The Musaeum or Mouseion at Alexandria, which included the famous Library of Alexandria, was an institution said to have been founded by Ptolemy I Soter. This original Musaeum was the home of music or poetry, a philosophical school and library such as Plato's Academy a storehouse of texts, it did not have a collection of works of art, rather it was an institution that brought together some of the best scholars of the Hellenistic world, analogous to a modern university. This original Musaeum was the source for the modern usage of the word museum; the Musaeum was an institution founded, according to Johannes Tzetzes, by Ptolemy I Soter at Alexandria. It is more that Ptolemy II Philadelphus was the true founder; the Mouseion remained supported by the patronage of the royal family of the Ptolemies. Such a Greek Mouseion was the home of music or poetry, a philosophical school and library such as Plato's Academy a storehouse of texts. Mouseion, connoting an assemblage gathered together under the protection of the Muses, was the title given to a collection of stories about the esteemed writers of the past assembled by Alcidamas, an Athenian sophist of the fourth century BC.
Though the Musaeum at Alexandria did not have a collection of sculpture and painting presented as works of art, as was assembled by the Ptolemies' rival Attalus at the Library of Pergamum, it did have a room devoted to the study of anatomy and an installation for astronomical observations. Rather than a museum in the sense that has developed since the Renaissance, it was an institution that brought together some of the best scholars of the Hellenistic world, as Germain Bazin compared it, "analogous to the modern Institute for Advanced Study in Princeton or to the Collège de France in Paris."More than 1,000 scholars lived in the Mouseion at a given time. Staff members and scholars were paid no taxes, they received free meals, free room and board, free servants. The Mouseion was administered by a priest appointed by the Pharaoh; the Mouseion's scholars conducted scientific research, published and collected as much literature as possible from the known world. In addition to Greek works, foreign texts were translated from Assyrian, Jewish, Indian languages, other sources.
The edited versions of the Greek literary canon that we know today, from Homer and Hesiod forward, exist in editions that were collated and corrected by the scholars assembled in the Musaeum at Alexandria. The Greek geographer Strabo described the Musaeum and Library as richly decorated edifices in a campus of buildings and gardens. "The Mouseion is part of the palaces, possessing a peripatos and exedra and large oikos, in which the common table of the philologoi, men who are members of the Mouseion, is located. This synodos has property in common and a priest in charge of the Mouseion appointed by the kings, but now by Caesar." --Strabo The Mouseion featured a roofed walkway, an arcade of seats, a communal dining room where scholars ate and shared ideas. The building was filled with private study rooms, residential quarters, lecture halls, theaters; the following scholars are known to have studied, written, or performed their experiments at the Musaeum of Alexandria. Archimedes – father of engineering Aristarchus of Samos – proposed the first heliocentric system of the universe Callimachus – a noted poet and scholar Erasistratus – physician and co-founder of the Academy of Medicine in Alexandria along with Herophilus Eratosthenes – argued for a spherical earth and calculated its circumference to near-accuracy Euclid – father of geometry Herophilus – notable physician and founder of the scientific method Hipparchus – founder of trigonometry Pappus – mathematician Hero – father of mechanics The classic period of the Musaeum did not survive the purge and expulsion of most of the intellectuals attached to it in 145 BC, when Aristarchus of Samothrace resigned his position.
The Musaeum continued as an institution in the Roman period when Strabo gave his description of it, according to Suetonius, the emperor Claudius added an additional building. Under the emperors, membership of the Musaeum was awarded to prominent scholars and statesmen as a reward to supporters of the emperor. Emperor Caracalla suppressed the Musaeum in 216 as a temporary measure. By this time, the center of learning in Alexandria had moved to the Serapeum; the last known references to Musaeum membership occur in the 260s. The Bruchion, the section of Alexandria that included the Musaeum, was destroyed by fire on the orders of Emperor Aurelian in 272, although we do not know for sure whether it still existed in 272, the area having been set ablaze during the occupation by Julius Caesar. Scattered references in sources suggest that a Musaeum was reestablished in the 4th century on a different site, but little is known about this organisation and it is unlikely to have had the resources of its predecessor.
The mathematician Theon, father of Hypatia, is described in the tenth century Suda as "the man from the Mouseion." It is not known what connection he had with the Musaeum. Zacharias Rhetor and Aeneas of Gaza both speak of a physical space known as the "Mouseion" in the 5th century; this original Musaeum or Institution of the Muses was the source for the modern usage of the word museum. In early modern France, it denoted as much a community of scholars brought together under one roof as it did the collectio
Archimedes of Syracuse was a Greek mathematician, engineer and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity. Considered the greatest mathematician of antiquity and one of the greatest of all time, Archimedes anticipated modern calculus and analysis by applying concepts of infinitesimals and the method of exhaustion to derive and rigorously prove a range of geometrical theorems, including the area of a circle, the surface area and volume of a sphere, the area under a parabola. Other mathematical achievements include deriving an accurate approximation of pi, defining and investigating the spiral bearing his name, creating a system using exponentiation for expressing large numbers, he was one of the first to apply mathematics to physical phenomena, founding hydrostatics and statics, including an explanation of the principle of the lever. He is credited with designing innovative machines, such as his screw pump, compound pulleys, defensive war machines to protect his native Syracuse from invasion.
Archimedes died during the Siege of Syracuse when he was killed by a Roman soldier despite orders that he should not be harmed. Cicero describes visiting the tomb of Archimedes, surmounted by a sphere and a cylinder, which Archimedes had requested be placed on his tomb to represent his mathematical discoveries. Unlike his inventions, the mathematical writings of Archimedes were little known in antiquity. Mathematicians from Alexandria read and quoted him, but the first comprehensive compilation was not made until c. 530 AD by Isidore of Miletus in Byzantine Constantinople, while commentaries on the works of Archimedes written by Eutocius in the sixth century AD opened them to wider readership for the first time. The few copies of Archimedes' written work that survived through the Middle Ages were an influential source of ideas for scientists during the Renaissance, while the discovery in 1906 of unknown works by Archimedes in the Archimedes Palimpsest has provided new insights into how he obtained mathematical results.
Archimedes was born c. 287 BC in the seaport city of Syracuse, Sicily, at that time a self-governing colony in Magna Graecia, located along the coast of Southern Italy. The date of birth is based on a statement by the Byzantine Greek historian John Tzetzes that Archimedes lived for 75 years. In The Sand Reckoner, Archimedes gives his father's name as Phidias, an astronomer about whom nothing else is known. Plutarch wrote in his Parallel Lives that Archimedes was related to King Hiero II, the ruler of Syracuse. A biography of Archimedes was written by his friend Heracleides but this work has been lost, leaving the details of his life obscure, it is unknown, for instance, whether he married or had children. During his youth, Archimedes may have studied in Alexandria, where Conon of Samos and Eratosthenes of Cyrene were contemporaries, he referred to Conon of Samos as his friend, while two of his works have introductions addressed to Eratosthenes. Archimedes died c. 212 BC during the Second Punic War, when Roman forces under General Marcus Claudius Marcellus captured the city of Syracuse after a two-year-long siege.
According to the popular account given by Plutarch, Archimedes was contemplating a mathematical diagram when the city was captured. A Roman soldier commanded him to come and meet General Marcellus but he declined, saying that he had to finish working on the problem; the soldier was enraged by this, killed Archimedes with his sword. Plutarch gives a lesser-known account of the death of Archimedes which suggests that he may have been killed while attempting to surrender to a Roman soldier. According to this story, Archimedes was carrying mathematical instruments, was killed because the soldier thought that they were valuable items. General Marcellus was angered by the death of Archimedes, as he considered him a valuable scientific asset and had ordered that he must not be harmed. Marcellus called Archimedes "a geometrical Briareus"; the last words attributed to Archimedes are "Do not disturb my circles", a reference to the circles in the mathematical drawing that he was studying when disturbed by the Roman soldier.
This quote is given in Latin as "Noli turbare circulos meos," but there is no reliable evidence that Archimedes uttered these words and they do not appear in the account given by Plutarch. Valerius Maximus, writing in Memorable Doings and Sayings in the 1st century AD, gives the phrase as "...sed protecto manibus puluere'noli' inquit,'obsecro, istum disturbare'" – "... but protecting the dust with his hands, said'I beg of you, do not disturb this.'" The phrase is given in Katharevousa Greek as "μὴ μου τοὺς κύκλους τάραττε!". The tomb of Archimedes carried a sculpture illustrating his favorite mathematical proof, consisting of a sphere and a cylinder of the same height and diameter. Archimedes had proven that the volume and surface area of the sphere are two thirds that of the cylinder including its bases. In 75 BC, 137 years after his death, the Roman orator Cicero was serving as quaestor in Sicily, he had heard stories about the tomb of Archimedes, but none of the locals were able to give him the location.
He found the tomb near the Agrigentine gate in Syracuse, in a neglected condition and overgrown with bushes. Cicero had the tomb cleaned up, was able to see the carving and read some of the verses, added as an inscription. A tomb discovered in the courtyard of the Hotel Panorama in Syracuse in the early 1960s was claimed to be that of Archimedes, but there was no compelling evidence
Aristarchus of Samos
Aristarchus of Samos was an ancient Greek astronomer and mathematician who presented the first known heliocentric model that placed the Sun at the center of the known universe with the Earth revolving around it. He was influenced by Philolaus of Croton, but Aristarchus identified the "central fire" with the Sun, he put the other planets in their correct order of distance around the Sun. Like Anaxagoras before him, he suspected that the stars were just other bodies like the Sun, albeit further away from Earth, his astronomical ideas were rejected in favor of the geocentric theories of Aristotle and Ptolemy. Nicolaus Copernicus attributed the heliocentric theory to Aristarchus; the original text has been lost, but a reference in Archimedes' book The Sand Reckoner describes a work by Aristarchus in which he advanced the heliocentric model as an alternative hypothesis to geocentrism: You are now aware that the "universe" is the name given by most astronomers to the sphere the centre of, the centre of the earth, while its radius is equal to the straight line between the centre of the sun and the centre of the earth.
This is the common account. But Aristarchus has brought out a book consisting of certain hypotheses, wherein it appears, as a consequence of the assumptions made, that the universe is many times greater than the "universe" just mentioned, his hypotheses are that the fixed stars and the sun remain unmoved, that the earth revolves about the sun on the circumference of a circle, the sun lying in the middle of the orbit, that the sphere of the fixed stars, situated about the same centre as the sun, is so great that the circle in which he supposes the earth to revolve bears such a proportion to the distance of the fixed stars as the centre of the sphere bears to its surface. Aristarchus suspected the stars were other suns that are far away, that in consequence there was no observable parallax, that is, a movement of the stars relative to each other as the Earth moves around the Sun. Since stellar parallax is only detectable with telescopes, his accurate speculation was unprovable at the time, it is a common misconception that the heliocentric view was held as sacrilegious by the contemporaries of Aristarchus.
Lucio Russo traces this to Gilles Ménage's printing of a passage from Plutarch's On the Apparent Face in the Orb of the Moon, in which Aristarchus jokes with Cleanthes, head of the Stoics, a sun worshipper, opposed to heliocentrism. In the manuscript of Plutarch's text, Aristarchus says. Ménage's version, published shortly after the trials of Galileo and Giordano Bruno, transposes an accusative and nominative so that it is Aristarchus, purported to be impious; the resulting misconception of an isolated and persecuted Aristarchus is still transmitted today. According to Plutarch, while Aristarchus postulated heliocentrism only as a hypothesis, Seleucus of Seleucia, a Hellenistic astronomer who lived a century after Aristarchus, maintained it as a definite opinion and gave a demonstration of it but no full record has been found. In his Naturalis Historia, Pliny the Elder wondered whether errors in the predictions about the heavens could be attributed to a displacement of the Earth from its central position.
Pliny and Seneca referred to the retrograde motion of some planets as an apparent phenomenon, an implication of heliocentrism rather than geocentrism. Still, no stellar parallax was observed, Plato and Ptolemy preferred the geocentric model, held as true throughout the Middle Ages; the heliocentric theory was revived by Copernicus, after which Johannes Kepler described planetary motions with greater accuracy with his three laws. Isaac Newton gave a theoretical explanation based on laws of gravitational attraction and dynamics; the only known surviving work attributed to Aristarchus, On the Sizes and Distances of the Sun and Moon, is based on a geocentric world view. It has been read as stating that the angle subtended by the Sun's diameter is two degrees, but Archimedes states in The Sand Reckoner that Aristarchus had a value of ½ degree, much closer to the actual average value of 32' or 0.53 degrees. The discrepancy may come from a misinterpretation of what unit of measure was meant by a certain Greek term in the text of Aristarchus.
Aristarchus claimed that at half moon, the angle between the Sun and Moon was 87°. He might have proposed 87° as a lower bound, since gauging the lunar terminator's deviation from linearity to one degree of accuracy is beyond the unaided human ocular limit. Aristarchus is known to have studied light and vision. Using correct geometry, but the insufficiently accurate 87° datum, Aristarchus concluded that the Sun was between 18 and 20 times farther away than the Moon; the implicit false solar parallax of under three degrees was used by astronomers up to and including Tycho Brahe, c. AD 1600. Aristarchus pointed out that the Moon and Sun have nearly equal apparent angular sizes, therefore their diameters must be in proportion to their distances from Earth. Aristarchus's a lunar crater Heath, Sir Thomas. Aristarchus of Samos, the ancient Copernicus.
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is a harmonic oscillator: it swings back and forth in a precise time interval dependent on its length, resists swinging at other rates. From its invention in 1656 by Christiaan Huygens until the 1930s, the pendulum clock was the world's most precise timekeeper, accounting for its widespread use. Throughout the 18th and 19th centuries pendulum clocks in homes, factories and railroad stations served as primary time standards for scheduling daily life, work shifts, public transportation, their greater accuracy allowed the faster pace of life, necessary for the Industrial Revolution; the home pendulum clock was replaced by cheaper synchronous electric clocks in the 1930s and'40s, they are now kept for their decorative and antique value. Pendulum clocks must be stationary to operate; the pendulum clock was invented in 1656 by Dutch scientist and inventor Christiaan Huygens, patented the following year.
Huygens contracted the construction of his clock designs to clockmaker Salomon Coster, who built the clock. Huygens was inspired by investigations of pendulums by Galileo Galilei beginning around 1602. Galileo discovered the key property that makes pendulums useful timekeepers: isochronism, which means that the period of swing of a pendulum is the same for different sized swings. Galileo had the idea for a pendulum clock in 1637, constructed by his son in 1649, but neither lived to finish it; the introduction of the pendulum, the first harmonic oscillator used in timekeeping, increased the accuracy of clocks enormously, from about 15 minutes per day to 15 seconds per day leading to their rapid spread as existing'verge and foliot' clocks were retrofitted with pendulums. These early clocks, due to their verge escapements, had wide pendulum swings of 80–100°. In his 1673 analysis of pendulums, Horologium Oscillatorium, Huygens showed that wide swings made the pendulum inaccurate, causing its period, thus the rate of the clock, to vary with unavoidable variations in the driving force provided by the movement.
Clockmakers' realization that only pendulums with small swings of a few degrees are isochronous motivated the invention of the anchor escapement around 1670, which reduced the pendulum's swing to 4–6°. The anchor became the standard escapement used in pendulum clocks. In addition to increased accuracy, the anchor's narrow pendulum swing allowed the clock's case to accommodate longer, slower pendulums, which needed less power and caused less wear on the movement; the seconds pendulum, 0.994 m long, in which the time period is two seconds, became used in quality clocks. The long narrow clocks built around these pendulums, first made by William Clement around 1680, became known as grandfather clocks; the increased accuracy resulting from these developments caused the minute hand rare, to be added to clock faces beginning around 1690. The 18th and 19th century wave of horological innovation that followed the invention of the pendulum brought many improvements to pendulum clocks; the deadbeat escapement invented in 1675 by Richard Towneley and popularized by George Graham around 1715 in his precision "regulator" clocks replaced the anchor escapement and is now used in most modern pendulum clocks.
Observation that pendulum clocks slowed down in summer brought the realization that thermal expansion and contraction of the pendulum rod with changes in temperature was a source of error. This was solved by the invention of temperature-compensated pendulums. With these improvements, by the mid-18th century precision pendulum clocks achieved accuracies of a few seconds per week; until the 19th century, clocks were handmade by individual craftsmen and were expensive. The rich ornamentation of pendulum clocks of this period indicates their value as status symbols of the wealthy; the clockmakers of each country and region in Europe developed their own distinctive styles. By the 19th century, factory production of clock parts made pendulum clocks affordable by middle-class families. During the Industrial Revolution, daily life was organized around the home pendulum clock. More accurate pendulum clocks, called regulators, were installed in places of business and railroad stations and used to schedule work and set other clocks.
The need for accurate timekeeping in celestial navigation to determine longitude drove the development of the most accurate pendulum clocks, called astronomical regulators. These precision instruments, installed in naval observatories and kept accurate within a second by observation of star transits overhead, were used to set marine chronometers on naval and commercial vessels. Beginning in the 19th century, astronomical regulators in naval observatories served as primary standards for national time distribution services that distributed time signals over telegraph wires. From 1909, US National Bureau of Standards based the US time standard on Riefler pendulum clocks, accurate to about 10 milliseconds per day. In 1929 it switched to the Shortt-Synchronome free pendulum clock before phasing in quartz standards in the 1930s. With an error of around one second per year, the Shortt was the most accurate commercially produced pendulum clock. Pendulum clocks remained the world standard for accurate timekeeping for 270 years, until the invention of the quartz clock in 1927, we
Compressed air is air kept under a pressure, greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes. Compressed air is used for power tools such as air hammers, drills and others. Compressed air is used to atomize paint, to operate air cylinders for automation, can be used to propel vehicles. Brakes applied by compressed air made large railway trains more efficient to operate. Compressed air brakes are found on large highway vehicles. Compressed air is used as a breathing gas by underwater divers, it may be carried by the diver in a high pressure diving cylinder, or supplied from the surface at lower pressure through an air line or diver's umbilical. Similar arrangements are used in breathing apparatus used by firefighters, mine rescue workers and industrial workers in hazardous atmospheres. In Europe, 10 percent of all industrial electricity consumption is to produce compressed air—amounting to 80 terawatt hours consumption per year.
Industrial use of piped compressed air for power transmission was developed in the mid 19th century. An early major application of compressed air was in the drilling of the Mont Cenis Tunnel in Switzerland in 1861, where a 600 kPa compressed air plant provided power to pneumatic drills, increasing productivity over previous manual drilling methods. Compressed air drills were applied at mines in the United States in the 1870s. George Westinghouse invented air brakes for trains starting in 1869. In the 19th century, Paris had a system of pipes installed for municipal distribution of compressed air to power machines and to operate generators for lighting. Early air compressors were steam-driven, but in certain locations a trompe could directly obtain compressed air from the force of falling water. Air for breathing may be stored at high pressure and released when needed, as in scuba diving. Air for breathing must be free of oil and other contaminants. Air compressors and supply systems intended for breathing air are not also used for pneumatic tools or other purposes.
Workers constructing the foundations of bridges or other structures may be working in a pressurized enclosure called a caisson, where water is prevented from entering the open bottom of the enclosure by filling it with air under pressure. It was known as early as the 17th century that workers in diving bells experienced shortness of breath and risked asphyxia, relieved by the release of fresh air into the bell; such workers experienced pain and other symptoms when returning to the surface, as the pressure was relieved. Denis Papin suggested in 1691 that the working time in a diving bell could be extended if fresh air from the surface was continually forced under pressure into the bell. By the 19th century, caissons were used in civil construction, but workers experienced serious, sometimes fatal, symptoms on returning to the surface, a syndrome called caisson disease or decompression sickness. Many workers were killed by the disease on projects such as the Brooklyn Bridge and the Eads Bridge and it was not until the 1890s that it was understood that workers had to decompress to prevent the formation of dangerous bubbles in tissues.
Air under moderately high pressure, such as is used when diving below about 20 metres, has an increasing narcotic effect on the nervous system. Nitrogen narcosis is a hazard. For diving much beyond 30 metres, it is less safe to use air alone and special breathing mixes containing helium are used. In industry, compressed air is so used that it is regarded as the fourth utility, after electricity, natural gas and water. However, compressed air is more expensive than the other three utilities when evaluated on a per unit energy delivered basis. Compressed air is used for many purposes, including: Pneumatics, the use of pressurized gases to do work Pneumatic post, using capsules to move paper and small goods through tubes. Air tools HVAC control systems Vehicle propulsion Energy storage Air brakes, including: railway braking systems road vehicle braking systems Underwater diving, for breathing and to inflate buoyancy devices Refrigeration using a vortex tube Air-start systems in engines Ammunition propulsion in: Air guns Airsoft equipment Paintball equipment Cleaning dust and small debris in tiny spaces Sandblasting in machine shops Injection molding Food and beverage capping and fermentation Compressed air from Lysefjorden/Preikestolen is being sold in cans to China.
Compressor rooms must be designed with ventilation systems to remove waste heat produced by the compressors. When air at atmospheric pressure is compressed, it contains much more water vapor than the high-pressure air can hold. Relative humidity is not affected by air pressure. After compressed air cools the vaporized water turns to liquefied water. Management of the excessive moisture is a requirement of a compressed air distribution system. System designers must ensure that piping maintains a slope, to prevent accumulation of moisture in low parts of the piping system. Drain valves may be installed at multiple points of a large system to allow trapped water to be blown out. Taps from piping headers may be arranged at the tops of pipes, so that moisture is not carried over into piping branches feeding equipment. Piping sizes are sel
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists are interested in the root or ultimate causes of phenomena, frame their understanding in mathematical terms. Physicists work across a wide range of research fields, spanning all length scales: from sub-atomic and particle physics, through biological physics, to cosmological length scales encompassing the universe as a whole; the field includes two types of physicists: experimental physicists who specialize in the observation of physical phenomena and the analysis of experiments, theoretical physicists who specialize in mathematical modeling of physical systems to rationalize and predict natural phenomena. Physicists can apply their knowledge towards solving practical problems or to developing new technologies; the study and practice of physics is based on an intellectual ladder of discoveries and insights from ancient times to the present.
Many mathematical and physical ideas used today found their earliest expression in ancient Greek culture, for example in the work of Euclid, Thales of Miletus and Aristarchus. Roots emerged in ancient Asian culture and in the Islamic medieval period, for example the work of Alhazen in the 11th century; the modern scientific worldview and the bulk of physics education can be said to flow from the scientific revolution in Europe, starting with the work of Galileo Galilei and Johannes Kepler in the early 1600s. Newton's laws of motion and Newton's law of universal gravitation were formulated in the 17th century; the experimental discoveries of Faraday and the theory of Maxwell's equations of electromagnetism were developmental high points during the 19th century. Many physicists contributed to the development of quantum mechanics in the early-to-mid 20th century. New knowledge in the early 21st century includes a large increase in understanding physical cosmology; the broad and general study of nature, natural philosophy, was divided into several fields in the 19th century, when the concept of "science" received its modern shape.
Specific categories emerged, such as "biology" and "biologist", "physics" and "physicist", "chemistry" and "chemist", among other technical fields and titles. The term physicist was coined by William Whewell in his 1840 book The Philosophy of the Inductive Sciences. A standard undergraduate physics curriculum consists of classical mechanics and magnetism, non-relativistic quantum mechanics, statistical mechanics and thermodynamics, laboratory experience. Physics students need training in mathematics, in computer science. Any physics-oriented career position requires at least an undergraduate degree in physics or applied physics, while career options widen with a Master's degree like MSc, MPhil, MPhys or MSci. For research-oriented careers, students work toward a doctoral degree specializing in a particular field. Fields of specialization include experimental and theoretical astrophysics, atomic physics, biological physics, chemical physics, condensed matter physics, geophysics, gravitational physics, material science, medical physics, molecular physics, nuclear physics, radiophysics, electromagnetic field and microwave physics, particle physics, plasma physics.
The highest honor awarded to physicists is the Nobel Prize in Physics, awarded since 1901 by the Royal Swedish Academy of Sciences. National physics professional societies have many awards for professional recognition. In the case of the American Physical Society, as of 2017, there are 33 separate prizes and 38 separate awards in the field; the three major employers of career physicists are academic institutions and private industries, with the largest employer being the last. Physicists in academia or government labs tend to have titles such as Assistants, Professors, Sr./Jr. Scientist, or postdocs; as per the American Institute of Physics, some 20% of new physics Ph. D.s holds jobs in engineering development programs, while 14% turn to computer software and about 11% are in business/education. A majority of physicists employed apply their skills and training to interdisciplinary sectors. Job titles for graduate physicists include Agricultural Scientist, Air Traffic Controller, Computer Programmer, Electrical Engineer, Environmental Analyst, Medical Physicist, Oceanographer, Physics Teacher/Professor/Researcher, Research Scientist, Reactor Physicist, Engineering Physicist, Satellite Missions Analyst, Science Writer, Software Engineer, Systems Engineer, Microelectronics Engineer, Radar Developer, Technical Consultant, etc.
A majority of Physics terminal bachelor's degree holders are employed in the private sector. Other fields are academia and military service, nonprofit entities and teaching. Typical duties of physicists with master's and doctoral degrees working in their domain involve research and analysis, data preparation, instrumentation and development of industrial or medical equipment and software development, etc. Chartered Physicist is a chartered status and a professional qualification awarded by the Institute of Physics, it is denoted by the postnominals "CPhys". Achieving chartered status in any profession denotes to the wider community a high level of specialised subject knowledge and professional competence. According to the Institute of Physics, holders of the award of the Chartered Physicist demonst
Apollonius of Perga
Apollonius of Perga was a Greek geometer and astronomer known for his theories on the topic of conic sections. Beginning from the theories of Euclid and Archimedes on the topic, he brought them to the state they were in just before the invention of analytic geometry, his definitions of the terms ellipse and hyperbola are the ones in use today. Apollonius worked including astronomy. Most of the work has not survived except in fragmentary references in other authors, his hypothesis of eccentric orbits to explain the aberrant motion of the planets believed until the Middle Ages, was superseded during the Renaissance. For such an important contributor to the field of mathematics, scant biographical information remains; the 6th century Palestinian commentator, Eutocius of Ascalon, on Apollonius’ major work, states: “Apollonius, the geometrician... came from Perga in Pamphylia in the times of Ptolemy Euergetes, so records Herakleios the biographer of Archimedes....” Perga at the time was a Hellenized city of Pamphylia in Anatolia.
The ruins of the city yet stand. It was a center of Hellenistic culture. Euergetes, “benefactor,” identifies Ptolemy III Euergetes, third Greek dynast of Egypt in the diadochi succession, his “times” are his regnum, 246-222/221 BC. Times are always recorded by ruler or officiating magistrate, so that if Apollonius was born earlier than 246, it would have been the “times” of Euergetes’ father; the identity of Herakleios is uncertain. The approximate times of Apollonius are thus certain; the figure Specific birth and death years stated by the various scholars are only speculative. Eutocius appears to associate Perga with the Ptolemaic dynasty of Egypt. Never under Egypt, Perga in 246 BC belonged to the Seleucid Empire, an independent diadochi state ruled by the Seleucid dynasty. During the last half of the 3rd century BC, Perga changed hands a number of times, being alternatively under the Seleucids and under the Kingdom of Pergamon to the north, ruled by the Attalid dynasty. Someone designated "of Perga" might well be expected to have worked there.
To the contrary, if Apollonius was identified with Perga, it was not on the basis of his residence. The remaining autobiographical material implies that he lived and wrote in Alexandria. A letter by the Greek mathematician and astronomer Hypsicles was part of the supplement taken from Euclid's Book XIV, part of the thirteen books of Euclid's Elements. "Basilides of Tyre, O Protarchus, when he came to Alexandria and met my father, spent the greater part of his sojourn with him on account of the bond between them due to their common interest in mathematics. And on one occasion, when looking into the tract written by Apollonius about the comparison of the dodecahedron and icosahedron inscribed in one and the same sphere, to say, on the question what ratio they bear to one another, they came to the conclusion that Apollonius' treatment of it in this book was not correct, but I myself afterwards came across another book published by Apollonius, containing a demonstration of the matter in question, I was attracted by his investigation of the problem.
Now the book published by Apollonius is accessible to all. "For my part, I determined to dedicate to you what I deem to be necessary by way of commentary because you will be able, by reason of your proficiency in all mathematics and in geometry, to pass an expert judgment upon what I am about to write, because, on account of your intimacy with my father and your friendly feeling towards myself, you will lend a kindly ear to my disquisition. But it is time to have done with the preamble and to begin my treatise itself." Apollonius lived toward the end of a historical period now termed the Hellenistic Period, characterized by the superposition of Hellenic culture over extensive non-Hellenic regions to various depths, radical in some places, hardly at all in others. The change was initiated by Philip II of Macedon and his son, Alexander the Great, subjecting all of Greece is a series of stunning victories, went on to conquer the Persian Empire, which ruled territories from Egypt to Pakistan. Philip was assassinated in 336 BC.
Alexander went on to fulfill his plan by conquering the vast Persian empire. The material is located in the surviving false “Prefaces” of the books of his Conics; these are letters delivered to influential friends of Apollonius asking them to review the book enclosed with the letter. The Preface to Book I, addressed to one Eudemus, reminds him that Conics was requested by a house guest at Alexandria, the geometer, otherwise unknown to history. Naucrates had the first draft of all eight books in his hands by the end of the visit. Apollonius refers to them as being “without a thorough purgation”, he intended releasing each one as it was completed. Hearing of this plan from Apollonius himself on a subsequent visit of the latter to Pergamon, Eudemus had insisted Apollonius send him each book before release; the circumstances imply that at this stage Apollonius was a young geometer seeking the company and advice of established professionals. Pappus states. Euclid was long gone; this stay had been the final stage of Apollonius’ education.
Eudemus was a senior figure in his earlier education at Pergamon.