A projectile is any object thrown into space by the exertion of a force. Although any object in motion through space may be called a projectile, the term more refers to a ranged weapon. Mathematical equations of motion are used to analyze projectile trajectory. An object projected at an angle to the horizontal has both the vertical and horizontal components of velocity; the vertical component of the velocity on the y-axis given as Vy=USin while the horizontal component of the velocity Vx=UCos. There are various terms used in projectiles at specific angle teta 1. Time to reach maximum height, it is symbolized as, the time taken for the projectile to reach the maximum height from the plane of projection. Mathematically, it is give as t=USin/g Where g=acceleration due to gravity U= initial velocity teta= angle made by the projectile with the horizontal axis. 2. Time of flight: this is the total time taken for the projectile to fall back to the same plane from which it was projected. Mathematically it is given as T=2USin/g 3.
Maximum Height: this is the maximum height attained by the projectile OR the maximum displacement on the vertical axis covered by the projectile. It is given as H= U²Sin²/2g 4. Range: The Range of a projectile is the horizontal distance covered by the projectile. Mathematically, R= U²Sin2/g; the Range is maximum when angle teta= 45° I.e Sin2=1. Blowguns and pneumatic rifles use compressed gases, while most other guns and cannons utilize expanding gases liberated by sudden chemical reactions. Light-gas guns use a combination of these mechanisms. Railguns utilize electromagnetic fields to provide a constant acceleration along the entire length of the device increasing the muzzle velocity; some projectiles provide propulsion during flight by means of a rocket jet engine. In military terminology, a rocket is unguided. Note the two meanings of "rocket": an ICBM is a guided missile with a rocket engine. An explosion, whether or not by a weapon, causes the debris to act as multiple high velocity projectiles.
An explosive weapon, or device may be designed to produce many high velocity projectiles by the break-up of its casing, these are termed fragments. Many projectiles, e.g. shells, may carry an explosive charge or another chemical or biological substance. Aside from explosive payload, a projectile can be designed to cause special damage, e.g. fire, or poisoning. In projectile motion the most important force applied to the ‘projectile’ is the propelling force, in this case the propelling forces are the muscles that act upon the ball to make it move, the stronger the force applied, the more propelling force, which means the projectile will travel farther. See pitching, bowling. A projectile that does not contain an explosive charge or any other kind of payload is termed a kinetic projectile, kinetic energy weapon, kinetic energy warhead, kinetic warhead or kinetic penetrator. Typical kinetic energy weapons are blunt projectiles such as rocks and round shots, pointed ones such as arrows, somewhat pointed ones such as bullets.
Among projectiles that do not contain explosives are those launched from railguns and mass drivers, as well as kinetic energy penetrators. All of these weapons work by attaining a high muzzle velocity, or initial velocity up to, collide with their targets, converting their kinetic energy into destructive shock waves and heat. Other types of kinetic weapons are accelerated over time by gravity. In either case, it is the kinetic energy of the projectile; some kinetic weapons for targeting objects in spaceflight are anti-satellite weapons and anti-ballistic missiles. Since in order to reach an object in orbit it is necessary to attain an high velocity, their released kinetic energy alone is enough to destroy their target. For example: the energy of TNT is 4.6 MJ/kg, the energy of a kinetic kill vehicle with a closing speed of 10 km/s is of 50 MJ/kg. This saves costly weight and there is no detonation to be timed; this method, requires direct contact with the target, which requires a more accurate trajectory.
Some hit-to-kill warheads are additionally equipped with an explosive directional warhead to enhance the kill probability. With regard to anti-missile weapons, the Arrow missile and MIM-104 Patriot PAC-2 have explosives, while the Kinetic Energy Interceptor, Lightweight Exo-Atmospheric Projectile, THAAD do not. A kinetic projectile can be dropped from aircraft; this is applied by replacing the explosives of a regular bomb with a non-explosive material, for a precision hit with less collateral damage. A typical bomb has a speed of impact of 800 km/h, it is applied for training the act of dropping a bomb with explosives. This method has been used in Operation Iraqi Freedom and the subsequent military operations in Iraq by mating concrete-filled training bombs with JDAM GPS guidance kits, to attack vehicles and other "soft" targets located too close to civilian structures for the use of conventional high explosive bombs. A Prompt Global Strike may use a kinetic weapon. A kinetic bombardment may involve a projectile dropped from Earth orbit.
A hypothetical kinetic weapon that travels at a significant fraction of the speed of light found in science fiction, is termed a relativistic kill vehicle (RKV
Simon Stevin, sometimes called Stevinus, was a Flemish mathematician and military engineer. He made various contributions in many areas of science and engineering, both theoretical and practical, he translated various mathematical terms into Dutch, making it one of the few European languages in which the word for mathematics, was not a loanword from Greek but a calque via Latin. Little is known with certainty about Stevin's life and what we know is inferred from other recorded facts; the exact birth date and the date and place of his death are uncertain. It is assumed he was born in Bruges since he enrolled at Leiden University under the name Simon Stevinus Brugensis, his name is written as Stevin, but some documents regarding his father use the spelling Stevijn. This is a normal spelling shift in 16th-century Dutch, he was born around Anthonis Stevin and Catelyne van der Poort. His father is believed to have been a cadet son of a mayor of Veurne and a member of the schuttersgilde Sint-Barbara of Bruges.
While Simon's father was not mentioned in the book of burghers, the fact that he was a member of the militia allows a safe assumption that he was. Many other Stevins were mentioned in the Poorterboeken. Simon Stevin's mother Cathelijne was the daughter of a wealthy family from Ypres, her father Hubert was a poorter of Bruges. Simon's mother Cathelijne married Joost Sayon, involved in the carpet and silk trade and a member of the schuttersgilde Sint-Sebastiaan. Through her marriage Cathelijne became a member of a family of Calvinists and Simon was brought up in the Calvinist faith, it is believed that Stevin grew up in a affluent environment and enjoyed a good education. He was educated at a Latin school in his hometown. Stevin left Bruges in 1571 without a particular destination. Stevin was most a Calvinist since a Catholic would not have risen to the position of trust he occupied with Maurice, Prince of Orange, it is assumed that he left Bruges to escape the religious persecution of Protestants by the Spanish rulers.
Based on references in his work "Wisconstighe Ghedaechtenissen", it has been inferred that he must have moved first to Antwerp where he began his career as a merchant's clerk. Some biographers mention that he travelled to Prussia, Denmark and Sweden and other parts of Northern Europe, between 1571 and 1577, it is possible. In 1577 Simon Stevin returned to Bruges and was appointed city clerk by the aldermen of Bruges, a function he occupied from 1577-1581, he worked in the office of Jan de Brune of the castellany of Bruges. Why he had returned to Bruges in 1577 is not clear, it may have been related to the political events of that period. Bruges was the scene of intense religious conflict. Catholics and Calvinists alternately controlled the government of the city, they opposed each other but would collaborate in order to counteract the dictates of King Philip II of Spain. In 1576 a certain level of official religious tolerance was decreed; this could explain why Stevin returned to Bruges in 1577. The Calvinists seized power in many Flemish cities and incarcerated Catholic clerics and secular governors supportive of the Spanish rulers.
Between 1578 and 1584 Bruges was ruled by Calvinists. In 1581 Stevin moved to Leiden where he attended the Latin school. On 16 February 1583 he enrolled, under the name Simon Stevinus Brugensis, at Leiden University, founded by William the Silent in 1575. Here he befriended William the Count of Nassau. Stevin is listed in the University's registers until 1590 and never graduated. Following William the Silent's assassination and Prince Maurice's assumption of his father's office, Stevin became the principal advisor and tutor of Prince Maurice. Prince Maurice asked his advice on many occasions, made him a public officer – at first director of the so-called "waterstaet" from 1592, quartermaster-general of the army of the States-General. Prince Maurice asked Stevin to found an engineering school within the University of Leiden. Stevin moved to The Hague where he bought a house in 1612, he had four children. It is known that he left a widow with two children at his death in Leiden or The Hague in 1620.
Stevin is responsible for many inventions. He was a pioneer of the development and the practical application of science such as mathematics and applied science like hydraulic engineering and surveying, he was thought to have invented the Decimal fractions until the middle of the 20th century, but researchers discovered that decimal fractions were introduced by the medieval Islamic scholar al-Uqlidisi in a book written in 952. Moreover, a systematic development of decimal fractions was given well before Stevin in the book Miftah al-Hisab written in 1427 by Al-Kashi, his contemporaries were most struck by his invention of a so-called land yacht, a carriage with sails, of which a model was preserved in Scheveningen until 1802. The carriage itself had been lost long before. Around the year 1600 Stevin, with Prince Maurice of Orange and twenty-six others, used the carriage on the beach between Sche
In mathematics, a parabola is a plane curve, mirror-symmetrical and is U-shaped. It fits several superficially different other mathematical descriptions, which can all be proved to define the same curves. One description of a parabola involves a line; the focus does not lie on the directrix. The parabola is the locus of points in that plane that are equidistant from both the directrix and the focus. Another description of a parabola is as a conic section, created from the intersection of a right circular conical surface and a plane, parallel to another plane, tangential to the conical surface; the line perpendicular to the directrix and passing through the focus is called the "axis of symmetry". The point on the parabola that intersects the axis of symmetry is called the "vertex", is the point where the parabola is most curved; the distance between the vertex and the focus, measured along the axis of symmetry, is the "focal length". The "latus rectum" is the chord of the parabola, parallel to the directrix and passes through the focus.
Parabolas can open up, left, right, or in some other arbitrary direction. Any parabola can be repositioned and rescaled to fit on any other parabola—that is, all parabolas are geometrically similar. Parabolas have the property that, if they are made of material that reflects light light which travels parallel to the axis of symmetry of a parabola and strikes its concave side is reflected to its focus, regardless of where on the parabola the reflection occurs. Conversely, light that originates from a point source at the focus is reflected into a parallel beam, leaving the parabola parallel to the axis of symmetry; the same effects occur with other forms of energy. This reflective property is the basis of many practical uses of parabolas; the parabola has many important applications, from a parabolic antenna or parabolic microphone to automobile headlight reflectors to the design of ballistic missiles. They are used in physics and many other areas; the earliest known work on conic sections was by Menaechmus in the fourth century BC.
He discovered a way to solve the problem of doubling the cube using parabolas. The area enclosed by a parabola and a line segment, the so-called "parabola segment", was computed by Archimedes via the method of exhaustion in the third century BC, in his The Quadrature of the Parabola; the name "parabola" is due to Apollonius. It means "application", referring to "application of areas" concept, that has a connection with this curve, as Apollonius had proved; the focus–directrix property of the parabola and other conic sections is due to Pappus. Galileo showed that the path of a projectile follows a parabola, a consequence of uniform acceleration due to gravity; the idea that a parabolic reflector could produce an image was well known before the invention of the reflecting telescope. Designs were proposed in the early to mid seventeenth century by many mathematicians including René Descartes, Marin Mersenne, James Gregory; when Isaac Newton built the first reflecting telescope in 1668, he skipped using a parabolic mirror because of the difficulty of fabrication, opting for a spherical mirror.
Parabolic mirrors are used in most modern reflecting telescopes and in satellite dishes and radar receivers. A parabola can be defined geometrically as a set of points in the Euclidean plane: A parabola is a set of points, such that for any point P of the set the distance | P F | to a fixed point F, the focus, is equal to the distance | P l | to a fixed line l, the directrix: The midpoint V of the perpendicular from the focus F onto the directrix l is called vertex and the line F V the axis of symmetry of the parabola. If one introduces cartesian coordinates, such that F =, f > 0, the directrix has the equation y = − f one obtains for a point P = from | P F | 2 = | P l | 2 the equation x 2 + 2 = 2. Solving for y yields y = 1 4 f x 2; the parabola is U-shaped. The horizontal chord through the focus is called the latus rectum; the latus rectum is parallel to the directrix. The semi-latus
Mercury is the smallest and innermost planet in the Solar System. Its orbital period around the Sun of 87.97 days is the shortest of all the planets in the Solar System. It is named after the messenger of the gods. Like Venus, Mercury orbits the Sun within Earth's orbit as an inferior planet, never exceeds 28° away from the Sun when viewed from Earth; this proximity to the Sun means the planet can only be seen near the western or eastern horizon during the early evening or early morning. At this time it may appear as a bright star-like object, but is far more difficult to observe than Venus; the planet telescopically displays the complete range of phases, similar to Venus and the Moon, as it moves in its inner orbit relative to Earth, which reoccurs over the so-called synodic period every 116 days. Mercury is tidally locked with the Sun in a 3:2 spin-orbit resonance, rotates in a way, unique in the Solar System; as seen relative to the fixed stars, it rotates on its axis three times for every two revolutions it makes around the Sun.
As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two Mercurian years. Mercury's axis has the smallest tilt of any of the Solar System's planets, its orbital eccentricity is the largest of all known planets in the Solar System. Mercury's surface appears cratered and is similar in appearance to the Moon's, indicating that it has been geologically inactive for billions of years. Having no atmosphere to retain heat, it has surface temperatures that vary diurnally more than on any other planet in the Solar System, ranging from 100 K at night to 700 K during the day across the equatorial regions; the polar regions are below 180 K. The planet has no known natural satellites. Two spacecraft have visited Mercury: Mariner 10 flew by in 1974 and 1975; the BepiColombo spacecraft is planned to arrive at Mercury in 2025. Mercury appears to have a solid silicate crust and mantle overlying a solid, iron sulfide outer core layer, a deeper liquid core layer, a solid inner core.
Mercury is one of four terrestrial planets in the Solar System, is a rocky body like Earth. It is the smallest planet in the Solar System, with an equatorial radius of 2,439.7 kilometres. Mercury is smaller—albeit more massive—than the largest natural satellites in the Solar System and Titan. Mercury consists of 70% metallic and 30% silicate material. Mercury's density is the second highest in the Solar System at 5.427 g/cm3, only less than Earth's density of 5.515 g/cm3. If the effect of gravitational compression were to be factored out from both planets, the materials of which Mercury is made would be denser than those of Earth, with an uncompressed density of 5.3 g/cm3 versus Earth's 4.4 g/cm3. Mercury's density can be used to infer details of its inner structure. Although Earth's high density results appreciably from gravitational compression at the core, Mercury is much smaller and its inner regions are not as compressed. Therefore, for it to have such a high density, its core must be rich in iron.
Geologists estimate. Research published in 2007 suggests. Surrounding the core is a 500–700 km mantle consisting of silicates. Based on data from the Mariner 10 mission and Earth-based observation, Mercury's crust is estimated to be 35 km thick.. One distinctive feature of Mercury's surface is the presence of numerous narrow ridges, extending up to several hundred kilometers in length, it is thought that these were formed as Mercury's core and mantle cooled and contracted at a time when the crust had solidified. Mercury's core has a higher iron content than that of any other major planet in the Solar System, several theories have been proposed to explain this; the most accepted theory is that Mercury had a metal–silicate ratio similar to common chondrite meteorites, thought to be typical of the Solar System's rocky matter, a mass 2.25 times its current mass. Early in the Solar System's history, Mercury may have been struck by a planetesimal of 1/6 that mass and several thousand kilometers across.
The impact would have stripped away much of the original crust and mantle, leaving the core behind as a major component. A similar process, known as the giant impact hypothesis, has been proposed to explain the formation of the Moon. Alternatively, Mercury may have formed from the solar nebula before the Sun's energy output had stabilized, it would have had twice its present mass, but as the protosun contracted, temperatures near Mercury could have been between 2,500 and 3,500 K and even as high as 10,000 K. Much of Mercury's surface rock could have been vaporized at such temperatures, forming an atmosphere of "rock vapor" that could have been carried away by the solar wind. A third hypothesis proposes that the solar nebula caused drag on the particles from which Mercury was accreting, which meant that lighter particles were lost from the accreting material and not gathered by Mercury; each hypothesis predicts a different surface composition, there are two space missions set to make observations.
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, the largest among planetary satellites relative to the size of the planet that it orbits; the Moon is after Jupiter's satellite Io the second-densest satellite in the Solar System among those whose densities are known. The Moon is thought to have formed not long after Earth; the most accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body called Theia. The Moon is in synchronous rotation with Earth, thus always shows the same side to Earth, the near side; the near side is marked by dark volcanic maria that fill the spaces between the bright ancient crustal highlands and the prominent impact craters. After the Sun, the Moon is the second-brightest visible celestial object in Earth's sky, its surface is dark, although compared to the night sky it appears bright, with a reflectance just higher than that of worn asphalt.
Its gravitational influence produces the ocean tides, body tides, the slight lengthening of the day. The Moon's average orbital distance is 1.28 light-seconds. This is about thirty times the diameter of Earth; the Moon's apparent size in the sky is the same as that of the Sun, since the star is about 400 times the lunar distance and diameter. Therefore, the Moon covers the Sun nearly during a total solar eclipse; this matching of apparent visual size will not continue in the far future because the Moon's distance from Earth is increasing. The Moon was first reached in September 1959 by an unmanned spacecraft; the United States' NASA Apollo program achieved the only manned lunar missions to date, beginning with the first manned orbital mission by Apollo 8 in 1968, six manned landings between 1969 and 1972, with the first being Apollo 11. These missions returned lunar rocks which have been used to develop a geological understanding of the Moon's origin, internal structure, the Moon's history. Since the Apollo 17 mission in 1972, the Moon has been visited only by unmanned spacecraft.
Both the Moon's natural prominence in the earthly sky and its regular cycle of phases as seen from Earth have provided cultural references and influences for human societies and cultures since time immemorial. Such cultural influences can be found in language, lunar calendar systems and mythology; the usual English proper name for Earth's natural satellite is "the Moon", which in nonscientific texts is not capitalized. The noun moon is derived from Old English mōna, which stems from Proto-Germanic *mēnô, which comes from Proto-Indo-European *mḗh₁n̥s "moon", "month", which comes from the Proto-Indo-European root *meh₁- "to measure", the month being the ancient unit of time measured by the Moon; the name "Luna" is used. In literature science fiction, "Luna" is used to distinguish it from other moons, while in poetry, the name has been used to denote personification of Earth's moon; the modern English adjective pertaining to the Moon is lunar, derived from the Latin word for the Moon, luna. The adjective selenic is so used to refer to the Moon that this meaning is not recorded in most major dictionaries.
It is derived from the Ancient Greek word for the Moon, σελήνη, from, however derived the prefix "seleno-", as in selenography, the study of the physical features of the Moon, as well as the element name selenium. Both the Greek goddess Selene and the Roman goddess Diana were alternatively called Cynthia; the names Luna and Selene are reflected in terminology for lunar orbits in words such as apolune and selenocentric. The name Diana comes from the Proto-Indo-European *diw-yo, "heavenly", which comes from the PIE root *dyeu- "to shine," which in many derivatives means "sky and god" and is the origin of Latin dies, "day"; the Moon formed 4.51 billion years ago, some 60 million years after the origin of the Solar System. Several forming mechanisms have been proposed, including the fission of the Moon from Earth's crust through centrifugal force, the gravitational capture of a pre-formed Moon, the co-formation of Earth and the Moon together in the primordial accretion disk; these hypotheses cannot account for the high angular momentum of the Earth–Moon system.
The prevailing hypothesis is that the Earth–Moon system formed after an impact of a Mars-sized body with the proto-Earth. The impact blasted material into Earth's orbit and the material accreted and formed the Moon; the Moon's far side has a crust, 30 mi thicker than that of the near side. This is thought to be; this hypothesis, although not perfect best explains the evidence. Eighteen months prior to an October 1984 conference on lunar origins, Bill Hartmann, Roger Phillips, Jeff Taylor challenged fellow lunar scientists: "You have eighteen months. Go back to your Apollo data, go back to your computer, do whatever you have to, but make up your mind. Don't come to our conference unless you have something to say about the Moon's birth." At the 1984 conference at Kona, the giant impact hypothesis emerged as the most consensual theory. Before the conference, there were parti
Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars and light—are brought toward one another. On Earth, gravity gives weight to physical objects, the Moon's gravity causes the ocean tides; the gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing, forming stars – and for the stars to group together into galaxies – so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become weaker on farther objects. Gravity is most described by the general theory of relativity which describes gravity not as a force, but as a consequence of the curvature of spacetime caused by the uneven distribution of mass; the most extreme example of this curvature of spacetime is a black hole, from which nothing—not light—can escape once past the black hole's event horizon. However, for most applications, gravity is well approximated by Newton's law of universal gravitation, which describes gravity as a force which causes any two bodies to be attracted to each other, with the force proportional to the product of their masses and inversely proportional to the square of the distance between them.
Gravity is the weakest of the four fundamental forces of physics 1038 times weaker than the strong force, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak force. As a consequence, it has no significant influence at the level of subatomic particles. In contrast, it is the dominant force at the macroscopic scale, is the cause of the formation and trajectory of astronomical bodies. For example, gravity causes the Earth and the other planets to orbit the Sun, it causes the Moon to orbit the Earth, causes the formation of tides, the formation and evolution of the Solar System and galaxies; the earliest instance of gravity in the Universe in the form of quantum gravity, supergravity or a gravitational singularity, along with ordinary space and time, developed during the Planck epoch from a primeval state, such as a false vacuum, quantum vacuum or virtual particle, in a unknown manner. Attempts to develop a theory of gravity consistent with quantum mechanics, a quantum gravity theory, which would allow gravity to be united in a common mathematical framework with the other three forces of physics, are a current area of research.
Archimedes discovered the center of gravity of a triangle. He postulated that if the centers of gravity of two equal weights wasn't the same, it would be located in the middle of the line that joins them; the Roman architect and engineer Vitruvius in De Architectura postulated that gravity of an object didn't depend on weight but its "nature". Aryabhata first identified the force to explain why objects are not thrown out when the earth rotates. Brahmagupta described gravity as an attractive force and used the term "gruhtvaakarshan" for gravity. Modern work on gravitational theory began with the work of Galileo Galilei in the late 16th and early 17th centuries. In his famous experiment dropping balls from the Tower of Pisa, with careful measurements of balls rolling down inclines, Galileo showed that gravitational acceleration is the same for all objects; this was a major departure from Aristotle's belief that heavier objects have a higher gravitational acceleration. Galileo postulated air resistance as the reason that objects with less mass fall more in an atmosphere.
Galileo's work set the stage for the formulation of Newton's theory of gravity. In 1687, English mathematician Sir Isaac Newton published Principia, which hypothesizes the inverse-square law of universal gravitation. In his own words, "I deduced that the forces which keep the planets in their orbs must reciprocally as the squares of their distances from the centers about which they revolve: and thereby compared the force requisite to keep the Moon in her Orb with the force of gravity at the surface of the Earth; the equation is the following: F = G m 1 m 2 r 2 Where F is the force, m1 and m2 are the masses of the objects interacting, r is the distance between the centers of the masses and G is the gravitational constant. Newton's theory enjoyed its greatest success when it was used to predict the existence of Neptune based on motions of Uranus that could not be accounted for by the actions of the other planets. Calculations by both John Couch Adams and Urbain Le Verrier predicted the general position of the planet, Le Verrier's calculations are what led Johann Gottfried Galle to the discovery of Neptune.
A discrepancy in Mercury's orbit pointed out flaws in Newton's theory. By the end of the 19th century, it was known that its orbit showed slight perturbations that could not be accounted for under Newton's theory, but all searches for another perturbing body had been fruitless; the issue was resolved in 1915 by Albert Einstein's new theory of general relativity, which accounted for the small discrepancy in Mercury's orbit. This discrepancy was the advance in the perihelion of Mercury of 42.98 arcseconds per century. Although Newton's theory has been superseded by Einstein's general relativity, most modern non-relativistic gravitational calculations are still made using Newton
Hendrik Antoon Lorentz was a Dutch physicist who shared the 1902 Nobel Prize in Physics with Pieter Zeeman for the discovery and theoretical explanation of the Zeeman effect. He derived the transformation equations underpinning Albert Einstein's theory of special relativity. According to the biography published by the Nobel Foundation, "It may well be said that Lorentz was regarded by all theoretical physicists as the world's leading spirit, who completed what was left unfinished by his predecessors and prepared the ground for the fruitful reception of the new ideas based on the quantum theory." He received many honours and distinctions, including a term as chairman of the International Committee on Intellectual Cooperation, the forerunner of UNESCO, between 1925 and 1928. Hendrik Lorentz was born in Arnhem, Netherlands, the son of Gerrit Frederik Lorentz, a well-off nurseryman, Geertruida van Ginkel. In 1862, after his mother's death, his father married Luberta Hupkes. Despite being raised as a Protestant, he was a freethinker in religious matters.
From 1866 to 1869, he attended the "Hogere Burger School" in Arnhem, a new type of public high school established by Johan Rudolph Thorbecke. His results in school were exemplary. In 1870, he passed the exams in classical languages which were required for admission to University. Lorentz studied physics and mathematics at the Leiden University, where he was influenced by the teaching of astronomy professor Frederik Kaiser. After earning a bachelor's degree, he returned to Arnhem in 1871 to teach night school classes in mathematics, but he continued his studies in Leiden in addition to his teaching position. In 1875, Lorentz earned a doctoral degree under Pieter Rijke on a thesis entitled "Over de theorie der terugkaatsing en breking van het licht", in which he refined the electromagnetic theory of James Clerk Maxwell. On 17 November 1877, only 24 years of age, Hendrik Antoon Lorentz was appointed to the newly established chair in theoretical physics at the University of Leiden; the position had been offered to Johan van der Waals, but he accepted a position at the Universiteit van Amsterdam.
On 25 January 1878, Lorentz delivered his inaugural lecture on "De moleculaire theoriën in de natuurkunde". In 1881, he became member of the Royal Netherlands Academy of Sciences. During the first twenty years in Leiden, Lorentz was interested in the electromagnetic theory of electricity and light. After that, he extended his research to a much wider area while still focusing on theoretical physics. Lorentz made significant contributions to fields ranging from hydrodynamics to general relativity, his most important contributions were in the area of electromagnetism, the electron theory, relativity. Lorentz theorized that atoms might consist of charged particles and suggested that the oscillations of these charged particles were the source of light; when a colleague and former student of Lorentz's, Pieter Zeeman, discovered the Zeeman effect in 1896, Lorentz supplied its theoretical interpretation. The experimental and theoretical work was honored with the Nobel prize in physics in 1902. Lorentz' name is now associated with the Lorentz-Lorenz formula, the Lorentz force, the Lorentzian distribution, the Lorentz transformation.
In 1892 and 1895, Lorentz worked on describing electromagnetic phenomena in reference frames that move relative to the postulated luminiferous aether. He discovered that the transition from one to another reference frame could be simplified by using a new time variable that he called local time and which depended on universal time and the location under consideration. Although Lorentz did not give a detailed interpretation of the physical significance of local time, with it, he could explain the aberration of light and the result of the Fizeau experiment. In 1900 and 1904, Henri Poincaré called local time Lorentz's "most ingenious idea" and illustrated it by showing that clocks in moving frames are synchronized by exchanging light signals that are assumed to travel at the same speed against and with the motion of the frame. In 1892, with the attempt to explain the Michelson-Morley experiment, Lorentz proposed that moving bodies contract in the direction of motion. In 1899 and again in 1904, Lorentz added time dilation to his transformations and published what Poincaré in 1905 named Lorentz transformations.
It was unknown to Lorentz that Joseph Larmor had used identical transformations to describe orbiting electrons in 1897. Larmor's and Lorentz's equations look somewhat dissimilar, but they are algebraically equivalent to those presented by Poincaré and Einstein in 1905. Lorentz's 1904 paper includes the covariant formulation of electrodynamics, in which electrodynamic phenomena in different reference frames are described by identical equations with well defined transformation properties; the paper recognizes the significance of this formulation, namely that the outcomes of electrodynamic experiments do not depend on the relative motion of the reference frame. The 1904 paper includes a detailed discussion of the increase of the inertial mass of moving objects in a useless attempt to make momentum look like Newtonian momentum.