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28 Aug4 Sep 2010
Vallico Sotto, Tuscany, Italy
Mike Towler, Antony Valentini
Contact address
Dr. Mike Towler
Cavendish Laboratory
University of Cambridge
United Kingdom


21st-century directions in de Broglie-Bohm theory and beyond

A quantum foundations discussion workshop on the de Broglie-Bohm formulation of quantum mechanics and related topics is to take place in late August/early September 2010 at the Apuan Alps Centre for Physics, a 15th-century Tuscan former monastery in the mountains near the beautiful Italian city of Lucca. It is hoped that the meeting will be of great interest to anyone stimulated by the work of physicists Louis de Broglie and David Bohm, and by the directions their ideas have followed through the work of many people over more than eighty years. The meeting is being organized by Cambridge University physicist Dr. Mike Towler, who
owns and runs the monastery, and Prof. Antony Valentini of Imperial College, London and Clemson University in South Carolina. In its six years of operation, the monastery has become well-known as a unique communal venue where the community spirit and magnificent location have inspired a series of memorable meetings; we very much hope this workshop will continue this tradition.

The usual format of workshops at this venue is intended to encourage a relaxed and intellectually-stimulating atmosphere rather different to the 8am to 7pm grind of your regular conference. Formal talks are restricted to the mornings, and participants are given the freedom and space to think and to contemplate and discuss the issues at hand in front of the many available blackboards. For the young and vigorous, afternoon mountain walks, caving, and other healthy outdoor pursuits are organized, whilst the unfit and elderly might enjoy artistic tours, reading and conversation
in the garden, and gentle country strolls, with all participants reuniting in the evening for excellent Tuscan dinners in local restaurants. It is hoped that by taking part in these activities, whilst breathing clean mountain air and having access to good food and wine, participants will be able to return home mentally and physically refreshed as well as having learned something new about science.

De Broglie-Bohm theory is a 'hidden variables' formulation of quantum mechanics initially developed by de Broglie from 1923-1927 and clarified and extended by Bohm beginning in 1952. In non-relativistic quantum theory it differs from the orthodox viewpoint in that the notion of 'probability'
refers to the probability that a particle *is* at some position, rather than to its probability of being found there in a suitable measurement. From this seemingly subtle difference it is easy to show that - contrary to popular belief - QM can be interpreted as a dynamical theory of particle trajectories rather than as a statistical theory of observation. In such a formalism the standard paradoxes related to measurement, observation and wave function collapse (Schroedinger's cat, and so on) largely evaporate. The classical limit does not have to be presupposed and emerges from the theory in a relatively clear way. All the 'talk' is replaced by sharply-defined mathematics, it becomes possible to 'visualize' the reality of most quantum events, and - most importantly - the theory is completely consistent with the full range of QM predictive-observational data. While some believe the study of interpretational questions to be mere semantics or 'just philosophy', it is often forgotten that the location of the boundary between philosophy and physics is unknown, and that one's philosophical perspective can guide mathematical developments. For many people it is clear that de Broglie-Bohm theory should be studied, not only because it is beginning to make apparently testable predictions, but also because it has the
potential to suggest possible directions towards the next generation of ideas in theoretical physics.

Over the years the subject has been somewhat contentious, both internally and in its relationship with people working in other areas. It is however clear that - because of its fringe nature in modern physics - there is a singular need for researchers in the field to move forward with a common purpose. The meeting therefore intends to focus the energies of professionals in quantum foundations by resolving, in so far as is possible, any conflicts that have arisen. Areas of disagreement will be identified, and inspired by the relaxed environment and generous spirit engendered by the monastery, participants shall work towards achieving a
harmonious understanding. The formation of new collaborations, the beginning of new projects, and the identification of the best new directions for 21st-century research are to be encouraged. Participants will also work towards mutually satisfactory answers to specific objections levelled by critics of de Broglie-Bohm theory (some of whom will be invited); a summary of the best answers to such objections - if we can agree on them - will be put on a suitable website afterwards.

Though the format of the meeting is highly flexible and suggestions are most welcome, an initial suggestion for possible topics might include:

- Quantum non-equilibrium and 'signal non-locality'. Dynamical relaxation to quantum equilibrium. Potential instabilities in the Bohm dynamics.

- Possible deeper interpretations of de Broglie-Bohm theory (such as Basil Hiley's new quantum algebra work).

- Pilot-wave field theories and relativistic generalizations

- De Broglie-Bohm quantum cosmology

- 'Deconstructing' the wave function. Can the theory be reduced to 3-space waves? Norsen's 'theory of exclusively local beables'.

- Proposed experimental tests (Valentini, Riggs, etc..)

- The ontological status of the theory. First or Second order? Energy. Empty waves. The arguments for and against psi-epistemic hidden-variables theories. Alternative formulations of deterministic hidden variables theories. Non-Markovian trajectory theories.

- Comparison with the consistent histories formulation.

- Use of trajectories for efficient numerical simulations in quantum chemistry.

- Spin, antisymmetry, the exclusion principle and the 'quantum force.'

- Responses to common objections (it's not possible for particles to exist; particles going round corners ought to radiate etc.).

- The best way to teach the subject. Why should young people be interested in these ideas, when showing interest in quantum foundations still might harm their careers? Of what use is de Broglie-Bohm theory and why is it to be studied?

In deciding on suitable topics for talks, speakers are encouraged to avoid rehashing old arguments to which, ultimately, the answers are a matter of opinion. Rather, we are looking for genuinely new, forward-looking material which can guide future research in quantum foundations.

Given the nature of the event, most participants will be specifically invited, but anyone who feels they have something to contribute and wishes to attend the meeting should contact the organizers for further details. The initial list of people to be invited is as follows:

Guido Bacciagaluppi, Herman Batalaan, Andrew Bennett, Harvey Brown, Jeremy Butterfield, Samuel Colin, Murray Daw, Maaneli Derakhshani, Chris Dewdney, Felipe Falciano, Arthur Fine, Sheldon Goldstein, Jonathan Halliwell, James Hartle, Lucien Hardy, Basil Hiley, Peter Holland, Adrian Kent, Creon Levit, Tim Maudlin, David Mermin, Alberto Montina, Lubos Motl, Wayne Myrvold, Hrvoje
Nikolic, Travis Norsen, Philip Pearle, Roger Penrose, Alejandro Perez, Patrick Peter, Nelson Pinto-Neto, Paavo Pylkkanen, Peter Riggs, Carlo Rovelli, Jack Sarfatti, Simon Saunders, Maximilian Schlosshauer, Ilja Schmelzer, Lee Smolin, Rafael Sorkin, Rob Spekkens, Ward Struyve, Mike Towler, Roderick Tumulka, Jos Uffink, Lev Vaidman, Antony Valentini, David Wallace, Howard Wiseman, Robert Wyatt, James Yearsley.

Space permitting, students and family members are welcome.

For further practical details, such as transport, accommodation, excursions, food, technical equipment and so on, please see the draft workshop programme document available on the monastery website (follow the link 'PUBLIC EVENTS').

We look forward to seeing you in Tuscany in summer 2010.

Mike Towler and Antony Valentini