Sunday, March 16, 2014
With the help of his family, Beijernick entered Delft Polytechnical Academy and although he studied chemistry his main interest remained botany. While there he met J. H. Van Hoft who he remained friendly throughout his career and served as an adviser to Beijernick. Beijernick earned a bachelors in chemical engineering in 1872 and then when to the University of Leiden where he earned his doctorate in 1877. While working on his doctorate Beijernick taught, but he was a poor teacher who berated his students for wrong answers and he did not remain in one teaching position for long. In 1885 Beijernick became a microbiologist at the Netherlands Yeast and Alcohol Manufactory in Delft. In 1895 he established the School of Microbiology at Delft Polytechnical.
Beijernick was unique among microbiologists at the time in that he researched the microorganisms that affected plants rather than those that affect humans. He was the first to discover that viruses were smaller than bacteria when he found that he was unable to filter the tobacco mosaic virus unlike bacteria. He was the first to isolate a sulfate reducing bacteria, the first microorganism that did not use carbon as a source of nutrition. He was also the first to isolate bacteria that complete nitrogen fixation. Nitrogen gas makes up 78% of the atmosphere but because the nitrogen-nitrogen bond is so stable nitrogen gas does not react with other atoms. Nitrogen fixating bacteria reduce nitrogen gas to become ammonia, which can react with other atoms and is used by plants as a nitrogen source. This is an important source of nitrogen, that is used to make amino acids, which are used to synthesize proteins by living organisms.
Beijernick retired in 1921 and died on January 1, 1931.
Chung, King-Thom and Ferris, Dean Hunter; "Martinus Willem Beijernick (1851-1931) Pioneer of General Microbiology"; ASM News (1996)62:539-543
Johnson, James; "Martinus Willem Beijernick: 1851-1931"; retrieved from apsnet.org.
Martinus Beijernick Wikipedia Entry
Sunday, March 9, 2014
Fabricius is most remembered for being the first to observe a variable star, the variable star later named Mira. A variable star is a star whose brightness, as observed from earth, changes over time. Fabricus first observed the variable star in 1596 and watched it first brighten and then disappear over the course of three weeks. At first Fabricus believed he had observed a nova (a dying star, which shines brightly then disappears) but when the star reappeared he realized that it was a star that changed it's brightness over time. This observation was largely forgotten until the mid 1600s when it was rediscovered by Polish astronomer Johannes Hevelius and French astronomer Ismail Bouillaud. It was Bouillaud who determined that the star had a period of 333 days. The fact that there was an star that changed it's brightness over time was revolutionary and contradicted the Aristotelian idea that the heavens are unchanging that was church doctrine at the time.
Fabricius' oldest son, Johannes, was also an astronomer and the pair used a camera obscura so that they could observe the sun and were the first to publish the existence of sunspots. From his observations Fabricus correctly predicted the axial rotation of the sun. Fabricus corresponded with Tycho Brahe and Johannes Kepler. Kepler used some of Fabricius observations of Mars in constructing his model of the solar system with the sun at the center and the planets orbiting it in elliptical orbits. Fabricius never believed in this model and instead he believed in the Tychoean model with the planets orbiting the sun and the sun, as well as all the stars, orbiting the Earth.
Fabricius was killed on May 7, 1617, by a shovel-wielding parishioner whom he had accused of stealing a goose.
Boner, Patrick J.; "David Fabricius"; in Biographical Encyclopedia of Astronomers; Springer; 2007
Granada, Miguel A.; "Johannes Kepler and David Fabricius: Their Discussion of the Nova of 1604"; in Change and Continuity in Early Modern Cosmology; Patrick J. Boner, Editor; Springer; 2011
Shiga, David; "Astrophile: The Rebel Star that Broke the Medieval Sky"; New Scientist; October 14, 2011
David Fabricius Wikipedia Entry
Sunday, March 2, 2014
Initially Condon studied chemistry at Berkeley, but when his old high school teacher W. H. Williams took a job in the physics department at Berkeley, Condon switched to physics. Condon excelled in physics, earning his bachelors in three years and then going directly to graduate work, earning his PhD in 1926. For his thesis he outlined what has come to be known as the Franck-Condon Principle. When the elctrons of a molecule are excited the nucleus remains in the same position. The electron will jump up energy levels and then fall back, emitting electromagnetic radiation, but he nuclei of the molecule or atom remains relatively stationary.
At the time an doctorate in physics was not complete without a trip to Germany to study quantum mechanics, which at the time was quickly being discovered. Condon received a National Research Council fellowship and made the trip to Germany in the fall of 1926. While there he studied under Max Born and was soon overwhelmed by the unprecedented pace at which new developments in quantum mechanics were being published. In 1927 he took a job writing popular science for Bell Laboratories. In 1928 he took a position as a lecturer at Columbia University, where he taught graduate level classes on quantum mechanics and electromagnetic radiation. In 1927 Condon took a position as an associate professor of physics at Princeton University. During the years at Princeton Condon co-wrote with Philip M. Morse the first English language treatment of quantum mechanics, published in 1929, and with G.H. Shortly he wrote Theory of Atomic Spectra, a primary text on the subject, published in 1935.
In 1937 Condon became associate research director at the Westinghouse Electric Company, where he brought the company into the nuclear age. He briefly worked on the Manhattan project, but resigned because he disagreed with the reading and censorship of personal letters. Afterward Condon worked at Berkeley on the problem of separating uranium-235 from uranium-238. In 1945 Condon was appointed director of the National Bureau of Standards (now known as the NIST). During his time at the NIST Condon was dogged by questions about his loyalty to his country. In 1951 Condon was forced to testify before the United States House Un-American Activities Committee. The scientific community widely supported Condon and during his troubles with the HUAC Condon was elected president of the American Association for the Advancement of Science. Condon also served as the president of the American Physical Society. Condon worked as a professor of physics at Washington University in Saint Louis, Missouri from 1956 to 1963 and at the University of Colorado at Boulder from 1963 to 1970. Condon retired in 1970.
Condon died on March 26, 1974.
Branscomb, Lewis; "Edward U. Condon: 1902-1974"; retrieved from library.wustl.ed
Edward U. Condon interviewed by Charles Weiner; retrieved from aip.org
Morse, Philip M.: "Edward Uhler Condon: 1902-1974"; from Biorgraphical Memoirs; National Academy Press;
Edward Condon Wikipedia Entry