Robert Andrews Millikan

Robert Andrews Millikan (March 22, 1868 – December 19, 1953) was an American experimental physicist honored with the Nobel Prize for Physics in 1923 for the measurement of the elementary electric charge and for his work on the photoelectric effect.

Millikan graduated from Oberlin College in 1891 and obtained his doctorate at Columbia University in 1895. In 1896 he became an assistant at the University of Chicago, where he became a full professor in 1910. In 1909 Millikan began a series of experiments to determine the electric charge carried by a single electron. He began by measuring the course of charged water droplets in an electric field. The results suggested that the charge on the droplets is a multiple of the elementary electric charge, but the experiment was not accurate enough to be convincing. He obtained more precise results in 1910 with his famous oil-drop experiment in which he replaced water (which tended to evaporate too quickly) with oil.

In 1914 Millikan took up with similar skill the experimental verification of the equation introduced by Albert Einstein in 1905 to describe the photoelectric effect. He used this same research to obtain an accurate value of Planck’s constant. In 1921 Millikan left the University of Chicago to become director of the Norman Bridge Laboratory of Physics at the California Institute of Technology (Caltech) in Pasadena, California. There he undertook a major study of the radiation that the physicist Victor Hess had detected coming from outer space. Millikan proved that this radiation is indeed of extraterrestrial origin, and he named it "cosmic rays." As chairman of the Executive Council of Caltech (the school's governing body at the time) from 1921 until his retirement in 1945, Millikan helped to turn the school into one of the leading research institutions in the United States.[4][5] He also served on the board of trustees for Science Service, now known as Society for Science & the Public, from 1921 to 1953.

Robert A. Millikan
Robert Andrews Millikan 1920s
1st President of California Institute of Technology
In office
Succeeded byLee Alvin DuBridge
Personal details
Robert Andrews Millikan

March 22, 1868
Morrison, Illinois, U.S.
DiedDecember 19, 1953 (aged 85)
San Marino, California, U.S.
NationalityUnited States
Alma mater
Known for
Spouse(s)Greta née Blanchard
Scientific career
ThesisOn the polarization of light emitted from the surfaces of incandescent solids and liquids. (1895)
Doctoral advisor
Other academic advisorsMihajlo Pupin
Albert A. Michelson
Walther Nernst
Doctoral students
Military career
Service/branchUnited States Army[3]
Years of service1917–1918
RankLieutenant Colonel
UnitAviation Section, U.S. Signal Corps
Robert Andrews Milliken signature



Robert Andrews Millikan was born on March 22, 1868, in Morrison, Illinois.[6] Millikan went to high school in Maquoketa, Iowa. Millikan received a bachelor's degree in the classics from Oberlin College in 1891 and his doctorate in physics from Columbia University in 1895[7] – he was the first to earn a Ph.D. from that department.[8]

At the close of my sophomore year [...] my Greek professor [...] asked me to teach the course in elementary physics in the preparatory department during the next year. To my reply that I did not know any physics at all, his answer was, "Anyone who can do well in my Greek can teach physics." "All right," said I, "you will have to take the consequences, but I will try and see what I can do with it." I at once purchased an Avery's Elements of Physics, and spent the greater part of my summer vacation of 1889 at home – trying to master the subject. [...] I doubt if I have ever taught better in my life than in my first course in physics in 1889. I was so intensely interested in keeping my knowledge ahead of that of the class that they may have caught some of my own interest and enthusiasm.[9]

Millikan's enthusiasm for education continued throughout his career, and he was the coauthor of a popular and influential series of introductory textbooks,[10] which were ahead of their time in many ways. Compared to other books of the time, they treated the subject more in the way in which it was thought about by physicists. They also included many homework problems that asked conceptual questions, rather than simply requiring the student to plug numbers into a formula.

Charge of the electron

Millikan’s oil-drop apparatus 1
Millikan's original oil-drop apparatus, circa 1909–1910
Robert A. Millikan 1924
Millikan receives a check for over $40,000 for winning the Nobel Prize

Starting in 1908, while a professor at the University of Chicago, Millikan worked on an oil-drop experiment in which he measured the charge on a single electron. J. J. Thomson had already discovered the charge-to-mass ratio of the electron. However, the actual charge and mass values were unknown. Therefore, if one of these two values were to be discovered, the other could easily be calculated. Millikan and his then graduate student Harvey Fletcher used the oil-drop experiment to measure the charge of the electron (as well as the electron mass, and Avogadro's number, since their relation to the electron charge was known).

Professor Millikan took sole credit, in return for Harvey Fletcher claiming full authorship on a related result for his dissertation.[11] Millikan went on to win the 1923 Nobel Prize for Physics, in part for this work, and Fletcher kept the agreement a secret until his death.[12] After a publication on his first results in 1910,[13] contradictory observations by Felix Ehrenhaft started a controversy between the two physicists.[14] After improving his setup, Millikan published his seminal study in 1913.[15]

The elementary charge is one of the fundamental physical constants, and accurate knowledge of its value is of great importance. His experiment measured the force on tiny charged droplets of oil suspended against gravity between two metal electrodes. Knowing the electric field, the charge on the droplet could be determined. Repeating the experiment for many droplets, Millikan showed that the results could be explained as integer multiples of a common value (1.592 × 10−19 coulomb), which is the charge of a single electron. That this is somewhat lower than the modern value of 1.602 176 53(14) x 10−19 coulomb is probably due to Millikan's use of an inaccurate value for the viscosity of air.[16][17]

Although at the time of Millikan's oil-drop experiments it was becoming clear that there exist such things as subatomic particles, not everyone was convinced. Experimenting with cathode rays in 1897, J. J. Thomson had discovered negatively charged 'corpuscles', as he called them, with a charge-to-mass ratio 1840 times that of a hydrogen ion. Similar results had been found by George FitzGerald and Walter Kaufmann. Most of what was then known about electricity and magnetism, however, could be explained on the basis that charge is a continuous variable; in much the same way that many of the properties of light can be explained by treating it as a continuous wave rather than as a stream of photons.

The beauty of the oil-drop experiment is that as well as allowing quite accurate determination of the fundamental unit of charge, Millikan's apparatus also provided a 'hands on' demonstration that charge is actually quantized. The General Electric Company's Charles Steinmetz, who had previously thought that charge is a continuous variable, became convinced otherwise after working with Millikan's apparatus.

Data selection controversy

There is some controversy over selectivity in Millikan's use of results from his second experiment measuring the electron charge. This issue has been discussed by Allan Franklin,[18] a former high-energy experimentalist and current philosopher of science at the University of Colorado. Franklin contends that Millikan's exclusions of data do not affect the final value of the charge obtained, but that Millikan's substantial "cosmetic surgery" reduced the statistical error. This enabled Millikan to give the charge of the electron to better than one half of one percent; in fact, if Millikan had included all of the data he discarded, the error would have been less than 2%. While this would still have resulted in Millikan's having measured the charge of e better than anyone else at the time, the slightly larger uncertainty might have allowed more disagreement with his results within the physics community, which Millikan likely tried to avoid. David Goodstein argues that Millikan's statement, that all drops observed over a sixty-day period were used in the paper, was clarified in a subsequent sentence which specified all "drops upon which complete series of observations were made". Goodstein attests that this is indeed the case and notes that five pages of tables separate the two sentences.[19]

Photoelectric effect

Millikan and Einstein 1932
Robert Millikan and Albert Einstein at the California Institute of Technology in 1932

When Einstein published his seminal 1905 paper on the particle theory of light, Millikan was convinced that it had to be wrong, because of the vast body of evidence that had already shown that light was a wave. He undertook a decade-long experimental program to test Einstein's theory, which required building what he described as "a machine shop in vacuo" in order to prepare the very clean metal surface of the photo electrode. His results published in 1914 confirmed Einstein's predictions in every detail,[20] but Millikan was not convinced of Einstein's interpretation, and as late as 1916 he wrote, "Einstein's photoelectric equation... cannot in my judgment be looked upon at present as resting upon any sort of a satisfactory theoretical foundation," even though "it actually represents very accurately the behavior" of the photoelectric effect. In his 1950 autobiography, however, he simply declared that his work "scarcely permits of any other interpretation than that which Einstein had originally suggested, namely that of the semi-corpuscular or photon theory of light itself".[21]

Since Millikan's work formed some of the basis for modern particle physics, it is ironic that he was rather conservative in his opinions about 20th century developments in physics, as in the case of the photon theory. Another example is that his textbook, as late as the 1927 version, unambiguously states the existence of the ether, and mentions Einstein's theory of relativity only in a noncommittal note at the end of the caption under Einstein's portrait, stating as the last in a list of accomplishments that he was "author of the special theory of relativity in 1905 and of the general theory of relativity in 1914, both of which have had great success in explaining otherwise unexplained phenomena and in predicting new ones."

Millikan is also credited with measuring the value of Planck's constant by using photoelectric emission graphs of various metals.[22]

Later life

Robert A. Millikan around 1923

In 1917, solar astronomer George Ellery Hale convinced Millikan to begin spending several months each year at the Throop College of Technology, a small academic institution in Pasadena, California, that Hale wished to transform into a major center for scientific research and education. A few years later Throop College became the California Institute of Technology (Caltech), and Millikan left the University of Chicago in order to become Caltech's "chairman of the executive council" (effectively its president). Millikan would serve in that position from 1921 to 1945. At Caltech most of his scientific research focused on the study of "cosmic rays" (a term which he coined). In the 1930s he entered into a debate with Arthur Compton over whether cosmic rays were composed of high-energy photons (Millikan's view) or charged particles (Compton's view). Millikan thought his cosmic ray photons were the "birth cries" of new atoms continually being created to counteract entropy and prevent the heat death of the universe. Compton would eventually be proven right by the observation that cosmic rays are deflected by the Earth's magnetic field (and so must be charged particles).

Robert Millikan was Vice Chairman of the National Research Council during World War I. During that time, he helped to develop anti-submarine and meteorological devices. He received the Chinese Order of Jade. After the War, Millikan contributed to the works of the League of Nations' Committee on Intellectual Cooperation (from 1922, in replacement to George E. Hale, to 1931), with other prominent researchers (Marie Curie, Albert Einstein, Hendrik Lorentz, etc.).[23] In his private life, Millikan was an enthusiastic tennis player. He was married and had three sons, the eldest of whom, Clark B. Millikan, became a prominent aerodynamic engineer. Another son, Glenn, also a physicist, married the daughter (Clare) of George Leigh Mallory of "Because it's there" Mount Everest fame. Glenn was killed in a climbing accident in Cumberland Mountains in 1947.[24]

A religious man and the son of a minister, in his later life Millikan argued strongly for a complementary relationship between Christian faith and science.[25][26][27][28] He dealt with this in his Terry Lectures at Yale in 1926–27, published as Evolution in Science and Religion.[29] He was a Christian theist and proponent of theistic evolution.[30] A more controversial belief of his was eugenics. This led to his association with the Human Betterment Foundation and his praising of San Marino, California, for being "the westernmost outpost of Nordic civilization ... [with] a population which is twice as Anglo-Saxon as that existing in New York, Chicago, or any of the great cities of this country."[31]

Westinghouse time capsule

In 1938, he wrote a short passage to be placed in the Westinghouse Time Capsules.[32]

At this moment, August 22, 1938, the principles of representative ballot government, such as are represented by the governments of the Anglo-Saxon, French, and Scandinavian countries, are in deadly conflict with the principles of despotism, which up to two centuries ago had controlled the destiny of man throughout practically the whole of recorded history. If the rational, scientific, progressive principles win out in this struggle there is a possibility of a warless, golden age ahead for mankind. If the reactionary principles of despotism triumph now and in the future, the future history of mankind will repeat the sad story of war and oppression as in the past.

Death and legacy

Robert A. Millikan 1954
Robert A. Millikan circa 1953
The Millikan Library at Caltech

Millikan died of a heart attack at his home in San Marino, California in 1953 at age 85, and was interred in the "Court of Honor" at Forest Lawn Memorial Park Cemetery in Glendale, California.

Millikan Middle School (formerly Millikan Junior High School) in the suburban Los Angeles neighborhood of Sherman Oaks is named in his honor, as is Robert A. Millikan High School in Long Beach, California. The Millikan Library, the tallest building on the Caltech campus is also named after him. Additionally, a major street through the Tektronix campus in Portland, Oregon, is named after him, with the Millikan Way (MAX station), a station on Portland, Oregon's MAX Blue Line named after the street. One of four suites at the Athenaeum Hotel on the Caltech campus is named after him; Room #50, The Millikan Suite.

On January 26, 1982, he was honored by the United States Postal Service with a 37¢ Great Americans series (1980–2000) postage stamp.

Personal life

Greta Ervin Millikan 1923
Greta Millikan in 1923

In 1902 he married Greta Ervin Blanchard (1876-1955). They had three sons: Clark Blanchard, Glenn Allan, and Max Franklin.

Famous statements

"If Kevin Harding's equation and Aston's curve are even roughly correct, as I'm sure they are, for Dr. Cameron and I have computed with their aid the maximum energy evolved in radioactive change and found it to check well with observation, then this supposition of an energy evolution through the disintegration of the common elements is from the one point of view a childish Utopian dream, and from the other a foolish bugaboo."[33]

‘’”No more earnest seekers after truth, no intellectuals of more penetrating vision can be found anywhere at any time than these, and yet every one of them has been a devout and professed follower of religion.”’’[34]


  • Goodstein, D., "In defense of Robert Andrews Millikan", Engineering and Science, 2000. No 4, pp30–38 (pdf).
  • Millikan, R A (1950). The Autobiography of Robert Millikan
  • Millikan, Robert Andrews (1917). The Electron: Its Isolation and Measurements and the Determination of Some of its Properties. The University of Chicago Press.
  • Nobel Lectures, "Robert A. Millikan – Nobel Biography". Elsevier Publishing Company, Amsterdam.
  • Segerstråle, U (1995) Good to the last drop? Millikan stories as "canned" pedagogy, Science and Engineering Ethics vol 1, pp197–214
  • Robert Andrews Millikan "Robert A. Millikan – Nobel Biography".
  • The NIST Reference on Constants, Units, and Uncertainty
  • Kevles, Daniel A (1979). "Robert A. Millikan". Scientific American. 240 (1): 142–151. Bibcode:1979SciAm.240a.142K. doi:10.1038/scientificamerican0179-142.
  • Kargon, Robert H (1977). "The Conservative Mode: Robert A. Millikan and the Twentieth-Century Revolution in Physics". Isis. 68 (4): 509–526. doi:10.1086/351871. JSTOR 230006.
  • Kargon, Robert H (1982). The rise of Robert Millikan: portrait of a life in American science. Ithaca: Cornell University Press.

See also

Robert Millikan is widely believed to have been denied the 1920 prize for physics owing to Felix Ehrenhaft's claims to have measured charges smaller than Millikan's elementary charge. Ehrenhaft's claims were ultimately dismissed and Millikan was awarded the prize in 1923.



  1. ^ "Comstock Prize in Physics". National Academy of Sciences. Archived from the original on December 29, 2010. Retrieved February 13, 2011.
  2. ^ "Millikan, son, aide get medals of merit". New York Times. March 22, 1949. Retrieved August 30, 2018.
  3. ^ Bates, Charles C. & Fuller, John F. (July 1, 1986). "Chapter 2: The Rebirth of Military Meteorology". America's Weather Warriors, 1814–1985. Texas A&M University Press. pp. 17–20. ISBN 978-0890962404.
  5. ^ "Robert A. Millikan - Biographical".
  6. ^ Millikan, Robert. "Nobel Prize in Physics 1923". Retrieved September 20, 2012.
  7. ^ Millikan, Robert Andrews (1895). On The Polarization Of Light Emitted From The Surfaces Of Incandescent Solids And Liquids (Ph.D.). Columbia University. OCLC 10542040 – via ProQuest. (Subscription required (help)). Cite uses deprecated parameter |subscription= (help)
  8. ^ "Robert A. Millikan". IEEE Global History Network. IEEE. Retrieved July 25, 2011.
  9. ^ Millikan, Robert Andrews (1980) [reprint of original 1950 edition]. The autobiography of Robert A. Millikan. Prentice-Hall. p. 14.
  10. ^ The books, coauthored with Henry Gordon Gale, were A First Course in Physics (1906), Practical Physics (1920), Elements of Physics (1927), and New Elementary Physics (1936).
  11. ^ David Goodstein (January 2001). "In defense of Robert Andrews Millikan" (PDF). American Scientist: 54–60.
  12. ^ Harvey Fletcher (June 1982). "My Work with Millikan on the Oil-drop Experiment". Physics Today. 35: 43. Bibcode:1982PhT....35f..43F. doi:10.1063/1.2915126.
  13. ^ Millikan, R.A. (1910). "A new modification of the cloud method of determining the elementary electrical charge and the most probable value of that charge". Phil. Mag. 6. 19: 209. doi:10.1080/14786440208636795.
  14. ^ Ehrenhaft, F (1910). "Über die Kleinsten Messbaren Elektrizitätsmengen". Phys. Z. 10: 308.
  15. ^ Millikan, R.A. (1913). "On the Elementary Electric charge and the Avogadro Constant". Physical Review. II. 2: 109–143. Bibcode:1913PhRv....2..109M. doi:10.1103/physrev.2.109.
  16. ^ Feynman, Richard, "Cargo Cult Science" (adapted from 1974 California Institute of Technology commencement address), Donald Simanek's Pages, Lock Haven University, rev. August 2008.
  17. ^ Feynman, Richard Phillips; Leighton, Ralph; Hutchings, Edward (1997-04-01). "Surely you're joking, Mr. Feynman!": adventures of a curious character. New York: W. W. Norton & Company. p. 342. ISBN 978-0-393-31604-9. Retrieved 10 July 2010.
  18. ^ Franklin, A. (1997). "Millikan's Oil-Drop Experiments". The Chemical Educator. 2 (1): 1–14. doi:10.1007/s00897970102a.
  19. ^ Goodstein, David (2000). "In defense of Robert Andrews Millikan" (PDF). Engineering and Science. Pasadena, California: California Institute of Technology. Archived from the original (Portable Document Format) on 2010-06-25. Retrieved 30 August 2018.
  20. ^ Millikan, R. (1914). "A Direct Determination of "h."". Physical Review. 4 (1): 73–75. Bibcode:1914PhRv....4R..73M. doi:10.1103/PhysRev.4.73.2.
  21. ^ Anton Z. Capri, "Quips, quotes, and quanta: an anecdotal history of physics" (World Scientific 2007) p.96
  22. ^ Millikan, R. (1916). "A Direct Photoelectric Determination of Planck's "h"" (PDF). Physical Review. 7 (3): 355–388. Bibcode:1916PhRv....7..355M. doi:10.1103/PhysRev.7.355.
  23. ^ Grandjean, Martin (2018). Les réseaux de la coopération intellectuelle. La Société des Nations comme actrice des échanges scientifiques et culturels dans l'entre-deux-guerres [The Networks of Intellectual Cooperation. The League of Nations as an Actor of the Scientific and Cultural Exchanges in the Inter-War Period] (in French). Lausanne: Université de Lausanne.
  24. ^ Severinghaus, John W.; Astrup, Poul B. (1986). "History of blood gas analysis. VI. Oximetry". Journal of Clinical Monitoring and Computing. 2 (4): 270–288 (278). doi:10.1007/BF02851177.
  25. ^ "Millikan, Robert Andrew", Who's Who in America v. 15, 1928–1929, p. 1486
  26. ^ The Religious Affiliation of Physicist Robert Andrews Millikan.
  27. ^ Nobel biography.
  28. ^ "Medicine: Science Serves God," Time, June 4, 1923. Accessed 19 January 2013.
  29. ^ Evolution in Science and Religion (1927), 1973 edition: Kennikat Press, ISBN 0-8046-1702-3
  30. ^ Long, Edward Le Roy. (1952). Religious Beliefs of American Scientists. Westminster Press. pp. 45-48
  31. ^ "Judgment At Pasadena", Washington Post, March 16, 2000, p. C1. Retrieved on March 30, 2007.
  32. ^ The Time Capsule. Westinghouse Electric & Manufacturing Company. September 23, 1938. p. 46.
  33. ^ Millikan, Robert Andrews, Science and the New Civilization [1st Ed.], Charles Scribner's and Sons, 1930, p. 95
  34. ^ Millikan, Robert A., “A Scientist Confesses His Faith”-Christian Century

Other sources

External links

Academic offices
Preceded by
James Scherer
as President of the Throop College of Technology
President of the California Institute of Technology
1921 – 1946
Succeeded by
Lee DuBridge
1923 in science

The year 1923 in science and technology involved some significant events, listed below.

ASME Medal

The ASME Medal, created in 1920, is the highest award of ASME (founded as the American Society of Mechanical Engineers) for "eminently distinguished engineering achievement".The yearly award consists of a gold medal, inscribed with the words "What is not yet, may be", a certificate and $15,000 of cash.ASME also gives out a number of other awards yearly, including the Edwin F. Church Medal, the Holley medal, and the Soichiro Honda medal.

California Institute of Technology

The California Institute of Technology (Caltech) is a private doctorate-granting research university in Pasadena, California. Known for its strength in natural science and engineering, Caltech is often ranked as one of the world's top-ten universities.Although founded as a preparatory and vocational school by Amos G. Throop in 1891, the college attracted influential scientists such as George Ellery Hale, Arthur Amos Noyes and Robert Andrews Millikan in the early 20th century. The vocational and preparatory schools were disbanded and spun off in 1910 and the college assumed its present name in 1921. In 1934, Caltech was elected to the Association of American Universities and the antecedents of NASA's Jet Propulsion Laboratory, which Caltech continues to manage and operate, were established between 1936 and 1943 under Theodore von Kármán. The university is one among a small group of institutes of technology in the United States which is primarily devoted to the instruction of pure and applied sciences.

Caltech has six academic divisions with strong emphasis on science and engineering, managing $332 million in 2011 in sponsored research. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. First-year students are required to live on campus and 95% of undergraduates remain in the on-campus House System at Caltech. Although Caltech has a strong tradition of practical jokes and pranks, student life is governed by an honor code which allows faculty to assign take-home examinations. The Caltech Beavers compete in 13 intercollegiate sports in the NCAA Division III's Southern California Intercollegiate Athletic Conference.

As of October 2018, Caltech alumni, faculty and researchers include 73 Nobel Laureates (chemist Linus Pauling being the only individual in history to win two unshared prizes), 4 Fields Medalists, and 6 Turing Award winners. In addition, there are 53 non-emeritus faculty members (as well as many emeritus faculty members) who have been elected to one of the United States National Academies, 4 Chief Scientists of the U.S. Air Force and 71 have won the United States National Medal of Science or Technology. Numerous faculty members are associated with the Howard Hughes Medical Institute as well as NASA. According to a 2015 Pomona College study, Caltech ranked number one in the U.S. for the percentage of its graduates who go on to earn a PhD.

Centrifugal gun

A centrifugal gun is a type of rapid-fire projectile accelerator, like a machine gun but operating on a different principle. Centrifugal guns use a rapidly rotating disc to impart energy to the projectiles, replacing gunpowder with centrifugal force.

A steam-powered centrifugal gun built by Charles Dickinson of Boston was tested during the American Civil War. This gun was popularly but incorrectly attributed to pro-Southern Maryland millionaire and inventor Ross Winans. Another hand-cranked centrifugal gun that fired musket balls was designed by Robert McCarty during the same period. Despite repeated tests, including one in the presence of Abraham Lincoln, McCarty's gun never saw service. Dahlgren however took the idea seriously, and after testing McCarty's prototype, he built a steam-powered 12 pounder which could fire 15 rounds in 16 seconds and had a range of a mile. It was extremely inaccurate however. As historian Robert V. Bruce notes: "the sole casualty of centrifugal gunfire during the Civil War seems to have been one ill-starred Army mule".The idea was even tested during World War I by the US Bureau of Standards, using a prototype built by lawyer Edward T. Moore, and advertised as a silent machine gun. The prototype used a powerful electric motor to spin the gun's grooved rotor. It was abandoned due to extremely poor accuracy. Moore was granted USPTO patent number 1332992. Another design can be found in USPTO patent number 1311492, granted in July 1919. Another effort during World War I was to build a centrifugal gun powered by an aircraft's engine. This design was advanced by E. L. Rice and taken seriously by Robert Andrews Millikan and the National Research Council; the project ultimately proved "beyond resolution".In 2005, a new centrifugal weapon called DREAD, invented by Charles St George, was discussed in New Scientist and in Annals of Improbable Research. DREAD, patented in 2003, claims to launch projectiles with the speed of a handgun, at about 300 m/s.In an episode from the 2007 season of MythBusters Adam and Jamie built a replica of the Winans Steam Gun and found it unreliable.

Charles H. Holbrow

Charles H. Holbrow (born September 23, 1935) is an American physicist.

Chung-Yao Chao

Chung-Yao Chao (simplified Chinese: 赵忠尧; traditional Chinese: 趙忠堯; pinyin: Zhào Zhōngyáo; Wade–Giles: Chao Chung-yao; 27 June 1902 – 28 May 1998) was a Chinese physicist. He studied the scattering of gamma rays in lead by pair production in 1930, without knowing that positrons were involved in the anomalously high scattering cross-section. When the positron was discovered by Carl David Anderson in 1932, confirming the existence of Paul Dirac's "antimatter", it became clear that positrons could explain Chung-Yao Chao's earlier experiments, with the gamma rays being emitted from electron-positron annihilation.

He entered Nanjing Higher Normal School (later renamed National Southeastern University, National Central University and Nanjing University), in 1920 and earned a B.S. in physics in 1925. Then he earned a Ph.D. degree in physics under supervision of Nobel Prize laureate Robert Andrews Millikan at California Institute of Technology in 1930. Later he went back to China and joined the physics faculty of Tsinghua University in Beijing.

Cunningham correction factor

In fluid dynamics, the Cunningham correction factor or Cunningham slip correction factor is used to account for noncontinuum effects when calculating the drag on small particles. The derivation of Stokes Law, which is used to calculate the drag force on small particles, assumes a No-slip condition which is no longer correct at high Knudsen number. The Cunningham slip correction factor allows predicting the drag force on a particle moving a fluid with Knudsen number between the continuum regime and free molecular flow.

The drag coefficient calculated with standard correlations is divided by the Cunningham correction factor, C given below.

Ebenezer Cunningham derived the correction factor in 1910 and with Robert Andrews Millikan, verified the correction in the same year.


C is the correction factor
λ is the mean free path
d is the particle diameter
An are experimentally determined coefficients.
For air (Davies, 1945):
A1 = 1.257
A2 = 0.400
A3 = 0.55

The Cunningham correction factor becomes significant when particles become smaller than 15 micrometers, for air at ambient conditions.

For sub-micrometer particles, Brownian motion must be taken into account.

Faraday Lectureship Prize

The Faraday Lectureship Prize, previously known simply as the Faraday Lectureship is awarded once every three years (approximately) by the Royal Society of Chemistry for "exceptional contributions to physical or theoretical chemistry". Named after Michael Faraday, the first Faraday Lecture was given in 1869, two years after Faraday's death, by Jean-Baptiste Dumas. As of 2009, the prize was worth £5000, with the recipient also receiving a medal and a certificate. As the name suggests, the recipient also gives a public lecture describing his or her work.

Gerry Neugebauer

Gerhart "Gerry" Neugebauer (3 September 1932 – 26 September 2014) was an American astronomer known for his pioneering work in infrared astronomy.

Neugebauer was born in Göttingen, Germany and is the son of Otto Neugebauer, an Austrian-American mathematician and historian of science, and Grete Bruck. After moving to the United States at age seven, he received his A.B. in physics from Cornell University in 1954 and his Ph.D. in physics from Caltech in 1960, with a thesis on the photoproduction of negative and positive pions from deuterium.

During his military service with the U.S. Army he was stationed at the Jet Propulsion Laboratory and worked for the Ordnance Corps until 1962. He joined the Caltech faculty in 1962 as an assistant professor, becoming a full professor of physics in 1970. He was named Howard Hughes Professor in 1985 and Chairman of the Division of Physics, Math and Astronomy in 1988. At the time of his death, he was the Robert Andrews Millikan Professor of Physics, Emeritus and an adjunct faculty member of the University of Arizona's Steward Observatory.

Neugebauer served as the director of the Palomar Observatory from 1980 to 1994.

Neugebauer was active in infrared astronomy, and played a leading role in infrared studies of the planets. In addition—and largely through his activities with the Infrared Astronomical Satellite (IRAS) and the Infrared Processing and Analysis Center (IPAC)—he led both ground- and space-based infrared studies of the stars, the Milky Way and other galaxies. Observations by him and his colleagues at Mount Wilson and Palomar observatories revealed thousands of infrared sources in the sky, and afforded the first infrared view of the galactic center. Together with Robert B. Leighton, he completed the Two-Micron Sky Survey, the first infrared survey of the sky, which cataloged more than 5,000 infrared sources. Together with Eric Becklin, he discovered the Becklin–Neugebauer Object, an intense source of infrared radiation in the Orion Nebula that is one of the brightest objects in the sky at wavelengths less than 10 micrometres.

Neugebauer played a role in the design and construction of the W. M. Keck Observatory in Hawaii. Among Neugebauer's numerous awards are two NASA Exceptional Scientific Achievement Medals (1972, 1984), the 1985 Space Science Award of the American Institute of Aeronautics and Astronautics, the 1985 Richmyer Lecture Award, the 1986 Rumford Prize, the 1996 Henry Norris Russell Lectureship, the 1998 Herschel Medal, and the 2010 Bruce Medal. He was named California Scientist of the Year for 1986 by the California Museum of Science and Industry, and he was elected to the National Academy of the Sciences, the American Philosophical Society, the American Academy of Arts and Sciences and the Royal Astronomical Society.

Neugebauer was married to the geophysicist Marcia Neugebauer, a pioneer in solar wind research at the Jet Propulsion Laboratory, and the two resided in Tucson, Arizona. He died on 26 September 2014 in Tucson, due to spinocerebellar ataxia.

Harvey Fletcher

Harvey Fletcher (September 11, 1884 – July 23, 1981) was an American physicist. Known as the "father of stereophonic sound," he is credited with the invention of the 2-A audiometer and an early electronic hearing aid. He was an investigator into the nature of speech and hearing, and made contributions in acoustics, electrical engineering, speech, medicine, music, atomic physics, sound pictures, and education.

Judith R. Goodstein

Judith Ronnie Goodstein (née Koral, born 1939) is an American historian of science, historian of mathematics, archivist, and book author. She worked for many years at the California Institute of Technology (Caltech), where she is University Archivist Emeritus.

Matteucci Medal

The Matteucci Medal is an Italian award for physicists, named after Carlo Matteucci. It was established to award physicists for their fundamental contributions. Under an Italian Royal Decree dated July 10, 1870, the Italian Society of Sciences was authorized to receive a donation from Carlo Matteucci for the establishment of the Prize.

Matteucci MedalistsSource: Italian Society of Sciences

Morris E. Leeds

Morris E. Leeds (March 6, 1869 in Philadelphia – February 8, 1952) was an American electrical engineer known for his many inventions in the field of electrical measuring devices and controls.

Murray Gell-Mann

Murray Gell-Mann (; born September 15, 1929) is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. He is the Robert Andrews Millikan Professor of Theoretical Physics Emeritus at the California Institute of Technology, a distinguished fellow and co-founder of the Santa Fe Institute, a professor of physics at the University of New Mexico, and the Presidential Professor of Physics and Medicine at the University of Southern California.Gell-Mann has spent several periods at CERN, among others as a John Simon Guggenheim Memorial Foundation fellow in 1972.

Oersted Medal

The Oersted Medal recognizes notable contributions to the teaching of physics. Established in 1936, it is awarded by the American Association of Physics Teachers. The award is named for Hans Christian Ørsted. It is the Association's most prestigious award.

Well-known recipients include Nobel laureates Robert Andrews Millikan, Edward M. Purcell, Richard Feynman, Isidor I. Rabi, Norman F. Ramsey, Hans Bethe, and Carl Wieman; as well as Arnold Sommerfeld, George Uhlenbeck, Jerrold Zacharias, Philip Morrison, Melba Phillips, Victor Weisskopf, Gerald Holton, John A. Wheeler, Frank Oppenheimer, Robert Resnick, Carl Sagan, Freeman Dyson, Daniel Kleppner, and Lawrence Krauss, and Anthony French, David Hestenes, Robert Karplus, Robert Pohl, and Francis Sears.

The 2008 medalist, Mildred S. Dresselhaus, is the third woman to win the award in its 70-plus-year history.

Philip Sporn

Philip Sporn (November 25, 1896 in Folotwin, Austria – January 23, 1978 in New York City) was an Austrian electrical engineer known for his work as the president and chief executive officer of the American Gas and Electric Company. He received the IEEE Edison Medal for "contributions to the art of economical and dependable power generation and transmission".

Samuel Collins (physicist)

Samuel Cornette Collins (September 28, 1898 in Kentucky – June 19, 1984 in Washington, DC.) was an American physicist. He developed the first mass-produced helium liquefier, the Collins Helium Cryostat.

Powered by a two-piston expansion engine, his refrigerators provided the first reliable supplies of liquid helium in quantities of several hundred to several thousand liters. Among other uses, these refrigerators were used to liquefy and transport helium and deuterium for the first hydrogen bomb explosion, Ivy Mike in 1952.He was awarded the John Price Wetherill Medal in 1951 and the Rumford Prize in 1965.


A spinthariscope is a device for observing individual nuclear disintegrations caused by the interaction of ionizing radiation with a phosphor (see radioluminescence) or scintillator.


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