Hahn was successful in splitting the uranium atom with his assistant Fritz Strasmann, and anticipated the possible destructive use to which his discovery could be put, and would be; it eventually resulted in the construction of the atomic bomb
optics, translated into Latin in 1270 as Opticae thesaurus Alhazeni libri vii, Alhazen published theories on refraction, reflection, binocular vision, focussing with lenses, the rainbow, parabolic and spherical mirrors, spherical aberration, atmospheric refraction, and the apparent increase in size of planetary bodies near the Earth's horizon. He was first to give an accurate account of vision, correctly stating that light comes from the object seen to the eye. One of his celebrated problem is the so-called 'Alhazen's problem': At which point on a spherical mirror is light from a given point source reflected into the eye of a given observer? In Opticae Thesaurus, introduced the idea that light rays emanate in straight lines in all directions from every point on a luminous surface. In Epitome of Astronomy, he took a position against Ptolemy, insisting that the hypothetical spheres corresponded "to the true movements of really existing hard or yielding bodies [and] so...were accountable to the laws of physics" (Duhem 1908:28). This led to disagreements that persisted through the twelfth century.
Hamilton grew up with his uncle who was a bit of an eccentric; for instance, he tied a string around young William's toe at night, ran it through a hole in the wall into his own bedroom, and then early each morning he would tug on the string to wake him and start him on his studies. By the age of 12, Hamilton was fluent in 10 languages and was appointed to a Mathematics Chair at the Royal Observatory in Dublin at a youthful age. One of Hamilton's successes was in proving that Newton's Equations and Lagrangian Mechanics were equivalent when the Lagrangian was the difference between the kinetic and potential energy of a system. Up to that time there were arguments over which was correct. He showed that they were different manifestations of the same thing.
He also put some ideas of Fermat into a new perspective. Hamilton took Lagrange's action property and showed that the path a particle would take would be the path of least action. This correlation between the motion of waves (as light was understood at the time) and that of particles could be described in a common way, hints, in retrospect at least, to the wave-particle duality that we understand in modern quantum theory. Perhaps Hamilton's most important contribution came from his reformulation of Newton's Laws. In the same way that Lagrange provided a new method for solving mechanical problems, Hamilton put forward still another formalism. He showed that the results were equivalent in the three methods, but his proves to be most useful for a certain class of problems. The theory stems from a new variable called the Hamiltonian, which is the sum of the system's kinetic and potential energy. And the equations of motion derive from this. It turns out that Hamiltonian mechanics were the starting point for Schrödinger's development of his Wave Mechanics, the classical theory simply twisted to account for the quantum observations.
Hansteen, a physicist and astronomer, devoted his time to the study of geomagnetism. In 1701 Halley had already published a map of magnetic declinations, and the subject was studied by Humboldt, de Borda, and Gay-Lussac, among others. Hansteen collected available data and also mounted an expedition to Siberia, where he took many measurements for an atlas of magnetic strength and declination
Hantaro Nagaoka became the foremost Japanese professor of modern physics during the early 20th-century and was best known for his Saturnian model of the atom first proposed in 1903. Nagaoka pursued his theoretical model as a tool to account for line and band spectra, the interactions of atoms, radioactivity, and other phenomena. However, Nagaoka abandoned the model a few years later when the research of J. J. Thomson determined a fatal flaw. As a result, Nagaoka turned to spectroscopy in order to understand the arrangement of electrons in the atom. Nagaoka played a crucial role in the development of a sustained and credible research tradition in Japan during the early 20th-century. Less than 100 years after the Meiji Restoration in 1868, original research in theoretical physics resulted in Hideki Yukawa winning the Nobel Prize for Physics in 1949, an event firmly placing Japan in the advanced ranks of physics research. Nagaoka Hantaro was awarded the Order of Culture in 1937.
The British theoretical physicist Hawking, b. Jan. 8, 1942, is a leading figure in modern cosmology. He studied physics and mathematics at the universities of Oxford and Cambridge. He set out to link quantum mechanics and relativity, the two major theories of modern physics, by developing a quantum theory of gravity. His speculations include the existence of “mini” black holes no larger than elementary particles, and multiple universes linked by tiny quantum fluctuations in space ("wormholes."). He is known for this popular nontechnical books of physics such as “A Brief History of Time”. Hawking has a degenerative disorder of the nervous system known as Lou Gehrig's disease
Astronomer and mathematician who calculated as a first one the Sun parallax and the distance between the Earth and the Sun. A 1970 Czechoslovakian stamp honors this German astronomer, dressed as a Laplander. It was there that he was first to observe a transit of Venus. He was director of the astronomy observatory in Vienna, even after the Suppression of the Jesuits. A lunar crater is named after him. Maximilian Hell, S.J. died 200 years ago in 1792, after falling victim to the defamation of Jesuits during the Suppression of the Society. Accused of altering his data during the 1769 transit of Venus, he was not exonerateed until a century later when the renowned American astronomer Simon Newcomb found Hell's readings to be correct, his scholarship above suspicion and his accusers guilty of slander. The damage done his reputation, however, survived him because of historians who failed to report his rehabilitation.
Because of his personal qualities as well as his scientific adventures Hell was held in high esteem by all who knew him. He was elected to the most prestigious scientific academies of Europe. The rulers of both England and Denmark offered him large honorary pensions which he modestly declined. At the urging of fellow scientists he attempted to form an imperial academy of science, but was thwarted by political enemies of the Jesuits. He did succeed in publishing a very timely and indispensable journal concerning the latest scientific discoveries. A lunar crater is named after Hell and a 1970 Czechoslovakian stamp honors him dressed as a Laplander recalling his famous scientific expedition.
Maximilian Hell was born into a family of engineers in 1720 in the city of Selmecz (Schemnitz), Hungary. His father was the chief engineer of the local mines and his brother invented an ingenious machine to pump water out of the mine shafts. After joining the Jesuits Maximilian taught mathematics, astronomy, physics and technology and attracted large numbers to his celebrated lectures. He also was a prodigious writer having no less than 35 entries in Sommervogel's Bibliography and requiring 20 pages of narration. Both his teaching and writings promoted a popular understanding and enthusiasm for astronomy, spreading Hell's reputation throughout Europe.
Among his adventures were experiments in magnetism applied to medicine. This was unchartered ground. By assuming very unconventional premises he started something quite remarkable. Using lodestone he devised an arrangement of magnetic plates for the lessening of pain from diseases, including attacks of rheumatism from which he himself suffered. He met with considerable success in relieving the pain. His magnetic medicine attracted the attention of a young man named Franz Mesmer, recently graduated from the Jesuit University of Dillingen in Bavaria. Mesmer disregarded the magnets and developed a different, but even more peculiar theory of healing based on circulating cosmic fluids in the body. The hypothesis of both men were found to be groundless but eventually investigators of these phenomena made mesmerism, or hypnotism, an accepted medical practice.
The story of Hell's detractors can be found in the Dictionary of Scientific Biography, in ISIS and in the modern histories of astronomy. Just before the Suppression, Jesuits directed 30 of the world's 130 major astronomical observatories. Maximilian Hell was so successful in setting up smaller observatories that in 1755 Maria Theresa of Austria and Hungary named him her court astronomer and commissioned him to organize a great central observatory in Vienna. He did so and remained its director for a quarter century. For 37 years he published his unique periodical Ephemerides Astronomicae containing scientific papers and observations which was widely used by the imperial navy, for purposes of the merchant fleet, geodetic surveys and the exact mapping of the empire.
In 1767 he accepted an invitation from King Christian VII of Denmark and Norway to direct the scientific expedition to the island station Vardø near Lapland within the Arctic Circle. The purpose was to gather data from the 1769 transit of Venus which crosses the face of the sun about twice a century. If the contact points of the sun with Venus, upon entering and exiting the sun's circumference, are properly observed from different vantage points on earth, this transit can provide data needed for computing the solar parallax, which can then be used to compute that elemental astronomical unit, the sun's distance to the earth. This adventure was an effort by scientists of various nationalities to simultaneously collect data in Vardø, Manila, Batavia, California, Peking, and Tahiti. The value of the sun's distance accepted today, 93 million miles, was determined at a later date when finer instruments and better methods were available. This 1769 effort, however, was significant because it was among the earliest examples of international scientific cooperation.
The day of the transit was 3 June, 1769 and the observers had the good fortune to have clear weather to make their observations, for which they sang a Te Deum in gratitude. Hell and his team stayed in Vardø for about eight months, spending most of their time collecting other scientific data for an anticipated encyclopedia concerning the arctic regions. This was to contain studies in biology, meteorology, oceanography, zoology, geography, natural history and linguistic analysis. Hell saw the transit as only one part of a larger expedition. Nothing came of Hell's encyclopedia, however, because of the Suppression of the Society in 1773.
Meanwhile the astronomers who had stayed home were anxious to get his observations, since Hell's ability to observe was considered the most reliable of the scientists involved. Hell, however, felt his first priority was to report to his Danish sponsor and would not be hurried or coerced. This irritated the French Academy who accused him of having nothing to report and of waiting so that he could create figures to correspond with the observations made elsewhere. This accusation implied the worst crime a scientist could commit. Eventually in 1772 Hell's observations with all their intricate detail were published.
For a time the ugly insinuations ceased until Carl Littrow became one of Hell's successors at the Vienna observatory with access to all the records. When Littrow found Hell's original data sheets concerning the 1769 transit he claimed to finally have evidence that Hell's figures had been falsified. He asserted that the data contained erasures which were corrected by scratching in a slightly different colored ink. This indictment of Hell was more serious than the original vague insinuations because it seemed to carry the aura of scientific proof. Thus was Hell discredited and his reputation as a reliable scientist destroyed.
It was not until a century later when the American astronomer, Simon Newcomb who was especially interested in the rare transits of Venus, examined Littrow's evidence and found it fictitious. Newcomb found that Hell's figures were exactly what they should have been. They were much more in accord with the true value of the parallax than the data of any other observer. The scratched out figures were merely a matter of Hell using a defective pen in the cold arctic air. Alterations had indeed been made by rubbing out the ink with a finger. But unquestionably this had been done before the ink had dried, not months later as had been charged. Finally, Newcomb discovered that Littrow was colorblind. In fact his defect was so severe that he "could not distinguish the tint of Aldebaran from the whitest star." Newcomb's imposing stature was such that all the charges against Hell were declared spurious by all astronomical societies. Hell was vindicated and his illustrious reputation recovered.
Physicist and physiologist and the inventor of a opthalmoscope. Investigation of the speed of the neural impulse and his research on vision and hearing Provided the first empirical measurement of the rate of conduction by stimulating a motor nerve and the attached muscle in the leg of a frog Interested in a measurement itself not in the psychology. Revised and extended a theory of colour vision published in 1802 by Thomas Young; known as Young-Helmholtz theory of color vision. Research in audition specifically the perception of tone.
An English astronomer--noted in his day for the excellence and size of the telescopes he built--and the careful observations he (with his sister Caroline) made of the heavens. He began his career as a musician--but became interested in optics and astronomy early in his career. Until 1779 this was considered only a side-line--when a member of the Bath Literary and Philosophical Society discovered his work with telescopes and invited Herschel to present his work to the Society. He soon became a member of this Society--and began to devote himself to astronomy. In 1781 while scanning the heavens with one of his powerful telescopes, he discovered a new planet in the solar system--far beyond even Saturn. The Planet came to be named "Uranus." This discovery brought him entry into the British Royal Society--and a new position as personal astronomer to King George III. It was Herschel who, through his persistent effort to count stars, came to conclude that the sky was full of huge disk-shaped wispy clouds which were actually star clusters of millions of stars each. Our sun was part of such a star cluster--the rest of which we observed as the Milky Way. All of this made it very clear to him that the universe was vastly larger than we hitherto had even come close to imagining. He also cataloged about 2000 nebulae, discovered several satellites of Uranus and Saturn, studied the rotation of planets. Discovered and studied binary stars.
Heinrich Rudolf Hertz was born on 22nd February 1857 in Hamburg. His father Dr. jur. Gustav Ferdinand Hertz was Jewish, who had converted to Christianity. He was an advocate in Hamburg, then Oberlandsgerichtsrat, and from 1887 Senator and head of the administration of justice. His mother Anna Elisabeth, née Pfefferkorn, was the daughter of the Frankfurt doctor, Dr. Pfefferkorn. After attending a private Realschule, Heinrich prepared himself, by private study, for the Johanneum at which, after only a year, he passed his Abitur (GCE A-levels), the best in his class. He showed an early interest in the natural sciences, and a practical skill in building physics equipment in the family workshop. He was also an enthusiastic linguist, learning Arabic and Sanskrit. . From 1885 to 1889 he was a professor of physics at the technical school in Karlsruhe and after 1889 a professor of physics at the University in Bonn. Hertz clarified and expanded the electromagnetic theory of light that had been put forth by the British physicist James Clerk Maxwell in 1884. Hertz proved that electricity can be transmitted in electromagnetic waves, which travel at the speed of light and which possess many other properties of light. His experiments with these electromagnetic waves led to the development of the wireless telegraph and the radio. His name also became the term used for radio and electrical frequencies: hertz (Hz), as in kilohertz (KHz) or megahertz (MHz). The hertz designation has been an official part of the international metric system since 1933. Before Hertz gained professorships in Karlsruhe and Bonn, he had studied under the famous scientist Hermann von Helmholtz in Bonn, and it was Helmholtz who encouraged Hertz to attempt to win the science prize that led to some of Hertz's most important discoveries. From 1885 to 1889 Hertz became the first person to broadcast and receive radio waves, and to establish the fact that light was a form of electromagnetic radiation. (The Italian Marconi didn't begin his own wireless experiments until 1894, based on the earlier work of Hertz, Maxwell, and others.) Hertz suffered from a bone disease during Summer 1892. Heinrich Hertz died of blood poisoning on 1st January 1894 when not quite 37. His tragic early death occurred after several years of poor health and cut short a brilliant career. He is buried in the Jewish cemetery in Ohlsdorf
Johann Hevelius (1611-87) was a wealthy brewer in Danzig who dedicated his life and fortune to the study of astronomy. He built enormously long telescopes and other outsize apparatus on the roof of his house (Newton's reflecting telescope had not yet been invented). He mapped and named craters and mountains on the moon and in 1647 published Selenographia, the first illustrated work of astronomy dealing exclusively with the moon. He also published a stellar atlas, Firmamentum Sobiescianum, observed and mapped nebulosities including the Andromeda nebula, and recorded several decades of sunspot observations. These Polish stamps show Hevelius from a portrait in Selenographia superimposed on a chart of constellations, and also with his six foot radius brass sextant on the roof of his house. His celestial atlas Uranographia of 1690 may be viewed on the website of the Brera Astronomical Observatory.
1961 Nobel Physics prize for his pioneering studies of electron scattering in atomic nuclei and for his thereby achieved discoveries concerning the structure of the nucleons. 1915- Physicist Robert Hofstadter, famous for dissecting the proton and neutron, is born in New York City.
Born: 14 April 1629 in The Hague, Netherlands
Died: 8 July 1695 in The Hague, Netherlands
Dutch physicist who made a number of contributions to science in a number of different subfields. He developed the pendulum clock, the telescope, and added to our knowledge of the planet Saturn and its satellite rings and moons. He is perhaps most notable for his theory that light functioned as a wave rather than as particles (in contrast to Newton). He claimed that light moved along a vibrational path through invisible ether to reach the eye and produce vision.
In 1659 he made the first sketch of a feature of Mars recognizable today-Syrtis Major. Huygens also was able to track this feature and determined that the length of a Mars day was about the same as that of an Earth day-24 hours.