Physics
Physics is the natural science that studies matter, its motion, behavior through space and time, that studies the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, its main goal is to understand how the universe behaves. Physics is one of the oldest academic disciplines and, through its inclusion of astronomy the oldest. Over much of the past two millennia, chemistry and certain branches of mathematics, were a part of natural philosophy, but during the scientific revolution in the 17th century these natural sciences emerged as unique research endeavors in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, the boundaries of physics which are not rigidly defined. New ideas in physics explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in academic disciplines such as mathematics and philosophy. Advances in physics enable advances in new technologies.
For example, advances in the understanding of electromagnetism and nuclear physics led directly to the development of new products that have transformed modern-day society, such as television, domestic appliances, nuclear weapons. Astronomy is one of the oldest natural sciences. Early civilizations dating back to beyond 3000 BCE, such as the Sumerians, ancient Egyptians, the Indus Valley Civilization, had a predictive knowledge and a basic understanding of the motions of the Sun and stars; the stars and planets were worshipped, believed to represent gods. While the explanations for the observed positions of the stars were unscientific and lacking in evidence, these early observations laid the foundation for astronomy, as the stars were found to traverse great circles across the sky, which however did not explain the positions of the planets. According to Asger Aaboe, the origins of Western astronomy can be found in Mesopotamia, all Western efforts in the exact sciences are descended from late Babylonian astronomy.
Egyptian astronomers left monuments showing knowledge of the constellations and the motions of the celestial bodies, while Greek poet Homer wrote of various celestial objects in his Iliad and Odyssey. Natural philosophy has its origins in Greece during the Archaic period, when pre-Socratic philosophers like Thales rejected non-naturalistic explanations for natural phenomena and proclaimed that every event had a natural cause, they proposed ideas verified by reason and observation, many of their hypotheses proved successful in experiment. The Western Roman Empire fell in the fifth century, this resulted in a decline in intellectual pursuits in the western part of Europe. By contrast, the Eastern Roman Empire resisted the attacks from the barbarians, continued to advance various fields of learning, including physics. In the sixth century Isidore of Miletus created an important compilation of Archimedes' works that are copied in the Archimedes Palimpsest. In sixth century Europe John Philoponus, a Byzantine scholar, questioned Aristotle's teaching of physics and noting its flaws.
He introduced the theory of impetus. Aristotle's physics was not scrutinized until John Philoponus appeared, unlike Aristotle who based his physics on verbal argument, Philoponus relied on observation. On Aristotle's physics John Philoponus wrote: “But this is erroneous, our view may be corroborated by actual observation more than by any sort of verbal argument. For if you let fall from the same height two weights of which one is many times as heavy as the other, you will see that the ratio of the times required for the motion does not depend on the ratio of the weights, but that the difference in time is a small one, and so, if the difference in the weights is not considerable, that is, of one is, let us say, double the other, there will be no difference, or else an imperceptible difference, in time, though the difference in weight is by no means negligible, with one body weighing twice as much as the other”John Philoponus' criticism of Aristotelian principles of physics served as an inspiration for Galileo Galilei ten centuries during the Scientific Revolution.
Galileo cited Philoponus in his works when arguing that Aristotelian physics was flawed. In the 1300s Jean Buridan, a teacher in the faculty of arts at the University of Paris, developed the concept of impetus, it was a step toward the modern ideas of momentum. Islamic scholarship inherited Aristotelian physics from the Greeks and during the Islamic Golden Age developed it further placing emphasis on observation and a priori reasoning, developing early forms of the scientific method; the most notable innovations were in the field of optics and vision, which came from the works of many scientists like Ibn Sahl, Al-Kindi, Ibn al-Haytham, Al-Farisi and Avicenna. The most notable work was The Book of Optics, written by Ibn al-Haytham, in which he conclusively disproved the ancient Greek idea about vision, but came up with a new theory. In the book, he presented a study of the phenomenon of the camera obscura (his thousand-year-old
Very Large Telescope
The Very Large Telescope is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2 m across, which are used separately but can be used together to achieve high angular resolution. The four separate optical telescopes are known as Antu, Kueyen and Yepun, which are all words for astronomical objects in the Mapuche language; the telescopes form an array, complemented by four movable Auxiliary Telescopes of 1.8 m aperture. The VLT operates at infrared wavelengths; each individual telescope can detect objects four billion times fainter than can be detected with the naked eye, when all the telescopes are combined, the facility can achieve an angular resolution of about 0.002 arc-second. In single telescope mode of operation angular resolution is about 0.05 arc-second. The VLT is the most productive ground-based facility for astronomy, with only the Hubble Space Telescope generating more scientific papers among facilities operating at visible wavelengths.
Among the pioneering observations carried out using the VLT are the first direct image of an exoplanet, the tracking of individual stars moving around the supermassive black hole at the centre of the Milky Way, observations of the afterglow of the furthest known gamma-ray burst. The VLT consists of an arrangement of four large telescopes with optical elements that can combine them into an astronomical interferometer, used to resolve small objects; the interferometer includes a set of four 1.8 meter diameter movable telescopes dedicated to interferometric observations. The first of the UTs started operating in May 1998 and was offered to the astronomical community on 1 April 1999; the other telescopes became operational in 2000, enabling multi-telescope VLT capability. Four 1.8-metre Auxiliary Telescopes have been added to the VLTI to make it available when the UTs are being used for other projects. These ATs were installed and became operational between 2004 and 2007; the VLT's 8.2-meter telescopes were designed to operate in three modes: as a set of four independent telescopes. as a single large coherent interferometric instrument, for extra resolution.
This mode is used, only for observations of bright sources with small angular extent. As a single large incoherent instrument, for extra light-gathering capacity; the instrumentation required to obtain a combined incoherent focus was not built. In 2009, new instrumentation proposals were put forward to make that observing mode available. Multiple telescopes are sometimes independently pointed at the same object, either to increase the total light-gathering power or to provide simultaneous observations with complementary instruments; the UTs are equipped with a large set of instruments permitting observations to be performed from the near-ultraviolet to the mid-infrared, with the full range of techniques including high-resolution spectroscopy, multi-object spectroscopy and high-resolution imaging. In particular, the VLT has several adaptive optics systems, which correct for the effects of atmospheric turbulence, providing images as sharp as if the telescope were in space. In the near-infrared, the adaptive optics images of the VLT are up to three times sharper than those of the Hubble Space Telescope, the spectroscopic resolution is many times better than Hubble.
The VLTs are noted for their high level of observing automation. The 8.2 m-diameter telescopes are housed in compact, thermally controlled buildings, which rotate synchronously with the telescopes. This design minimises any adverse effects on the observing conditions, for instance from air turbulence in the telescope tube, which might otherwise occur due to variations in the temperature and wind flow; the principal role of the main VLT telescopes is to operate as four independent telescopes. The interferometry is used about 20 percent of the time for high-resolution on bright objects, for example, on Betelgeuse; this mode allows astronomers to see details up to 25 times finer than with the individual telescopes. The light beams are combined in the VLTI using a complex system of mirrors in underground tunnels where the light paths must be kept equal within differences of less than 1/1000 mm over a light path of a hundred metres. With this kind of precision the VLTI can reconstruct images with an angular resolution of milliarcseconds.
It had long been ESO's intention to provide "real" names to the four VLT Unit Telescopes, to replace the original technical designations of UT1 to UT4. In March 1999, at the time of the Paranal inauguration, four meaningful names of objects in the sky in the Mapuche language were chosen; this indigenous people lives south of Santiago de Chile. An essay contest was arranged in this connection among schoolchildren of the Chilean II Region of which Antofagasta is the capital to write about the implications of these names, it drew many entries dealing with the cultural heritage of ESO's host country. The winning essay was submitted by 17-year-old Jorssy Albanez Castilla from Chuquicamata near the city of Calama, she received an amateur telescope, during the inauguration of the Paranal site. Unit Telescopes 1–4 are since known as Antu, Kueyen and Yepun, respectively. There was some confusion as to whether Yepun stands for the even
NASA
The National Aeronautics and Space Administration is an independent agency of the United States Federal Government responsible for the civilian space program, as well as aeronautics and aerospace research. NASA was established in 1958; the new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science. Since its establishment, most US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles; the agency is responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA science is focused on better understanding Earth through the Earth Observing System. From 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1.
In the early 1950s, there was challenge to launch an artificial satellite for the International Geophysical Year. An effort for this was the American Project Vanguard. After the Soviet launch of the world's first artificial satellite on October 4, 1957, the attention of the United States turned toward its own fledgling space efforts; the US Congress, alarmed by the perceived threat to national security and technological leadership, urged immediate and swift action. On January 12, 1958, NACA organized a "Special Committee on Space Technology", headed by Guyford Stever. On January 14, 1958, NACA Director Hugh Dryden published "A National Research Program for Space Technology" stating: It is of great urgency and importance to our country both from consideration of our prestige as a nation as well as military necessity that this challenge be met by an energetic program of research and development for the conquest of space... It is accordingly proposed that the scientific research be the responsibility of a national civilian agency...
NACA is capable, by rapid extension and expansion of its effort, of providing leadership in space technology. While this new federal agency would conduct all non-military space activity, the Advanced Research Projects Agency was created in February 1958 to develop space technology for military application. On July 29, 1958, Eisenhower signed the National Aeronautics and Space Act, establishing NASA; when it began operations on October 1, 1958, NASA absorbed the 43-year-old NACA intact. A NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA. A significant contributor to NASA's entry into the Space Race with the Soviet Union was the technology from the German rocket program led by Wernher von Braun, now working for the Army Ballistic Missile Agency, which in turn incorporated the technology of American scientist Robert Goddard's earlier works. Earlier research efforts within the US Air Force and many of ARPA's early space programs were transferred to NASA.
In December 1958, NASA gained control of the Jet Propulsion Laboratory, a contractor facility operated by the California Institute of Technology. The agency's leader, NASA's administrator, is nominated by the President of the United States subject to approval of the US Senate, reports to him or her and serves as senior space science advisor. Though space exploration is ostensibly non-partisan, the appointee is associated with the President's political party, a new administrator is chosen when the Presidency changes parties; the only exceptions to this have been: Democrat Thomas O. Paine, acting administrator under Democrat Lyndon B. Johnson, stayed on while Republican Richard Nixon tried but failed to get one of his own choices to accept the job. Paine was confirmed by the Senate in March 1969 and served through September 1970. Republican James C. Fletcher, appointed by Nixon and confirmed in April 1971, stayed through May 1977 into the term of Democrat Jimmy Carter. Daniel Goldin was appointed by Republican George H. W. Bush and stayed through the entire administration of Democrat Bill Clinton.
Robert M. Lightfoot, Jr. associate administrator under Democrat Barack Obama, was kept on as acting administrator by Republican Donald Trump until Trump's own choice Jim Bridenstine, was confirmed in April 2018. Though the agency is independent, the survival or discontinuation of projects can depend directly on the will of the President; the first administrator was Dr. T. Keith Glennan appointed by Republican President Dwight D. Eisenhower. During his term he brought together the disparate projects in American space development research; the second administrator, James E. Webb, appointed by President John F. Kennedy, was a Democrat who first publicly served under President Harry S. Truman. In order to implement the Apollo program to achieve Kennedy's Moon la
Einstein Observatory
Einstein Observatory was the first imaging X-ray telescope put into space and the second of NASA's three High Energy Astrophysical Observatories. Named HEAO B before launch, the observatory's name was changed to honor Albert Einstein upon its attaining orbit; the Einstein Observatory, HEAO-2, was launched on November 13, 1978, from Cape Canaveral, Florida, on an Atlas-Centaur SLV-3D booster rocket into a near-circular orbit with an initial altitude above 500 km. Its orbital inclination orbit was 23.5 degrees. The Einstein Observatory satellite re-entered the Earth's atmosphere and burned up on March 25, 1982; the Einstein Observatory carried a single large grazing-incidence focusing X-ray telescope that provided unprecedented levels of sensitivity and arc-second angular resolution of point sources and extended objects. It had instruments sensitive in the 0.2 to 3.5 keV energy range. A collection of four focal-plane instruments was installed in the satellite: HRI, or High Resolution Imaging camera, 0.15-3 keV IPC, or Imaging Proportional Counter, 0.4 to 4 keV SSS, or Solid State Spectrometer, 0.5 to 4.5 keV FPCS, or Bragg Focal Plane Crystal SpectrometerThere was a coaxial instrument'MPC', the Monitor Proportional Counter, working in the 1-20 keV range, two filters that could be used with the imaging detectors: BBFS, Broad Band Filter Spectrometer OGS, Objective grating spectrometer HEAO Program High Energy Astronomy Observatory 1 High Energy Astronomy Observatory 3 Timeline of artificial satellites and space probes Einstein Observatory
X-ray astronomy
X-ray astronomy is an observational branch of astronomy which deals with the study of X-ray observation and detection from astronomical objects. X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude by balloons, sounding rockets, satellites. X-ray astronomy is the space science related to a type of space telescope that can see farther than standard light-absorption telescopes, such as the Mauna Kea Observatories, via x-ray radiation. X-ray emission is expected from astronomical objects that contain hot gases at temperatures from about a million kelvin to hundreds of millions of kelvin. Moreover, the maintenance of the E-layer of ionized gas high in the Earth's Thermosphere suggested a strong extraterrestrial source of X-rays. Although theory predicted that the Sun and the stars would be prominent X-ray sources, there was no way to verify this because Earth's atmosphere blocks most extraterrestrial X-rays, it was not until ways of sending instrument packages to high altitude were developed that these X-ray sources could be studied.
The existence of solar X-rays was confirmed early in the rocket age by V-2s converted to sounding rocket purpose, the detection of extraterrestrial X-rays has been the primary or secondary mission of multiple satellites since 1958. The first cosmic X-ray source was discovered by a sounding rocket in 1962. Called Scorpius X-1, the X-ray emission of Scorpius X-1 is 10,000 times greater than its visual emission, whereas that of the Sun is about a million times less. In addition, the energy output in X-rays is 100,000 times greater than the total emission of the Sun in all wavelengths. Many thousands of X-ray sources have since been discovered. In addition, the space between galaxies in galaxy clusters is filled with a hot, but dilute gas at a temperature between 10 and 100 megakelvins; the total amount of hot gas is five to ten times the total mass in the visible galaxies. The first sounding rocket flights for X-ray research were accomplished at the White Sands Missile Range in New Mexico with a V-2 rocket on January 28, 1949.
A detector was placed in the nose cone section and the rocket was launched in a suborbital flight to an altitude just above the atmosphere. X-rays from the Sun were detected by the U. S. Naval Research Laboratory Blossom experiment on board. An Aerobee 150 rocket was launched on June 12, 1962 and it detected the first X-rays from other celestial sources, it is now known that such X-ray sources as Sco X-1 are compact stars, such as neutron stars or black holes. Material falling into a black hole may emit X-rays; the energy source for the X-ray emission is gravity. Infalling gas and dust is heated by the strong gravitational fields of these and other celestial objects. Based on discoveries in this new field of X-ray astronomy, starting with Scorpius X-1, Riccardo Giacconi received the Nobel Prize in Physics in 2002; the largest drawback to rocket flights is their short duration and their limited field of view. A rocket launched from the United States will not be able to see sources in the southern sky.
In astronomy, the interstellar medium is the gas and cosmic dust that pervade interstellar space: the matter that exists between the star systems within a galaxy. It fills interstellar space and blends smoothly into the surrounding intergalactic medium; the interstellar medium consists of an dilute mixture of ions, molecules, larger dust grains, cosmic rays, magnetic fields. The energy that occupies the same volume, in the form of electromagnetic radiation, is the interstellar radiation field. Of interest is the hot ionized medium consisting of a coronal cloud ejection from star surfaces at 106-107 K which emits X-rays; the ISM is full of structure on all spatial scales. Stars are born deep inside large complexes of molecular clouds a few parsecs in size. During their lives and deaths, stars interact physically with the ISM. Stellar winds from young clusters of stars and shock waves created by supernovae inject enormous amounts of energy into their surroundings, which leads to hypersonic turbulence.
The resultant structures are stellar wind superbubbles of hot gas. The Sun is traveling through the Local Interstellar Cloud, a denser region in the low-density Local Bubble. To measure the spectrum of the diffuse X-ray emission from the interstellar medium over the energy range 0.07 to 1 keV, NASA launched a Black Brant 9 from White Sands Missile Range, New Mexico on May 1, 2008. The Principal Investigator for the mission is Dr. Dan McCammon of the University of Wisconsin–Madison. Balloon flights can carry instruments to altitudes of up to 40 km above sea level, where they are above as much as 99.997% of the Earth's atmosphere. Unlike a rocket where data are collected during a brief few minutes, balloons are able to stay aloft for much longer; however at such altitudes, much of the X-ray spectrum is still absorbed. X-rays with energies less than 35 keV cannot reach balloons. On July 21, 1964, the Crab Nebula supernova remnant was discovered to be a hard X-ray source by a scintillation counter flown on a balloon launched from Palestine, United States.
This was the first balloon-based detection of X-rays from a discrete cosmic X-ray source. The high-energy focusing telescope is a balloon-borne experiment to
Johns Hopkins University
Johns Hopkins University is a private research university in Baltimore, Maryland. Founded in 1876, the university was named for its first benefactor, the American entrepreneur and philanthropist Johns Hopkins, his $7 million bequest —of which half financed the establishment of Johns Hopkins Hospital—was the largest philanthropic gift in the history of the United States up to that time. Daniel Coit Gilman, inaugurated as the institution's first president on February 22, 1876, led the university to revolutionize higher education in the U. S. by integrating teaching and research. Adopting the concept of a graduate school from Germany's ancient Heidelberg University, Johns Hopkins University is considered the first research university in the United States. Over the course of several decades, the university has led all U. S. universities in annual research and development expenditures. In fiscal year 2016, Johns Hopkins spent nearly $2.5 billion on research. Johns Hopkins is organized into 10 divisions on campuses in Maryland and Washington, D.
C. with international centers in Italy and Singapore. The two undergraduate divisions, the Zanvyl Krieger School of Arts and Sciences and the Whiting School of Engineering, are located on the Homewood campus in Baltimore's Charles Village neighborhood; the medical school, the nursing school, the Bloomberg School of Public Health are located on the Medical Institutions campus in East Baltimore. The university consists of the Peabody Institute, the Applied Physics Laboratory, the Paul H. Nitze School of Advanced International Studies, the School of Education, the Carey Business School, various other facilities. Johns Hopkins was a founding member of the American Association of Universities. Johns Hopkins University is cited as among the world's top universities; the university is ranked 10th among undergraduate programs at National Universities in U. S. News & World Report latest rankings, 10th among global universities by U. S. News & World Report in its 2019 rankings, as well as 12th globally in the Times Higher Education World University Rankings.
Over the course of more than 140 years, 37 Nobel laureates and 1 Fields Medalist have been affiliated with Johns Hopkins. Founded in 1883, the Blue Jays men's lacrosse team has captured 44 national titles and joined the Big Ten Conference as an affiliate member in 2014. On his death in 1873, Johns Hopkins, a Quaker entrepreneur and childless bachelor, bequeathed $7 million to fund a hospital and university in Baltimore, Maryland. At that time this fortune, generated from the Baltimore and Ohio Railroad, was the largest philanthropic gift in the history of the United States; the first name of philanthropist Johns Hopkins is the surname of his great-grandmother, Margaret Johns, who married Gerard Hopkins. They named their son Johns Hopkins. Samuel named one of his sons for his father and that son would become the university's benefactor. Milton Eisenhower, a former university president, once spoke at a convention in Pittsburgh where the Master of Ceremonies introduced him as "President of John Hopkins."
Eisenhower retorted that he was "glad to be here in Pittburgh." The original board opted for an novel university model dedicated to the discovery of knowledge at an advanced level, extending that of contemporary Germany. Building on the Humboldtian model of higher education, the German education model of Wilhelm von Humboldt, it became dedicated to research. Johns Hopkins thereby became the model of the modern research university in the United States, its success shifted higher education in the United States from a focus on teaching revealed and/or applied knowledge to the scientific discovery of new knowledge. The trustees worked alongside four notable university presidents – Charles W. Eliot of Harvard, Andrew D. White of Cornell, Noah Porter of Yale College and James B. Angell of Michigan, they each vouched for Daniel Coit Gilman to lead the new University and he became the university's first president. Gilman, a Yale-educated scholar, had been serving as president of the University of California prior to this appointment.
In preparation for the university's founding, Gilman visited University of Freiburg and other German universities. Gilman launched what many at the time considered an audacious and unprecedented academic experiment to merge teaching and research, he dismissed the idea that the two were mutually exclusive: "The best teachers are those who are free and willing to make original researches in the library and the laboratory," he stated. To implement his plan, Gilman recruited internationally known luminaries such as the mathematician James Joseph Sylvester. Gilman focused on the expansion of graduate support of faculty research; the new university fused advanced scholarship with such professional schools as medicine and engineering. Hopkins became the national trendsetter in doctoral programs and the host for numerous scholarly journals and associations; the Johns Hopkins University Press, founded in 1878, is the oldest American university press in continuous operation. With the completion of Johns Hopkins Hospital in 1889 and the medical school in 1893, the university's research-focused mode of instruction soon began attracting world-renowned faculty members who would become major figures in the emerging field of acad
