite the song being banned by some U.S. radio stations, in Kansas City and elsewhere, because of supposed drug references to heroin use ("horse" is a common slang term for heroin), the song ascended to number one on the U.S. "Billboard" Hot 100, and the album quickly reached platinum status. The song charted earlier in Ireland (reaching number 4), the Netherlands (reaching number 11) and the UK (reaching number 3, the band's only Top 40 hit in the country) than it did in the United States.


title: A Horse with No Name

text: The song's resemblance to some of Neil Young's work aroused some controversy. For example, in their review of "A Horse with No Name" "Cash Box" described America as "CSN&Y soundalikes." "I know that virtually everyone, on first hearing, assumed it was Neil", Bunnell said. "I never fully shied away from the fact that I was inspired by him. I think it's in the structure of the song as much as in the tone of his voice. It did hurt a little, because we got some pretty bad backlash. I've always attributed it more to people protecting their own heroes more than attacking me." By coincidence, it was "A Horse with No Name" that replaced Young's "Heart of Gold" at the number 1 spot on the U.S. pop chart.


title: A Horse with No Name

text: The single achieved sales of over 50,000 copies in Australia, being eligible for the award of a gold disc.


title: A Horse with No Name

text: The song has received criticism for its lyrics, including "The heat was hot"; "There were plants, and birds, and rocks, and things"; and "'Cause there ain't no one for to give you no pain." According to an anecdote from Robert Christgau, Randy Newman dismissed "A Horse With No Name" as a "song about a kid who he’s taken acid".


title: A Horse with No Name

text: Penn Jillette asked the band about their lyrics, "there were plants, and birds, and rocks, and things" after a show in Atlantic City, where America opened for Penn & Teller. According to Jillette, their explanation for the lyrics was that they were intoxicated with cannabis while writing it. In a 2012 interview, Beckley disputed Jillette's story, saying, "I don't think Dew was stoned."


title: A Horse with No Name

text: In the season 4 episode of "BoJack Horseman" "The Old Sugarman Place", the title character drives through the desert to Patrick Carney and Michelle Branch's interpretation of the song. This version also appears on the soundtrack album of the series.


title: A Horse with No Name

text: For the "Breaking Bad" episode, Caballo sin Nombre, the episode begins with Walter White driving through the New Mexico desert while listening to the song.


title: A Horse with No Name

text: The song appears on both the fictional in-game radio station "K-DST" and on the official CD soundtrack boxset for Rockstar Games' 2004 open-world video game "".


title: A Horse with No Name

text: Michael Jackson's song "A Place with No Name" was released posthumously by TMZ as a 25-second snippet on July 16, 2009. The snippet closely resembles "A Horse with No Name". Jim Morey, both Jackson's and America's former band manager, has stated that "America was honored that Michael chose to do their song and they hope it becomes available for all Michael's fans to hear." The song was remastered and released in its entirety along with the original Michael Jackson recording on Jackson's 2014 album, "Xscape".


title: A Horse with No Name

text: The song was sampled by Milo in his song "Geometry and Theology" from his album "Cavalcade", in which every song samples a song by America.


title: Adam Jones (musician)

text: Adam Thomas Jones (born January 15, 1965) is an American musician and visual artist, best known as the guitarist for Tool. Jones has been rated the 75th-greatest guitarist of all time by the "Rolling Stone" and placed ninth in "Guitar World"s Top 100 Greatest Metal Guitarists. With experience in special effects and set design in the Hollywood film industry, Jones is also the director of the majority of Tool's music videos.


title: Adam Jones (musician)

text: Jones was born in Park Ridge, Illinois and raised in Libertyville, Illinois. He was accepted into the Suzuki program, and continued to play violin through his freshman year in high school. As a child, he had an interest in animation, turning his ideas into three-dimensional sculptures, which explains why Tool's music videos often had 3D-clay effects. He later began to play the double bass in an orchestra.


title: Adam Jones (musician)

text: In addition to playing classical music, Jones played bass guitar in the band Electric Sheep, with Tom Morello of Rage Against the Machine playing guitar, until Jones moved to California (Morello soon followed). According to both of them, the band was quite unpopular at the time. Jones never received traditional guitar lessons, but he and Morello learned from each other.


title: Adam Jones (musician)

text: Jones was offered a film scholarship but declined and chose to move to Los Angeles to study art and sculpture. His interest shifted to film, and he began to work as a sculptor and special effects designer, where he learned the stop motion camera techniques he would later apply in Tool's music videos, such as "Sober", "Prison Sex", "Stinkfist", "Ænema", "Schism", "Parabola", and "Vicarious". He graduated in 1987.


title: Adam Jones (musician)

text: After graduation, he went to work at Rick Lazzarini's Character Shop. During the next two years, he worked on the TV show "Monsters". He designed and fabricated a Grim Reaper makeup and a zombie head on a spike (later used in "Ghostbusters II") among others. After that, he went to Stan Winston's special effects workshop, where he worked on "Predator 2", sculpting a unique-looking skull for the Predator's spaceship interior.


title: Adam Jones (musician)

text: Jones worked on several other films in Hollywood doing makeup and set design, including "Jurassic Park", "Batman Returns", "", "Dances with Wolves", and "Ghostbusters II".


title: Adam Jones (musician)

text: He also worked on commercials for salad dressing (never aired), Olympic Paints & Stains (Albert Einstein makeup), and Duracell (boxers and taxicabs).


title: Adam Jones (musician)

text: Jones also toured with Jello Biafra/The Melvins band and contributed to their albums "Never Breathe What You Can't See" and "Sieg Howdy!". Jones and Melvins guitarist/vocalist Buzz Osborne are close friends. Jones also appeared on the Melvins album "Hostile Ambient Takeover", the Melvins/Lustmord collaboration "Pigs of the Roman Empire" and the Isis album "Wavering Radiant".


title: Adam Jones (musician)

text: On "Mr. Show", he appeared as the fictional guitarist of Puscifer along with bandmate Keenan, and can also be spotted in the audience seated at a table with Keenan in the series' first episode.


title: Adam Jones (musician)

text: On August 14, 2011, Jones performed the national anthem of the United States at the outset of WWE's SummerSlam (2011) wrestling event in Los Angeles.


title: Adam Jones (musician)

text: Adam Jones is known for not predominantly using any particular guitar playing technique, but rather combining many techniques such as "alternately utilizing power chords, scratchy noise, chiming arpeggios, off-beat rhythm patterns, and a quiet minimalism". On the 2019 release, "Fear Inoculum", Jones used drop D tuning almost exclusively. He has used other tunings outside of drop D in songs like "Parabola" and "Prison Sex". In the song "7empest", Jones uses a 7/8 time signature throughout the intro of the song. On "Lateralus" and "10,000 Days", he made heavy use of triplets. Other techniques used to expand his band's sound repertoire require forms of instrumental experimentation and applications of non-instrumental experimentation as well, such as his use of an epilator as a plectrum on the " Ænima " and "Lateralus" albums for example; continuing in this direction on the Tool song, "Jambi", Jones uses a talk box. In the song "Third Eye", he makes use of a pick slide for the opening. Live, Jones can be seen with a large pedalboard of effects, including a DOD FX-40B Equalizer (EQ) pedal, Boss BF-2 Flanger, Boss DD-3 Digital Delay, a Dunlop BB535 Cry Baby Wah and a MXR Micro Amp, among others. In a 1994 interview, he mentioned the band Helmet as an influence. Jones is most often seen using his prized 1979 Custom Silverburst Gibson Les Paul, which would later be sold as a signature model for Jones by Gibson in 2020. He uses multiple amplifiers live and when recording, mainly consisting of Marshall, Diezel, and Mesa Boogie amps.


title: Adam Jones (musician)

text: Jones created the cover and inside liner art for many of Tool's albums and also the re-release of Peach's "Giving Birth to a Stone", on which Jones's fellow Tool member Justin Chancellor played bass.


title: Adam Jones (musician)

text: In 2007, he received the Grammy Award for Best Recording Package as art director for his work on "10,000 Days".


title: Adam Jones (musician)

text: In his spare time, Jones shoots photography that is used for the visuals at live Tool concerts. The blending of photos and art appear on many large monitors in concert venues as well as a background for the band. The images are set in order to appear with specific songs on the set list.


title: Adam Jones (musician)

text: Jones draws his own comics, an artistic ability he developed as a young child. An "X-Files/30 Days of Night" crossover in 2010 was co-written by Jones and "30 Days" creator Steve Niles with artwork by Tom Mandrake.


title: Lucifer Morningstar

text: Lucifer Morningstar (also known as Samael before his banishment from heaven) is a fictional character and titular protagonist of the urban fantasy comedy-drama television series "Lucifer". The character is portrayed by Welsh actor Tom Ellis and is based on the protagonist of "The Sandman" comic book series along with his own spin-off series, both published by DC Comics' Vertigo publications. The character is based on the Devil from Christianity who has arisen to Los Angeles for a vacation from Hell with his ex-lover and companion, the demoness Mazikeen, to run a nightclub.


title: Lucifer Morningstar

text: The character was adapted for television by Joe Henderson as the showrunner for a series based on the "Sandman" character Lucifer, with Ellis tapped to play the titular role in February 2015. Ellis' performance has been particularly praised by critics and the character has become a fan-favorite among many.


title: Lucifer Morningstar

text: Samael is a fallen archangel who, after leading an unsuccessful rebellion against Heaven, was banished by God to serve as Lord of Hell. After his fall, he changed his name to Lucifer. Lucifer is shown to hold a deep resentment towards his father for that, as well as his mother for doing nothing. In 2011, Lucifer became bored with his life, so he abdicated his throne and moved to Los Angeles to run his own high-end nightclub called "Lux" for the next five years; during which time he was assisted by John Constantine in retrieving Mazikeen from Hell so she could continue serving as his bodyguard. Lucifer would later repay this debt by helping Constantine and his allies recover Oliver Queen's soul from Purgatory. After five years, Lucifer became a civilian consultant for the Los Angeles Police Department in the pilot episode, while still running his nightclub.


title: Lucifer Morningstar

text: Lucifer is very open about his identity as the Devil, always telling people who he is. However, very few take this seriously unless he lets them see his "Devil Face" – i.e., his true demonic appearance – which he usually does to frighten evildoers. Lucifer is highly sexual, bisexual, and is irresistible to most people.


title: Lucifer Morningstar

text: As a fallen angel, Lucifer possesses several supernatural traits and abilities. He has superhuman strength, enough to throw a grown man several yards or hold an accelerating car still (if he is adequately braced). Lucifer is immortal and his human body is highly durable; he can withstand gunfire or walk through a burning building without harm. He can, however, be injured by Mazikeen's mystical karambits which all celestial beings are vulnerable to. Lucifer originally had a pair of angelic wings, which he had severed by Maze when he arrived in Los Angeles. These wings grew back at the end of season two. The wings are as durable as Lucifer's body; they can resist gunfire and, when flapped, can generate a wind strong enough to knock down a human. Lucifer also possesses the supernatural ability to make people tell him their hidden desires by simply making eye contact and asking them. It is neither hypnosis nor telepathy, and is dependent upon whether the person it is being used upon is a simple or complex person (the more complex or complicated a person is, the more they can resist, and the more time and effort is needed to overcome their resistance), and only Chloe Decker has been shown to be immune to the effect.


title: Lucifer Morningstar

text: Lucifer's principal weakness is that he becomes vulnerable to harm whenever Chloe Decker is close to him or in the immediate vicinity. If he is mortally injured when Chloe is nearby, he can die just like any other human. This effect even renders Lucifer susceptible to minor cuts or painfully stubbing his toe. Once Chloe is far enough away from him, Lucifer's body regains its durability. However, in the pilot episode, he was still invulnerable near Chloe, not manifesting until after a moment of emotional vulnerability, where Chloe sees the scars on Lucifer's back, where his wings were. Chloe's presence does not deprive Lucifer of any of his other supernatural traits, such as his strength. This suggests that Lucifer's physical vulnerability is a manifestation of his emotional vulnerability towards Chloe.


title: Lucifer Morningstar

text: Lucifer is shown to have a complicated relationship with his family. During season 1, his brother Amenadiel tries to force him to return to his hell duties, but he steadfastly refuses to comply with his father's wishes. When the container holding his wings was stolen in the episode "Favorite Son", Lucifer recovers them only to set them on fire as a sign of his rebellion against God's wishes. However, in the season finale, Lucifer prays to God to save Chloe's life after he is shot, willing to do anything in exchange. God gives him a vision: Lucifer's mother has escaped Hell and it is his duty to bring her back.


title: Lucifer Morningstar

text: Season 2 shows his complicated relationship with his mother. While he initially intends to help her return to Heaven (so she and his father will destroy each other), he finally decides to send her to another universe, where she could create her own world free from God's influence. Also, in season 2's finale, his wings were restored.


title: Lucifer Morningstar

text: On Earth, Lucifer creates a connection with Detective Chloe Decker, who's immune to his abilities. After Chloe kisses him in the season 2 episode "Stewardess Interruptus", he discovers she is the result of a miracle done by Amenadiel on God's orders and pushes her away for her own good.


title: Lucifer Morningstar

text: In season 3, he has to deal with the new precinct lieutenant, Marcus Pierce. When he discovers Pierce is Cain the first murderer, he agrees to help him find a way to die to annoy his father, but backs off after Chloe is in danger. He also struggles with his feelings for her when she starts dating Pierce, and his inability to express them. He also loses his "Devil Face" at the beginning of the season. In the penultimate episode, "Quintessential Deckerstar", Lucifer and Chloe kiss again after he confesses his feelings for her. However, this happens just before he kills Cain and recovers his true "Devil Face", which Chloe finally sees in the season finale.


title: Lucifer Morningstar

text: In season 4, Lucifer has to deal with the aftermath of Chloe finally learning the truth (resulting in her hesitantly conspiring with a priest named Father Kinley to send Lucifer back to Hell) and the return of Eve, a former lover of his. Meanwhile, Amenadiel learns that Linda is pregnant with their half angel son. Due to Chloe's betrayal, Lucifer resumes his relationship with Eve, who claims to be in love with him and accepts him for who he is. As the season progresses, Lucifer's growing hatred of himself cause his angel wings to become demon wings and he gains a more demonic alternate form. At the same time, Father Kinley reveals to Chloe a prophecy that Lucifer and his first love will unleash evil upon the Earth. Meanwhile, with Eve at his side urging him on, Lucifer goes back to his old habits, going as far as brutally crippling a criminal as punishment. But he later realizes he doesn't like who he is around Eve and breaks up with her.


title: Lucifer Morningstar

text: In the season finale, after Eve kills Kinley and summons the demon Dromos into his body, Lucifer has to rescue his nephew Charlie, Linda and Amenadiel's newborn son, scaring the demons into returning to Hell using his full demonic form before Chloe. Chloe finally accepts Lucifer completely, even after seeing his demonic form and admits her love for him. However, Lucifer decides that he must return to Hell to keep the demons in line, recognizing that Chloe was his true love, even if Eve was his first. After a tearful goodbye and last kiss with Chloe, Lucifer uses his wings, angelic white once again, to return to his throne in Hell.


title: Lucifer Morningstar

text: In season 5, Lucifer returns from Hell to confront his twin brother Michael, who attempts to steal his identity, leaving Amenadiel in his place. Later he learns from Amenadiel that God relieved him from his duties as the guardian of Hell and moves forward with his relationship with Chloe.


title: Lucifer Morningstar

text: After his father retired, he began competing with his brother Michael for the title of God. He fought his brother to the death, but the fight was stopped after Michael killed Chloe. Despite the fact that Lucifer would burn if he flew to heaven, he went there to resurrect Chloe. Once there, he helped her get back to earth, and died himself. However, he was resurrected and returned to earth, stopping Chloe from killing Michael. He finished the duel with his brother, but did not kill him, only cut off his wings, saying that everyone deserves a second chance. After this he was recognized and accepted as God, by demons and other angels, including Michael.


title: Lucifer Morningstar

text: Neil Gaiman's Lucifer was partly inspired by David Bowie, but the show's creators decided against trying to mimic Bowie. Tom Ellis saw the character as a sort of Oscar Wilde or Noël Coward character "with added rock and roll spirit", approaching his portrayal as if he were the "lovechild of Noël Coward and Mick Jagger, with a dash of British actor Terry-Thomas".


title: Lucifer Morningstar

text: Ellis received praise for his performance as Lucifer Morningstar. "Bleeding Cool"s Dan Wickline offered praise to Ellis' sarcastic, wittingly charming take on the Devil, stating, "the show itself is enjoyable because of the great dialogue and flawless delivery from its lead" and "This version of Lucifer refuses to take almost anything seriously and the show is better for it." Max Nicholson of "IGN" rated the pilot episode a 6.9/10, praising Tom Ellis's performance as Lucifer and the lighthearted tone of the series, but criticizing the series for essentially being another crime procedural series.


title: Voyager program

text: The Voyager program is an American scientific program that employs two robotic interstellar probes, "Voyager 1" and "Voyager 2". They were launched in 1977 to take advantage of a favorable alignment of Jupiter and Saturn, to fly near them while collecting data for transmission back to Earth. After launch the decision was taken to send "Voyager 2" near Uranus and Neptune to collect data for transmission back to Earth.


title: Voyager program

text: As of 2022, the Voyagers are still in operation past the outer boundary of the heliosphere in interstellar space. They collect and transmit useful data to Earth.


title: Voyager program

text: , "Voyager 1" was moving with a velocity of , or 17 km/s, relative to the Sun, and was from the Sun reaching a distance of from Earth as of February 10, 2022. On 25 August 2012, data from "Voyager 1" indicated that it had entered interstellar space.


title: Voyager program

text: , "Voyager 2" was moving with a velocity of , or 15 km/s, relative to the Sun, and was from the Sun reaching a distance of from Earth as of February 10, 2022. On 5 November 2019, data from "Voyager 2" indicated that it also had entered interstellar space. On 4 November 2019, scientists reported that, on 5 November 2018, the "Voyager 2" probe had officially reached the interstellar medium (ISM), a region of outer space beyond the influence of the solar wind, as did "Voyager 1" in 2012.


title: Voyager program

text: Although the Voyagers have moved beyond the influence of the solar wind, they still have a long way to go before exiting the Solar System. NASA indicates "[I]f we define our solar system as the Sun and everything that primarily orbits the Sun, Voyager 1 will remain within the confines of the solar system until it emerges from the Oort cloud in another 14,000 to 28,000 years."


title: Voyager program

text: Data and photographs collected by the Voyagers' cameras, magnetometers and other instruments revealed unknown details about each of the four giant planets and their moons. Close-up images from the spacecraft charted Jupiter's complex cloud forms, winds and storm systems and discovered volcanic activity on its moon Io. Saturn's rings were found to have enigmatic braids, kinks and spokes and to be accompanied by myriad "ringlets".


title: Voyager program

text: At Uranus, "Voyager 2" discovered a substantial magnetic field around the planet and ten more moons. Its flyby of Neptune uncovered three rings and six hitherto unknown moons, a planetary magnetic field and complex, widely distributed auroras. As of 2022, "Voyager 2" remains the only spacecraft to have ever visited the ice giants Uranus and Neptune.


title: Voyager program

text: In August 2018, NASA confirmed, based on results by the "New Horizons" spacecraft, the existence of a "hydrogen wall" at the outer edges of the Solar System that was first detected in 1992 by the two Voyager spacecraft.


title: Voyager program

text: The Voyager spacecraft were built at the Jet Propulsion Laboratory in Southern California and funded by the National Aeronautics and Space Administration (NASA), which also financed their launches from Cape Canaveral, Florida, their tracking and everything else concerning the probes.


title: Voyager program

text: The cost of the original program was $865 million, with the later-added Voyager Interstellar Mission costing an extra $30 million.


title: Voyager program

text: The two Voyager space probes were originally conceived as part of the Mariner program, and they were thus initially named Mariner 11 and Mariner 12. They were then moved into a separate program named "Mariner Jupiter-Saturn", later renamed the Voyager Program because it was thought that the design of the two space probes had progressed sufficiently beyond that of the Mariner family to merit a separate name.


title: Voyager program

text: The Voyager Program was similar to the Planetary Grand Tour planned during the late 1960s and early 70s. The Grand Tour would take advantage of an alignment of the outer planets discovered by Gary Flandro, an aerospace engineer at the Jet Propulsion Laboratory. This alignment, which occurs once every 175 years, would occur in the late 1970s and make it possible to use gravitational assists to explore Jupiter, Saturn, Uranus, Neptune, and Pluto. The Planetary Grand Tour was to send several pairs of probes to fly by all the outer planets (including Pluto, then still considered a planet) along various trajectories, including Jupiter-Saturn-Pluto and Jupiter-Uranus-Neptune. Limited funding ended the Grand Tour program, but elements were incorporated into the Voyager Program, which fulfilled many of the flyby objectives of the Grand Tour except a visit to Pluto.


title: Voyager program

text: "Voyager 2" was the first to be launched. Its trajectory was designed to allow flybys of Jupiter, Saturn, Uranus, and Neptune. "Voyager 1" was launched after "Voyager 2", but along a shorter and faster trajectory that was designed to provide an optimal flyby of Saturn's moon Titan, which was known to be quite large and to possess a dense atmosphere. This encounter sent "Voyager 1" out of the plane of the ecliptic, ending its planetary science mission. Had "Voyager 1" been unable to perform the Titan flyby, the trajectory of "Voyager 2" could have been altered to explore Titan, forgoing any visit to Uranus and Neptune. "Voyager 1" was not launched on a trajectory that would have allowed it to continue to Uranus and Neptune, but could have continued from Saturn to Pluto without exploring Titan.


title: Voyager program

text: During the 1990s, "Voyager 1" overtook the slower deep-space probes Pioneer 10 and Pioneer 11 to become the most distant human-made object from Earth, a record that it will keep for the foreseeable future. The "New Horizons" probe, which had a higher launch velocity than "Voyager 1", is travelling more slowly due to the extra speed "Voyager 1" gained from its flybys of Jupiter and Saturn. "Voyager 1" and Pioneer 10 are the most widely separated human-made objects anywhere since they are travelling in roughly opposite directions from the Solar System.


title: Voyager program

text: In December 2004, "Voyager 1" crossed the termination shock, where the solar wind is slowed to subsonic speed, and entered the heliosheath, where the solar wind is compressed and made turbulent due to interactions with the interstellar medium. On 10 December 2007, "Voyager 2" also reached the termination shock, about closer to the Sun than from where "Voyager 1" first crossed it, indicating that the Solar System is asymmetrical.


title: Voyager program

text: In 2010 "Voyager 1" reported that the outward velocity of the solar wind had dropped to zero, and scientists predicted it was nearing interstellar space. In 2011, data from the Voyagers determined that the heliosheath is not smooth, but filled with giant magnetic bubbles, theorized to form when the magnetic field of the Sun becomes warped at the edge of the Solar System.


title: Voyager program

text: In June 2012, Scientists at NASA reported that "Voyager 1" was very close to entering interstellar space, indicated by a sharp rise in high-energy particles from outside the Solar System. In September 2013, NASA announced that "Voyager 1" had crossed the heliopause on 25 August 2012, making it the first spacecraft to enter interstellar space.


title: Voyager program

text: In December 2018, NASA announced that "Voyager 2" had crossed the heliopause on 5 November 2018, making it the second spacecraft to enter interstellar space.


title: Voyager program

text: In July 2019, a revised power management plan was implemented to better manage the two probes' dwindling power supply.


title: Voyager program

text: The Voyager spacecraft each weigh . Of this total weight, each spacecraft carries of scientific instruments. The identical Voyager spacecraft use three-axis-stabilized guidance systems that use gyroscopic and accelerometer inputs to their attitude control computers to point their high-gain antennas towards the Earth and their scientific instruments towards their targets, sometimes with the help of a movable instrument platform for the smaller instruments and the electronic photography system.