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

Sat 28th August - Sat 4th September 2010
The Apuan Alps Centre for Physics @ TTI
Vallico Sotto, Tuscany, Italy


Conference programme

Conference web page

Cambridge deBB graduate course with bibliography

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 current list of participants is as follows:

Guido Bacciagaluppi (University of Aberdeen, U.K.)
Herman Batelaan (University of Nebraska, U.S.A.)
Dionigi Benincasa (Imperial College, London)
Andrew Bennett (Oregon State University, Corvallis, U.S.A.)
Jeffrey Bub (University of Maryland, U.S.A)
Howard Burton (Founding Director, Perimeter Institute, Canada, now independent)
John Bush (Department of Mathematics, MIT, U.S.A.)
Jeremy Butterfield (University of Cambridge, U.K.)
Murray Daw (Clemson University, U.S.A.)
Maaneli Derakhshani (Stony Brook University, U.S.A.)
Chris Dewdney (University of Portsmouth, U.K.)
Christos Efthimiopoulos (Academy of Athens, Greece)
Maurice de Gosson (University of Vienna, Austria)
Jonathan Halliwell (Imperial College, London, U.K.)
Lucien Hardy (Perimeter Institute, Waterloo, Canada)
Richard Havery (University of Portsmouth, U.K.)
Basil Hiley (Birkbeck College, London, U.K.)
Kris Krogh (University of California, U.S.A.)
Tim Maudlin (Rutgers University, U.S.A.)
Alberto Montina (Perimeter Institute, Canada)
Wayne Myrvold (University of Western Ontario, Canada)
Gillie Naaman-Marom (Tel Aviv University, Israel)
Hrvoje Nikolic (Rudjer Boskovic Institute, Zagreb, Croatia)
Travis Norsen (Marlboro College, U.S.A.)
Xavier Oriols (Universitat Autònoma de Barcelona, Spain)
F. David Peat (Pari Centre, Italy)
Roger Penrose (University of Oxford, U.K.)
Pedro Naranjo Pérez (University of Seville, Spain)
Patrick Peter (Institut d'Astrophysique de Paris, France)
Nelson Pinto-Neto (CBPF, Rio de Janeiro, Brazil)
Enrico Prati (CNR, Italy)
Paavo Pylkkänen (University of Skövde, Sweden)
Anton Ramsak (Ljubljana University, Slovenia)
Peter Riggs (V) (Australian National University, Canberra, Australia)
Joshua Rosaler (University of Oxford, U.K.)
Carlo Rovelli (Centre de Physique Theorique de Luminy, Marseilles, France)
Shantena Sabbadini (Pari Centre, Italy)
Simon Saunders (University of Oxford, U.K.)
Maximilian Schlosshauer (Neils Bohr Institute, Copenhagen, Denmark)
Ilja Schmelzer (Berlin, Germany)
Lee Smolin (Perimeter Institute, Waterloo, Canada)
Rafael Sorkin (Perimeter Institute, Waterloo, Canada)
Ward Struyve (Katholieke Universiteit Leuven, Belgium)
Mike Towler (Cambridge University, U.K.)
Jos Uffink (University of Utrecht, Holland)
Lev Vaidman (Tel Aviv University, Israel)
Wouter Valentin (Leiden University, Holland)
Antony Valentini (Imperial College, London, U.K.)
Georg Wikman (SHI, Sweden)
James Yearsley (Imperial College, London)

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.

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

Warm regards,
Mike Towler (mdt26 at
Antony Valentini (a.valentini at

Quotes from previous participants in scientific events in Vallico Sotto

"Just a brief note to thank you again for hosting the QMC summer school. I had a wonderful time in Tuscany, it was probably the best conference/school I've attended. The science was excellent, and the location, obviously, stunning. TTI is a very impressive place. Every one of the participants was a pleasure to spend time with, and I've come away with some friends with whom I intend to keep in contact. The success of the school was down to your organization and hard work, and I just wanted to say "grazie" to you for all your efforts."

"First, an enormous thank-you to you and Sam for your extraordinary hospitality and kindness that made QMC in the Apuan Alps a quite unforgettable experience for me, and quite unlike any other conference. The excellent science and the wonderful social programme provide a model for other conferences."

"I will advice your school to anyone on the earth.."

"I am really happy to see that you are preparing a new Summer School in Vallico Sotto. It remains for me the most profitable workshop I have ever had, associating the top quality of lectures and the excellent practical training, making very difficult things to become accessible. It remains also for me the type of ideal ambience associating work, scientific discussion and entertainments."

"..thank you very much for organizing the conference -- it was amazing and I have a lot of fun memories! You're right that bringing a whole load of like-minded people together in one place at the same time is fantastic; it was great to have this unique experience.."

"Thanks again! Besides having fun and learning at the school, I'm truly impressed with what you did with the TTI and how the whole school was organized. I've been to a few before, but this was special!"

"Thanks for putting on the entire school and making it a wonderful (and well organised) week! I've never experienced quite the combination of excessive learning and excessive exercise."

"The stay at Tuscany will be a lifetime memory for me!"

"The summer school is an excellent in my whole life and I have really got inspired. I think every one who attends the QMC school will go back to home with great spirits. My words fail to explain how much I have enjoyed the lectures and outing trips. Thanks a lot for everything.. I will really miss you."

"This is the unique school I have got in my life which will be remembered through out my life. School with whole lots of adventures... Thank you."

"I want thank you very much the amazing experience.. It was nice to meet people like all of you. I hope to see you again. I am really grateful to you to enable climb Monte Procinto and to scale the waterfall too, because I think, it was been the most exciting adventure in my life."

"Thank you very much for everything. It just because of you we had a wonderful time. You are not only a [EMBARRASSING PRAISE DELETED] but a [EMBARRASSING PRAISE DELETED]. I will be grateful for the hospitality you provided in the summer school. .. Wishing you a very good luck and may God fulfil you with lots of joy and happiness. Hats off to you."

"Thank you for all. It has been a really nice summer school, and a pleasure to have such lovely days with you, your family, Pablo and Neil. You have made a really good job organizing everything, and making sure that everybody enjoyed this summer school. I am in a debt of gratitude with you."

"Thanks for the wonderful week! You are an amazing host, and TTI is fantastic!"

"Thanks a lot for the opportunity you have given, at least my eyes have opened to a new world of research. I have to thank you for this."

"The school was a great blessing to me. Thank you for giving me the opportunity to meet new brains and make new friends."

"Thanks for everything. I will never forget this great week!"

"And, again, let me express that I enjoyed the conference very much, both the academic and the fun part. Thanks for the excellent organization."

"Thank you so much for your hospitality in QMC in the Apuan Alps!! During this stay, I really enjoyed the fruitful discussions, tasty dishes, wonderful views, and exciting excursions! This stay in TTI became a memorable event for me."

"Thank you again for giving me the opportunity to present my work in the TTI. It is surely the greatest conference on earth."

"Thank you so much for organising the summer school. It is really a wonderful experience and I wish I would have another chance to return soon."

"I want to say again, 'Thank you for a good time in Tuscany'. All particular facets of school was great, including lectures, practice, place, people, activities, food etc. It was my first summer school (conference) but I think it shall be hard to find something better. Thanks."

"It was a pleasure to be in the summer school last week in Vallico Sotto, to meet you and your team, this "strange foreign people" (including myself), and Sammy and Saska. I liked very much the lectures, learned many things and enjoyed a lot our excursions and dinners. We really had a good time, congratulations on the organization of this fantastic enterprise. Thank you very much!"

"Thank you for hosting the wonderful summer school on earth. I had really enjoyed that."

"Thank you - you, Neil and Pablo brought us such a fruitful and joyful summer school! I have learned so much.."

"You bet how wonderful time I had (I believe others students did too) in this fantastic summer school!! I would like to quote a very popular Chinese poem to show my personal feeling of the almost ideal life in Vallico Sotto. The author is Tao Yuan-ming, an extremely all-time popular poet of reclusion throughout Chinese history after him. And Tao's philosophy of life is epitomized by his house or hut as a central metaphor for self and universe.

Song No. 5 of 20 by Tao Yuan-ming

I built my hut within where others live,
But there is no noise of carriages and horses.
You ask how this is possible:
When the heart is distant, solitude comes.
I pluck chrysanthemums by the eastern fence
And see the distant southern mountains.
The mountain air is fresh at dusk.
Flying birds return in flocks.
In these things there lies a great truth,
But when I try to express it, I cannot find the words.

This can be recited by almost every Chinese fellow. I am also grateful for the night of awesome firework, which was like special "time tunnel" to bring me back to my childhood. Thank you and thank you!! I was in a bit hurry I didn't bring camera with me, but the whole beautiful scenery has been deeply impressed in my memory, which is unfadable for sure.."