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Early Period Miranda, AzelAnn T. 2PSY01 Foreign Physicists Early Period 1544-1603 William Gilbert hypothesized that the Earth is a giant magnet English 1564-1642 Galileo Galilei performed fundamental observations, experiments, and mathematical Italian analyses in astronomy and physics; discovered mountains and craters on the moon, the phases of Venus, and the four largest satellites of Jupiter: Io, Europa, Callisto, and Ganymede 1580-1626 Willebrod Snell discovered law of refraction (Snell's law) Dutch 1623-1662 Blaise Pascal discovered that pressure applied to an enclosed fluid is transmitted French undiminished to every part of the fluid and to the walls of its container (Pascal's principle) 1629-1695 Christiaan Huygens proposed a simple geometrical wave theory of light, now known as Dutch ``Huygen's principle''; pioneered use of the pendulum in clocks 1635-1703 Robert Hooke discovered Hooke's law of elasticity English 1643-1727 Sir Isaac Newton developed theories of gravitation and mechanics, and invented English differential calculus 1700-1782 Daniel Bernoulli developed the fundamental relationship of fluid flow now known as Swiss Bernoulli's principle 1706-1790 Benjamin Franklin the first American physicist; characterized two kinds of electric charge, American which he named ``positive'' and ``negative'' 1707-1783 Leonard Euler made fundamental contributions to fluid dynamics, lunar orbit theory Swiss (tides), and mechanics; also contributed prolifically to all areas of classical mathematics 1731-1810 Henry Cavendish discovered and studied hydrogen; first to measure Newton's gravitational British constant; calculated mass and mean density of Earth 1736-1806 Charles Augustin de experiments on elasticity, electricity, and magnetism; established French Coulomb experimentally nature of the force between two charges 1736-1813 Joseph-Louis developed new methods of analytical mechanics French Lagrange 1736-1819 James Watt invented the modern condensing steam engine and a centrifugal Scottish governor 1745-1827 Count Alessandro pioneer in study of electricity; invented the first electric battery Italian Volta 1768-1830 Joseph Fourier established the differential equation governing heat diffusion and solved French it by devising an infinite series of sines and cosines capable of approximating a wide variety of functions 1773-1829 Thomas Young studied light and color; known for his double-slit experiment that British demonstrated the wave nature of light 1774-1862 Jean-Babtiste Biot studied polarization of light; co-discovered that intensity of magnetic field French set up by a current flowing through a wire varies inversely with the distance from the wire 1775-1836 André Marie Ampère father of electrodynamics French 1776-1856 Amadeo Avogadro developed hypothesis that all gases at same volume, pressure, and Italian temperature contain same number of atoms 1777-1855 Johann Carl Friedrich formulated separate electrostatic and electrodynamical laws, including German Gauss ``Gauss' law''; contributed to development of number theory, differential geometry, potential theory, theory of terrestrial magnetism, and methods of calculating planetary orbits 1777-1851 Hans Christian discovered that a current in a wire can produce magnetic effects Danish Oersted 1781-1868 Sir David Brewster deduced ``Brewster's law'' giving the angle of incidence that produces English reflected light which is completely polarized; invented the kaleidoscope and the stereoscope, and improved the spectroscope 1788-1827 Augustin-Jean studied transverse nature of light waves French Fresnel 1789-1854 Georg Ohm discovered that current flow is proportional to potential difference and German inversely proportional to resistance (Ohm's law) 1791-1867 Michael Faraday discovered electromagnetic induction and devised first electrical English transformer 1791-1841 Felix Savart co-discovered that intensity of magnetic field set up by a current flowing French through a wire varies inversely with the distance from the wire 1796-1832 Sadi Carnot founded the science of thermodynamics French 1797-1878 Joseph Henry performed extensive fundamental studies of electromagnetic American phenomena; devised first practical electric motor Middle Period 1803-1853 Christian Doppler experimented with sound waves; derived an expression for the apparent Austrian change in wavelength of a wave due to relative motion between the source and observer 1804-1891 Wilhelm E. Weber developed sensitive magnetometers; worked in electrodynamics and the German electrical structure of matter 1805-1865 Sir William Hamilton developed the principle of least action and the Hamiltonian form of Irish classical mechanics 1818-1889 James Prescott Joule discovered mechanical equivalent of heat British 1819-1896 Armand-Hippolyte- made the first terrestrial measurement of the speed of light; invented French Louis Fizeau one of the first interferometers; took the first pictures of the Sun on daguerreotypes; argued that the Doppler effect with respect to sound should also apply to any wave motion, particularly that of light 1819-1868 Jean-Bernard-Léon accurately measured speed of light; invented the gyroscope; French Foucault demonstrated the Earth's rotation 1819-1903 Sir George Gabriel described the motion of viscous fluids by independently discovering the British Stokes Navier-Stokes equations of fluid mechanics (or hydrodynamics); developed Stokes theorem by which certain surface integrals may be reduced to line integrals; discovered fluorescence 1821-1894 Hermann von developed first law of thermodynamics, a statement of conservation of German Helmholtz energy 1822-1888 Rudolf Clausius developed second law of thermodynamics, a statement that the entropy German of the Universe always increases 1824-1907 Lord Kelvin proposed absolute temperature scale, of essence to development of British (born William thermodynamics Thomson) 1824-1887 Gustav Kirchhoff developed three laws of spectral analysis and three rules of electric circuit German analysis; also contributed to optics 1825-1898 Johann Balmer developed empirical formula to describe hydrogen spectrum Swiss 1828-1914 Sir Joseph Wilson developed a carbon-filament incandescent light; patented the carbon British Swan process for printing photographs in permanent pigment 1831-1879 James Clerk Maxwell propounded the theory of electromagnetism; developed the kinetic Scottish theory of gases 1835-1893 Josef Stefan studied blackbody radiation Austrian 1838-1916 Ernst Mach studied conditions that occur when an object moves through a fluid at Austrian high speed (the ``Mach number'' gives the ratio of the speed of the object to the speed of sound in the fluid); proposed ``Mach's principle,'' which states that the inertia of an object is due to the interaction between the object and the rest of the universe 1839-1903 Josiah Gibbs developed chemical thermodynamics; introduced concepts of free energy American and chemical potential 1842-1923 James Dewar liquified nitrogen and invented the Dewar flask, which is critical for low- British temperature work 1842-1912 Osborne Reynolds contributed to the fields of hydraulics and hydrodynamics; developed British mathematical framework for turbulence and introduced the ``Reynolds number,'' which provides a criterion for dynamic similarity and correct modeling in many fluid-flow experiments 1844-1906 Ludwig Boltzmann developed statistical mechanics and applied it to kinetic theory of gases Austrian 1848-1919 Roland Eötvös demonstrated equivalence of gravitational and inertial mass Hungarian 1850-1925 Oliver Heaviside contributed to the development of electromagnetism; introduced English operational calculus and invented the modern notation for vector calculus; predicted existence of the Heaviside layer (a layer of the Earth's ionosphere) 1851-1901 George Francis hypothesized foreshortening of moving bodies (Lorentz-FitzGerald Irish FitzGerald contraction) to explain the result of the Michelson-Morley experiment 1852-1914 John Henry Poynting demonstrated that the energy flow of electromagnetic waves could be British calculated by an equation (now called Poynting's vector) 1854-1912 Henri Poincaré founded qualitative dynamics (the mathematical theory of dynamical French systems); created topology; contributed to solution of the three-body problem; first described many properties of deterministic chaos; contributed to the development of special relativity 1854-1919 Janne Rydberg analyzed the spectra of many elements; discovered many line series were Swedish described by a formula that depended on a universal constant (the Rydberg constant) 1855-1938 Edwin H. Hall discovered the ``Hall effect,'' which occurs when charge carriers moving American through a material are deflected because of an applied magnetic field - the deflection results in a potential difference across the side of the material that is transverse to both the magnetic field and the current direction 1857-1894 Heinrich Hertz worked on electromagnetic phenomena; discovered radio waves and the German photoelectric effect 1857-1943 Nikola Tesla created alternating current (Serbian-born American) 1837-1923 Johannes van der worked on equations of state for gases and liquids Dutch Waals 1842-1919 Lord Rayleigh discovered argon; explained how light scattering is responsible for red British (born John William color of sunset and blue color of sky Strutt) 1845-1923 Wilhelm Röntgen discovered and studied x rays German 1852-1908 Antoine Henri discovered natural radioactivity French Becquerel 1852-1931
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