Johannes Diderik van der Waals
Johannes Diderik van der Waals was a Dutch theoretical physicist and thermodynamicist famous for his work on an equation of state for gases and liquids. His name is associated with the van der Waals equation of state that describes the behavior of gases and their condensation to the liquid phase, his name is associated with van der Waals forces, with van der Waals molecules, with van der Waals radii. As James Clerk Maxwell said about Van der Waals, "there can be no doubt that the name of Van der Waals will soon be among the foremost in molecular science."In his 1873 thesis, van der Waals noted the non-ideality of real gases and attributed it to the existence of intermolecular interactions. He introduced the first equation of state derived by the assumption of a finite volume occupied by the constituent molecules. Spearheaded by Ernst Mach and Wilhelm Ostwald, a strong philosophical current that denied the existence of molecules arose towards the end of the 19th century; the molecular existence was considered the molecular hypothesis unnecessary.
At the time van der Waals' thesis was written, the molecular structure of fluids had not been accepted by most physicists, liquid and vapor were considered as chemically distinct. But van der Waals's work affirmed the reality of molecules and allowed an assessment of their size and attractive strength, his new formula revolutionized the study of equations of state. By comparing his equation of state with experimental data, Van der Waals was able to obtain estimates for the actual size of molecules and the strength of their mutual attraction; the effect of Van der Waals's work on molecular physics in the 20th century was direct and fundamental. By introducing parameters characterizing molecular size and attraction in constructing his equation of state, Van der Waals set the tone for modern molecular science; that molecular aspects such as size, shape and multipolar interactions should form the basis for mathematical formulations of the thermodynamic and transport properties of fluids is presently considered an axiom.
With the help of the van der Waals's equation of state, the critical-point parameters of gases could be predicted from thermodynamic measurements made at much higher temperatures. Nitrogen, oxygen and helium subsequently succumbed to liquefaction. Heike Kamerlingh Onnes was influenced by the pioneer work of van der Waals. In 1908, Onnes became the first to make liquid helium. Van der Waals started his career as a school teacher, he became the first physics professor of the University of Amsterdam when in 1877 the old Athenaeum was upgraded to Municipal University. Van der Waals won the 1910 Nobel Prize in physics for his work on the equation of state for gases and liquids. Johannes Diderik van der Waals was born on 23 November 1837 in Leiden in the Netherlands, he was the eldest of ten children born to Elisabeth van den Berg. His father was a carpenter in Leiden; as was usual for working-class children in the 19th century, he did not go to the kind of secondary school that would have given him the right to enter university.
Instead he went to a school of “advanced primary education”, which he finished at the age of fifteen. He became a teacher's apprentice in an elementary school. Between 1856 and 1861 he followed courses and gained the necessary qualifications to become a primary school teacher and head teacher. In 1862, he began to attend lectures in mathematics and astronomy at the University in his city of birth, although he was not qualified to be enrolled as a regular student in part because of his lack of education in classical languages. However, the University of Leiden had a provision that enabled outside students to take up to four courses a year. In 1863 the Dutch government started a new kind of secondary school. Van der Waals—at that time head of an elementary school—wanted to become a HBS teacher in mathematics and physics and spent two years studying in his spare time for the required examinations. In 1865, he was appointed as a physics teacher at the HBS in Deventer and in 1866, he received such a position in The Hague, close enough to Leiden to allow van der Waals to resume his courses at the University there.
In September 1865, just before moving to Deventer, van der Waals married the eighteen-year-old Anna Magdalena Smit. Van der Waals still lacked the knowledge of the classical languages that would have given him the right to enter university as a regular student and to take examinations. However, it so happened that the law regulating the university entrance was changed and dispensation from the study of classical languages could be given by the minister of education. Van der Waals was given this dispensation and passed the qualification exams in physics and mathematics for doctoral studies. At Leiden University, on June 14, 1873, he defended his doctoral thesis Over de Continuïteit van den Gas- en Vloeistoftoestand under Pieter Rijke. In the thesis, he introduced the concepts of molecular attraction. In September 1877 van der Waals was appointed the first professor of physics at the newly founded Municipal University of Amsterdam. Two of his notable colleagues were the physical chemist Jacobus Henricus van't Hoff and the biologist Hugo de Vries.
Until his retirement at the age of 70 van der Waals remained at the Amsterdam University. He was succeeded by his
University of Toronto
The University of Toronto is a public research university in Toronto, Canada, located on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution of higher learning in the colony of Upper Canada. Controlled by the Church of England, the university assumed the present name in 1850 upon becoming a secular institution; as a collegiate university, it comprises eleven colleges, which differ in character and history, each with substantial autonomy on financial and institutional affairs. It has two satellite campuses in Mississauga; the university is ranked as the best Canadian university, according to various major publications. Academically, the University of Toronto is noted for influential movements and curricula in literary criticism and communication theory, known collectively as the Toronto School; the university was the birthplace of insulin and stem cell research, was the site of the first practical electron microscope, the development of deep learning, multi-touch technology, the identification of the first black hole Cygnus X-1, the development of the theory of NP-completeness.
By a significant margin, it receives the most annual scientific research funding of any Canadian university. It is one of two members of the Association of American Universities outside the United States, the other being McGill University in Montreal, Canada; the Varsity Blues are the athletic teams that represent the university in intercollegiate league matches, with long and storied ties to gridiron football and ice hockey. The earliest recorded college football game was played in the University of Toronto's University College in the 1860s; the university's Hart House is an early example of the North American student centre serving cultural and recreational interests within its large Gothic-revival complex. The University of Toronto has educated three Governors General of Canada, four Prime Ministers of Canada, four foreign leaders, fourteen Justices of the Supreme Court; as of March 2019, ten Nobel laureates, five Turing Award winners, 94 Rhodes Scholars, one Fields Medalist have been affiliated with the university.
The founding of a colonial college had long been the desire of John Graves Simcoe, the first Lieutenant-Governor of Upper Canada. As an Oxford-educated military commander who had fought in the American Revolutionary War, Simcoe believed a college was needed to counter the spread of republicanism from the United States; the Upper Canada Executive Committee recommended in 1798 that a college be established in York, the colonial capital. On March 15, 1827, a royal charter was formally issued by King George IV, proclaiming "from this time one College, with the style and privileges of a University... for the education of youth in the principles of the Christian Religion, for their instruction in the various branches of Science and Literature... to continue for to be called King's College." The granting of the charter was the result of intense lobbying by John Strachan, the influential Anglican Bishop of Toronto who took office as the college's first president. The original three-storey Greek Revival school building was built on the present site of Queen's Park.
Under Strachan's stewardship, King's College was a religious institution aligned with the Church of England and the British colonial elite, known as the Family Compact. Reformist politicians opposed the clergy's control over colonial institutions and fought to have the college secularized. In 1849, after a lengthy and heated debate, the newly elected responsible government of Upper Canada voted to rename King's College as the University of Toronto and severed the school's ties with the church. Having anticipated this decision, the enraged Strachan had resigned a year earlier to open Trinity College as a private Anglican seminary. University College was created as the nondenominational teaching branch of the University of Toronto. During the American Civil War, the threat of Union blockade on British North America prompted the creation of the University Rifle Corps, which saw battle in resisting the Fenian raids on the Niagara border in 1866; the Corps was part of the Reserve Militia lead by Professor Henry Croft.
Established in 1878, the School of Practical Science was precursor to the Faculty of Applied Science and Engineering, nicknamed Skule since its earliest days. While the Faculty of Medicine opened in 1843, medical teaching was conducted by proprietary schools from 1853 until 1887, when the faculty absorbed the Toronto School of Medicine. Meanwhile, the university continued to confer medical degrees; the university opened the Faculty of Law in 1887, followed by the Faculty of Dentistry in 1888, when the Royal College of Dental Surgeons became an affiliate. Women were first admitted to the university in 1884. A devastating fire in 1890 gutted the interior of University College and destroyed 33,000 volumes from the library, but the university restored the building and replenished its library within two years. Over the next two decades, a collegiate system took shape as the university arranged federation with several ecclesiastical colleges, including Strachan's Trinity College in 1904; the university operated the Royal Conservatory of Music from 1896 to 1991 and the Royal Ontario Museum from 1912 to 1968.
The University of Toronto Press was founded in 1901 as Canada's first academic publishing house. The Faculty of Forestry, founded in 1907 with Bernhard Fernow as dean, was Canada's first university faculty devoted to forest science. In 1910, the Faculty of Education opened its laboratory school, the University of Toro
Lethbridge is a city in the province of Alberta and the largest city in southern Alberta. It is Alberta's fourth-largest city by population after Calgary and Red Deer, the third-largest by land area after Calgary and Edmonton; the nearby Canadian Rockies contribute to the city's warm summers, mild winters, windy climate. Lethbridge lies southeast of Calgary on the Oldman River. Lethbridge is the commercial, financial and industrial centre of southern Alberta; the city's economy developed from drift mining for coal in the late 19th century and agriculture in the early 20th century. Half of the workforce is employed in the health, education and hospitality sectors, the top five employers are government-based; the only university in Alberta south of Calgary is in Lethbridge, two of the three colleges in southern Alberta have campuses in the city. Cultural venues in the city include performing art theatres and sports centres. Before the 19th century, the Lethbridge area was populated by several First Nations at various times.
The Blackfoot referred to the area as Mek-kio-towaghs, Assini-etomochi and Sik-ooh-kotok. The Sarcee referred to it as Chadish-kashi, the Cree as Kuskusukisay-guni, the Nakoda as Ipubin-saba-akabin; the Kutenai people referred to it as ʔa•kwum. After the US Army stopped alcohol trading with the Blackfeet Nation in Montana in 1869, traders John J. Healy and Alfred B. Hamilton started a whiskey trading post at Fort Hamilton, near the future site of Lethbridge; the post's nickname became Fort Whoop-Up. The whiskey trade led to the Cypress Hills Massacre of many native Assiniboine in 1873; the North-West Mounted Police, sent to stop the trade and establish order, arrived at Fort Whoop-Up on 9 October 1874. They managed the post for the next 12 years. Lethbridge's economy developed from drift mines opened by Nicholas Sheran in 1874 and the North Western Coal and Navigation Company in 1882. North Western's president was William Lethbridge. By the turn of the century, the mines employed about 150 men and producing 300 tonnes of coal each day.
In 1896, local collieries were the largest coal producers in the Northwest Territories, with production peaking during World War I. An internment camp was set up at the Exhibition Building in Lethbridge from September 1914 to November 1916. After the war, increasing oil and natural gas production replaced coal production, the last mine in Lethbridge closed in 1957; the first rail line in Lethbridge was opened on August 28, 1885 by the Alberta Railway and Coal Company, which bought the North Western Coal and Navigation Company five years later. The rail industry's dependence on coal and the Canadian Pacific Railway's efforts to settle southern Alberta with immigrants boosted Lethbridge's economy. After the Canadian Pacific Railway moved the divisional point of its Crowsnest Line from Fort Macleod to Lethbridge in 1905, the city became the regional centre for Southern Alberta. In the mid-1980s, the CPR moved its rail yards in downtown Lethbridge to nearby Kipp, Lethbridge ceased being a rail hub.
Between 1907 and 1913, a development boom occurred in Lethbridge, making it the main marketing and service centre in southern Alberta. Such municipal projects as a water treatment plant, a power plant, a streetcar system, exhibition buildings—as well as a construction boom and rising real estate prices—transformed the mining town into a significant city. Between World War I and World War II, the city experienced an economic slump. Development slowed, drought drove farmers from their farms, coal mining declined from its peak. After World War II, irrigation of farmland near Lethbridge led to growth in the city's population and economy. Lethbridge College opened in April 1957 and the University of Lethbridge in 1967; the city of Lethbridge is located at 49.7° north latitude and 112.833° west longitude and covers an area of 127.19 square kilometres. The city is divided by the Oldman River; the city is Alberta's fourth largest by population after Calgary and Red Deer. It is the third largest in area after Calgary and Edmonton and is near the Canadian Rockies, 210 kilometres southeast of Calgary.
Lethbridge is split into three geographical areas: north and west. The Oldman River separates West Lethbridge from the other two while Crowsnest Trail and the Canadian Pacific Railway rail line separate North and South Lethbridge; the newest of the three areas, West Lethbridge is home to the University of Lethbridge, opened at that site in 1971, but the first housing was not completed until 1974 and the prime Whoop-Up Drive access opened only in 1975. Much of the city's recent growth has been on the west side, it has the youngest median age of the three; the north side was populated by workers from local coal mines. It has the oldest population of the three areas, is home to multiple industrial parks and includes the former Hamlet of Hardieville, annexed by Lethbridge in 1978. South Lethbridge is the commercial heart of the city, it contains the downtown core, the bulk of retail and hospitality establishments, the Lethbridge College. Lethbridge has a semi-arid climate with an average maximum temperature of 12.3 °C and an average minimum temperature of −1.1 °C.
With precipitation averaging 365 mm
Clifford Glenwood Shull was a Nobel Prize-winning American physicist. He attended Schenley High School in Pittsburgh, received BS from Carnegie Institute of Technology and PhD from New York University, he worked for The Texas Company at Beacon, New York during the wartime, followed by a position in the Clinton Laboratory, joined MIT in 1955, retired in 1986. Clifford G. Shull was awarded the 1994 Nobel Prize in Physics with Canadian Bertram Brockhouse; the two won the prize for the development of the neutron scattering technique. He conducted research on condensed matter. Professor Shull's prize was awarded for his pioneering work in neutron scattering, a technique that reveals where atoms are within a material like ricocheting bullets reveal where obstacles are in the dark; when a beam of neutrons is directed at a given material, the neutrons bounce off, or are scattered by, atoms in the sample being investigated. The neutrons' directions change, depending on the location of the atoms they hit, a diffraction pattern of the atoms' positions can be obtained.
Understanding where atoms are in a material and how they interact with one another is the key to understanding a material's properties. "Then we can think of how we can make better window glass, better semiconductors, better microphones. All of these things go back to understanding the basic science behind their operation," Professor Shull 79, said on the day of the Nobel announcement.... He started in 1946 at. At that time, he said, "Scientists at Oak Ridge were anxious to find real honest-to-goodness scientific uses for the information and technology, developed during the war at Oak Ridge and at other places associated with the wartime Manhattan Project." Professor Shull teamed up with Ernest Wollan, for the next nine years they explored ways of using the neutrons produced by nuclear reactors to probe the atomic structure of materials. In Professor Shull's opinion the most important problem he worked on at the time dealt with determining the positions of hydrogen atoms in materials. "Hydrogen atoms are ubiquitous in all biological materials and in many other inorganic materials," he once said, "but you couldn't see them with other techniques.
With neutrons it turned out that, different, we were pleased and happy to find that we could learn things about hydrogen-containing structures." As he refined the scattering technique, Professor Shull studied the fundamental properties of the neutron itself. He initiated the first neutron diffraction investigations of magnetic materials.... "If there is a...'Father of Neutron Scattering' in the United States, it is Professor Shull," wrote Anthony Nunes... professor of physics at the University of Rhode Island.... Professor Shull came to MIT as a full professor in 1955 and retired in 1986, though he continued to visit and to "look over the shoulders" of students doing experiments in the "remnants of my old research laboratory." Professor Shull's awards include the Buckley Prize, which he received from the American Physical Society in 1956, election to the American Academy of Arts and Sciences and to the National Academy of Sciences. In 1993 he received the Royal Swedish Academy of Sciences' Gregori Aminoff prize for his "development and application of neutron diffraction methods for studies of atomic and magnetic structures of solids."'
Awarded the Oliver E. Buckley Prize, American Physical Society, 1956 Elected to the American Academy of Arts and Sciences, 1956 Elected to the National Academy of Sciences, 1975 Awarded the Gregori Aminoff Prize, Royal Swedish Academy of Sciences, 1993 Awarded the Nobel Prize in Physics, 1994, which he shared with Canadian physicist Bertram Brockhouse. Shull Rocks, in Antarctica named in his honor Carroll, Cindy. "Carnegie Mellon University Receives Nobel Laureate Clifford Shull Papers Grant and Additional Gift Will Make the Collection Available to Researchers",: Carnegie Mellon University. Stevenson, Daniel C. "Shull wins Physics Nobel for work done 40 years ago", The Tech-Online Edition. Vol. 114, no. 68, Feb. 7, 1995: Massachusetts Institute of Technology. "Oak Ridge Pays Tribute to its Nobel Prize Winner", Oak Ridge National Laboratory. The Clifford G. Shull Prize in Neutron Physics, The Neutron Scattering Society of America. Clifford G. Shull Fellowship, Oak Ridge National Laboratory. Shull, C.
G. Wollan, E. O. & M. C. Marney. "Neutron Diffraction Studies", Oak Ridge National Laboratory, United States Department of Energy. Rundle, R. E. Shull, C. G. & E. O. Wollan. "The Crystal Structure of Thorium and Zirconium Dihydrides by X-ray and Neutron Diffraction", Ames Laboratory, Oak Ridge National Laboratory, United States Department of Energy. Nathans, R. Riste, T. Shirane, G. & C. G. Shull. "Polarized Neutron Studies on Antiferromagnetic Single Crystals: Technical Report No. 4", Massachusetts Institute of Technology, Brookhaven National Laboratory, United States Department of Energy, National Security Agency, Air Force Office of Scientific Research. Shull, C. G. "Low Temperature and Neutron Physics Studies: Final Progress Report, March 1, 1986--May 31, 1987", Massachusetts Institute of Technology, United States Department of Energy. 1994 Nobel Physics winners Nobel Autobiography Full-text digital archive of Clifford G. Shull papers
Nobel Prize in Physics
The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions for humankind in the field of physics. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the first Nobel Prize in Physics was awarded to physicist Wilhelm Röntgen in recognition of the extraordinary services he rendered by the discovery of the remarkable rays. This award is administered by the Nobel Foundation and regarded as the most prestigious award that a scientist can receive in physics, it is presented in Stockholm at an annual ceremony on 10 December, the anniversary of Nobel's death. Through 2018, a total of 209 individuals have been awarded the prize. Only three women have won the Nobel Prize in Physics: Marie Curie in 1903, Maria Goeppert Mayer in 1963, Donna Strickland in 2018. Alfred Nobel, in his last will and testament, stated that his wealth be used to create a series of prizes for those who confer the "greatest benefit on mankind" in the fields of physics, peace, physiology or medicine, literature.
Though Nobel wrote several wills during his lifetime, the last one was written a year before he died and was signed at the Swedish-Norwegian Club in Paris on 27 November 1895. Nobel bequeathed 94% of his total assets, 31 million Swedish kronor, to establish and endow the five Nobel Prizes. Due to the level of skepticism surrounding the will, it was not until April 26, 1897 that it was approved by the Storting; the executors of his will were Ragnar Sohlman and Rudolf Lilljequist, who formed the Nobel Foundation to take care of Nobel's fortune and organise the prizes. The members of the Norwegian Nobel Committee who were to award the Peace Prize were appointed shortly after the will was approved; the prize-awarding organisations followed: the Karolinska Institutet on June 7, the Swedish Academy on June 9, the Royal Swedish Academy of Sciences on June 11. The Nobel Foundation reached an agreement on guidelines for how the Nobel Prize should be awarded. In 1900, the Nobel Foundation's newly created statutes were promulgated by King Oscar II.
According to Nobel's will, The Royal Swedish Academy of sciences were to award the Prize in Physics. A maximum of three Nobel laureates and two different works may be selected for the Nobel Prize in Physics. Compared with other Nobel Prizes, the nomination and selection process for the prize in Physics is long and rigorous; this is a key reason why it has grown in importance over the years to become the most important prize in Physics. The Nobel laureates are selected by the Nobel Committee for Physics, a Nobel Committee that consists of five members elected by The Royal Swedish Academy of Sciences. In the first stage that begins in September, around 3,000 people – selected university professors, Nobel Laureates in Physics and Chemistry, etc. – are sent confidential forms to nominate candidates. The completed nomination forms arrive at the Nobel Committee no than 31 January of the following year; these nominees are scrutinized and discussed by experts who narrow it to fifteen names. The committee submits a report with recommendations on the final candidates into the Academy, where, in the Physics Class, it is further discussed.
The Academy makes the final selection of the Laureates in Physics through a majority vote. The names of the nominees are never publicly announced, neither are they told that they have been considered for the prize. Nomination records are sealed for fifty years. While posthumous nominations are not permitted, awards can be made if the individual died in the months between the decision of the prize committee and the ceremony in December. Prior to 1974, posthumous awards were permitted; the rules for the Nobel Prize in Physics require that the significance of achievements being recognized has been "tested by time". In practice, it means that the lag between the discovery and the award is on the order of 20 years and can be much longer. For example, half of the 1983 Nobel Prize in Physics was awarded to Subrahmanyan Chandrasekhar for his work on stellar structure and evolution, done during the 1930s; as a downside of this approach, not all scientists live long enough for their work to be recognized.
Some important scientific discoveries are never considered for a prize, as the discoverers die by the time the impact of their work is appreciated. A Physics Nobel Prize laureate earns a gold medal, a diploma bearing a citation, a sum of money; the Nobel Prize medals, minted by Myntverket in Sweden and the Mint of Norway since 1902, are registered trademarks of the Nobel Foundation. Each medal has an image of Alfred Nobel in left profile on the obverse; the Nobel Prize medals for Physics, Physiology or Medicine, Literature have identical obverses, showing the image of Alfred Nobel and the years of his birth and death. Nobel's portrait appears on the obverse of the Nobel Peace Prize medal and the Medal for the Prize in Economics, but with a different design; the image on the reverse of a medal varies according to the institution awarding the prize. The reverse sides of the Nobel Prize medals for Chemistry and Physics share the same design of Nature, as a Goddess, whose veil is held up by the Genius of Science.
These medals and the ones for Physiology/Medicine and Literature were designed by Erik Lindberg in 1902. Nobel laureates receive a diploma directly from the hands of the
Antoine Henri Becquerel was a French engineer, Nobel laureate, the first person to discover evidence of radioactivity. For work in this field he, along with Marie Skłodowska-Curie and Pierre Curie, received the 1903 Nobel Prize in Physics; the SI unit for radioactivity, the becquerel, is named after him. Becquerel was born in Paris into a wealthy family which produced four generations of physicists: Becquerel's grandfather and son. Henri started off his education by attending the Lycée Louis-le-Grand school, a prep school in Paris, he studied engineering at the École des Ponts et Chaussées. In 1874, Henri married Lucie Zoé Marie Jamin, who would die while giving birth to Jean. In 1890 he married Louise Désirée Lorieux. In Becquerel's early career, he became the third in his family to occupy the physics chair at the Muséum National d'Histoire Naturelle in 1892. On in 1894, Becquerel became chief engineer in the Department of Bridges and Highways before he started with his early experiments. Becquerel's earliest works centered on the subject of his doctoral thesis: the plane polarization of light, with the phenomenon of phosphorescence and absorption of light by crystals.
Early in his career, Becquerel studied the Earth's magnetic fields. Becquerel's discovery of spontaneous radioactivity is a famous example of serendipity, of how chance favors the prepared mind. Becquerel had long been interested in phosphorescence, the emission of light of one color following a body's exposure to light of another color. In early 1896, there was a wave of excitement following Wilhelm Conrad Röntgen's discovery of X-rays on the 5th of January. During the experiment, Röntgen "found that the Crookes tubes he had been using to study cathode rays emitted a new kind of invisible ray, capable of penetrating through black paper." Learning of Röntgen's discovery from earlier that year during a meeting of the French Academy of Sciences caused Becquerel to be interested, soon "began looking for a connection between the phosphorescence he had been investigating and the newly discovered x-rays" of Röntgen, thought that phosphorescent materials, such as some uranium salts, might emit penetrating X-ray-like radiation when illuminated by bright sunlight.
By May 1896, after other experiments involving non-phosphorescent uranium salts, he arrived at the correct explanation, namely that the penetrating radiation came from the uranium itself, without any need for excitation by an external energy source. There followed a period of intense research into radioactivity, including the determination that the element thorium is radioactive and the discovery of additional radioactive elements polonium and radium by Marie Skłodowska-Curie and her husband Pierre Curie; the intensive research of radioactivity led to Henri publishing seven papers on the subject in 1896. Becquerel's other experiments allowed him to research more into radioactivity and figure out different aspects of the magnetic field when radiation is introduced into the magnetic field. "When different radioactive substances were put in the magnetic field, they deflected in different directions or not at all, showing that there were three classes of radioactivity: negative and electrically neutral."As happens in science, radioactivity came close to being discovered nearly four decades earlier in 1857, when Abel Niépce de Saint-Victor, investigating photography under Michel Eugène Chevreul, observed that uranium salts emitted radiation that could darken photographic emulsions.
By 1861, Niepce de Saint-Victor realized that uranium salts produce "a radiation, invisible to our eyes". Niepce de Saint-Victor knew Henri Becquerel's father. In 1868, Edmond Becquerel published La lumière: ses causes et ses effets. On page 50 of volume 2, Edmond noted that Niepce de Saint-Victor had observed that some objects, exposed to sunlight could expose photographic plates in the dark. Niepce further noted that on the one hand, the effect was diminished if an obstruction were placed between a photographic plate and the object, exposed to the sun, but " … d'un autre côté, l'augmentation d'effet quand la surface insolée est couverte de substances facilement altérables à la lumière, comme le nitrate d'urane … ". Describing them to the French Academy of Sciences on 27 February 1896, he said: One wraps a Lumière photographic plate with a bromide emulsion in two sheets of thick black paper, such that the plate does not become clouded upon being exposed to the sun for a day. One places on the sheet of paper, on the outside, a slab of the phosphorescent substance, one exposes the whole to the sun for several hours.
When one develops the photographic plate, one recognizes that the silhouette of the phosphorescent substance appears in black on the negative. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative... One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduce silver salts, but further experiments led him to doubt and abandon this hypothesis. On 2 March 1896 he reported: I will insist upon the following fact, which seems to me quite important and beyond the phenomena which one could expec
Philipp Eduard Anton von Lenard was a German physicist and the winner of the Nobel Prize for Physics in 1905 for his research on cathode rays and the discovery of many of their properties. Lenard was a anti-Semite. Notably, he labeled Albert Einstein's contributions to science as "Jewish physics". Philipp Lenard was born in Pressburg, on 7 June 1862 in the Kingdom of Hungary; the Lenard family had come from Tyrol in the 17th century, Lenard's parents were German-speakers. His father, Philipp von Lenardis, was a wine-merchant in Pressburg, his mother was Antonie Baumann. The young Lenard studied at the Pozsonyi Királyi Katolikus Főgymnasium, as he writes it in his autobiography, this made a big impression on him. In 1880, he studied chemistry in Vienna and in Budapest. In 1882, Lenard left Budapest and returned to Pressburg, but in 1883, he moved to Heidelberg after his tender for an assistant's position in the University of Budapest was refused. In Heidelberg, he studied under the illustrious Robert Bunsen, interrupted by one semester in Berlin with Hermann von Helmholtz, he obtained a doctoral degree in 1886.
In 1887 he worked again in Budapest under Loránd Eötvös as a demonstrator. After posts at Aachen, Breslau and Kiel, he returned to the University of Heidelberg in 1907 as the head of the Philipp Lenard Institute. In 1905, Lenard became a member of the Royal Swedish Academy of Sciences, in 1907, of the Hungarian Academy of Sciences, his early work included the conductivity of flames. As a physicist, Lenard's major contributions were in the study of cathode rays, which he began in 1888. Prior to his work, cathode rays were produced in primitive evacuated glass tubes that had metallic electrodes in them, across which a high voltage could be placed. Cathode rays were difficult to study using this arrangement, because they were inside sealed glass tubes, difficult to access, because the rays were in the presence of air molecules. Lenard overcame these problems by devising a method of making small metallic windows in the glass that were thick enough to be able to withstand the pressure differences, but thin enough to allow passage of the rays.
Having made a window for the rays, he could pass them out into the laboratory, or, into another chamber, evacuated. These windows have come to be known as Lenard windows, he was able to conveniently detect the rays and measure their intensity by means of paper sheets coated with phosphorescent materials. Lenard observed that the absorption of cathode rays was, to first order, proportional to the density of the material they were made to pass through; this appeared to contradict the idea. He showed that the rays could pass through some inches of air of a normal density, appeared to be scattered by it, implying that they must be particles that were smaller than the molecules in air, he confirmed some of J. J. Thomson's work, which arrived at the understanding that cathode rays were streams of negatively charged energetic particles, he called them quanta of electricity or for short quanta, after Helmholtz, while J. J. Thomson proposed the name corpuscles, but electrons became the everyday term. In conjunction with his and other earlier experiments on the absorption of the rays in metals, the general realization that electrons were constituent parts of the atom enabled Lenard to claim that for the most part atoms consist of empty space.
He proposed that every atom consists of empty space and electrically neutral corpuscules called "dynamids", each consisting of an electron and an equal positive charge. As a result of his Crookes tube investigations, he showed that the rays produced by irradiating metals in a vacuum with ultraviolet light were similar in many respects to cathode rays, his most important observations were that the energy of the rays was independent of the light intensity, but was greater for shorter wavelengths of light. These latter observations were explained by Albert Einstein as a quantum effect; this theory predicted that the plot of the cathode ray energy versus the frequency would be a straight line with a slope equal to Planck's constant, h. This was shown to be the case some years later; the photo-electric quantum theory was the work cited when Einstein was awarded the Nobel Prize in Physics. Suspicious of the general adulation of Einstein, Lenard became a prominent skeptic of relativity and of Einstein's theories generally.
Lenard received the 1905 Nobel Prize for Physics in recognition of this work. Lenard was the first person to study what has been termed the Lenard effect in 1892; this is the separation of electric charges accompanying the aerodynamic breakup of water drops. It is known as spray electrification or the waterfall effect, he conducted studies on the size and shape distributions of raindrops and constructed a novel wind tunnel in which water droplets of various sizes could be held stationary for a few seconds. He was the first to recognize that large raindrops are not tear-shaped, but are rather shaped something like a hamburger bun. Lenard is remembered today as a strong German nationalist who despised "English physics", which he considered to have stolen its ideas from Germany, he joined the Nation