Important historic dates in science

July 31: Hendrik Christoffel van de Hulst
(Born November 19, 1918: Died July 31, 2000)
Dutch astronomer who predicted theoretically (1944) that in interstellar space the amount of neutral atomic hydrogen, which in its hyperfine transition radiates and absorbs at a wavelength of 21 cm, might be expected to occur at such high column densities as to provide a spectral line sufficiently strong as to be measurable. Shortly after the end of the war several groups set about to test this prediction. The 21-cm line of atomic hydrogen was detected in 1951, first at Harvard University followed within a few weeks by others. The discovery demonstrated that astronomical research, which at that time was limited to conventional light, could be complemented with observations at radio wavelengths, revealing a range of new physical processes.

July 30: Atomic energy
On this day in 1957 the International Atomic Energy Agency was established by the United Nations.

July 29: I.I. Rabi
(Born July 28, 1898: Died January 11, 1988)
Isidor Isaac Rabi was an American physicist who was awarded the Nobel Prize for Physics in 1944 for his invention (in 1937) of the atomic and molecular beam magnetic resonance method of measuring magnetic properties of atoms, molecules, and atomic nuclei. He spent most of his life at Columbia University (1929-67), where he performed most of his pioneering research in radar and the magnetic moment associated with electron spin in the 1930s and 1940s. His Nobel-winning work led to the invention of the laser, the atomic clock, and diagnostic uses of nuclear magnetic resonance. He originated the idea for the CERN nuclear research center in Geneva (founded 1954).

July 28: Otto Hahn
(Born March 8, 1879: Died July 28, 1968)
German chemist who, with the radiochemist Fritz Strassmann, is credited with the discovery of nuclear fission. He was awarded the Nobel Prize for Chemistry in 1944 and shared the Enrico Fermi Award in 1966 with Strassmann and Lise Meitner. Element 105 carries the name hahnium in recognition of his work.

July 27: Bertram Borden Boltwood
(Born July 27, 1870)
Bertram Borden Boltwood was an American chemist and physicist whose work on the radioactive decay of uranium and thorium was important in the development of the theory of isotopes. Boltwood studied the "radioactive series" whereby radioactive elements sequentially decay into other isotopes or elements. Since lead was always present in such ores, he concluded (1905) that lead must be the stable end product from their radioactive decay. Each decay proceeds at a characteristic rate. In 1907, he proposed that the ratio of original radioactive material to its decay products measured how long the process had been taking place. Thus the ore in the earth's crust could be dated, and give the age of the earth as 2.2 billion years.

July 26: Curie marriage
In 1895, Pierre Curie married Marie Sklodowska (Curie) in Sceaux, France. In 1896, Marie Curie decided to investigate the Becquerel discovery of the radiactivity of uranium, as a research topic for her doctoral thesis. In 1897 she gave birth to a daughter, Irène. Pierre subsequently followed her into research into radioactivity (1898).

July 25: Nuclear Treaty
In 1963, the United States, the Soviet Union and Britain initialed a treaty in Moscow prohibiting the testing of nuclear weapons in the atmosphere, in space or underwater.

July 24: Sir James Chadwick
(Born October 20, 1891: Died July 24, 1974)
Physicist, English, discovered the neutron and later worked on the Manhattan Project to develop the atom bomb. Nobel laureate (1935).

July 23: Three Mile Island Unit 2 re-entered
In 1980, the first human re-entry was made into the Three Mile Island Unit-2 containment building since shutdown after the 28 Mar 1979 accident, when the core of the nuclear power plant lost water coolant and began a partial melt-down incident.

July 22: Gustav Hertz
(Born July 22, 1887: Died October 30, 1975)
German quantum physicist who, with James Franck, received the Nobel Prize for Physics in 1925 for the Franck-Hertz experiment, which confirmed the quantum theory that energy can be absorbed by an atom only in definite amounts and provided an important confirmation of the Bohr atomic model. He was a nephew of Heinrich Hertz. Although he fought on the German side in World War I, being of Jewish descent, he was forced to resign his professorship (1934) when Hitler took power. From 1945 he worked in the Soviet Union, and then in 1955 was a professor of physics in Leipzig, East Germany.

July 21: Three Mile Island accident
In 1982, the first look at the Three Mile Island Unit 2 partial core meltdown was recorded by a mini-TV camera. This was the first inspection of the core made since the nuclear power plant in Harrisburg, Pennsylvania, first experienced a serious accident on 28 Mar 1979, due to a loss of water coolant. Now, as the camera was lowered, "One foot, two foot... three feet," nothing was seen. Then, "Five foot. Got something." And that was recognition for the first time that five feet of the core was gone. That's when it was known the core had been severely damaged. Fifty percent of the core was destroyed or molten and something on the order of twenty tons of uranium found its way to the bottom head of the pressure vessel.

July 20: Gerd Binnig
(Born July 20, 1947)
German-born physicist who co-invented the scanning tunneling microscope with Heinrich Rohrer. They shared the 1986 Nobel Prize for Physics with Ernst Ruska, who designed the first electron microscope. This instrument is not a true microscope ( i.e. an instrument that gives a direct image of an object) since it is based on the principle that the structure of a surface can be studied using a stylus that scans the surface at a fixed distance from it. Vertical adjustment of the stylus is controlled by means of what is termed the tunnel effect - hence the name of the instrument.

July 19: Edward Pickering
(Born July 19, 1846: Died February 3, 1919)
Edward Charles Pickering, was born Boston, Mass., U.S. physicist and astronomer. After graduating from Harvard, he taught physics for ten years at MIT where he built the first instructional physics laboratory in the United States. At age 30, he directed the Harvard College Observatory for 42 years. His observations were assisted by a staff of women, including Annie Jump Cannon. He introduced the use of the meridian photometer to measure the magnitude of stars, and established the Harvard Photometry (1884), the first great photometric catalog. By establishing a station in Peru (1891) to make the southern photographs, he published the first all-sky photographic map (1903).

July 18: Pierre-Louis Dulong
(Born February 12, 1785: Died July 18, 1838)
Chemist and physicist who helped formulate the Dulong-Petit law of specific heats (1819), which proved useful in determining atomic weights.

July 17: Gordon Gould
(Born July 17, 1920)
Physicist, coined the word "laser": acronym for Light Amplification by Stimulated Emission of Radiation. Even before high school, thinking of Marconi, Bell, and Edison, Gould intended to be an inventor. During WWII, Gould worked with the Manhattan Project on the separation of uranium isotopes. By the 50's, he was a graduate student at Columbia University. On November 9, 1957, during a Saturday night without sleep, he had the inventor's inspiration and began to write down the principles of what he called a laser in his notebook Although Charles Townes and Arthur Schawlow, also successfully developed the laser, eventually Gould gained his long-denied patent rights.

July 16: Atomic bomb
In 1945, the first atomic bomb was exploded at Los Alamos, New Mexico. The atomic bomb was invented by two refugee German scientists in Britain, Professor Rudolph Peierls and Otto Frisch, of Birmingham University. They designed a "blue-print" for making an atom bomb in 1940. It actually began when the Italian-born physicist Enrico Fermi, working in the United States, invented an apparatus which produced the first atomic chain reactions. In 1940 both the Americans and British were researching the atom bomb and when the United States entered WW2, the British joined the American "Manhattan Project" and production of the bomb went on ahead in the US.

July 15: Pavel Alekseyevich Cherenkov
Born July 15, 1904: Died January 6, 1990.
Soviet physicist who shared the 1958 Nobel Prize for Physics with fellow Soviet scientists Igor Y. Tamm and Ilya M. Frank for their investigation of the phenomenon called Cherenkov radiation. Cherenkov discovered (1934) that a faint blue light is emitted by electrons as they pass through a transparent medium at a speed higher than the speed of light in that medium. This phenomenon, which was interpreted by Tamm and Frank, led to the development of the Cherenkov counter, or Cherenkov detector, which was later used extensively in experimental nuclear and particle physics.

July 14: Maurice de Brogile
( Born April 27, 1875: Died July 14, 1960)
(6th duke) (Louis-César-Victor-) Maurice de Broglie was a French physicist who made many contributions to the study of X rays. While in the navy (1895-1908), he first distinguished himself by installing the first French shipboard wireless. From 1912, his chief interest was X-ray spectroscopy. His "method of the rotating crystal" was an application of Bragg's "focussing effect" to eliminate spurious spectral lines. De Broglie discovered the third L absorption edge (1916), which led to the exploration of "corpuscular spectra." During 1921-22, he worked with his brother Louis to refine Bohr's specification of the substructure of the various atomic shells. He also did pioneer work in nuclear physics and cosmic radiation.

July 13: Patrick M.S. Blackett
(Born November 18, 1897: Died July 13, 1974)
(Baron Blackett of Chelsea) Patrick Maynard Stuart Blackett was an English physicist and winner of the Nobel Prize for Physics in 1948 for his discoveries in the field of cosmic radiation. In these studies he used cloud-chamber photographs that revealed the way in which a stable atomic nucleus can be disintegrated by bombarding it with alpha particles (helium nuclei). Although such nuclear disintegration had been observed previously, his data explained this phenomenon for the first time and were useful in explaining disintegration by other means.

July 12: Willis Lamb
(Born July 12, 1913)
Willis Eugene Lamb, Jr. was an American physicist and joint winner, with Polykarp Kusch, of the Nobel Prize for Physics in 1955 "for his discoveries concerning the fine structure of the hydrogen spectrum." His experimental work spurred refinements in the quantum theories of electromagnetic phenomena.

July 11: Samuel Abraham Goudsmit
(Born July 11, 1902: Died December 4, 1978)
Dutch-born U.S. physicist who, with George E. Uhlenbeck, a fellow graduate student at the University of Leiden, Neth., formulated (1925) the concept of electron spin. It led to recognition that spin was a property of protons, neutrons, and most elementary particles and to a fundamental change in the mathematical structure of quantum mechanics. Goudsmit also made the first measurement of nuclear spin and its Zeeman effect with Ernst Back (1926-27), developed a theory of hyperfine structure of spectral lines, made the first spectroscopic determination of nuclear magnetic moments (1931-33), contributed to the theory of complex atoms and the theory of multiple scattering of electrons, and invented the magnetic time-of-flight mass spectrometer (1948).

July 10: Owen Chamberlain
(Born July 10, 1920)
American physicist who shared the Nobel Prize for Physics in 1959 with Emilio Segrè for their discovery of the antiproton. This previously postulated subatomic particle was the second antiparticle to be discovered and led directly to the discovery of many additional antiparticles.

July 9: John Wheeler
(Born July 9, 1911)
John Archibald Wheeler was the first American physicist involved in the theoretical development of the atomic bomb. He also originated a novel approach to the unified field theory. Wheeler was awarded the 1997 Wolf Prize "for his seminal contributions to black hole physics, to quantum gravity, and to the theories of nuclear scattering and nuclear fission." After recognizing that any large collection of cold matter has no choice but to yield to the pull of gravity and undergo total collapse, Wheeler first coined the term "black hole" in 1967.

July 8: Human Rickover
(January 27, 1900: Died July 8, 1986)
Hyman (George) Rickover, born in Makow, Russia (now Poland), immigrated to the US (1906) and graduated from the Naval Academy in 1922. He eventually became an Admiral. He is known as the Father of the Nuclear Navy for his leadership to build the atomic-powered submarine, USS Nautilus (1954). He served on active duty with the United States Navy for more than 63 years, receiving exemptions from the mandatory retirement age due to his critical service in the building of the United States Navy's nuclear surface and submarine force.

July 7: Isaac Newton Receives Degree
In 1668, Sir Isaac Newton received his M.A. from Trinity College in Cambridge.

July 6: J. Carson Mark
(Born July 6, 1913: Died March 2, 1997)
Canadian-born American scientist who, as head of the theoretical division at the Los Alamos (N.M.) Scientific Laboratory, was instrumental in the development of the hydrogen bomb. He began at Los Alamos in 1945 as a collaborator on the Manhattan Project. He joined the staff in 1946 and became leader of T Division the following year until his retirement in 1973. At the Laboratory, he was involved in the development of various weapons systems, including thermonuclear bombs. He had a broad range of research interests, including hydrodynamics, neutron physics and transport theory. By the 1960s, much of the weapons work had been relocated and the T division diversified into working with outside agencies and private industry.

July 5: Georg Charles von Hevesy
(Born August 1, 1885: Died July 5, 1996)
Austrian-Hungarian chemist whose development of isotopic tracer techniques enabled understanding of the chemical paths of life processes. For this work, he was awarded the 1943 Nobel Prize for Chemistry. With Dirk Coster, he also discovered the element hafnium. He began to calculate the abundance of the chemical elements in 1926. After the preparation of a radioactive isotope of phosphorus, in 1934, he began to study life processes using these atoms as tracers attached to molecules. Thus labelled, the movement and changes of these molecules could followed in the body's life processes. He published Adventures in Radioisotope Research in two volumes (1962).

July 4: Marie Curie
(Born November 7, 1867: Died July 4, 1934)
Marie Marja Sklodowska Curie was a Polish-born French chemist and physicist. In 1898, her celebrated experiments on uranium minerals led to discovery of two new elements. First she separated polonium, and then radium a few months later. The quantity of radon in radioactive equilibrium with a gram of radium was named a curie. With Henri Becquerel and her husband, Pierre Curie, she was awarded the 1903 Nobel Prize for Physics. She was then sole winner of a second Nobel Prize in 1911, this time in Chemistry. Her family won five Nobel awards in two generations. She died of radiation poisoning from her pioneeing work before the need for protection was known.

July 3: Samuel P. Massie
(Born July 3, 1919)
Samuel Proctor Massie is an American chemist who was the U.S. Naval Academy's first African-American professor. He graduated from high school at age 13, and received his B.S. degree at age 18. In 1943, while working on his Ph.D., Massie joined a team of scientists working for the Manhattan Project on the development of the atomic bomb. He was asked to develop liquid compounds of uranium, though this research later proved to be a dead end. His major contributions include studies in silicon chemistry, the chemistry of phenothiazine, antimalarial-antibacterial agents, and studies on environmental agents. He is recognized for encouraging disadvantaged students into science careers

July 2: Hans Albrecht Bethe
(Born July 2, 1906)
German-born American theoretical physicist who helped to shape classical physics into quantum physics and increased the understanding of the atomic processes responsible for the properties of matter and of the forces governing the structures of atomic nuclei. Bethe did work relating to armour penetration and the theory of shock waves of a projectile moving through air. He studied nuclear reactions and reaction cross sections (1935-38). In 1943, Oppenheimer asked Bethe to be the head of the Theoretical Division at Los Alamos on the Manhattan Project. After returning to Cornell University in 1946, Bethe became a leader promoting the social responsibility of science. He received the Nobel Prize for Physics (1967) for his work on the production of energy in star

July 1: X-ray
In 1934, the first X-ray photograph of the whole body taken in a one-second exposure, using ordinary clinical conditions such as would exist at an average hospital, was made at Rochester, N.Y. The one-piece radiograph was made by Arthur W. Fuchs of the Eastman Kodak Company. A selective filter was used for the first time, and the film size was 32"x72". It was exhibited by the Chicago Roentgen Society at the Century of Progress Exhibition in Chicago, Illinois.

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Photos courtsey of Today in Science