Antony Valentini

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Antony Valentini
Born
Antony Valentini

(1965-01-28) 28 January 1965 (age 59)
Greenwich, London, England
Alma mater
Known for
Scientific career
Fields
Institutions
Thesis On the Pilot-Wave Theory of Classical, Quantum and Subquantum Physics  (1992)
Doctoral advisor Dennis Sciama

Antony Valentini is a British-Italian theoretical physicist known for his work on the foundations of quantum physics. [1]

Contents

Education and career

Valentini obtained an undergraduate degree from Cambridge University, then earned his Ph.D. in 1992 [2] with Dennis Sciama at the International School for Advanced Studies (ISAS-SISSA) in Trieste, Italy. [1] [3] In 1999, after seven years in Italy, he took up a post-doc grant to work at the Imperial College with Lee Smolin and Christopher Isham. [1]

He worked at the Perimeter Institute for Theoretical Physics. In February 2011, he became professor of physics and astronomy at Clemson University; as of 2022, he was listed as adjunct faculty. [4] [5]

Together with Mike Towler, Royal Society research fellow of the University of Cambridge's Cavendish Laboratory, he organized a conference on the de Broglie-Bohm theory the Apuan Alps Centre for Physics in August 2010, hosted by the Towler Institute located in Vallico di Sotto in Tuscany, Italy, which is loosely associated with the Theory of Condensed Matter group of the Cavendish Laboratory. [6] [7] Among the questions announced for discussion, the organizers included "Why should young people be interested in these ideas, when showing interest in quantum foundations still might harm their careers?" [8]

Work

Valentini has been working on an extension of the causal interpretation of quantum theory. This interpretation had been proposed in conceptual terms in 1927 by Louis de Broglie, was independently re-discovered by David Bohm who brought it to a complete and systematic form in 1952, and was expanded on by Bohm and Hiley. Emphasizing de Broglie's contribution, Valentini has consistently referred to the causal interpretation of quantum mechanics underlying his work as the "de Broglie–Bohm theory".

Quantum equilibrium, locality and uncertainty

In 1991, Valentini provided indications for deriving the quantum equilibrium hypothesis which states that in the frame work of the pilot wave theory. Valentini showed that the relaxation → may be accounted for by a H-theorem constructed in analogy to the Boltzmann H-theorem of statistical mechanics. Valentini showed that his expansion of the De Broglie–Bohm theory would allow "signal nonlocality" for non-equilibrium cases in which ≠. [9] [10] [11] According to Valentini, the universe is fundamentally nonlocal, and quantum theory merely describes a special equilibrium state in which nonlocality is hidden in statistical noise. [12] He furthermore showed that an ensemble of particles with known wave function and known nonequilibrium distribution could be used to perform, on another system, measurements that violate the uncertainty principle. [13]

In 1992, Valentini extended pilot wave theory to spin- fields and to gravitation. [14]

Background and implications

Valentini has been described as an "ardent admirer of de Broglie". He noted that "de Broglie (rather like Maxwell) emphasized an underlying 'mechanical' picture: particles were assumed to be singularities of physical waves in space". [15] He emphasized that de Broglie, with the assistance of Erwin Schrödinger, had constructed pilot wave theory, but later abandoned it in favor of quantum formalism. [3]

Valentini's derivation of the quantum equilibrium hypothesis was criticized by Detlef Dürr and co-workers in 1992, and the derivation of the quantum equilibrium hypothesis has remained a topic of active investigation. [16]

"Signal nonlocality", which is forbidden in orthodox quantum theory, would allow nonlocal quantum entanglement to be used as a stand-alone communication channel without the need of a classical light-speed limited retarded signal to unlock the entangled message from the sender to the receiver. This would be a major revolution in physics and would possibly make the cosmic landscape string theory Popper falsifiable.

Publications

Book
Articles

Related Research Articles

<span class="mw-page-title-main">Double-slit experiment</span> Physics experiment, showing light and matter can be modelled by both waves and particles

In modern physics, the double-slit experiment demonstrates that light and matter can satisfy the seemingly incongruous classical definitions for both waves and particles. This ambiguity is considered evidence for the fundamentally probabilistic nature of quantum mechanics. This type of experiment was first performed by Thomas Young in 1801, as a demonstration of the wave behavior of visible light. In 1927, Davisson and Germer and, independently George Paget Thomson and his research student Alexander Reid demonstrated that electrons show the same behavior, which was later extended to atoms and molecules. Thomas Young's experiment with light was part of classical physics long before the development of quantum mechanics and the concept of wave–particle duality. He believed it demonstrated that Christiaan Huygens' wave theory of light was correct, and his experiment is sometimes referred to as Young's experiment or Young's slits.

<span class="mw-page-title-main">Einstein–Podolsky–Rosen paradox</span> Historical critique of quantum mechanics

The Einstein–Podolsky–Rosen (EPR) paradox is a thought experiment proposed by physicists Albert Einstein, Boris Podolsky and Nathan Rosen which argues that the description of physical reality provided by quantum mechanics is incomplete. In a 1935 paper titled "Can Quantum-Mechanical Description of Physical Reality be Considered Complete?", they argued for the existence of "elements of reality" that were not part of quantum theory, and speculated that it should be possible to construct a theory containing these hidden variables. Resolutions of the paradox have important implications for the interpretation of quantum mechanics.

<span class="mw-page-title-main">Louis de Broglie</span> Nobel Laureate physicist (1892–1987)

Louis Victor Pierre Raymond, 7th Duc de Broglie was a French aristocrat and physicist who made groundbreaking contributions to quantum theory. In his 1924 PhD thesis, he postulated the wave nature of electrons and suggested that all matter has wave properties. This concept is known as the de Broglie hypothesis, an example of wave–particle duality, and forms a central part of the theory of quantum mechanics.

The de Broglie–Bohm theory, also known as the pilot wave theory, Bohmian mechanics, Bohm's interpretation, and the causal interpretation, is an interpretation of quantum mechanics. It postulates that in addition to the wavefunction, an actual configuration of particles exists, even when unobserved. The evolution over time of the configuration of all particles is defined by a guiding equation. The evolution of the wave function over time is given by the Schrödinger equation. The theory is named after Louis de Broglie (1892–1987) and David Bohm (1917–1992).

Bell's theorem is a term encompassing a number of closely related results in physics, all of which determine that quantum mechanics is incompatible with local hidden-variable theories, given some basic assumptions about the nature of measurement. "Local" here refers to the principle of locality, the idea that a particle can only be influenced by its immediate surroundings, and that interactions mediated by physical fields cannot propagate faster than the speed of light. "Hidden variables" are putative properties of quantum particles that are not included in quantum theory but nevertheless affect the outcome of experiments. In the words of physicist John Stewart Bell, for whom this family of results is named, "If [a hidden-variable theory] is local it will not agree with quantum mechanics, and if it agrees with quantum mechanics it will not be local."

<span class="mw-page-title-main">Schrödinger equation</span> Description of a quantum-mechanical system

The Schrödinger equation is a linear partial differential equation that governs the wave function of a quantum-mechanical system. Its discovery was a significant landmark in the development of quantum mechanics. It is named after Erwin Schrödinger, who postulated the equation in 1925 and published it in 1926, forming the basis for the work that resulted in his Nobel Prize in Physics in 1933.

<span class="mw-page-title-main">Wigner's friend</span> Thought experiment in theoretical quantum physics

Wigner's friend is a thought experiment in theoretical quantum physics, first published by the Hungarian-American physicist Eugene Wigner in 1961, and further developed by David Deutsch in 1985. The scenario involves an indirect observation of a quantum measurement: An observer observes another observer who performs a quantum measurement on a physical system. The two observers then formulate a statement about the physical system's state after the measurement according to the laws of quantum theory. In the Copenhagen interpretation, the resulting statements of the two observers contradict each other. This reflects a seeming incompatibility of two laws in the Copenhagen interpretation: the deterministic and continuous time evolution of the state of a closed system and the nondeterministic, discontinuous collapse of the state of a system upon measurement. Wigner's friend is therefore directly linked to the measurement problem in quantum mechanics with its famous Schrödinger's cat paradox.

<span class="mw-page-title-main">Wave function</span> Mathematical description of the quantum state of a system

In quantum physics, a wave function is a mathematical description of the quantum state of an isolated quantum system. The most common symbols for a wave function are the Greek letters ψ and Ψ. Wave functions are complex-valued. For example, a wave function might assign a complex number to each point in a region of space. The Born rule provides the means to turn these complex probability amplitudes into actual probabilities. In one common form, it says that the squared modulus of a wave function that depends upon position is the probability density of measuring a particle as being at a given place. The integral of a wavefunction's squared modulus over all the system's degrees of freedom must be equal to 1, a condition called normalization. Since the wave function is complex-valued, only its relative phase and relative magnitude can be measured; its value does not, in isolation, tell anything about the magnitudes or directions of measurable observables. One has to apply quantum operators, whose eigenvalues correspond to sets of possible results of measurements, to the wave function ψ and calculate the statistical distributions for measurable quantities.

In physics, a hidden-variable theory is a deterministic physical model which seeks to explain the probabilistic nature of quantum mechanics by introducing additional variables.

<span class="mw-page-title-main">Pilot wave theory</span> One interpretation of quantum mechanics

In theoretical physics, the pilot wave theory, also known as Bohmian mechanics, was the first known example of a hidden-variable theory, presented by Louis de Broglie in 1927. Its more modern version, the de Broglie–Bohm theory, interprets quantum mechanics as a deterministic theory, avoiding troublesome notions such as wave–particle duality, instantaneous wave function collapse, and the paradox of Schrödinger's cat. To solve these problems, the theory is inherently nonlocal.

<span class="mw-page-title-main">Wigner quasiprobability distribution</span> Wigner distribution function in physics as opposed to in signal processing

The Wigner quasiprobability distribution is a quasiprobability distribution. It was introduced by Eugene Wigner in 1932 to study quantum corrections to classical statistical mechanics. The goal was to link the wavefunction that appears in Schrödinger's equation to a probability distribution in phase space.

In quantum mechanics, the Kochen–Specker (KS) theorem, also known as the Bell–Kochen–Specker theorem, is a "no-go" theorem proved by John S. Bell in 1966 and by Simon B. Kochen and Ernst Specker in 1967. It places certain constraints on the permissible types of hidden-variable theories, which try to explain the predictions of quantum mechanics in a context-independent way. The version of the theorem proved by Kochen and Specker also gave an explicit example for this constraint in terms of a finite number of state vectors.

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Basil J. Hiley, is a British quantum physicist and professor emeritus of the University of London.

James Thomas Cushing was an American theoretical physicist and philosopher of science. He was professor of physics as well as professor of philosophy at the University of Notre Dame.

Michael D. Towler is a theoretical physicist associated with the Cavendish Laboratory of the University of Cambridge and formerly research associate at University College, London and College Lecturer at Emmanuel College, Cambridge. He created and owns the Towler Institute in Vallico di Sotto in Tuscany, Italy.

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References

  1. 1 2 3 Lee Smolin: The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next , First Mariner book edition 2007, ISBN   978-0-618-55105-7, p. 322 and p. 326
  2. ↑ Antony Valentini Archived September 28, 2011, at the Wayback Machine at the Perimeter Institute (downloaded March 4, 2012)
  3. 1 2 Antony Valentini: On the Pilot-Wave Theory of Classical, Quantum and Subquantum Physics, Ph.D. Thesis, ISAS, Trieste 1992
  4. ↑ Clemson University Newcomers Archived May 16, 2011, at the Wayback Machine , published May 2, 2011
  5. ↑ "Antony Valentini". clemson.edu. Retrieved 2022-01-23.
  6. ↑ The Towler Institute
  7. ↑ 21st century directions in de Broglie–Bohm theory and beyond, Clemson University Physics and Astronomy Newsletter, vol. 5, no. 1, 2010
  8. ↑ 21st-century directions in de Broglie-Bohm theory and beyond, 2010 event announcement at vallico.net
  9. ↑ James T. Cushing: Quantum mechanics: historical contingency and the Copenhagen hegemony, The University of Chicago Press, 1994, ISBN   0-226-13202-1, p. 163
  10. ↑ Antony Valentini: Signal-locality, uncertainty, and the sub-quantum H-theorem, I, Physics Letters A, vol. 156, no. 5, 1991
  11. ↑ Antony Valentini: Hidden variables and the large-scale structure of space-time, in: William Lane Craig, Quentin Smith (eds.): Einstein, Relativity and Absolute Simultaneity, Routledge, 2007, ISBN   978-0-415-70174-7, pp. 125–155, p. 126
  12. ↑ Antony Valentini: Subquantum information and computation, 2002, Pramana Journal of Physics, vol. 59, no. 2, August 2002, p. 269–277, p. 270
  13. ↑ Antony Valentini: Subquantum information and computation, 2002, Pramana Journal of Physics, vol. 59, no. 2, August 2002, p. 269–277, p. 272
  14. ↑ James T. Cushing: Quantum mechanics: historical contingency and the Copenhagen hegemony, The University of Chicago Press, 1994, ISBN   0-226-13202-1, p. 270
  15. ↑ Antony Valentini: Pilot-wave theory of fields, gravitation and cosmology, in: James T. Cushing, Arthur Fine, Sheldon Goldstein (eds.): Bohmian mechanics and quantum theory: an appraisal, Kluwer Academic Publishers, 1996, p. 45–66, p. 47.
  16. ↑ Peter J. Riggs: Quantum Causality: Conceptual Issues in the Causal Theory of Quantum Mechanics, Studies in History and Philosophy of Science 23, Springer, 2009, ISBN   978-90-481-2402-2, doi : 10.1007/978-90-481-2403-9, p. 76
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