Question: The Born rule was formulated by German physicist Max Born, who was instrumental in the development of what?
Context: The Max Born Prize is a scientific prize awarded yearly by the German Physical Society (DPG) and the British Institute of Physics (IOP) in memory of the German physicist Max Born.  The terms of the award are that it is "to be presented for outstanding contributions to physics".  The award goes to physicists based in Germany and in the UK or Ireland in alternate years. The Cauchy–Born rule or Cauchy-Born approximation is a basic hypothesis used in the mathematical formulation of solid mechanics which relates the movement of atoms in a crystal to the overall deformation of the bulk solid.  It states that in a crystalline solid subject to a small strain, the positions of the atoms within the crystal lattice follow the overall strain of the medium.  The currently accepted form is Max Born's refinement of Cauchy's original hypothesis which was used to derive the equations satisfied by the Cauchy stress tensor.  The approximation generally holds for face-centered and body-centered cubic crystal systems. For complex lattices such as diamond, however, the rule has to be modified to allow for internal degrees of freedom between the sublattices.  The approximation can then be used to obtain bulk properties of crystalline materials such as stress-strain relationship. In physics, Born reciprocity, also called reciprocal relativity or Born–Green reciprocity, is a principle set up by theoretical physicist Max Born that calls for a duality-symmetry among space and momentum.  Born and his co-workers expanded his principle to a framework that is also known as reciprocity theory. The Max Planck Institute for Mathematics (German: "Max-Planck-Institut für Mathematik" , MPIM) is a research institute specializing in mathematics located in Bonn, Germany.  It is named in honor of the German physicist Max Planck.  The MPIM is one of the 80 institutes in the Max Planck Society ("Max-Planck-Gesellschaft"). The Max Planck Society for the Advancement of Science (German: "Max-Planck-Gesellschaft zur Förderung der Wissenschaften e. V." ; abbreviated MPG) is a formally independent non-governmental and non-profit association of German research institutes founded in 1911 as the Kaiser Wilhelm Society and renamed the Max Planck Society in 1948 in honor of its former president, theoretical physicist Max Planck.  The society is funded by the federal and state governments of Germany as well as other sources. Max Born (] ; 11 December 1882 – 5 January 1970) was a German physicist and mathematician who was instrumental in the development of quantum mechanics.  He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 1930s.  Born won the 1954 Nobel Prize in Physics for his "fundamental research in Quantum Mechanics, especially in the statistical interpretation of the wave function". The Born rule (also called the Born law, Born's rule, or Born's law) formulated by German physicist Max Born in 1926, is a law of quantum mechanics giving the probability that a measurement on a quantum system will yield a given result.  In its simplest form it states that the probability density of finding the particle at a given point is proportional to the square of the magnitude of the particle's wavefunction at that point.  The Born rule is one of the key principles of quantum mechanics.  There have been many attempts to derive the Born rule from the other assumptions of quantum mechanics, see Geometry of Quantum Theory, by V.S. Varadarajan for a rigorous derivation. Wolfgang Demtröder (b. 5 September 1931 in Attendorn) is a German physicist and spectroscopist.  He is the author of several textbooks on laser spectroscopy and a series of four textbooks on experimental physics.  His books entitled "Laserspektroskopie" and "Laser Spectroscopy" are considered classics in the field.  From 1970 til 1999, he was ordinary professor at Kaiserslautern University of Technology.  Awarded the Max Born Prize in 1994. Woldemar Voigt (] ; 2 September 1850 – 13 December 1919) was a German physicist, who taught at the Georg August University of Göttingen.  Voigt eventually went on to head the Mathematical Physics Department at Göttingen and was succeeded in 1914 by Peter Debye, who took charge of the theoretical department of the Physical Institute.  In 1921, Debye was succeeded by Max Born. Chloe Rose Lattanzi (born January 17, 1986) is an American singer and actress who was born in Los Angeles to actress and singer Olivia Newton-John and actor Matt Lattanzi.  Her maternal great-grandfather is Nobel prize-winning physicist Max Born.
Answer: quantum mechanics