ICTAM 2000 Poster: Meters of Motion Billy Morrow Jackson, 1998      Meters of Motion, a watercolor by Champaign-Urbana artist Billy Morrow Jackson, is the basis for the poster announcing the 20th International Congress of Theoretical and Applied Mechanics, to be held in Chicago in August of the year 2000.  These international congresses, initiated in 1924, have visited many of the great cities of the world: Copenhagen, Delft, Grenoble, Haifa, Istanbul, Kyoto, London, Moscow, Paris, Stockholm, Toronto, and Zürich among them.  They are the 'Olympic Games' of the science of mechanics, international forums where scientists and engineers from around the world meet every four years to present and discuss the latest results in the oldest of the physical sciences, the science of mechanics.      Jackson's image depicts several of the giants of mechanics.  In the center we have Isaac Newton (1642-1727) holding the device known as Newton's cradle, illustrating the laws of impact and momentum, today frequently used as an executive toy because of its pleasing periodic motion.  Above Newton the phases of the Moon and the falling apple--one of his key insights was the unification of the orbital motion of the Moon about Earth and the accelerated fall of an apple in Earth's gravitational field.  Newton's results on his universal law of gravitation were published in 1687 in the Principia, probably the most influential scientific treatise of all time.  Newton stands on the word 'PRINCIPIA' and his famous 'second law', force equals mass times acceleration or F = ma, appears at top right in the image.   To the left of Newton we find his intellectual predecessor Galileo (1564-1642) watching a swinging pendulum, timing its oscillations using his pulse.  Galileo made seminal contributions not only to kinematics, dynamics and observational astronomy, but also to the subject of strength of materials.  His work on kinematics and strength of materials, entitled Dialogues on Two New Sciences, is represented by the word 'DIALOGUES', itself a cantilever beam anchored in a brick wall and carrying a suspended weight.      Behind Galileo a ball and feather fall with the same acceleration.  Above Galileo, in the uppermost left-hand corner, we see Archimedes (287-212 B.C.), one of the great geniuses of antiquity who gave us the laws of hydrostatics and buoyancy, holding forth the symbol p, the ratio of the circumference to the diameter of a circle.  Archimedes was the first to realize the universality of this ratio and to determine approximations to its numerical value.      On the right we find Leonhard Euler (1707-1783), the great mathematician and mechanician, who cast Newton's laws in their enduring mathematical form using the calculus, and who solved legions of problems in both fluid and solid mechanics.  He is shown with the famous elastica curve emanating from his forefinger.  The elastica is the curve that gives the shape of a thin, perfectly elastic rod when it buckles under load.  This curve also arises in other contexts, for example in the shape of a concentrated vortex, such as the tornado seen in the background between Newton and Euler.  Below and between Newton and Euler we see another legend of mechanics and mathematics, Joseph Louis Lagrange (1736-1813), whose famous work Mecanique Analytique, published a century after Newton's Principia, set out the equations of dynamics in a novel variational formulation that gave a teleological interpretation to all motion in the Universe.  Lagrange's work has served as a paradigm of all physical theories since then, from optics to electromagnetism to modern quantum mechanical field theories.  Lagrange's formulation of dynamics also lends itself to the theory of vibrations.  Thus patterns of nodal lines on vibrating plates, so-called Chladni figures, flow like sheets from the manuscript he is holding.      The three remaining large figures in the picture are of three of the greats of mechanics in the 20th century, individuals whose initiative was important also for the inception of the international congresses of mechanics.  In the lower left-hand corner Theodore von Kármán (1881-1963) gazes out at sequences of vortices produced in the wakes of bluff bodies.  These organized patterns, today known as Kármán vortex streets, are ubiquitous in the wakes of everything from huge tankers to power lines 'singing in the wind'.      Between Newton and Galileo we see Ludwig Prandtl (1875-1953), von Kármán's teacher, and a seminal figure in both solid and fluid mechanics.  Prandtl is known for his work on the dynamics of the boundary layer, the thin layer of fluid adjacent to a moving rigid body, be it an airplane wing or a ship hull, a layer of fluid very much responsible for the resistance to motion experienced by the body.  Golf balls have dimples precisely so that they can 'fool' the boundary layer into offering less resistance to their motion than to that of a smooth sphere.  Prandtl is also known for his work on aerodynamics (hence the propeller churning to the right of him), on the strength of materials, and for conducting comprehensive experiments on a variety of mechanical phenomena.      In the lower right hand corner is G. I. Taylor (1886-1975), whose many contributions included a theory of dislocations in solids, early studies of turbulence in the atmosphere (hence the weather balloon), a theory of the fireball from a nuclear explosion (hence the series of fireballs depicted--a film record was released of the first nuclear explosion and G. I. Taylor developed a theory of the blast phenomenon that predicted the total, classified yield of the bomb).  Taylor was an avid sailor and he was very proud of his invention of a drop anchor (depicted).      The mathematician and novelist Sofia Kovalevskaya (1850-1891) discovered a very important solution to the problem of the 'heavy top'.  She made her lasting contributions to mechanics during a time when women were not allowed to attend lecture courses in universities.  She is standing between Newton and Galileo, below Prandtl, writing an equation (the famous Korteweg-deVries equation that describes water waves) on a blackboard .      Off to the right we have a bridge structure, where the members spell out IUTAM, acronym for the International Union of Theoretical and Applied Mechanics, the professional body responsible for the international congresses.  On the bridge we find current and past officers of IUTAM: past presidents Sir James Lighthill, Paul Germain, Leen van Wijngaarden and Daniel C. Drucker, and current president Werner Schiehlen.  We also see the current and past secretaries of IUTAM's Congress Committee, Niels Olhoff and H. Keith Moffatt.  The president of the 19th Congress in Kyoto, Tomomasa Tatsumi, is in the middle of this group.  Holding up the bridge are the president and secretary-general of the 20th Congress, Hassan Aref and James W. Phillips of the University of Illinois at Urbana-Champaign.      For further information about ICTAM 2000, see the website at http://www.tam.uiuc.edu/ICTAM2000.  Billy Morrow Jackson has a website at http://www.soltec.net/jacksonstudios/. --Hassan Aref, January 1999