Basil Hiley

Basil J. Hiley (born 1935), is a British quantum physicist and professor emeritus of the University of London.

Long-time colleague of David Bohm, Hiley is known for his work with Bohm on implicate orders and for his work on algebraic descriptions of quantum physics in terms of underlying symplectic and orthogonal Clifford algebras.

Hiley co-authored the book The Undivided Universe with David Bohm, which is considered the main reference for Bohm's interpretation of quantum theory.

The work of Bohm and Hiley has been characterized as primarily addressing the question "whether we can have an adequate conception of the reality of a quantum system, be this causal or be it stochastic or be it of any other nature" and meeting the scientific challenge of providing a mathematical description of quantum systems that matches the idea of an implicate order.

Basil Hiley was born 1935 in Burma, where his father worked for the military of the British Raj.

He moved to Hampshire, England, at the age of twelve, where he attended secondary school.

His interest in science was stimulated by his teachers at secondary school and by books, in particular The Mysterious Universe by James Hopwood Jeans and Mr Tompkins in Wonderland by George Gamow.

Hiley performed undergraduate studies at King's College London.

Initially Bohm's model of 1952 did not feature in their discussions; this changed when Hiley asked himself whether the "Einstein-Schrödinger equation", as Wheeler called it, might be found by studying the full implications of that model.

They worked together closely for three decades.

He published a paper in 1961 on the random walk of a macromolecule, followed by further papers on the Ising model, and on lattice constant systems defined in graph theoretical terms.

In 1961 Hiley was appointed assistant lecturer at Birkbeck College, where Bohm had taken the chair of Theoretical Physics shortly before.

Hiley wanted to investigate how physics could be based on a notion of process, and he found that David Bohm held similar ideas.

He reports that during the seminars he held together with Roger Penrose he "was particularly fascinated by John Wheeler's 'sum over three geometries' ideas that he was using to quantise gravity."

Hiley worked with David Bohm for many years on fundamental problems of theoretical physics.

In 1962 he obtained his PhD from King's College in condensed matter physics, more specifically on cooperative phenomena in ferromagnets and long chain polymer models, under the supervision of Cyril Domb and Michael Fisher.

Hiley first met David Bohm during a week-end meeting organized by the student society of King's College at Cumberland Lodge, where Bohm held a lecture.

In the 1970s Bohm, Hiley and co-workers at Birkbeck College expanded further on the theory presented by David Bohm in 1952.

They suggested to re-express the field equations of physics in a way that is independent of their spacetime description.

They interpreted Bell's theorem as a test of spontaneous localization, meaning a tendency of a many-body system to factorize into a product of localized states of its constituent particles, pointing out that such spontaneous localization removes the need for a fundamental role of the measuring apparatus in quantum theory.

They proposed that the fundamental new quality introduced by quantum physics is non-locality.

In 1975, they presented how in the causal interpretation of the quantum theory introduced by Bohm in 1952 the concept of a quantum potential leads to the notion of an "unbroken wholeness of the entire universe", and they proposed possible routes to a generalization of the approach to relativity by means of a novel concept of time.

By performing numeric computations on the basis of the quantum potential, Chris Philippidis, Chris Dewdney and Basil Hiley used computer simulations to deduce ensembles of particle trajectories that could account for the interference fringes in the double-slit experiment and worked out descriptions of scattering processes.

Their work renewed the interests of physicists in the Bohm interpretation of quantum physics.

In 1979, Bohm and Hiley discussed the Aharonov–Bohm effect which had recently found experimental confirmation.

They called attention to the importance of the early work of Louis de Broglie on pilot waves, emphasizing his insight and physical intuition and stating that developments based on his ideas aimed at a better understanding than mathematical formalism alone.

They offered ways of understanding quantum non-locality and the measurement process, the limit of classicality, interference and quantum tunneling.

They showed how in the Bohm model, introducing the concept of active information, the measurement problem and the collapse of the wave function, could be understood in terms of the quantum potential approach, and that this approach could be extended to relativistic quantum field theories.

They described the measurement process and the impossibility of measuring position and momentum simultaneously as follows: "The ѱ field itself changes since it must satisfy the Schrödinger equation, which now contains the interaction between the particle and apparatus, and it is this change that makes it impossible to measure position and momentum together".

The collapse of the wave function of the Copenhagen interpretation of quantum theory is explained in the quantum potential approach by the demonstration that information can become inactive in the sense that from then on "all the packets of the multi-dimensional wave function that do not correspond to the actual result of measurement have no effect on the particle".

Summarizing Bohm's and his own interpretation, Hiley has explained that the quantum potential "does not give rise to a mechanical force in the Newtonian sense. Thus while the Newtonian potential drives the particle along the trajectory, the quantum potential organises the form of the trajectories in response to the experimental conditions."

The quantum potential can be understood as an aspect of "some kind of self-organising process" involving a basic underlying field.

The quantum potential (or information potential) links the quantum system under investigation to the measuring apparatus, thereby giving that system a significance within the context defined by the apparatus.

It acts on each quantum particle individually, each particle influencing itself.

Hiley cites the wording of Paul Dirac: "Each electron only interferes with itself" and adds: "Somehow the 'quantum force' is a 'private' force. It thus cannot be regarded as a distortion of some underlying sub-quantum medium as was originally suggested by de Broglie".

It is independent of field intensity, thus fulfilling a precondition for non-locality, and it carries information about the whole experimental arrangement in which the particle finds itself.

In processes of non-signalling transmission of qubits in a system consisting of multiple particles (a process that is generally called "quantum teleportation" by physicists), active information is transferred from one particle to another, and in the Bohm model this transfer is mediated by the non-local quantum potential.

Together they wrote many publications, including the book The Undivided Universe: An Ontological Interpretation of Quantum Theory, published 1993, which is now considered the major reference for Bohm's interpretation of quantum theory.

In 1995, Basil Hiley was appointed to the chair in physics at Birkbeck College at the University of London.

He was awarded the 2012 Majorana Prize in the category The Best Person in Physics for the algebraic approach to quantum mechanics and furthermore in recognition of ″his paramount importance as natural philosopher, his critical and open minded attitude towards the role of science in contemporary culture".