Philosophers
Mortimer Adler Rogers Albritton Alexander of Aphrodisias Samuel Alexander William Alston Anaximander G.E.M.Anscombe Anselm Louise Antony Thomas Aquinas Aristotle David Armstrong Harald Atmanspacher Robert Audi Augustine J.L.Austin A.J.Ayer Alexander Bain Mark Balaguer Jeffrey Barrett William Barrett William Belsham Henri Bergson George Berkeley Isaiah Berlin Richard J. Bernstein Bernard Berofsky Robert Bishop Max Black Susanne Bobzien Emil du Bois-Reymond Hilary Bok Laurence BonJour George Boole Émile Boutroux Daniel Boyd F.H.Bradley C.D.Broad Michael Burke Lawrence Cahoone C.A.Campbell Joseph Keim Campbell Rudolf Carnap Carneades Nancy Cartwright Gregg Caruso Ernst Cassirer David Chalmers Roderick Chisholm Chrysippus Cicero Randolph Clarke Samuel Clarke Anthony Collins Antonella Corradini Diodorus Cronus Jonathan Dancy Donald Davidson Mario De Caro Democritus Daniel Dennett Jacques Derrida René Descartes Richard Double Fred Dretske John Dupré John Earman Laura Waddell Ekstrom Epictetus Epicurus Austin Farrer Herbert Feigl Arthur Fine John Martin Fischer Frederic Fitch Owen Flanagan Luciano Floridi Philippa Foot Alfred Fouilleé Harry Frankfurt Richard L. Franklin Bas van Fraassen Michael Frede Gottlob Frege Peter Geach Edmund Gettier Carl Ginet Alvin Goldman Gorgias Nicholas St. John Green H.Paul Grice Ian Hacking Ishtiyaque Haji Stuart Hampshire W.F.R.Hardie Sam Harris William Hasker R.M.Hare Georg W.F. Hegel Martin Heidegger Heraclitus R.E.Hobart Thomas Hobbes David Hodgson Shadsworth Hodgson Baron d'Holbach Ted Honderich Pamela Huby David Hume Ferenc Huoranszki Frank Jackson William James Lord Kames Robert Kane Immanuel Kant Tomis Kapitan Walter Kaufmann Jaegwon Kim William King Hilary Kornblith Christine Korsgaard Saul Kripke Thomas Kuhn Andrea Lavazza Christoph Lehner Keith Lehrer Gottfried Leibniz Jules Lequyer Leucippus Michael Levin Joseph Levine George Henry Lewes C.I.Lewis David Lewis Peter Lipton C. Lloyd Morgan John Locke Michael Lockwood Arthur O. Lovejoy E. Jonathan Lowe John R. Lucas Lucretius Alasdair MacIntyre Ruth Barcan Marcus Tim Maudlin James Martineau Nicholas Maxwell Storrs McCall Hugh McCann Colin McGinn Michael McKenna Brian McLaughlin John McTaggart Paul E. Meehl Uwe Meixner Alfred Mele Trenton Merricks John Stuart Mill Dickinson Miller G.E.Moore Thomas Nagel Otto Neurath Friedrich Nietzsche John Norton P.H.Nowell-Smith Robert Nozick William of Ockham Timothy O'Connor Parmenides David F. Pears Charles Sanders Peirce Derk Pereboom Steven Pinker Plato Karl Popper Porphyry Huw Price H.A.Prichard Protagoras Hilary Putnam Willard van Orman Quine Frank Ramsey Ayn Rand Michael Rea Thomas Reid Charles Renouvier Nicholas Rescher C.W.Rietdijk Richard Rorty Josiah Royce Bertrand Russell Paul Russell Gilbert Ryle Jean-Paul Sartre Kenneth Sayre T.M.Scanlon Moritz Schlick Arthur Schopenhauer John Searle Wilfrid Sellars Alan Sidelle Ted Sider Henry Sidgwick Walter Sinnott-Armstrong J.J.C.Smart Saul Smilansky Michael Smith Baruch Spinoza L. Susan Stebbing Isabelle Stengers George F. Stout Galen Strawson Peter Strawson Eleonore Stump Francisco Suárez Richard Taylor Kevin Timpe Mark Twain Peter Unger Peter van Inwagen Manuel Vargas John Venn Kadri Vihvelin Voltaire G.H. von Wright David Foster Wallace R. Jay Wallace W.G.Ward Ted Warfield Roy Weatherford C.F. von Weizsäcker William Whewell Alfred North Whitehead David Widerker David Wiggins Bernard Williams Timothy Williamson Ludwig Wittgenstein Susan Wolf Scientists David Albert Michael Arbib Walter Baade Bernard Baars Jeffrey Bada Leslie Ballentine Marcello Barbieri Gregory Bateson Horace Barlow John S. Bell Mara Beller Charles Bennett Ludwig von Bertalanffy Susan Blackmore Margaret Boden David Bohm Niels Bohr Ludwig Boltzmann Emile Borel Max Born Satyendra Nath Bose Walther Bothe Jean Bricmont Hans Briegel Leon Brillouin Stephen Brush Henry Thomas Buckle S. H. Burbury Melvin Calvin Donald Campbell Sadi Carnot Anthony Cashmore Eric Chaisson Gregory Chaitin Jean-Pierre Changeux Rudolf Clausius Arthur Holly Compton John Conway Jerry Coyne John Cramer Francis Crick E. P. Culverwell Antonio Damasio Olivier Darrigol Charles Darwin Richard Dawkins Terrence Deacon Lüder Deecke Richard Dedekind Louis de Broglie Stanislas Dehaene Max Delbrück Abraham de Moivre Bernard d'Espagnat Paul Dirac Hans Driesch John Eccles Arthur Stanley Eddington Gerald Edelman Paul Ehrenfest Manfred Eigen Albert Einstein George F. R. Ellis Hugh Everett, III Franz Exner Richard Feynman R. A. Fisher David Foster Joseph Fourier Philipp Frank Steven Frautschi Edward Fredkin Benjamin Gal-Or Howard Gardner Lila Gatlin Michael Gazzaniga Nicholas Georgescu-Roegen GianCarlo Ghirardi J. Willard Gibbs James J. Gibson Nicolas Gisin Paul Glimcher Thomas Gold A. O. Gomes Brian Goodwin Joshua Greene Dirk ter Haar Jacques Hadamard Mark Hadley Patrick Haggard J. B. S. Haldane Stuart Hameroff Augustin Hamon Sam Harris Ralph Hartley Hyman Hartman Jeff Hawkins John-Dylan Haynes Donald Hebb Martin Heisenberg Werner Heisenberg John Herschel Basil Hiley Art Hobson Jesper Hoffmeyer Don Howard John H. Jackson William Stanley Jevons Roman Jakobson E. T. Jaynes Pascual Jordan Eric Kandel Ruth E. Kastner Stuart Kauffman Martin J. Klein William R. Klemm Christof Koch Simon Kochen Hans Kornhuber Stephen Kosslyn Daniel Koshland Ladislav Kovàč Leopold Kronecker Rolf Landauer Alfred Landé Pierre-Simon Laplace Karl Lashley David Layzer Joseph LeDoux Gerald Lettvin Gilbert Lewis Benjamin Libet David Lindley Seth Lloyd Hendrik Lorentz Werner Loewenstein Josef Loschmidt Ernst Mach Donald MacKay Henry Margenau Owen Maroney David Marr Humberto Maturana James Clerk Maxwell Ernst Mayr John McCarthy Warren McCulloch N. David Mermin George Miller Stanley Miller Ulrich Mohrhoff Jacques Monod Vernon Mountcastle Emmy Noether Donald Norman Alexander Oparin Abraham Pais Howard Pattee Wolfgang Pauli Massimo Pauri Wilder Penfield Roger Penrose Steven Pinker Colin Pittendrigh Walter Pitts Max Planck Susan Pockett Henri Poincaré Daniel Pollen Ilya Prigogine Hans Primas Zenon Pylyshyn Henry Quastler Adolphe Quételet Pasco Rakic Nicolas Rashevsky Lord Rayleigh Frederick Reif Jürgen Renn Giacomo Rizzolati Emil Roduner Juan Roederer Jerome Rothstein David Ruelle David Rumelhart Tilman Sauer Ferdinand de Saussure Jürgen Schmidhuber Erwin Schrödinger Aaron Schurger Sebastian Seung Thomas Sebeok Franco Selleri Claude Shannon Charles Sherrington David Shiang Abner Shimony Herbert Simon Dean Keith Simonton Edmund Sinnott B. F. Skinner Lee Smolin Ray Solomonoff Roger Sperry John Stachel Henry Stapp Tom Stonier Antoine Suarez Leo Szilard Max Tegmark Teilhard de Chardin Libb Thims William Thomson (Kelvin) Richard Tolman Giulio Tononi Peter Tse Alan Turing Francisco Varela Vlatko Vedral Mikhail Volkenstein Heinz von Foerster Richard von Mises John von Neumann Jakob von Uexküll C. S. Unnikrishnan C. H. Waddington John B. Watson Daniel Wegner Steven Weinberg Paul A. Weiss Herman Weyl John Wheeler Wilhelm Wien Norbert Wiener Eugene Wigner E. O. Wilson Günther Witzany Stephen Wolfram H. Dieter Zeh Semir Zeki Ernst Zermelo Wojciech Zurek Konrad Zuse Fritz Zwicky Presentations Biosemiotics Free Will Mental Causation James Symposium |
Frederick Reif
Frederick "Fred" Reif earned his Ph.D in physics from Harvard University in 1953, with Ed Purcell as his thesis adviser. He went to work with Enrico Fermi at the University of Chicago. Seven years later, he went to the University of California, Berkeley, where he taught for twenty-nine years. At Berkeley he authored a classic text in statistical physics and thermodynamics, Statistical and Thermal Physics, published in 1965. At that time, the National Science Foundation supported the development of more modern textbook series in the physical sciences aimed at high schools students. At MIT, Jerrold Zacharias led the Physical Science Study Committee. At Harvard, Gerald Holton and Fletcher Watson led Project Physics. At Berkeley, Reif rewrote his textbook, titled simply Statistical Physics, as volume 5 of the Berkeley Physics Course. This book incorporated the first sophisticated computer calculations of the motions of gas molecules. As such, it was a landmark in the field of computational methods of solving problems in physics as opposed to solving mathematical differential equations. Displayed as frames in a movie film, the book's front cover illustrated the diffusion of molecules from an initial state concentrated in the left half of a two-dimensional space to filling the whole space after seven frames. Reif's work was a visualization of the second law of thermodynamics. Reif's movie frames led scientist Stephen Wolfram to develop his "New Kind of Science" using computational principles to derive the fundamental laws of physics.
On the back cover of the Reif book, the velocities of all the particles were reversed and the successive frames show the molecules making their way back into the left half. But they do not return to the exact original positions, due to "round-off errors" in the calculations. In principle, if the computer could have unlimited information about the positions and velocities (an infinite number of significant figures), all the molecule positions in the past and the future could be determined by Newton's laws of motion (F=ma, etc.). Classical physics is deterministic. In 1814, Pierre-Simon Laplace wrote in the introduction to his Essai philosophique sur les probabilités, "We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes." LaPlace was extending an earlier idea of Newton's contemporary Gottfried Leibniz, but it became famous as Laplace's Demon, a key concept of strict physical determinism. In his latest book, The Second Law, Stephen Wolfram says he spent fifty years trying to understand the deep physical significance of Reif's movie frames and the computations that produced them.
The great question for Wolfram, and for Reif, is this: if the equations of motion for microscopic collisions between gas particles are reversible, why are the macroscopic properties of gases irreversible, for example the entropy can only increase, never decrease, as the second law claims. In a recent YouTube video, Wolfram described the problem, And in his most recent book The Second Law (p.219), Wolfram describes Fred's book that started his fifty-year quest to understand the second law as follows.
The Backstory of the Book Cover That Started It All
What is the backstory of the book cover that launched my long journey with the Second Law? The book was published in 1965, and inside its front flap we find:
The book covers
The movie strips on the covers illustrate the fundamental ideas of irreversibility and fluctuations by showing the motion of 40 particles inside a two-dimensional box. The movie strips were produced by an electronic computer programmed to calculate particle trajectories. (For details, see pp. 7, 24, and 25 inside the book.) The front cover illustrates the irreversible approach to equilibrium starting from the highly nonrandom initial situation where all the particles are located in the left half of the box. The back cover (read in the upward direction from bottom to top) illustrates the irreversible approach to equilibrium if, starting from the initial situation at the top of the front cover, all the particle velocities are reversed (or equivalently, if the direction of time is imagined to be reversed). The back-cover and front-cover movie strips together, read consecutively in the downward direction, illustrate a very large fluctuation occurring extremely rarely in equilibrium. Wolfram designed the covers of his book to match the look of Fred's book, but with the computer calculations likely redone using his Mathematica and Wolfram Language tools, or perhaps the evolving hypergraphs of his cellular automata?
Is Physics Reversible or Irreversible?
The answer hinges on the question of fundamental randomness. Ludwig Boltzmann hypothesized there is some unknown process causing random behavior in the gas molecules that he called "molecular disorder" (molekular ungeordnete).
Since Newton's microscopic laws of motion of the gas particles are completely deterministic and time reversible, the great question for the past one-hundred and fifty years is how macroscopically, the gas appears to be irreversible. What can we say about the views of Fred Reif and Stephen Wolfram on the questions of randomness and reversibility? We can actually tell a lot by looking very carefully at the results of their computer calculations shown on the front and back covers of their books. Here are the front cover and back cover movie strips side by side.
Let's now carefully compare the starting frame on the front covers to the ending frame on the back covers. What can we say about the physics? Both back covers start by reversing the velocities of the molecules in the last frame on the front cover. Wolfram shows that explicitly by reversing the little white arrows. Let's look more closely at the starting and ending frames. Both evolve back to the left half of the frames, as if time itself was being reversed. But note that Reif's computations do not return each molecule back to its exact starting position, as do Wolfram's. Reif's calculations were done by Berni Alder on one of the most powerful computers in the 1960's, the Livermore Advanced Research Computer (LARC). Despite its power, the computer undoubtedly had roundoff errors, which caused the failure to return to their starting positions. Wolfram's molecules start in a rigid grid pattern, initially four rows of three squares, perhaps an artifact of his cellular automata? Although the back cover unfortunately cuts off the bottom row of four molecules, the 12 upper molecules have returned to their exact original positions, as classical Newtonian physics predicts. In Wolfram's terminology, classical physics is computationally reducible. |