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
Applied physics is intended for a particular technological or practical use. It is considered as a bridge or connection between physics and engineering. "Applied" is distinguished from "pure" by a subtle combination of factors, such as the motivation and attitude of researchers and the nature of the relationship to the technology or science that may be affected by the work. Applied physics is rooted in the fundamental truths and basic concepts of the physical sciences, but is concerned with the utilization of scientific principles in practical devices and systems, in the application of physics in other areas of science, it differs from engineering in that an applied physicist may not be designing something in particular, but rather is using physics or conducting physics research with the aim of developing new technologies or solving an engineering problem. This approach is similar to that of applied mathematics. In other words, applied physics is rooted in the fundamental truths and basic concepts of the physical sciences but is concerned with the utilization of these scientific principles in practical devices and systems.
Applied physicists can be interested in the use of physics for scientific research. For instance, the field of accelerator physics can contribute to research in theoretical physics by working with engineers enabling design and construction of high-energy colliders; the transistor, first invented by physicists John Bardeen, Walter Brattain and William Shockley in 1947 Lasers, such as Vertical-cavity surface-emitting lasers Photonic crystals and quantum optics Magnetic resonance imaging Microscopy Semiconductors Accelerator physics Quantum information science Quantum technology Astrodynamics Electromagnetic propulsion Stealth technology Nuclear engineering Engineering Physics Electronics Sonar Radar Lidar Biophysics Chemical Physics Geophysics
Heike Kamerlingh Onnes
Professor Heike Kamerlingh Onnes FRSFor HFRSE FCS was a Dutch physicist and Nobel laureate. He exploited the Hampson–Linde cycle to investigate how materials behave when cooled to nearly absolute zero and to liquefy helium for the first time, in 1908, he was the discoverer of superconductivity in 1911. Kamerlingh Onnes was born in Netherlands, his father, Harm Kamerlingh Onnes, was a brickworks owner. His mother was Anna Gerdina Coers of Arnhem. In 1870, Kamerlingh Onnes attended the University of Groningen, he studied under Robert Bunsen and Gustav Kirchhoff at the University of Heidelberg from 1871 to 1873. Again at Groningen, he obtained his masters in 1878 and a doctorate in 1879, his thesis was Nieuwe bewijzen voor de aswenteling der aarde. From 1878 to 1882 he was assistant to Johannes Bosscha, the director of the Delft Polytechnic, for whom he substituted as lecturer in 1881 and 1882, he had one child, named Albert. His brother Menso Kamerlingh Onnes was a well known painter, while his sister Jenny married another famous painter, Floris Verster.
From 1882 to 1923 Kamerlingh Onnes served as professor of experimental physics at the University of Leiden. In 1904 he founded a large cryogenics laboratory and invited other researchers to the location, which made him regarded in the scientific community; the laboratory is known now as Kamerlingh Onnes Laboratory. Only one year after his appointment as professor he became member of the Royal Netherlands Academy of Arts and Sciences. On 10 July 1908, he was the first to liquefy helium, using several precooling stages and the Hampson–Linde cycle based on the Joule–Thomson effect; this way he lowered the temperature to the boiling point of helium. By reducing the pressure of the liquid helium he achieved a temperature near 1.5 K. These were the coldest temperatures achieved on earth at the time; the equipment employed is at the Boerhaave Museum in Leiden. In 1911 Kamerlingh Onnes measured the electrical conductivity of pure metals at low temperatures; some scientists, such as William Thomson, believed that electrons flowing through a conductor would come to a complete halt or, in other words, metal resistivity would become infinitely large at absolute zero.
Others, including Kamerlingh Onnes, felt that a conductor's electrical resistance would decrease and drop to nil. Augustus Matthiessen said that when the temperature decreases, the metal conductivity improves or in other words, the electrical resistivity decreases with a decrease of temperature. On 8 April 1911, Kamerlingh Onnes found that at 4.2 K the resistance in a solid mercury wire immersed in liquid helium vanished. He realized the significance of the discovery, he reported that "Mercury has passed into a new state, which on account of its extraordinary electrical properties may be called the superconductive state". He published more articles about the phenomenon referring to it as "supraconductivity" and, only adopting the term "superconductivity". Kamerlingh Onnes received widespread recognition for his work, including the 1913 Nobel Prize in Physics for "his investigations on the properties of matter at low temperatures which led, inter alia, to the production of liquid helium"; some of the instruments he devised for his experiments can be seen at the Boerhaave Museum in Leiden.
The apparatus he used to first liquefy helium is on display in the lobby of the physics department at Leiden University, where the low-temperature lab is named in his honor. His student and successor as director of the lab Willem Hendrik Keesom was the first person, able to solidify helium, in 1926; the former Kamerlingh Onnes laboratory building is the Law Faculty at Leiden University and is known as "Kamerlingh Onnes Gebouw" shortened to "KOG". The current science faculty has a "Kamerlingh Onnes Laboratorium" named after him, as well as a plaque and several machines used by Kamerling Onnes in the main hall of the physics department; the Kamerlingh Onnes Award was established in his honour, recognising further advances in low-temperature science. The Onnes effect referring to the creeping of superfluid helium is named in his honor; the crater Kamerlingh Onnes on the Moon is named after him. Onnes is credited with coining the word "enthalpy". Onnes' discovery of superconductivity was named an IEEE Milestone in 2011.
Matteucci Medal Rumford Medal Nobel Prize in Physics Franklin Medal Kamerlingh Onnes, H. "Nieuwe bewijzen voor de aswenteling der aarde." Ph. D. dissertation. Groningen, Netherlands, 1879. Kamerlingh Onnes, H. "Algemeene theorie der vloeistoffen." Amsterdam Akad. Verhandl. Kamerlingh Onnes, H. "On the Cryogenic Laboratory at Leyden and on the Production of Very Low Temperature." Comm. Phys. Lab. Univ. Leiden. Kamerlingh Onnes, H. "Théorie générale de l'état fluide." Haarlem Arch. Neerl.. Kamerlingh Onnes, H. "Further experiments with liquid helium. C. On the change of electric resistance of pure metals at low temperatures, etc. IV; the resistance of pure mercury at helium temperatures." Comm. Phys. Lab. Univ. Leiden. 120b, 1911. Kamerlingh Onnes, H. "Further experiments with liquid helium. D. On the change of electric resistance of pure metals at low temperatures, etc. V; the disappearance of the resistance of mercury." Comm. Phys. Lab. Uni
Pierre Curie was a French physicist, a pioneer in crystallography, magnetism and radioactivity. In 1903, he received the Nobel Prize in Physics with his wife, Marie Skłodowska-Curie, Henri Becquerel, "in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel". Born in Paris on 15 May 1859, Pierre Curie was the son of Eugene Curie, a doctor of French Huguenot Protestant origin from Alsatia, Sophie-Claire Depouilly Curie, he was educated by his father and in his early teens showed a strong aptitude for mathematics and geometry. When he was 16, he earned his math degree. By the age of 18, he had completed the equivalent of a higher degree, but did not proceed to a doctorate due to lack of money. Instead he worked as a laboratory instructor; when Pierre Curie was preparing for his bachelor of science degree, he worked in the laboratory of Jean-Gustave Bourbouze in the Faculty of Science. In 1880 Pierre and his older brother Jacques demonstrated that an electric potential was generated when crystals were compressed, i.e. piezoelectricity.
To aid this work they invented the piezoelectric quartz electrometer. The following year they demonstrated the reverse effect: that crystals could be made to deform when subject to an electric field. All digital electronic circuits now rely on this in the form of crystal oscillators. In subsequent work on magnetism Pierre Curie defined the Curie scale; this work involved delicate equipment - balances, etc. Pierre Curie was introduced to Maria Skłodowska by physicist Józef Wierusz-Kowalski. Curie took her into his laboratory as his student, his admiration for her grew. He began to regard Skłodowska as his muse, she refused his initial proposal, but agreed to marry him on 26 July 1895. It would be a beautiful thing, a thing I dare not hope, if we could spend our life near each other, hypnotized by our dreams: your patriotic dream, our humanitarian dream, our scientific dream; the Curies had a happy, affectionate marriage, they were known for their devotion to each other. Prior to his famous doctoral studies on magnetism, he designed and perfected an sensitive torsion balance for measuring magnetic coefficients.
Variations on this equipment were used by future workers in that area. Pierre Curie studied ferromagnetism and diamagnetism for his doctoral thesis, discovered the effect of temperature on paramagnetism, now known as Curie's law; the material constant in Curie's law is known as the Curie constant. He discovered that ferromagnetic substances exhibited a critical temperature transition, above which the substances lost their ferromagnetic behavior; this is now known as the Curie temperature. The Curie temperature is used to study plate tectonics, treat hypothermia, measure caffeine, to understand extraterrestrial magnetic fields. Pierre Curie formulated what is now known as the Curie Dissymmetry Principle: a physical effect cannot have a dissymmetry absent from its efficient cause. For example, a random mixture of sand in zero gravity has no dissymmetry. Introduce a gravitational field, there is a dissymmetry because of the direction of the field; the sand grains can'self-sort' with the density increasing with depth.
But this new arrangement, with the directional arrangement of sand grains reflects the dissymmetry of the gravitational field that causes the separation. Curie worked with his wife in isolating radium, they were the first to use the term "radioactivity", were pioneers in its study. Their work, including Marie Curie's celebrated doctoral work, made use of a sensitive piezoelectric electrometer constructed by Pierre and his brother Jacques Curie. Pierre Curie's 1898 publication with his wife Mme. Curie and with M. G. Bémont for their discovery of radium and polonium was honored by a Citation for Chemical Breakthrough Award from the Division of History of Chemistry of the American Chemical Society presented to the ESPCI ParisTech in 2015. Curie and one of his students, Albert Laborde, made the first discovery of nuclear energy, by identifying the continuous emission of heat from radium particles. Curie investigated the radiation emissions of radioactive substances, through the use of magnetic fields was able to show that some of the emissions were positively charged, some were negative and some were neutral.
These correspond to alpha and gamma radiation. The curie is a unit of radioactivity named in honor of Curie by the Radiology Congress in 1910, after his death. Subsequently, there has been some controversy over whether the naming was in honor of Pierre, Marie, or both. In the late nineteenth century, Pierre Curie was investigating the mysteries of ordinary magnetism when he became aware of the spiritualist experiments of other European scientists, such as Charles Richet and Camille Flammarion. Pierre Curie thought systematic investigation into the paranormal could help with some unanswered questions about magnetism, he wrote to his fiancée Marie: "I must admit that those spiritual phenomena intensely interest me. I think in them are questions that deal with physics." Pierre Curie's notebooks from this period show. He did not attend séances such as those of Eusapia Palladino in Paris in 1905–6 as a mere
William Henry Bragg
Sir William Henry Bragg was a British physicist, chemist and active sportsman who uniquely shared a Nobel Prize with his son Lawrence Bragg – the 1915 Nobel Prize in Physics: "for their services in the analysis of crystal structure by means of X-rays". The mineral Braggite is named after his son, he was knighted in 1920. Bragg was born at Westward, near Wigton, the son of Robert John Bragg, a merchant marine officer and farmer, his wife Mary née Wood, a clergyman's daughter; when Bragg was seven years old, his mother died, he was raised by his uncle named William Bragg, at Market Harborough, Leicestershire. He was educated at the Grammar School there, at King William's College on the Isle of Man and, having won an exhibition, at Trinity College, Cambridge, he graduated in 1884 as third wrangler, in 1885 was awarded a first class honours in the mathematical tripos. In 1885, at the age of 23, Bragg was appointed Elder Professor of Mathematics and Experimental Physics in the University of Adelaide and started work there early in 1886.
Being a skilled mathematician, at that time he had limited knowledge of physics, most of, in the form of applied mathematics he had learnt at Trinity. At that time, there were only about a hundred students doing full courses at Adelaide, of whom less than a handful belonged to the science school, whose deficient teaching facilities Bragg improved by apprenticing himself to a firm of instrument makers. Bragg was an popular lecturer. Bragg's interest in physics developed in the field of electromagnetism. In 1895, he was visited by Ernest Rutherford, en route from New Zealand to Cambridge. Bragg had a keen interest in the new discovery of Wilhelm Röntgen. On 29 May 1896 at Adelaide, Bragg demonstrated before a meeting of local doctors the application of "X-rays to reveal structures that were otherwise invisible". Samuel Barbour, senior chemist of F. H. Faulding & Co. an Adelaide pharmaceutical manufacturer, supplied the necessary apparatus in the form of a Crookes tube, a glass discharge tube. The tube had been obtained at Leeds, where Barbour visited the firm of Reynolds and Branson, a manufacturer of photographic and laboratory equipment.
Barbour returned to Adelaide in April 1896. Barbour had conducted his own experiments shortly after return to Australia, but results were limited due to limited battery power. At the University, the tube was attached to an induction coil and a battery borrowed from Sir Charles Todd, Bragg's father-in-law; the induction coil was utilized to produce the electric spark necessary for Bragg and Barbour to "generate short bursts of X-rays". The audience was favorably impressed. Bragg availed himself as a test subject, in the manner of Röntgen and allowed an X-ray photograph to be taken of his hand; the image of the fingers in his hand revealed "an old injury to one of his fingers sustained when using the turnip chopping machine on his father's farm in Cumbria". As early as 1895, Professor William H. Bragg was working on wireless telegraphy, though public lectures and demonstrations focussed on his X-ray research which would lead to his Nobel Prize. In a hurried visit by Rutherford, he was reported as working on a Hertzian oscillator.
There were many common practical threads to the two technologies and he was ably assisted in the laboratory by Arthur Lionel Rogers who manufactured much of the equipment. On 21 September 1897 Bragg gave the first recorded public demonstration of the working of wireless telegraphy in Australia during a lecture meeting at the University of Adelaide as part of the Public Teachers' Union conference. Bragg departed Adelaide in December 1897, spent all of 1898 on a 12-month leave of absence, touring Great Britain and Europe and during this time visited Marconi and inspected his wireless facilities, he returned to Adelaide in early March 1899, on 13 May 1899, Bragg and his father-in-law, Sir Charles Todd, were conducting preliminary tests of wireless telegraphy with a transmitter at the Observatory and a receiver on the South Road. Experiments continued throughout the southern winter of 1899 and the range was progressively extended to Henley Beach. In September the work was extended to two way transmissions with the addition of a second induction coil loaned by Mr. Oddie of Ballarat.
It was desired to extend the experiments cross a sea path and Todd was interested in connecting Cape Spencer and Althorpe Island, but local costs were considered prohibitive while the charges for patented equipment from the Marconi Company were exorbitant. At the same time Bragg's interests were leaning towards X-rays and practical work in wireless in South Australia was dormant for the next decade; the turning-point in Bragg's career came in 1904 when he gave the presidential address to section A of the Australasian Association for the Advancement of Science at Dunedin, New Zealand, on "Some Recent Advances in the Theory of the Ionization of Gases". This idea was followed up "in a brilliant series of researches" which, within three years, earned him a fellowship of the Royal Society of London; this paper was the origin of his first book Studies in Radioactivity. Soon after the delivery of his 1904 address, some radium bromide was made available to Bragg for experimentation. In December 1904 his paper "On the Absorption of α Rays and on the Classification of the α Rays from Radium" appeared in the Philosophical Magazine, in the same issue a paper "On the Ionization Curves of Radium", written in col
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.