422-003+Big+Time+Line+Project+S.Napoleon+Big+Time+Line+Project

Democritus-460 BC - died ca 370 BC Aristotle- 384 BC - died 322 BC Euclid Alexandria- 325 BC - died 265
 * //Abdera//**

__John Dalton__-September 6, 1766 – July 27, 1844 Englishman John Dalton was one of the first scientists to decide that all matter is made up of small particles, or atoms. He is also remembered for his weather observations, which he began recording in 1787 using instruments he made himself. In 1793 Dalton published //Meteorological Observations and Essays//, one of the first books of its kind. His studies led him to develop theories about water vapor and mixed gases, and in 1801 he came up with Dalton's law of partial pressures: that in a mixture of gases, each component exerts the same pressure as it would if it alone made up the whole volume of the mixture. From there Dalton decided that all matter, not only gases, must consist of small particles. He revived the ancient theory of atoms and prepared the first table of atomic weights, and announced his notions publicly in 1803. By the end of his life his atomic theory was widely accepted, and in 1833 he was awarded an annual pension from the king.
 * //England//**

__Wilhelm C. Roentgen__-March 27, 1845 – February 10, 1923 Wilhelm Conrad Röntgen ([|March 27], [|1845] – [|February 10], [|1923]) was a [|German] [|physicist], of the [|University of Würzburg], who, on November 8, 1895, produced and detected [|electromagnetic radiation] in a [|wavelength] range today known as [|x-rays] or Röntgen rays, an achievement that earned him the first [|Nobel Prize in Physics] in 1901.
 * //Germany//**

__Henri Becquerel__-December 15, 1852 – August 25, 1908 Becquerel was born in Paris; his early scientific and engineering training was at the Ecole Polytechnique and the School of Bridges and Highways, and in 1876 he started teaching at the Polytechnique. From 1875 he researched into various aspects of optics and obtained his doctorate in 1888. In 1899 he was elected to the French Academy of Sciences, continuing the family tradition as his father and grandfather, both renowned physicists, had also been members. He held chairs at the Ecole Polytechnique, the Museum of Natural History, and the National Conservatory of Arts and Crafts, and became chief engineer in the department of bridges and highways.
 * //France//**

Becquerel is remembered as the discoverer of radioactivity in 1896. Following Wilhelm Röntgen's discovery of x-rays the previous year, Becquerel began to look for x-rays in the [|fluorescence] observed when certain salts absorb [|ultraviolet radiation]. His method was to take crystals of potassium [|uranyl sulfate] and place them in sunlight next to a piece of photographic film wrapped in black paper. The reasoning was that the sunlight induced fluorescence in the crystals and any x-rays present would [|penetrate] the black paper and [|darken] the film.

The experiments appeared to work and his first conclusion was that x-rays were present in the fluorescence. The true explanation of the darkened plate was discovered by chance. He left a plate in black paper next to some crystals in a [|drawer] and some time later developed the plate. He found that this too was fogged, even though the crystals were not fluorescing. Becquerel investigated further and discovered that the salt gave off a [|penetrating] radiation independently, without [|ultraviolet] radiation. He deduced that the radiation came from the [|uranium] in the salt.

Becquerel went on to study the properties of this radiation; in 1899 he showed that part of it could be deflected by a magnetic field and thus consisted of charged particles. In 1903 he shared the Nobel Prize for physics with Pierre and Marie Curie.

__J.J. Thomson-__December 18, 1856 – August 30, 1940 Joseph John Thomson was born in [|1856] in [|Cheetham Hill], [|Manchester] in England, of [|Scottish] parentage. He studied engineering at [|University of Manchester] known as [|Owens College] at that time, and moved on to [|Trinity College, Cambridge]. In 1880, he obtained his BA in mathematics (2nd Wrangler and 2nd Smith's prize) and MA (with Adams prize) in 1883. In [|1884] he became [|Cavendish Professor of Physics]. One of his students was [|Ernest Rutherford], who would later succeed him in the post. In 1890 he married Rose Elisabeth Paget, daughter of Sir George Edward Paget, KCB, a physician and then [|Regius Professor of Physic at Cambridge]. He fathered one son, [|George Paget Thomson], and one daughter, Joan Paget Thomson, with her. His son became a noted physicist in his own right, winning the Nobel Prize himself for proving the wavelike properties of electrons.
 * //Manchester//**

__Marie Curie__- November 7, 1867 – July 4, 1934 A towering figure in the history of chemistry and physics, Marie Curie was a Polish scientist who worked with her husband, [|Pierre Curie], on a series of radiation experiments that led to the discovery of the elements polonium and radium. Prohibited from higher education in her native Poland (then controlled by Russia), she moved to Paris in 1891 and studied at the Sorbonne. In 1895 Marie married Pierre (who was by then a noted scientist), and together they began working on radiation experiments with uranium. (It was Marie who first coined the term "radioactivity" to describe the emission of uranic rays.) In 1898 the Curies discovered polonium and radium, and in 1903 they shared the [|Nobel] Prize for physics with Henri Becquerel. When Pierre was killed suddenly in 1906, Marie took over his post as a professor at the Sorbonne, becoming the first woman to teach there. She was awarded a second Nobel in 1911 (this time for chemistry) for her work on radium and its compounds. Concerned more with humanitarian causes than financial rewards, Marie Curie was one of the most celebrated scientists of her time, at a time when the field was almost exclusively for men.
 * //Poland//**

__Robert Millikan__-March 22, 1868 – December 19, 1953 The son of a Congregational minister from Morrison, Illinois, Millikan was educated at Oberlin, where he studied classics, and Columbia University, where he obtained his PhD in 1895. After a year in Europe, studying under Max Planck and Walther Nernst, he took up an appointment in 1896 at the University of Chicago, being promoted to a full professorship in 1910. Millikan moved to the California Institute of Technology in 1921 as director of the Norman Bridge Laboratory, a position he held until his retirement in 1945.
 * //America//**

In 1909 Millikan started on a project that was to win for him the 1923 Nobel Prize for physics – the determination of the electric charge of the electron. His apparatus consisted of two horizontal plates that could be made to take opposite charges. Between the plates he introduced a fine [|spray] of oil drops whose mass could be determined by measuring their fall under the influence of gravity and against the resistance of the air. When the air was ionized by x-rays and the plates charged, then an oil drop that had collected a charge would be either repelled from or attracted to the plates depending on whether it had collected a positive or negative charge. By measuring the change in the rate of fall and knowing the intensity of the electric field Millikan was able to calculate the charges on the oil drops. After taking many careful measurements he was able to come to the important conclusion that the charge was always a simple multiple of the same basic unit, which he found to be 4.774 ± 0.009 × 10–10 [|electrostatic units], a figure whose accuracy was not improved until 1928. Millikan followed this with a prolonged attempt from 1912 to 1916 to demonstrate the validity of the formula introduced by Albert Einstein in 1905 to describe the [|photoelectric effect], work that was cited in Einstein's Nobel award.

In 1923 he began a major study of cosmic rays, first identified in 1912 by Victor Hess, which was to occupy him for the rest of his career. His first aim was to show that they did not originate in our atmosphere. To do this he devised an [|ingenious] set of observations made at two lakes in the San Bernadino mountains of southern California. The lakes were many miles apart and differed by 6700 feet (2042 m) in altitude. The difference in altitude would have the same effect on intensity of cosmic rays as six feet of water. He found that the intensity of ionization produced by the incoming cosmic rays in the lower lake was the same as the intensity six feet deeper in the higher lake. This showed, he claimed, that the rays do come in definitely from above and that their origin is entirely outside the layer of atmosphere between the levels of the two lakes.

Millikan then went on to [|theorize] about the nature of the cosmic rays. He argued that they were electromagnetic radiation photons, for if they were charged particles they would be influenced by the Earth's magnetic field and therefore more likely to arrive in higher rather than lower latitudes. Millikan had failed to detect any such effect with latitude. In fact Millikan's theories were soon disproved for Arthur Compton did detect a latitude effect.

__Ernest Rutherford__-August 30,1871 - October 19, 1937 Ernest Rutherford was the brilliant New Zealand physicist who explained natural radioactivity, determined the structure of the atom, and changed one element into another (nitrogen to oxygen) by splitting an atom's nucleus. A farm boy from New Zealand's South Island, he spent most of his professional career overseas at McGill University in Montreal, Canada (1895-98), and at Manchester University (1898-1907) and Cambridge University (1919-37) in the United Kingdom. Rutherford was an energetic pioneer in nuclear physics: he discovered (and named) alpha and beta radiation, named the nucleus and proton and won the 1908 Nobel prize in chemistry for explaining radioactivity as the disintegration of atoms. Rutherford's description of an atomic structure with orbital electrons became the accepted model (with further help provided by his student and colleague, [|Niels Bohr]), and in 1920 he predicted the existence of the neutron, which was later discovered by James Chadwick. Rutherford was knighted in 1914, served as president of the Royal Society from 1925-30, and in 1931 was named Ernest, Lord Rutherford of Nelson (New Zealand).
 * //New Zealand//**

__Niels Bohr-__October 7, 1885 – November 18, 1962 Niels Bohr was the Danish physicist whose investigations of atomic structure earned him the 1922 Nobel Prize for physics. Bohr's work helped solve the problems classical physics could not explain about the nuclear model of the atom. He postulated that electrons moved in fixed orbits around the atom's nucleus, and he explained how they emitted or absorbed energy. Bohr attended the University of Copenhagen (1903-11), then studied for a time under [|Ernest Rutherford] in Manchester, England. By 1916 he was back at the University of Copenhagen as a professor of physics, and in 1920 he became the first director of the Institute of Theoretical Physics. Bohr's Institute became a gathering place for the world's top physicists, and he is considered one of the foremost scientists of modern physics, along with [|Albert Einstein], [|Erwin Schrödinger] and [|Enrico Fermi]. During World War II Bohr avoided [|Adolf Hitler]'s army and left Denmark in 1943; he ended up in the United States and was sent to Los Alamos, New Mexico to join [|Robert Oppenheimer] and others working to develop the atomic bomb. After the war he returned to Denmark and spent the rest of his career advocating the peaceful uses of atomic energy.
 * //Denmark//**

__Erwin Schrodinger__-August 12, 1887 – January 4, 1961 Erwin Schrödinger was a theoretical and experimental physicist in Vienna, Zürich and Berlin and a significant contributor to the wave theory of matter, a form of quantum physics. He mathematically devised an equation of wave mechanics that bears his name. Schrödinger's research was interrupted by two world wars, but he nonetheless advanced quantum theory and color theory. In 1933 he was a co-recipient of the Nobel Prize for physics. Today he is popularly known for the paradox of Schrödinger's Cat.
 * //Austria//**

__James Chadwick__- October 20, 1891 – July 24, 1974 Chadwick's early experiments established that atomic number is determined by the number of protons in an atom (now the definition). In 1932 he discovered the fourth known [|subatomic particle], the neutron (following the electron, [|photon], and proton); its existence had been suspected since 1924. Chadwick's later experiments with particle accelerators contributed to the invention of the [|nuclear fission] bomb.
 * //England//**

__Werner Heisenberg__-December 5, 1901 – February 1, 1976 Heisenberg, with mathematical help from Max Born, developed in 1925 the first version of quantum mechanics, a matrix method of calculating the behavior of electrons and other [|subatomic particles]. The method was superseded as a practical tool soon after by the more [|intuitive] wave equation of Erwin Schrödinger, but matrix mechanics remains a great intellectual accomplishment. Heisenberg's most lasting contribution was his discovery in 1927 of the uncertainty principle, a foundation of quantum theory. A few years later he introduced a new quantum number called [|isotopic spin]. Heisenberg continued to contribute to particle physics, introducing useful computational techniques in the 1950s.
 * //Germany//**