|Arlie Oswald Petters|
|Born||February 8, 1964
|Known for||Mathematical Theory of Gravitational Lensing.|
|Notable awards||Alfred P. Sloan Fellowship
NSF CAREER Award
Most Excellent Order of the British Empire
Arlie O. Petters, MBE (born February 8, 1964) is a Belizean American mathematical physicist, who is the Benjamin Powell Professor and Professor of Mathematics, Physics, and Business Administration at Duke University. Petters is a founder of mathematical astronomy, focusing on problems connected to the interplay of gravity and light and employing tools from astrophysics, cosmology, general relativity, high energy physics, differential geometry, singularities, and probability theory. His monograph "Singularity Theory and Gravitational Lensing" is the first to develop a mathematical theory of gravitational lensing. He was Chairman of the Council of Science Advisers to the Prime Minister of Belize (2010-2013).
Arlie Petters was raised by his grandparents in the rural community of Dangriga, Belize. His mother had immigrated to New York and married a U.S. citizen, with Arlie joining them when he was 13. He went to Canarsie High School in Brooklyn. 
Petters earned a B.A./M.A. in Mathematics and Physics from Hunter College, CUNY in 1986 with a thesis on "The Mathematical Theory of General Relativity", and began his Ph.D. at the Massachusetts Institute of Technology Department of Mathematics in the same year. After two years of doctoral studies, he became an exchange scholar in the Princeton University Department of Physics in absentia from MIT. Petters earned his Ph.D. in Mathematics in 1991 under advisers Bertram Konstant (MIT) and David Spergel (Princeton University).
His specialties are in mathematical physics, geometry and probability theory. Petters teaches quantitative finance in the Fuqua School of Business and works with MBA students to promote social entrepreneurship in science and technology in Belize and the developing world. He currently holds the Benjamin Powell endowed Chair at Duke University.
Petters is renowned for his pioneering work in the mathematical theory of gravitational lensing.
Over the ten-year period from 1991–2001, Petters systematically developed a mathematical theory of weak-deflection gravitational lensing, beginning with his 1991 MIT Ph.D. thesis on "Singularities in Gravitational Microlensing"  and followed by the 12 papers [AP1] - [AP12] below. The papers resolved an array of theoretical problems in weak-deflection gravitational lensing covering image counting, fixed-point images, image magnification, image time delays, local geometry of caustics, global geometry of caustics, wavefronts, caustic surfaces, and caustic surfing.  His work culminated with a 2001 mathematical tome [AP13] that, among other things, systematically created a framework of stability and genericity for k-plane gravitational lensing. The book drew upon powerful tools from the theory of singularities and put the subject of weak-deflection k-plane gravitational lensing on a rigorous and unified mathematical foundation. 
Following his 1991-2001 body of mathematical lensing work, Petters turned to more astrophysical lensing issues from 2002-2005. In collaboration with astronomers, he applied some of the mathematical theory in [AP13] to help develop a practical diagnostic test for the presence of dark substructures in galaxies lensing quasars;   classify the local astrometric (centroid) and photometric curves of an extended source when it crosses fold and cusp caustics due to generic lenses;   predict the quantitative astrometric curve's shape produced by Galactic binary lenses.   The classified local properties of the astrometric curves revealed a characteristic S-shape for fold crossings, parabolic and swallowtail features for cusp crossings, and a jump discontinuity for crossings over the fold arcs merging into a cusp. A formula for the size of the jump was also found.
During 2005-2007, Petters collaborated with astronomers and physicists to explore gravitational lensing in directions beyond its traditional confines in astronomy. In a series of three mathematical physics papers (2005–2006) with the astronomer Keeton, he utilized higher-order gravitational lensing effects by compact bodies to test different theories of gravity with Einstein's general theory of relativity among them. The first two papers computed beyond the standard weak-deflection limit the first- and second-order corrections to the image positions, magnifications, and time delays due to lensing in general relativity and alternative gravitational theories describable within the PPN formalism,  and even determined lensing invariants for the PPN family of models.  Their findings were applied to the Galactic black hole, binary pulsars, and gravitational microlensing scenarios to make testable predictions about lensed images and their time delays.  The third paper took on the difficult issue of how to test hyperspace models like braneworld gravity that postulate an extra dimension to physical space. The paper developed a semi-classical wave theory of braneworld black hole lensing and used that theory along with braneworld cosmology to predict a testable signature of microscopic braneworld black holes on gamma-ray light.   Additionally, in a 2007 paper, Petters and Werner found a system of equations that can be applied to test the Cosmic Censorship Hypothesis observationally using the realistic case of lensing by a Kerr black hole.  
Petters's previous work (1991–2007) dealt with non-random gravitational lensing. His recent research program (2008–present) has been to develop a mathematical theory of random (stochastic) gravitational lensing. In two papers, he, Rider, and Teguia took first steps in creating a mathematical theory of stochastic gravitational microlensing. They characterized to several asymptotic orders the probability densities of random time delay functions, lensing maps, and shear maps in stochastic microlensing and determined a Kac-Rice type formula for the global expected number of images due to a general stochastic lens system.   The work forms a concrete framework from which extensions to more general random maps can be made. In two additional papers, he and Aazami found geometric universal magnification invariants[disambiguation needed] of higher-order caustics occurring in lensing and caustics produced by generic general maps up to codimension five.    The invariants hold with a probability of 1 for random lenses and thereby form important consistency checks for research on random image magnifications of sources near stable caustics.
For more information, consult Petters's official Duke University CV  for a very useful road map with detailed and extensive summaries of his research papers.
Selected papers from 1991–2001: 
[AP1] "Morse Theory and Gravitational Microlensing," A. O. Petters, J. Math. Phys., 33, 1915 (1992).
[AP2] "Arnold's Singularity Theory and Gravitational Lensing," A. O. Petters, J. Math. Phys., 34, 3555 (1993).
[AP3] "Multiplane Gravitational Lensing I: Morse Theory and Image Counting," A. O. Petters, J. Math. Phys., 36, 4263 (1995).
[AP4] "Multiplane Gravitational Lensing II: Global Geometry of Caustics," A. O. Petters, J. Math. Phys., 36, 4276 (1995).
[AP5] "Multiplane Gravitational Lensing III. Upper Bound on Number of Images," A. O. Petters, J. Math. Phys., 38, 1605 (1997).
[AP6] "Caustics of the Double-Plane Two Point-Mass Gravitational Lens with Continuous Matter and Shear," A. O. Petters and F.J. Wicklin, Mon. Not. R. Astron. Soc., 277, 1399 (1995).
[AP7] "Lower Bounds on Image Magnification in Gravitational Lensing," A. O. Petters, Proc. R. Soc. Lond. A, 452, 1475 (1996).
[AP8] "Counting Formulas and Bounds on Number of Fixed Points due to Point-Mass Lenses," A. O. Petters and F.J. Wicklin, in Proceedings of the Eighth Marcel Grossmann Meeting on General Relativity, ed. R. Ruffini (World Scientific, Singapore, 1997).
[AP9] "Bounds on Number of Cusps due to Point Mass Gravitational Lenses with Continuous Matter and Shear," A. O. Petters and H. Witt, J. Math. Phys., 37, 2920 (1996).
[AP10] "Mathematical Aspects of Gravitational Lensing," A. O. Petters, in Proceedings of the Seventh Marcel Grossmann Meeting on General Relativity, vol. B, eds. R. T. Jantzen and G. M. Keiser (World Scientific, Singapore, 1996).
[AP11] "Fixed Points due to Gravitational Lenses," A.O. Petters and F.J. Wicklin, J. Math. Phys., 39, 1011 (1998)
[AP12] "Stable Lens Systems, Lensed Image Magnification, and Magnification Cross Sections," A. O. Petters, in Proceedings of the Ninth Marcel Grossmann Meeting on General Relativity, eds. V. Gurzadyan, R. T. Jantzen, and R. Ruffini (World Scientific, Singapore, 2001).
[AP13] Singularity Theory and Gravitational Lensing, A. O. Petters, H. Levine, and J. Wambsganns (Birkhauser, Boston, 2001)
Petters has given back significantly to the African-American community, which has included him serving as Director of the Reginaldo Howard Memorial Scholarship program at Duke University.  He has also been active in the African-American community particularly through his mentoring, recruiting, and lecturing.   He has received several community service awards for his social outreach.   Petters is also the first tenured African-American professor in Mathematics at Duke University.  He is very involved in the Belizean community and in 2005 founded the Petters Research Institute  to train Belizean young people in the mathematics, science, and technology fields and help develop green technologies as a serious contributor to the economy of Belize.   Petters has also authored a number of science and mathematics workbooks for Belizean students.   Through his joint appointment with Duke's Fuqua School of Business, Petters is promoting entrepreneurship and innovation in science and green technology in Belize.
Awards and honors
Petters is the recipient of numerous awards and honors,  which includes an Alfred P. Sloan Research Fellowship in Mathematics (1998),  a CAREER award from the National Science Foundation (1998),  and being the first winner of a Blackwell-Tapia Prize (2002).  He was selected in 2006 by the National Academy of Sciences to be part of a permanent Portrait Collection of Outstanding African-Americans in Science, Engineering, and Medicine.  In 2008 Petters was also included among the Human Relations Associates' list of "The Twenty-Five Greatest Scientists of African Ancestry," which went back as early as the 18th century.  He received an honorary Doctor of Science from his alma mater Hunter College in 2008.  Petters was named by the Queen of England in 2008 to membership in the Most Excellent Order of the British Empire.  In recognition of his scientific accomplishments and service to society, Petters's birthplace—Dangriga, Belize—honored him in 2009 with the Dr. Arlie Petters Street.  He became in 2011 the first Belizean to receive the Caribbean American Heritage Award for Excellence in Science and Technology.  In 2012 he became a fellow of the American Mathematical Society and the first Belizean American to be Grand Marshal of the seven-nation Central American Day Parade in L.A., where he received honors from the mayor of L.A. and COFECA.
- Duke University
- Mathematicians of the African Diaspora
- Government of Belize Official Press Release, April 28, 2010,
- Curriculum Vitae of Arlie O. Petters, Department of Mathematics, Duke University
- Claudia Dreifus. A CONVERSATION WITH: ARLIE PETTERS: A Journey to Bridge Math and the Cosmos, New York Times, May 27, 2003.
- Arlie Petters at the Mathematics Genealogy Project
- NOVA Science Now
- Big Think
- A. O. Petters, Ph.D. Thesis, MIT, Department of Mathematics (1991): "Singularities in Gravitational Microlensing." 
- Section A, "Research Period 1991-2001," Curriculum Vitae of Arlie O. Petters, Department of Mathematics, Duke University 
- Singularity Theory and Gravitational Lensing, A. O. Petters, H. Levine, and J. Wambsganss (Birkhauser, Boston, 2001). Amazon.com 
- "Identifying Lenses with Small-Scale Structure I. Cusp Lenses," C. Keeton, S. Gaudi, and A. O. Petters, Astrophys. J., 598, 138 (2003); astro-ph/0210318. 
- "Identifying Lenses with Small-Scale Structure II. Fold Lenses," C. Keeton, S. Gaudi, and A. O. Petters , Astrophys. J., 635, 35 (2005); astro-ph/0503452. 
- "Gravitational Microlensing Near Caustics I: Folds," B. S. Gaudi and A. O. Petters, Astrophys. J., 574, 970 (2002); astro-ph/0112531. 
- "Gravitational Microlensing Near Caustics II: Cusps," B. S. Gaudi and A. O. Petters, Astrophys. J., 580, 468 (2002); astro-ph/0206162. 
- "Formalism for Testing Theories of Gravity Using Lensing by Compact Objects. I. Static, Spherically Symmetric Case," C. Keeton and A. O. Petters, Phys. Rev. D, 72, 104006 (2005); gr-qc/0511019. 
- "Formalism for Testing Theories of Gravity Using Lensing by Compact Objects. II. Probing Post-Post-Newtonian Metrics," C. Keeton and A. O. Petters, Phys. Rev. D 73, 044024 (2006); gr-qc/0601053 
- "Formalism for Testing Theories of Gravity Using Lensing by Compact Objects. III. Braneworld Gravity," C. Keeton and A. O. Petters, Phys. Rev. D 73, 104032 (2006) gr-qc/0603061 
- "Scientist Predict How to Detect a Fourth Dimension," Duke News
- "Magnification Relations for Kerr Lensing and Testing Cosmic Censorship," M. C. Werner and A. O. Petters, Phys. Rev. D 76, 064024 (2007); gr-qc/0706.0132 
- "Seeking Objects Weirder than Black Holes," Duke News
- "A Mathematical Theory of Stochastic Microlensing I. Random Time Delay Functions and Lensing Maps," A. O. Petters, B. Rider, and A. M. Teguia, J. Math Phys., 50, 072503 (2009); astro-ph arXiv:0807.0232v2 
- "A Mathematical Theory of Stochastic Microlensing II. Random Images, Shear, and the Kac-Rice Formula," A. O. Petters, B. Rider, and A. M. Teguia (2008); astro-ph arXiv:0807.4984
- "A Universal Magnification Theorem for Higher-Order Caustic Singularities," A. B. Aazami and A. O. Petters, J. Math. Phys. 50, 032501 (2009); astro-ph arXiv:0811.3447v2 
- "A Universal Magnification Theorem II. Caustics up to Codimension Five," A. B. Aazami and A. O. Petters, 50, 082501 (2009); math-ph arXiv:0904.2236v4 
- National Science Foundation, Science360 News Server, April 16, 2009
- Publications of Arlie O. Petters, Department of Mathematics, Duke University: 
- The Reginaldo Howard Memorial Scholarship program, Duke University
- The Chronicle, Math Professor Reaches out to Minorities
- Arlie O. Petters, Curriculum Vitae--Service to Underrepresented Minority Community, Department of Mathematics, Duke University 
- Duke Magazine, "Star Professor"
- Arlie O. Petters, Curriculum Vitae-- Awards and Honors
- Petters Research Institute, Dangriga, Belize
- 7 News Belize
- Computer assembly course for Belizean students by Petters Research Institute and the Belize Defence Force 
- Amandala News
- Publications of Arlie O. Petters, Department of Mathematics, Duke University 
- Department of Mathematics, Duke University
- Petters Research Institute
- Arlie Petters, official Curriculum Vitae, Department of Mathematics, Duke University 
- Alfred P. Sloan Foundation, list of past fellows
- National Science Foundation, FY 98 CAREER Awardes (New Jersey)
- SIAM News
- National Academy of Sciences, African-American History Program
- Human Relations Associates, The Twenty-Five Greatest Scientists of African Ancestry 
- Hunter College News 2008
- London Gazette, Duke Today
- Duke Research
- Channel 5 News, Belize
- List of Fellows of the American Mathematical Society, retrieved 2013-05-05.
- NOVA scienceNOW http://www.pbs.org/wgbh/nova/sciencenow/3411/04.html
- New York Times http://www.nytimes.com/2003/05/27/science/a-conversation-with-arlie-petters-a-journey-to-bridge-math-and-the-cosmos.html
- National Academy of Sciences http://www.nasonline.org/site/PageServer?pagename=AAHP_Database_Bio_Petters
- Mathematicians of the African Diaspora http://www.math.buffalo.edu/mad/PEEPS/petters_arlie.html