who you are, most of the smartest people work for someone else", attributed to Sun Microsystems co-founder Bill Joy. Kepler's laws of planetary motion describe the motion of the planets around the sun. First articulated by Johannes Kepler. Kerckhoffs's principle of secure cryptography: A cryptosystem should be secure even if everything about the system, except the key, is public. Kirchhoff's laws are named after Gustav Kirchhoff and cover thermodynamics, thermochemistry, electrical circuits and spectroscopy (see Kirchhoff's laws (disambiguation)). Klaiber's law: the silicon wafer size will dictate the largest diameter of ultrapure water supply piping needed within a semiconductor wafer factory. Kluge's law: a sound law that purports to explain the origin of the Proto-Germanic long consonants. Named after Friedrich Kluge. Koomey's law: the energy of computation is halved every year and a half. Kopp's law: The molecular heat capacity of a solid compound is the sum of the atomic heat capacities of the elements composing it. Named for Hermann Franz Moritz Kopp. Korte's law: The greater the length of a path between two successively presented stimuli, the greater the stimulus onset asynchrony must be for an observer to perceive the two stimuli as a single moving object. Kranzberg's laws of technology: The first law states that technology is neither good nor bad; nor is it neutral. Kryder's law: on growth of density of magnetic disk storage, compared to Moore's law. L–M L'Hôpital's rule uses derivatives to find limits of indeterminate forms 0/0 or ±∞/∞, and only applies to such cases. Lamarck's theory of evolution has two laws: The first can be paraphrased as "use it or lose it". The second is the more famous law of soft inheritance. Lambert's cosine law describes the radiant intensity observed from an ideal diffusely reflecting surface or ideal diffuse radiator. Lanchester's laws are formulae for calculating the relative strengths of predator/prey pair and application in military conflict. Landauer's principle: there is a minimum possible amount of energy required to change one bit of information, known as the Landauer limit. LaSalle's invariance principle is a criterion for the asymptotic stability of an autonomous (possibly nonlinear) dynamical system. Named for mathematician Joseph P. LaSalle. Leavitt's law: In astronomy, a period-luminosity relation linking the luminosity of pulsating variable stars with their pulsation period. Named for American astronomer Henrietta Swan Leavitt. Lehman's laws of software evolution Leibniz's law is a principle in metaphysics also known as the Identity