What should be the public awareness of Physics? Is Physics a coherent body of useful contemporary knowledge? Or… only a Method of Inquiry unchanged since the Age of Enlightenment? Intro. Phys. I – to American Revolution Intro. Phys. II – to American Civil War Modern Phys. – to the Great Depression Relearning the ignorance of the “Enlightenment” Planetary motion (Copernicus, Galileo, Brahe, Kepler 1500-1600) Newton’s laws (Newton 1687) Electricity (Coulomb 1777) Magnetism (Oersted 1819) Line spectra (Kirchhoff 1859) Kinetic theory (Maxwell 1860) Relativity E&M (Voigt 1887) Atomic confirmation (Einstein 1905) ‘the concept of force has reached the end of its life cycle … (suggesting) its disbarment from the inventory of fundamental concepts in physics.’ Max Jammer, Concepts of Force, 1957 ‘In all methods and systems which involve the idea of force there is a leaven of artificiality… there is no necessity for the introduction of the word “force” nor the sense-suggested ideas on which it was originally based.” Peter G. Tait, Dynamics, 1895 ‘If people were to learn to conceive the world in a new way, without the old notion of “force,” it would alter not only their physical imagination, but probably also their morals and politics.’ Bertrand Russell, The ABC of Relativity, 1925 Quotes from Force-Trained students: ‘How can a rocket work in outer space where there is nothing for the force to push on?’ ‘The moon doesn’t fall to earth because the centrifugal force holds it out.’ ‘If weight is gravitational force, and orbiting astronauts are weightless, then they must be outside the range of gravity.’ ‘We know that nuclei are small because -projectiles miss them and go mainly forward. If nuclei were large, -particles would hit them, feel a force, and bounce backward.’ Are the problems we assign even realistic? ____________________________________ Am. J. Phys. 71, 1152 (2003); dispute / R.K. Adair 73, 184 (2005). 1. Viscous drag nonlinearly couples horizontal & vertical – solve numerically. 2. Aerodynamics of backspin dominates the range achieved. A lousy approximation! THE NATURE OF MATTER _________________________________________________________ All matter consists of little bits of positive and negative electricity: in perpetual motion; attract each other at short distances; repel each other when pressed too close together. ________________________________________________________ The most important discovery ever made. If all other scientific information we know were lost in some cataclysmic event, and only this information survived, all could be //// rediscovered in a very short time. - Richard P. Feynman ` (Ohio State Board of Education –12/10/02) Iron atoms positioned on a carbon surface Second Quantization - The Discrete Photon 700 keV Li+ beam (v=4.4 mm/ns) incident on a thin (3 g/cm2) carbon foil. The blue light is H-like 4f-5g in Li2+ (4500Å, =3 ns, x=1.3 cm). The green light is He-like 2s 3S-2p 3P in Li+ (5485Å, =44 ns, x=19 cm). Can we picture attractive and repulsive interactions without the force concept? Quantum Field Theory is conceptually easy! ACTION-AT-A-DISTANCE Exchange of a ‘gauge boson’ Particle exchange can produce both attraction and repulsion. It is intermittent, like rain on the roof. The Force concept requires an average over a time interval. Nature has revealed a beautiful secret! The behavior of the Universe becomes very simple if it is described in a way in which space and time are symmetric. What makes it seem hard, is the fact the we must live our lives by standing at a point in space and watching time pass, but not the reverse. It’s like our perspective in riding the Earth around the Sun, which seems as if the Sun were going around us. However, the heliocentric equations are much simpler. TIME “Time is what keeps everything from happening at once.” - Attributed to John Archibald Wheeler Quoted by Woody Allen “Time flies like an arrow; fruit flies like a banana.” - Groucho Marx ‘Backward turn, turn backward, O time in your flight. Make me a child again, just for tonight.’ - Elizabeth Akers Allen Electron-positron pair production The “photon-dressed” electron Electron-Positron Pair Creation and Annihilation Once created, e+ and e- are stable until annihilated Are they all really the same electron? time Future Here-Now space Past Why didn’t Isaac Newton think about the possibility of getting hit on the head when he sat under the apple tree? x Where does the pendulum spend the most time? The least time? Time exposure Dwell time: High: many / slow Low: Few / fast Equal time inside No time outside Most time at end points Least time at center Most time at aphelion and perihelion The secret of life, computers, & transitors Laplacian Determinacy – A Costly Mistake Pierre Simon Laplace - 1776: “An intelligence that knows all of the relations of the entities of the universe at one instant could state their positions, motions, and general effects any instant in the past of future. Henri Poincare – 1903: “Small differences in the initial conditions can produce very great ones in the final phenomena – prediction Then becomes impossible (1st recognition of chaos). Werner Heisenberg – 1924: There is a fundamental limit on the accuracy to which position and velocity can be co-determined. Stephen Hawking –1988: In the cosmology of the Big Bang and Black Holes, space and time themselves break down.