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 Belsham Henri Bergson George Berkeley Isaiah Berlin Richard J. Bernstein Bernard Berofsky Robert Bishop Max Black Susanne Bobzien Emil du BoisReymond Hilary Bok Laurence BonJour George Boole Émile Boutroux F.H.Bradley C.D.Broad Michael Burke C.A.Campbell Joseph Keim Campbell Rudolf Carnap Carneades 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 Herbert Feigl John Martin Fischer Owen Flanagan Luciano Floridi Philippa Foot Alfred Fouilleé Harry Frankfurt Richard L. Franklin 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 William James Lord Kames Robert Kane Immanuel Kant Tomis Kapitan Jaegwon Kim William King Hilary Kornblith Christine Korsgaard Saul Kripke Andrea Lavazza Keith Lehrer Gottfried Leibniz Leucippus Michael Levin George Henry Lewes C.I.Lewis David Lewis Peter Lipton C. Lloyd Morgan John Locke Michael Lockwood E. Jonathan Lowe John R. Lucas Lucretius Alasdair MacIntyre Ruth Barcan Marcus James Martineau 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 Friedrich Nietzsche John Norton P.H.NowellSmith 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 JeanPaul Sartre Kenneth Sayre T.M.Scanlon Moritz Schlick Arthur Schopenhauer John Searle Wilfrid Sellars Alan Sidelle Ted Sider Henry Sidgwick Walter SinnottArmstrong 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 William Whewell Alfred North Whitehead David Widerker David Wiggins Bernard Williams Timothy Williamson Ludwig Wittgenstein Susan Wolf Scientists Michael Arbib Bernard Baars Gregory Bateson John S. Bell Charles Bennett Ludwig von Bertalanffy Susan Blackmore Margaret Boden David Bohm Niels Bohr Ludwig Boltzmann Emile Borel Max Born Satyendra Nath Bose Walther Bothe Hans Briegel Leon Brillouin Stephen Brush Henry Thomas Buckle S. H. Burbury Donald Campbell Anthony Cashmore Eric Chaisson JeanPierre Changeux Arthur Holly Compton John Conway John Cramer E. P. Culverwell Charles Darwin Terrence Deacon Louis de Broglie Max Delbrück Abraham de Moivre Paul Dirac Hans Driesch John Eccles Arthur Stanley Eddington Paul Ehrenfest Albert Einstein Hugh Everett, III Franz Exner Richard Feynman R. A. Fisher Joseph Fourier Lila Gatlin Michael Gazzaniga GianCarlo Ghirardi J. Willard Gibbs Nicolas Gisin Paul Glimcher Thomas Gold A.O.Gomes Brian Goodwin Joshua Greene Jacques Hadamard Patrick Haggard Stuart Hameroff Augustin Hamon Sam Harris Hyman Hartman JohnDylan Haynes Martin Heisenberg Werner Heisenberg John Herschel Jesper Hoffmeyer E. T. Jaynes William Stanley Jevons Roman Jakobson Pascual Jordan Ruth E. Kastner Stuart Kauffman Martin J. Klein Simon Kochen Stephen Kosslyn Ladislav Kovàč Rolf Landauer Alfred Landé PierreSimon Laplace David Layzer Benjamin Libet Seth Lloyd Hendrik Lorentz Josef Loschmidt Ernst Mach Donald MacKay Henry Margenau James Clerk Maxwell Ernst Mayr Ulrich Mohrhoff Jacques Monod Emmy Noether Abraham Pais Howard Pattee Wolfgang Pauli Massimo Pauri Roger Penrose Steven Pinker Colin Pittendrigh Max Planck Susan Pockett Henri Poincaré Daniel Pollen Ilya Prigogine Hans Primas Adolphe Quételet Juan Roederer Jerome Rothstein David Ruelle Erwin Schrödinger Aaron Schurger Claude Shannon David Shiang Herbert Simon Dean Keith Simonton B. F. Skinner Roger Sperry John Stachel Henry Stapp Tom Stonier Antoine Suarez Leo Szilard William Thomson (Kelvin) Peter Tse Heinz von Foerster John von Neumann John B. Watson Daniel Wegner Steven Weinberg Paul A. Weiss John Wheeler Wilhelm Wien Norbert Wiener Eugene Wigner E. O. Wilson H. Dieter Zeh Ernst Zermelo Wojciech Zurek Presentations Biosemiotics Free Will Mental Causation James Symposium 
Max Planck
In 1900, Max Planck's hypothesized a quantum of action h and restricted the energy in oscillators radiating electromagnetic energy to integer multiples of hν, where ν is the radiant frequency. He then discovered a formula for the distribution of radiant energy in a black body at any temperature.
B_{ν} (v, T) = (2hν^{3} / c^{2}) (1 / ( e ^{hν / kT}  1) )
Planck solved the great problem of blackbody radiation by applying the statistical mechanics of the MaxwellBoltzmann velocity distribution law for particles to the distribution of energy in a radiation field. Planck did not suggest that light actually came in quantized (discrete) bundles of energy. That was the work of Albert Einstein five years later in his photoelectric effect paper (for which he won the Nobel Prize), in which he proposed his "lightquantum hypothesis." For Einstein, the particle equivalent of light (later called a "photon") contains hν units of energy, where h is Planck's constant and ν is the frequency of the light wave. Planck did not actually believe that light radiation itself existed as light quanta. His quantization assumption was for an ensemble of "oscillators" or "resonators" that were emitting and absorbing the radiation. Although the Lorentz theory of the electron was already complete, Planck did not accept electrons and instead described "the energy flowing across a spherical surface of a certain radius containing the resonator." He assumed the resonators could be described as having energy values limited to multiples of hν. Note the resemblance to the Bohr theory of the atom thirteen years later, where Bohr postulated stationary states of the electron and transitions between those states with the emission or absorption of continuous waves of energy equal to hν! Planck's assumption was simply a mathematical device to make the distribution of light as a function of frequency (and thus energy) resemble the MaxwellBoltzmann distribution of molecular velocities in a gas as a function of velocity (and thus energy). In 1925, he called his work "a fortunate guess at an interpolation formula" and "the quantum of action a fictitious quantity... nothing more than mathematical juggling." Note the resemblance between the distribution of blackbody radiation as a function of temperature and the MaxwellBoltzmann distribution of velocities.
The similarity between the two is the rise to a maximum with a power law on one side and an exponential decline on the other. The difference is because the radiant energy (the number of photons) increases greatly as temperature goes up, but the number of molecules is held constant. Planck in 1900 explained the spectral distribution of colors (wavelengths) in blackbody electromagnetic radiation by using Boltzmann’s principle that the entropy S of a gas is related to the probabilities W for the possible random distributions of molecules in different places in its container and with different velocities. S = k logW, where k is Boltzmann’s constant (so named by Planck. Boltzmann and Einstein used R/N) ). Boltzmann’s calculations of probabilities used the number of ways that particles can be distributed in various volumes of phase space. Planck used the same combinatorial analysis, but now for the number of ways that discrete elements of energy could be distributed among a number of radiation oscillators. To simplify calculations, both Boltzmann and Planck assumed that energies could be considered multiples of a unit of energy, E = ε, 2ε, 3ε ... Plank regarded this quantum hypothesis as a mathematically convenient device, but not representing reality. He found the density of radiation with frequency ν to be
ρ_{ν} = (8πhν^{3}/c^{2}) / (e^{hν/kT}  1). Planck's "blackbody" radiation law was the first known connection between the mechanical laws of matter and the laws of electromagnetic energy. Planck realized that he had made a great step in physical understanding, "the greatest discovery in physics since Newton," he reportedly told his sevenyearold son in 1900. In particular, Planck found that Boltzmann's statistical mechanics constant k = R/N, derived from the distribution of velocities of material gas particles, appears in his new law for the distribution of electromagnetic radiation energy. Boltzmann himself had never described this constant k as such. It was Planck who gave it a symbol and a name, although it is inscribed on Boltzmann's tomb in his famous formula relating entropy to probability, S = k logW Planck established an independent and very accurate value for Boltzmann's constant. His blackbody radiation distribution law of course also includes the new Planck constant h. He called it the "quantum of action" because it had the units of position times momentum. Planck's formula led him to a value for Avogadro's number of molecules in a mole (the gram molecular weight) of a gas and an estimate of the fundamental unit of electrical charge. These gave Planck great confidence that his "fictitious" formula must be correct. Five years later, Albert Einstein explained the photoelectric effect using "light quanta," discrete units of light energy, later called photons. Since the momentum of a particle is the energy divided by velocity of a particle, the momentum p of a photon is p = hν/c, where c is the velocity of light. To make the dual aspect of light as both waves and particles (photons) more plausible, Einstein interpreted the square of the light wave amplitude as the probable density of photons. In fact, Planck fundamentally disliked the idea that physical quantities might be discrete and not continuous. He did not truly accept quanta of light until many years after Einstein had shown the quantization of light in his 1905 explanation of the photoelectric effect. Nevertheless, Planck's constant h lies at the heart of quantum mechanics, which introduced an irreducible and ontological randomness or indeterminacy into physics, first recognized by Einstein in his 1916 work on transition probabilities for the emission and absorption of light quanta. Planck, along with Einstein, Erwin Schrödinger and others, opposed such indeterminism. Einstein called chance a "weakness in the theory." Planck remained convinced that determinism and strict causality were essential requirements for physical science and so must be true.
"Just as no physicist will in the last resort acknowledge the play of chance in human nature, so no physiologist will admit the play of chance in the absolute sense." Planck looked very closely at the problem of free will, and gave a rough version of the logical opposition between determinism and blind chance in the standard argument against free will. "And here a question arises which seems to set a definite impassable limit to the principle of strict causality, at least in the spiritual sphere. This question is of such urgent human interest that I think it will be well if I treat it here before I come to a close. It is the question of the freedom of the human will. Our own consciousness tells us that our wills are free. And the information which that consciousness directly gives us is the last and highest exercise of our powers of understanding. In 1925, as the development of quantum mechanics began in earnest, Planck republished a series of articles as the book A Survey of Physical Theory. In an article on "The Nature of Light," Planck describes Einstein's insight in 1905 that led to Einstein's "lightquantum hypothesis." But Planck does not explicitly mention Einstein! When ultraviolet rays fall on a piece of metal in a vacuum, a large number of electrons are shot off from the metal at a high velocity, and since the magnitude of this velocity does not essentially depend on the state of the metal, certainly not on its temperature, it is concluded that the energy of the electrons is not derived from the metal, but from the light rays which fall on the metal. This would not be strange in itself; it would even be assumed that the electromagnetic energy of light waves, is transformed into the kinetic energy of electronic movements. An apparently insuperable difficulty from the view of Huygens's wave theory is the fact (which was discovered by Philipp Lenard and others), that the velocity of the electrons does not depend on the intensity of the beam, but only on the wavelength, i.e. on the colour of light used. The velocity increases as the wavelength diminishes. If the distance between the metal and the source of light is continuously increased, using, for example, an electric spark as the source of light, the electrons continue to be flung off with the same velocity, in spite of the weakening of the illumination; the only difference is that the number of electrons thrown off per second decreases with the intensity of the light.In the final article. "The Origin and Development of Quantum Theory," which was to be Planck's last writing on quantum theory, as he turned back to classical problems, Planck has a minimum reference to Einstein. as one of many "who made use" of his quantum of action, and still no mention of Einstein's photoelectric effect prediction which Planck described extensively in the previous article. ...the restless, everadvancing labour of those workers who have made use of the quantum of action in their investigations.
Irreversibility
In 1909, Einstein first suggested that the elementary process of radiation emission may be irreversible.
In 1916, Einstein derived the Planck law of radiation and Bohr's two quantum postulates (stationary states and transitions between states with E = hν). By contrast, Planck's "discovery" of his law was accomplished by trial and error guesses at the mathematical form. Einstein derived it from more basic principles. Planck did give Einstein more credit in his 1920 Nobel lecture, "The Genesis and Present State of Development of the Quantum Theory". He asked whether the quantum of action was a fictional quantity or would it play a fundamental role in physics, ... something entirely new, never before heard of, which seemed called upon to basically revise all our physical thinking, built as this was ... on the acceptance of the continuity of all causative connections. He gave the major credit for the second alternative to Einstein: Experiment has decided for the second alternative. That the decision could be made so soon and so definitely was due not to the proving of the energy distribution law of heat radiation, still less to the special derivation of that law devised by me, but rather should it be attributed to the restless forward thrusting work of those research workers who used the quantum of action to help them in their own investigations and experiments. The first impact in this field was made by A. Einstein who, on the one hand, pointed out that the introduction of the energy quanta, determined by the quantum of action, appeared suitable for obtaining a simple explanation for a series of noteworthy observations during the action of light, such as Stokes' Law, electron emission, and gas ionization, and, on the other hand, derived a formula for the specific heat of a solid body through the identification of the expression for the energy of a system of resonators with that of the energy of a solid body, and this formula expresses, more or less correctly, the changes in specific heat, particularly its reduction with falling temperature. The result was the emergence, in all directions, of a number of problems whose more accurate and extensive elaboration in the course of time brought to light a mass of valuable material...
References
Scientific Autobiography (1947) Dynamical Laws and Statistical Laws The Genesis and Present State of Development of the Quantum Theory (Nobel Lecture  1920) Improvement in Wien Spectrum, October 19, 1900a Energy Distribution Law, December 14, 1900b Distribution of Energy in the Normal Spectrum, 1901a Original Papers in Quantum Physics, with Notes by H. Kangro The Origin and Development of Quantum Theory (A rewrite of the Nobel Lecture) Max Planck Biography, by K. A. G. Mendelssohn, from A Physics Anthology, ed. Norman Clarke, 1960
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