Follow infophilosopher:
|
|
|
|
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 Jeremy Butterfield 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 U.T.Place 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 John Duns Scotus Arthur Schopenhauer John Searle Wilfrid Sellars David Shiang Alan Sidelle Ted Sider Henry Sidgwick Walter Sinnott-Armstrong Peter Slezak 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 Augustin-Jean Fresnel 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 Travis Norsen 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 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 |
Epistemological Letters
Hidden Variables and Quantum Uncertainty
Between 1973 and 1984, thirty-six issues of a privately published newsletter were circulated to about 180 of the most prominent physicists in the world. It contained contributions on the foundations of physics inspired by the work of John Bell, which in turn had been inspired by David Bohm's revival of Louis de Broglie's "pilot wave theory."
The Epistemological Letters were digitized and cataloged at Notre Dame's Hesburgh Libraries under the supervision of philosopher of science Don Howard and his graduate student Sebastián Margueitio Ramírez.
Here is a rough translation of the "Elementary Introduction" in the first issue, De quoi s'agit-il? It set the stage and opened the discussion.
In the nineteenth century, Fresnel proves, by experiments considered as irrefutable, the wave character of light. 1905 Einstein suggests explaining the photoelectric effect by a corpuscular theory of light, using the quanta recently discovered by Planck. 1924 To explain whole numbers (quantum numbers) which appeared in the quantum theory and based on Hamilton-Jacobi mechanics, de Broglie conversely proposes to associate a wave with material corpuscles such as the electron. One therefore has, in these two fields, coexistence of a wave theory and a corpuscular theory. The problem arises of reconciling them. 1926 Born interprets the amplitude of the wave (or rather the square of its modulus) as a probability density of the presence of a particle, an interpretation universally accepted today. Bohr and Heisenberg introduce the notion of complementarity: according to the experiment one proposes to do, physical reality sometimes appears under the corpuscular aspect, sometimes under the wave aspect. Experiments show one or the other mutually exclusive aspect. There is never experimental contradiction. But our conception of physical reality must be a synthesis of these two aspects contradictory and yet complementary. 1927 At the Solvay congress, a big discussion between the great theoretical physicists. Einstein disputes the interpretation of Bohr and Heisenberg (Copenhagen School). De Broglie offers a so-called pilot wave theory or he admits that the trajectory of the corpuscle is determined by the wave as it is where it is (theory of the pilot wave ), Because it must be said that the Born statistical interpretation does not resolve every problems. Take for example Young's experience: We drill two holes in a screen A and we examine what happens on screen B when sending light through the holes
Epistemological Letters Index
Hidden Variables and Quantum Uncertainty
Issue 1, February 1973
|
On screen B we observe interference fringes which can be explained very well by a wave theory.
On the other hand, in a corpuscular theory, we
have great difficulties. Because the interference figure that we get on screen B is not
simply the superimposition of what we would get with each hole separately. To some
places, there is less light when the
two holes are open than when only one
is open. It’s also experiences of this
guy who had allowed Fresnel to lay down his
wave theory.
Suppose now that we send a light
very weak, so that it doesn’t fall on
The device that has a grain of light (photon)
sometimes. This photon will either pass through
one hole or through the other.
The trajectory of the photon which passes through a hole
must therefore be modified by the fact that the second hole is open or not, even if it no photon passes through this second hole.
Now what can pass through this second hole?
We have a ready answer: the wave associated
with the corpuscle.
But if this wave only represents a probability of presence, how can we understand that it physically influences the trajectory of the corpuscle? Because a probability, on an individual event represents nothing real: either a photon is in a certain area or else it is not
there. Probability only took meaning
statistically, over a large number of events
of the same type. As Ashby says, the
notion of probability makes it possible to artificially attribute to an individual event a property which belongs only to a set of events of the same type. How are we to understand how this
set of events, which are not concretely present at the time of the passage of the photon,
can influence its movement?
We therefore understand that L. de Broglie was led to formulate a so-called double theory
solution, which assumes that the equation of
Schrödinger admits two solutions: one being
the Ψ wave, giving the probability of presence,
the other being a physical wave u which could
influence the trajectory of the corpuscle of such
so that statistically the probability of
presence of the corpuscle restores that predicted by
the Ψ wave. (More precisely, the wave u would be
a nonlinear solution comprising singularities which would represent the corpuscles :)
But, faced with the mathematical difficulties encountered, he fell back on the theory of the more
simple pilot wave.
The discussion started at the Solvay congress did not
never completely die. The majority of physicists are rallying around the Copenhagen interpretation, which refuses to ask questions about an individual event in
space-time and is only interested in
what we can actually measure..
But some physicists, not least
(Einstein, Schrödinger, De Broglie, Bohm), all
admitting the experimental successes of quantum mechanics, remained of the opinion that
we should obtain a description having the true character of reality, that is to say,
not dependent on what the observer arbitrarily decided to measure.
An example may help to understand better:
in thermodynamics, we can describe a macroscopic system using global quantities::
temperature, pressure etc. and enact laws
for the evolution of these quantities.
Boltzmann and Gibbs succeeded, starting from a
model of molecules obeying the laws of mechanics
to find these macroscopic magnitudes and the laws which govern them.
From the point of view of macroscopic thermodynamics, the positions and velocities of individual molecules may be hidden variables?
not predictable. But we can make reasonable assumptions about these hidden variables and recover thermodynamics, its magnitudes and
its laws.
In this sense, macroscopic (or "phenomenological") thermodynamics
is not a complete description; it only processes molecules
by statistical, global quantities,
averages; it does not take into account movements
and individual deviations and proves unable to
predict phenomena such as fluctuations.
Likewise, according to Einstein and others, the same.
quantum quantum would not be a complete description. We will have to invent a theory making certain assumptions about hidden variables, inaccessible to experience, (such
as velocity, position, and trajectory of the corpuscles), the theory which underlies quantum mechanics like statistical mechanics underpins phenomenological thermodynamics. And
it's our ignorance of the value of some
parameters that would force us to fall back
on a statistical description. Indeterminism
it will not be in the things themselves, it would come from our ignorance.
The developments are as follows:
Bell was able to show in 1965 that, using certain reasonable assumptions, theories of
hidden variables had to satisfy a certain inequality, an inequality which would allow them
to differentiate their predictions from those of quantum mechanics.
An experiment was proposed by Shimony, Horne,
Holt and Clauser, then carried out by Freedman and
Clauser. It gave a result clearly supporting quantum mechanics and excluding
at least some type of hidden variable theories.
The discussion is open to evaluate the scope of the
exact results and the consequences
we must draw from it.
