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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
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.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
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
Jean-Pierre 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
John-Dylan Haynes
Martin Heisenberg
Werner Heisenberg
John Herschel
Jesper Hoffmeyer
E. T. Jaynes
William Stanley Jevons
Roman Jakobson
Pascual Jordan
Ruth E. Kastner
Stuart Kauffman
Simon Kochen
Stephen Kosslyn
Ladislav Kovàč
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
Ulrich Mohrhoff
Jacques Monod
Emmy Noether
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
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
 
John G. Cramer
John Cramer developed a new interpretation of the formalism of quantum mechanics called the "transactional interpretation."

The transactional interpretation makes no experimental predictions different from standard quantum mechanics. But it does remove some of the puzzling and perhaps unnecessary assumptions that are part of other Interpretations of quantum mechanics. In particular, it denies that conscious observers are needed to cause the "collapse of the wave function" (without which there is no actual "outcome" in the measurement process).

The transactional interpretation adds nothing ad hoc to the standard theory, such as "hidden variables or additional terms to the Schrōdinger equation to force a collapse. It is explicitly indeterministic and non-local. Cramer is exploring the radical possibility of sending information between entangled particles faster than the speed of light, as well as causal relations that go backwards in time (retrocausality). And, like Schrōdinger and the decoherence advocates, Cramer denies the existence of particles!

The core physics in the transactional interpretation is a way of looking at photon emissions and absorptions as an exchange of advanced and retarded waves that is based on the 1945 Wheeler-Feynman Absorber Theory of radiation, which was abandoned by Feynman, who went on to develop the Path Integral formulation of quantum mechanics and later, with Julian Schwinger and Sin-Itiro Tomonaga, the theory of Quantum Electrodynamics (QED).

While QED is a powerful theory that allows precise calculations of physical observables such as the motions of photons and electrons and the emission and absorption of a photon by an electron, the transactional interpretation is simply a way of looking at the emission and absorption of photons based on the Wheeler-Feynman attempt to describe the exchange of energy in the classical electromagnetic field as a time-symmetric process.

Wheeler-Feynman proposed adding advanced field potentials (which look like never-seen-in-nature incoming spherical waves converging on light sources) to the normal outgoing spherical waves (with retarded potentials) of classical electrodynamics. Wheeler and Feynman's goal was to symmetrize electrodynamics with respect to time. One view of the advanced-potential incoming waves is that they are going backwards in time. There is nothing inherent in electromagnetic theory that explains the time asymmetry we see in radiation propagation (forward-in-time outgoing waves only).

Cramer's transactional interpretation describes an electron as sending out probabilistic "offer waves" (OW) to potential absorbers. He adds what he calls "confirmation waves" (CW) incoming to an emitter from the many possible absorbers of an emitted photon. An offer wave is not an actual photon emission, and a confirmation wave is not an actual absorption or "detection" of a photon. But Cramer did see the two waves as connecting events in four-dimensional spacetime. Eventually, one advanced-potential confirmation wave indeterministically "handshakes" with the retarded-potential offer wave and produces an actual absorption.

This "handshake" completes the transaction, but perhaps not at a single point in spacetime. Cramer sees the transaction as "atemporal" in that it takes place all along the four-dimensional spacetime vector between the emission and absorption events. Because it happens over the extended space of a worldline of a photon between emission and absorption, Cramer says it is "explicitly nonlocal," but this linear space is tiny compared to the huge space of nonlocal behavior of two entangled particles in the EPR experiment, for example.

In the transactional interpretation the collapse of the state vector is interpreted as the completion of the transaction started by the OW and the CW exchanged between emitter and - absorber. The emergence of the transaction from the SV [state vector or wave function] does not occur at some particular location in space or at some particular instant of time, but rather forms along the entire four-vector that connects the emission locus with the absorption locus (or loci in the case of multiple correlated particles). The transaction employs both retarded and advanced waves, which propagate, respectively, along positive and negative lightlike (or timelike) four-vectors. Since the sum of these four-vectors can span spacelike and negative timelike and lightlike intervals, the "influence" of the transaction in enforcing the correlations of the quantum event is explicitly both nonlocal and atemporal.
Although Cramer does not specifically discuss the case of two entangled particles in the EPR experiment, his remarks about transactional atemporality apply to the case of Alice and Bob measuring particles at point a and point b. It does not matter whether Alice or Bob measures "first."
Since the transaction is atemporal, forming along the entire interval separating emission locus from absorption locus "at once, " it makes no difference to the outcome or the transactional description if separated experiments occur "simultaneously" or in any time sequence. There is likewise no issue of which of the separated measurements occurs first and precipitates the SV collapse, since in the transactional interpretation both measurements participate equally and symmetrically in the formation of the transaction. Furthermore, the paths across which the correlation enforcing exchange takes place are lightlike four-vectors and remain so under any Lorentz transformation. Therefore the outcome and the transactional description of any correlation experiment is the same independent of the inertial reference frame from which it is viewed, as it must be if quantum mechanics and relativity are to be compatible theories.
Cramer well knows that there are frames of reference moving with respect to the laboratory frame of the two observers in which the time order of the events can be reversed. In some moving frames Alice measures first, but in others Bob measures first.

If there is a special frame of reference (not a preferred frame in the relativistic sense), surely it is the one in which the origin of the two entangled particles is at rest. Assuming that Alice and Bob are also at rest in this special frame and equidistant from the origin, we arrive at the simple picture in which any measurement that causes the two-particle wave function to collapse makes both particles appear "simultaneously" at determinate places with fully correlated properties (just those that are needed to conserve energy, momentum, angular momentum, and spin).

In the two-particle case (instead of just one particle making an appearance), when either particle is measured, we know instantly those properties of the other particle that satisfy the conservation laws, including its location equidistant from, but on the opposite side of, the source, and its other properties such as spin.

We cannot measure just one particle in a two-particle wave function. As Schrödinger told Einstein in 1935, entanglement means that the particles cannot be represented as the product of single-particle wave functions.

Cramer says the transactional interpretation sheds light on the collapse of the state vector, identifying the collapse with as absorber's "handshake" with the emitter that completes the transaction. Is this in conflict with his view of transactions as time symmetric and fully reversible? Standard quantum mechanics insists that something thermodynamically irreversible must happen in a measurement. Cramer seems skeptical about irreversibility.

the Copenhagen interpretation implicitly associates with quantum events a time directionality that, while appropriate to macroscopic observers, is quite alien to and inconsistent with the even-handedness with which microphysics deals with the flow of time. Somehow the thermodynamic irreversibility of the macroscopic observer is intruding into the description of a fully reversible microscopic process. (p.651)

Wigner and others have suggested that the process of collapse should involve a special role for consciousness (Wigner, 1962), for permanent recording of experimental results (Schrödinger, 1935) or for entry of the system into the domain of thermodynamic irreversibility (Heisenberg, 1960). (p.654)

Where precisely is the border between macrophysics and microphysics and the border at which irreversibility begins? (p.683)

In the information interpretation, the collapse is when information about an event (it may not be a measurement) is irreversibly recorded in the universe. It need not be a measurement by an observer. Indeed, information must be recorded (for example, by a measuring instrument) before it can be seen by an observer.

Despite his description of the transactional "handshake" as atemporal, Cramer says the collapse occurs when the emitter accepts the confirmation wave from an absorber. It is the absorber that precipitates the collapse, he says,

In the transactional interpretation the collapse, i.e., the development of the transaction, is atemporal and thus avoids the contradictions and inconsistencies implicit in any time-localized SV collapse.

Furthermore, the transactional description does not need to invoke arbitrary collapse triggers, such as consciousness, etc., because it is the absorber rather than the observer which precipitates the collapse of the SV, and this can occur atemporally and nonlocally across any sort of interval between elements of the measuring apparatus.

Cramer is quite critical of the need for a "conscious observer."

This "consciousness" interpretation, while it is a reasonable working hypothesis for an observer who does not wish to find himself dissolved into the state vector of the system he is measuring, does beg a number of questions. Did the SV of the universe remain uncollapsed until the first consciousness evolved? Where is the borderline between consciousness and unconsciousness? Will "smart" measuring instruments eventually achieve the abihty to collapse SV's, and how will one know when they do? And so on.

Schrodinger (1935) suggested an alternative to the consciousness interpretation, which he called the principle of state distinction and which asserts, "states of a microscopic system which could be told apart by macroscopic observation are distinct from each other whether observed or not. " In other words, the SV collapses as soon as some macroscopic record of the result of a measurement is made, whether a conscious observer looks at that record or not. Heisenberg (1960) and others have suggested a variant of this position which asserts that as soon as the quantum measurement passes from the domain of reversible processes into the domain of thermodynamic irreversibility the SV collapses.

The latter two "collapse triggers" are more appealing to most physicists than the former because they avoid giving some special significance to consciousness and because, as pointed out by Weisskopf (1959,1980), they correspond more closely to the operating assumptions that practicing physicists use in thinking about how quantum measurements are done. However, these models also beg the question of borders: Where precisely is the border between macrophysics and microphysics and the border at which irreversibility begins?

The answer to Cramer's question about the border between microphysics and macrophysics is found in an analysis of the "quantum-to-classical transition" and in Heisenberg and von Neumann's speculations about the "cut" between quantum events and an observer's information, knowledge, or conscious awareness. Below the cut everything is governed by the wave function. Above the cut, Heisenberg and Bohr insisted a classical description must be used.

Decoherence theorists claim that the quantum-to-classical transition is caused by environmental interactions, but the information interpretation claims it is when a macroscopic object contains such a large number of atoms that independent quantum events that they can be averaged over, that their random phases cancel out, and that there is statistical determinism.

Heisenberg, von Neumann, Wigner, and many others puzzled over the location of the "cut," perhaps none more than John Bell, who drew a diagram of possible places for what he called the "shifty split." We can now edit Bell's diagram to point to the location of "cut" as the moment when irreversible information enters the universe.

The Possibilist Transactional Interpretation

In her 2012 book, The Transactional Interpretation of Quantum Mechanics, Ruth Kastner proposes to regard the outgoing offer wave and many incoming confirmation waves as "possible" transactions, only one of which indeterministically becomes "actual."

In our information interpretation of the wave function as a "possibilities" function, the possibilities are real in the sense that they can directly interfere with one another. Some thoughts are also real in the sense that they may lead to empirically observable actions.

Kastner is a possibilist who argues that OWs and CWs are possibilities that are "real." She says that they are less real than actual empirically measurable events, but more real than an idea or concept in a person's mind. She suggests the alternate term "potentia," Aristotle's term that she found Heisenberg had cited. For Kastner, the possibilities are physically real as compared to merely conceptually possible ideas that are consistent with physical law (for example, David Lewis' "possible worlds." But she says the "possibilities" described by offer and confirmation waves are "sub-empirical" and pre-spatiotemporal (i.e., they have not shown up as actual in spacetime). She calls these "incipient transactions."

The subtitle of Kastner's book is "The Reality of Possibility." She says that her main thesis is that "it is perfectly reasonable to be realist about the subject matter of quantum theory" (p.28). And she calls for a new metaphysical category to describe "not quite actual...possibilities."

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