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 Tom Clark 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 Werner Loewenstein Hendrik Lorentz Josef Loschmidt Alfred Lotka 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 A.A. Roback Emil Roduner Juan Roederer Jerome Rothstein David Ruelle David Rumelhart Robert Sapolsky 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 C. S. Unnikrishnan Francisco Varela Vlatko Vedral Vladimir Vernadsky Mikhail Volkenstein Heinz von Foerster Richard von Mises John von Neumann Jakob von Uexküll C. H. Waddington John B. Watson Daniel Wegner Steven Weinberg Paul A. Weiss Herman Weyl John Wheeler Jeffrey Wicken 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 |
Nonlocality
Nonlocality is today strongly associated with the idea of entanglement, but nonlocality is a property of a single quantum of light, whereas entanglement is a joint property of two quantum particles, depending on an even more subtle property called nonseparability.
Nonlocality is an essential element of the dual nature of light as both a wave and a particle. We can visualize the wave function of quantum mechanics in the following way. The wave function is a probability amplitude ψ whose squared modulus | ψ |2 gives the probability of finding a particle in a particular (sic) location. As this function spreads out in space, we can think of it as a "possibilities function," showing all the locations in space where there is a non-zero probability of finding a particle. The power of quantum mechanics is that we can calculate the probability of finding the particle for each possibility.
When an electron is freely traveling (as opposed to an electron bound in an atom), or when a photon is emitted from an electron and is traveling though space, there are always many possible locations for an interaction. Therefore we can say that the "possibilities function" (or the more formal quantum wave function) is inherently and intuitively nonlocal!
Since Werner Heisenberg and Paul Dirac first discussed the "collapse" of the wave function (Dirac's projection postulate), it has been appropriate to say that "one of the many possibilities has been made actual." In the language of nonlocality, we can now even more clearly say that one of the nonlocal possibilities has been actualized or localized!
Scattering is better understood as the absorption and rapid
In the case of the photon, it is localized when it has been scattered or absorbed by an electron. In the case of an electron, it might be a collision with another particle, or recombining with an ion to become bound in an atom. The electron is actually never found at a single point in four-dimensional space time, but remains nonlocal inside the minimal phase-space volume h3 required by the uncertainty principle (for example, a particular electron orbital wave function). Thus some physicists like to say there are no particles, just the appearance of a particle.
Albert Einstein was first to have seen single-particle nonlocality, in 1905, when he tried to understand how a spherical wave of light that goes off in many directions can be wholly absorbed at a single location. In his famous paper on the photo-electric effect (for which Einstein was awarded the Nobel Prize), he hypothesized that light must transmitted from one place to another as a discrete quantum of energy.
Einstein did not then use the term nonlocal or "local reality," but we can trace his thoughts backwards from 1935 to see that quantum nonlocality (and later nonseparability) were always major concerns, because neither can be made consistent with a continuous field theory and they may be inconsistent with the principle of relativity.
Einstein clearly described wave-particle duality as early as 1909, over a dozen years before the duality was made famous by Louis de Broglie's thesis showed that material particles also have a wavelike property.
When Einstein finished his great project of general relativity in 1916, he turned his attention back to light quanta and showed how electrons in atoms emit and absorb radiation. He found the process of emission was probabilistic (statistical). It is impossible to predict the time and the direction of the emission of a quantum of light, he said, just as Rutherford had shown the decay of a radioactive nucleus was statistical. The time and direction of an alpha particle ejected from a nucleus is pure chance.
Einstein said it was a "weakness" that the quantum theory was based on chance (Zufall in German). His 1916 work on the emission and absorption of light quanta (later called photons) predicted the amazing phenomenon of stimulated emission of radiation, which led to the development of the laser many decades later. As hard as it is to believe, most physicists, and especially Niels Bohr, refused to accept Einstein's theory of light quanta for another decade.
re-emission of a photon, as pointed out by Einstein and Paul Ehrenfest in 1933, in response to an article by Wolfgang Pauli ![]() Bohr's reaction to Einstein's presentation has been preserved. He didn't understand a word! He disingenuously claims he does not know what quantum mechanics is. His response is vague and ends with his vague ideas on complementarity and the inability to describe a causal spacetime reality. Twenty-two years later, in his contribution to the Schilpp memorial volume on Einstein, Bohr had no better response to Einstein's 1927 concerns. But he does remember and provides a picture of what Einstein drew on the blackboard. Here is Bohr's 1949 recollection:
At the general discussion in Como, we all missed the presence of Einstein, but soon after, in October 1927, I had the opportunity to meet him in Brussels at the Fifth Physical Conference of the Solvay Institute, which was devoted to the theme "Electrons and Photons."Although Bohr seems to have missed Einstein's point completely, Werner Heisenberg at least came to understand it very well. In his 1930 lectures at the University of Chicago, Heisenberg presented a critique of both particle and wave pictures, including a new example of nonlocality that Einstein had apparently developed since 1927. He wrote: In relation to these considerations, one other idealized experiment (due to Einstein) may be considered. We imagine a photon which is represented by a wave packet built up out of Maxwell waves. It will thus have a certain spatial extension and also a certain range of frequency. By reflection at a semi-transparent mirror, it is possible to decompose it into two parts, a reflected and a transmitted packet. There is then a definite probability for finding the photon either in one part or in the other part of the divided wave packet. After a sufficient time the two parts will be separated by any distance desired; now if an experiment yields the result that the photon is, say, in the reflected part of the packet, then the probability of finding the photon in the other part of the packet immediately becomes zero. The experiment at the position of the reflected packet thus exerts a kind of action (reduction of the wave packet) at the distant point occupied by the transmitted packet, and one sees that this action is propagated with a velocity greater than that of light. However, it is also obvious that this kind of action can never be utilized for the transmission of signals so that it is not in conflict with the postulates of the theory of relativity.Working backwards in time to Einstein's 1905 insight into nonlocality, we now review his amazing arguments about wave-particle duality in 1909. Einstein greatly expanded his light-quantum hypothesis in a presentation at the Salzburg conference in September, 1909. He argued that the interaction of radiation and matter involved elementary processes that are not reversible, a deep insight into the irreversibility of natural processes. While incoming spherical waves of radiation are mathematically possible, they are not practically achievable. Nature appears to be asymmetric in time. He speculates that the continuous electromagnetic field might be made up of large numbers of light quanta - singular points in the field that superimpose to create the wavelike behavior. Although he could not formulate a mathematical theory that does justice to both the oscillatory and quantum structures - the wave and particle pictures, Einstein argued that they are compatible. This was almost fifteen years before wave mechanics and quantum mechanics. And because gases behave statistically, he knows that the connection between wave and particles may involve probabilistic behavior, which he will prove in 1916. Here he is in 1909: When light was shown to exhibit interference and diffraction, it seemed almost certain that light should be considered a wave. The greatest advance in theoretical optics since the introduction of the oscillation theory was Maxwell's brilliant discovery that light can be understood as an electromagnetic process...One became used to treating electric and magnetic fields as fundamental concepts that did not require a mechanical interpretation. This path leads to the so-called relativity theory. I only wish to bring in one of its consequences, for it brings with it certain modifications of the fundamental ideas of physics. It turns out that the inertial mass of an object decreases by L / c2 when that object emits radiation of energy L...the inertial mass of an object is diminished by the emission of light.Now, back to 1905. Einstein's three 1905 papers on relativity, Brownian motion, and the light-quantum hypothesis (mischaracterized by many historians as the photo-electric effect), not only quantize the radiation field (Planck had only quantized matter, the virtual oscillators), but they also show on a careful reading that Einstein was concerned about faster-than-light actions thirty years before his Einstein-Podolsky-Rosen paper popularized the mysteries and paradoxes of quantum nonlocality and entanglement. Despite his foundational work quantizing radiation, Einstein rarely gets any credit for his contributions. There are a number of important reasons for this, which lead historians of quantum theory to start with Planck's quantum of action, then jump over Einstein's 1905 papers and his 1909 work on wave-particle duality to Niels Bohr's "old quantum theory" of the atom in 1913. Today, Bohr's "quantum jump" of an electron between stationary states is described as emitting or absorbing a "photon" of energy hν. In actuality, Bohr fought against Einstein's light-quantum hypothesis until the mid-1920's. Besides quantizing energy and seeing the interchangeability of radiation and matter, E = mc2, Einstein was the first scientist to see many of the most fundamental aspects of quantum physics, e.g., nonlocality and (the appearance of) instantaneous action-at-a-distance (1905), wave-particle duality (1909), statistical elementary processes that introduce indeterminism and acausality whenever matter and radiation interact (1916-17), coherence, interference, and the indistinguishability of elementary particles (1925), and the nonseparability and entanglement of interacting particles (1935). Ironically, and even tragically, Einstein could never accept most of his quantum discoveries, because they conflicted with his basic idea that nature is best described by a continuous field theory using differential equations that are functions of "local" variables, primarily the space-time four-vector of his general relativistic theory. Einstein's idea of a "local" reality is one where "action-at-a-distance" is limited to causal effects that propagate at or below the speed of light, according to his theory of relativity. He also famously disliked indeterminism ("God does not play dice"). Einstein's believed that quantum theory, as good as it is (and he saw nothing better), is "incomplete" because its statistical predictions (phenomenally accurate in the limit of large numbers of identical experiments - "ensembles" Einstein called them), tell us nothing about individual systems. Even worse, he thought that the wave functions of entangled systems predict faster-than-light correlations of properties between events in a space-like separation, violating his theory of relativity. This was the heart of his famous EPR paradox paper in 1935 (which introduced the concept of nonseparability), but we shall now see that Einstein was already concerned about faster-than-light transfer of energy in his very first paper on quantum theory.
The light-quantum hypothesis (1905)
Summary
We have shown that ever since Einstein hypothesized that light consists of small quanta of energy, he was concerned about a conflict with the picture of light as a wave. He saw that in many places distant from the point in space and time where the quantum actually appears as a detected particle, at that instant or a moment before, there existed the possibility (or probability) that the particle might have appeared somewhere else, somewhere separated in space so far as to prohibit signals from the detected quantum to that distant point where the particle did not appear.
How, he asked, or what sort of "action-at-a-distance" suppressed some sort of action happening at one of those other places where the probability of appearance had been non-zero? While Einstein is vague about the action that he has in mind, it is at least the disappearance, the sudden going to zero, of that probability. He cannot be imagining a second appearance of a particle. That would violate conservation of energy. He may be thinking of the interpretation of the wave function as representing some kind of knowledge about where the associated particle is likely to be found. How does that "knowledge" at the distant point or possible points "learn" that the particle will not in fact be appearing there?
Why does Einstein think that anything is needed beyond the fact that in this particular experiment, it appeared where it did and nowhere else?
something substantial = information
For Heisenberg - knowledge
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