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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 Bois-Reymond
Hilary Bok
Laurence BonJour
George Boole
Émile Boutroux
F.H.Bradley
C.D.Broad
Michael Burke
Lawrence Cahoone
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
Arthur Fine
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
Christoph Lehner
Keith Lehrer
Gottfried Leibniz
Jules Lequyer
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
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
William Whewell
Alfred North Whitehead
David Widerker
David Wiggins
Bernard Williams
Timothy Williamson
Ludwig Wittgenstein
Susan Wolf

Scientists

Michael Arbib
Walter Baade
Bernard Baars
Leslie Ballentine
Gregory Bateson
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
Hans Briegel
Leon Brillouin
Stephen Brush
Henry Thomas Buckle
S. H. Burbury
Donald Campbell
Anthony Cashmore
Eric Chaisson
Jean-Pierre Changeux
Arthur Holly Compton
John Conway
John Cramer
E. P. Culverwell
Olivier Darrigol
Charles Darwin
Richard Dawkins
Terrence Deacon
Lüder Deecke
Richard Dedekind
Louis de Broglie
Max Delbrück
Abraham de Moivre
Paul Dirac
Hans Driesch
John Eccles
Arthur Stanley Eddington
Gerald Edelman
Paul Ehrenfest
Albert Einstein
Hugh Everett, III
Franz Exner
Richard Feynman
R. A. Fisher
Joseph Fourier
Philipp Frank
Lila Gatlin
Michael Gazzaniga
GianCarlo Ghirardi
J. Willard Gibbs
Nicolas Gisin
Paul Glimcher
Thomas Gold
A.O.Gomes
Brian Goodwin
Joshua Greene
Jacques Hadamard
Mark Hadley
Patrick Haggard
Stuart Hameroff
Augustin Hamon
Sam Harris
Hyman Hartman
John-Dylan Haynes
Donald Hebb
Martin Heisenberg
Werner Heisenberg
John Herschel
Art Hobson
Jesper Hoffmeyer
E. T. Jaynes
William Stanley Jevons
Roman Jakobson
Pascual Jordan
Ruth E. Kastner
Stuart Kauffman
Martin J. Klein
Simon Kochen
Hans Kornhuber
Stephen Kosslyn
Ladislav Kovàč
Leopold Kronecker
Rolf Landauer
Alfred Landé
Pierre-Simon Laplace
David Layzer
Benjamin Libet
Seth Lloyd
Hendrik Lorentz
Josef Loschmidt
Ernst Mach
Donald MacKay
Henry Margenau
James Clerk Maxwell
Ernst Mayr
John McCarthy
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
Jürgen Renn/a>
Juan Roederer
Jerome Rothstein
David Ruelle
Tilman Sauer
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
Max Tegmark
William Thomson (Kelvin)
Giulio Tononi
Peter Tse
Vlatko Vedral
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
Konrad Zuse
Fritz Zwicky

Presentations

Biosemiotics
Free Will
Mental Causation
James Symposium
 
Christoph Lehner
Christoph Lehner is a philosopher of physics who has specialized in the history of quantum physics. He has been an adviser and organizer of a series of international conferences on the history of quantum physics.

His contribution to the 2014 Cambridge Companion to Einstein was on "Realism and Einstein's Critique of Quantum Mechanics." It was one of three articles focusing on Einstein's quantum physics. The others were Olivier Darrigol's "The Quantum Enigma" and Roger H. Stuewer's "The Experimental Challenge of Light Quanta."

Lehner's view of Einstein's realism is beyond the simple (though correct) idea that there is a real world of objects "out there" largely independent of human beings and especially physicists. It goes well beyond the logical empiricist view, derived from Immanuel Kant and Ernst Mach that it can logically (and phenomenologically) only consist of the "immediately given" sensations of experience, Kant's phenomenal world and Mach's economic summary of experiences.

And Einstein's "objective reality" takes us beyond the nonsense of many current quantum ideas, such as that nothing happens until a physicist make a measurement, at which point the universe splits, doubling its mass in extreme violation of the conservation laws that are the basis for Einstein's beliefs.

Einstein's Method

Lehner builds on philosopher of science Arthur Fine's view that Einstein is committed to a method, that Einstein's realism is not an epistemological claim about the relation between science and a mind-independent reality, but rather a "methodological" claim about science and its apparatus." Lehner calls this "methodological realism."

Einstein himself describes his method in his 1933 Herbert Spencer Lecture "On the Method of Theoretical Physics." Science is built on fundamental general "principles" rather than constructed on particular "facts." Einstein's principles are often invariances, like the constant speed of light in all inertial frames and the relativity principle that laws of physics are the same in all such frames, or the principle of covariance in his general relativity.

But well beyond his success in relativity, Einstein's principles include laws of symmetry and the conservation laws that derive from them. Where Niels Bohr spent many years challenging the conservation of energy when light interacts with matter, to preserve his idea that the light is a continuous wave and not Einstein's light quantum (our photon), Einstein based his predictions of how a photon would interact with an electron on the principle of conservation of momentum and energy, following his discovery that light particles have momentum.

Does the molecule receive an impulse when it absorbs or emits the energy ε? For example, let us look at emission from the point of view of classical electrodynamics. When a body emits the radiation ε it suffers a recoil (momentum) ε/c if the entire amount of radiation energy is emitted in the same direction. If, however, the emission is a spatially symmetric process, e.g., a spherical wave, no recoil at all occurs. This alternative also plays a role in the quantum theory of radiation. When a molecule absorbs or emits the energy ε in the form of radiation during the transition between quantum theoretically possible states, then this elementary process can be viewed either as a completely or partially directed one in space, or also as a symmetrical (nondirected) one. It turns out that we arrive at a theory that is free of contradictions, only if we interpret those elementary processes as completely directed processes.

Einstein had in 1916 and 1917 shown that Bohr's continuous and spherically symmetric radiation could not explain the randomly directed emissions of his light quanta. Bohr finally gave in when it was realized that Arthur Holly Compton's discovery of the "Compton Effect" had confirmed Einstein's prediction and invalidated the Bohr-Kramers-Slater claims.

Another of Einstein's basic principles is what he called "Boltzmann's principle" equating entropy with the logarithm of the number of possible arrangements of material particles in phase space, S = k lnW.

Lehner quotes Einstein's response to Moritz Schlick's book on physical reality,

What we now designate as "real" in physics is doubtlessly the "spatiotemporally arranged," not the "immediately given." The immediately given can be an illusion. The spatiotemporally arranged can be a sterile concept that doesn't contribute to the elucidation of the connections between the immediately given.

Lehner says that Einstein is proposing a distinction between "a phenomenal reality as the epistemological basis of our knowledge and a physical reality of spatiotemporally arranged events, which is an intellectual construct."

But as Einstein emphasizes, this "construct" is not built on empirical facts, but on "principles,"which are "free inventions of the human mind" that turn out to fit those facts in our experimental tests.

And Einstein's concern that "events" (point coincidences) in space time are "sterile" is precisely correct. Physics must also explain the behavior of "information structures," in particular their information exchanges (or interactions), which rise to the level of information "communications" between living things, the proper basis for the science of biology.

Information (e.g., one of Boltzmann's arrangements of molecules) is neither matter nor energy, though it needs matter for its embodiment and energy for its communication (or interaction).

Lehner's focus on space-time events reflects the concern of mathematical physicists who specialize in general relativity that "physical reality" consists of tenseless four-dimensional structures that describe all "past" and "future" events existing objectively the same as "present" events. This is John McTaggart's concept of an "A-series" and "B-series" of time.

In McTaggart's "B-series" all events have unchanging descriptions. It eliminates change, progress, and evolution. It was a "timeless" view, or as J. J. C. Smart called it, a "tenseless" view. It was influenced by the Einstein-Minkowski "block universe" in which events in the future are already out there in the four-dimensional space-time,

McTaggart argued that the A series is a necessary component of any full theory of time, since change only occurs in the "A series." But he said that the "A-series" is self-contradictory and that our perception of time is, therefore, ultimately an incoherent illusion.

A "tenseless" universe is the epitome of a deterministic universe, a view favored by most mathematical physicists and many philosophers of science.

Wave-particle duality
Lehner cites H. A. Lorentz's description of Einstein's tentative view, somewhat before Louis de Broglie's "matter waves"( which de Broglie credited to Einstein). In this view, light quanta are point particles whose motion is determined (statistically, of course) by a guiding wave or field (Führungsfeld). This had been Einstein's relation of wave to particle since at least 1909.

Lehner gives an extended discussion of Einstein's short extemporaneous presentation at the blackboard during the fifth Solvay conference. And several more pages are devoted to the fruitless debate with Bohr about the Einstein-Podolsky-Rosen paper and the "completeness" of quantum mechanics.

Lehner then discusses the new relevance of EPR in the light of John Bell's proposed experiments to test for the existence of (what Bell thought was) Einstein's idea of "additional variables", later called "hidden variables" by David Bohm. Bell's logic impressed many, including Lehner, but his physics is questionable.

Bell's work was presented as a theorem about measurable differences in the angular dependence of correlations between distant observers of spin or polarization components of entangled particles. He presented the theorem as a "inequalities" that would appear at certain angles. Young experimenters inspired by the charismatic Bell were very excited that their measurements might prove quantum physics wrong and (at least Bell's version of) Einstein's deterministic theory true. This was Bell's hope of course.

When the experiments confirmed quantum mechanics, Bell said sadly "Einstein's program fails." But it was only Bell's idea of Einstein's program that failed.

In the years since Bell derived his inequalities a large number of physicists work on the "foundations of physics," most hoping for a return to a determinist view, which they mistakenly think Einstein wanted. Einstein never doubted that indeterminism and a statistical interpretation would always be a part of quantum physics. His hopes were for a deeper unified field theory that would somehow underlie quantum physics.

Lehner quotes Einstein's worry that such a field theory might be impossible. He quotes Einstein:

"I consider it entirely possible that physics cannot be founded on the concept of a field, i.e:, on continuous constructs. Then, nothing will remain of my whole castle in the air, including the theory of gravitation, [but also the whole rest of contemporary physics."
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