Letter from the President, 2004-2007

I first visited the Aspen Center for Physics (ACP) in the summer of 1985, one year after I finished my PhD and joined the theory group at Bell Laboratories. That June I had the opportunity to spend one month with my now-good friends, Dieter Vollhardt and his post-doc supervisor, Peter Woelfle at the Max Plank Institute and the Technical University in Munich. Dieter and I had overlapped at Bell Labs during the previous academic year, part of which Dieter spent in Murray Hill as a Heisenberg Fellow. That year, Dieter was writing his well known Reviews of Modern Physics article on the Gutzwiller variational wave function for correlated fermions and I spent a lot of time talking to him trying to understand how to think about the Brinkman-Rice metal-to- insulator transition in a disordered correlated system like phosphorous-doped silicon. While visiting Dieter in Munich I came up with some initial ideas of how to reformulate the Brinkman-Rice transition in terms of “slave-bosons,” an approach I was hoping to apply to computing the spin and charge transport near the metal-to-insulator transition in phosphorous-doped silicon.

A month later Dieter, Peter, and I continued our discussions in Aspen where we all came together to attend the Workshop on Disorder and Interactions. It is during that same summer that I first met my friend and collaborator Gabi Kotliar who was also working on a slave-boson approach to correlated systems, and I reconnected with Piers Coleman, whom I had already met when we were both graduate students. Gabi and I eventually put our ideas together and published what is referred to as the Kotliar-Ruckenstein path integral representation of the Hubbard model – a reference that led a number of people to assume that my first name is Kotliar! During that same summer of 1985 I first met Elihu Abrahams, a role-model for many of us, and one of my dearest friends. A few years later Gabi and I joined Elihu and Piers in the Condensed Matter Theory group at Rutgers, where I was to spend the next 18 years of my scientific career. The other memorable event that summer was my first encounter with Sally Mencimer, the first administrative vice-president of the Center, whom it took me a few more years to impress enough to be assigned an apartment with real windows.

Starting with that first summer, the Center was going to play an important role in my professional and personal life, as it has and will for many past and future generations. In my case, apart from the tremendous intellectual stimulation the Center provided over the past 28 years, and its role in the history of modern physics, summers in Aspen have also reconnected me with music, my first avocation.

Over the years the combination of nature, physics, and music unique to Aspen has created strong connections among like-minded people that have enriched both the music and the science communities.

Over time some of the notable musicians in Aspen became friends of the Physics Center – to name a few: the late Robert Harth, Larry and Angela Foster, Alan Fletcher, Ed Berkeley, Stephen Kovacevich, and more recently Veda Kaplinsky. Dorothy DeLay, the grande dame of violin playing and the teacher of many of today’s great violinists was interested in the physics of violin playing and often tried to involve me (and probably others) in discussions of how the magic of great playing must rely on a perfect harmony between the physics of the violin and the muscle control of the performer. Since many of these discussions happened late in the night at various social gatherings and after some number of drinks for both of us, I was never quite clear on how serious she was about the “science of violin playing.” Most importantly, Ms. Delay coached some of the Physics Center “kids,” like Gil Shaham, Jennifer Frautschi, and Stefan Jackiw, to stardom. Orli Shaham, Gil’s sister, also developed into a major performing pianist before our eyes. Eventually (during the summer of 2005) I used my connections with music to convince the Festival and School administration, with support from Marty Flug and Veda Kaplinsky, to loan us a grand piano every summer and to use the Flug Forum to showcase some of the talented piano performance students, who enthusiastically embraced the chance to play in public. This is how the tradition, still alive today, of “Monday Music at the ACP” started.

I hope that these rather personal reflections are not perceived as too self-indulgent. In sharing them, I am trying to emphasize the unique Aspen experience and the effect that it has on each of us in defining collaborations and life-long deep relationships and friendships that would have been difficult to develop in any other context. Working together, hiking together, cooking together and taking pleasure in seeing each other’s children grow up creates a sense of group super-ego that is difficult to imagine. Nobody gets paid for the time spent on managing the many aspects of the Physics Center. All of us have worked and continue to work hard to make the Center as good as it can possibly be because it is “our place.” Some of us eventually became members of the Center, but everyone contributes: members and nonmembers alike.

It was with some surprise when early in 2004 I received a call from Tom Appelquist, then Chair of the Aspen Center for Physics Board of Trustees, asking me if I would accept serving as the next President of the Center. Without a doubt, this is not the kind of position you would ever campaign for and if you did you would completely undermine any chances of getting it. Needless to say, once you are offered this vote of confidence by such a distinguished group, there is no turning it down! This is how my three-year term as ACP President began. People still tell me – some with humor and affection, and some with annoyance – that I made everybody work too hard. As with childbirth, time and distance seem to slowly erase all but the big ideas and the sense of joy – this is at least in part because those who were once annoyed with me are now annoyed with others!

My Term as President

There were a number of goals I set for myself as I embarked on this job. First of all I was to “do no harm.” The ACP had been created through the work of many dedicated and smart people and had evolved into a unique world-class institution. But there were uncertainties on the horizon, some of which continue to this day. My plan was to address our challenges at two levels: there were immediate, short-term issues, like the renewal of our NSF grant; and then there were also longer-term strategic decisions that would shape the evolution of the Center’s future.

The Renewal of the NSF Grant

The end of my first year in office coincided with the renewal of our NSF grant, our principal source of operating funds. With help of a committee of very able long-term active members and trustees I submitted our renewal which was favorably reviewed and funded for an additional five years with a 30% increase in funding level. In part, the increase was the result of support from Program Directors in the Biology Directorate of the NSF who, after many discussions and a formal presentation highlighting the Center’s accomplishments in the increasingly important area of interdisciplinary biology, decided to begin contributing to our long-term funding.

The longer-term issues that concerned me were:

  • the Center’s role in and impact on:
    (i) the future of physics and, more generally, of science; and
    (ii) the quality of the intellectual life of the Roaring Fork community, and the appreciation and understanding of science by the public at large;
  • the commitment of the younger generation to the Center’s uniquely low-overhead operating model based to a great extent on the dedication, vision, and generous voluntary engagement of its members; and
  • the Center’s financial sustainability.

The Role of the Center

World Class Science

From a science perspective the Center had historically chartered new directions that eventually defined the mainstream of theoretical physics. The studies of the physics of neutron stars initiated by Baym, Pethick, and Pines and the “first superstring revolution” due to Green and Schwarz are perhaps the best-known examples. With the increasing interest of physicists in interdisciplinary areas – driven by, for example biology, finance, or engineering – I thought the Center needed to expand its horizons into other fields in which physicists were actually taking a lead and making important contributions – fields that were on the fringe of physics, as a discipline, and might or might not remain there. In spite of the conservative posture some of our distinguished members were taking with regard to the “purity of physics” there were very few institutions better positioned than the Physics Center to take risks in exploring new territory. If we didn’t do it nobody else would!

I took this view seriously and during my tenure I encouraged workshops and winter conferences in various areas of biology (systems and evolutionary biology, developmental biology, neuroscience, signaling networks…), climate modeling, and clean energy research, as well as activities in the history of physics, and science policy. A memorable event was the 2006 “Aspen Center for Physics Energy Forum,” which brought together leaders across many areas of energy research and policy, mostly physicists by background, who gave a high-level introduction to the status of the energy field both on science and policy fronts. Many of the participants in the Forum have either served or are now serving in key positions in the Obama administration. On that occasion we also collaborated with Walter Isaacson and his colleagues at the Aspen Institute in developing the “Energy Futures” track of the 2006 Aspen Ideas Festival.


With respect to the involvement with the local community and, more broadly, with the public at large, the Center had already organized two series of public lectures: the Heinz Pagels Lectures presented during the summer months, and the Nick and Maggie DeWolf Lectures featured during the Aspen Center for Physics Winter Conferences. Even though over the years we have made major efforts to choose speakers who were known to be able to translate their specialized work into common language, understandable to a diverse lay public, with few exceptions the use of jargon and the complexity of the ideas make it hard to communicate the essence and implications of the science. As hard as our speakers try, the large public lecture format is not conducive to the kind of informal interchange with the public that would get a key idea across in a convincing and satisfying way – and even less so when many in the audience are physicists from the Center, and when our well-meaning speakers have the urge, conscious or not, to impress colleagues with their performances. Having spent almost two decades at many public lectures, and after giving a number of them myself, I worried a great deal about what the lay public was really getting out of this experience.

In 2001 I suggested that we add a different type of event – a much more informal interaction between the public and one of the Center’s scientists on important ideas in physics – which I called “Dialogues on Physics.” The rules of the “Dialogues” prevented lecturers from using anything but the blackboard in presenting their topic and did not allow any other scientist but the presenter into the room with the public – this focused the lecturer’s attention on making sure the public left with some real understanding and eliminated any pressure to “perform” in front of distinguished colleagues one might have felt compelled to impress. These events have become increasingly popular over the past 11 years. Personally, I am not sure of the mechanics of current Dialogues because I insist on following the original rules, which only allow me to participate in a Dialogue as the one and only lecturer!

In 2005 we started our collaborations with the Aspen Science Center, a not-for-profit 501(c)3 focused on enhancing the public’s understanding of Science. The unstated idealistic goal, one can only dream about at high altitude, was to use the eclectic Aspen community as a venue for testing the premise that, with sufficient creativity and resources one could bring science into popular culture. The idea for the Science Center took shape during dinner conversations with Kevin and Helen Ward who were just moving into town. While Helen had a high-power job in New York, Kevin was looking to focus his infectious energy and leverage his connections to build something worthwhile in the Roaring Fork Valley. I connected Kevin with George Stranahan and the three of us became the founders of the Aspen Science Center.

My own feeling was that a Science Center focused on getting young people excited about science would also be an outlet for the boundless talent of the Physics Center, without refocusing or diluting the research mission and resources of the Center as an institution. Not surprisingly, the response of the physics community was overwhelming: in collaboration with the Science Center, the Physics Center launched the weekly “Physics is for Kids” picnics which filled the campus with six-to-twelve year olds and their parents, excited by talking and learning about physics from world-renowned scientists. The list of physicists interested in participating is oversubscribed and many general members of the Center have given a “Physics is for Kids” presentation. Like our public lectures, “Physics is for Kids” is taped and rerun on the local GrassRoots public television station throughout the summer. (I once fell asleep in front of the television and awoke in a cold sweat to my own voice talking about drunken soldiers running into light posts in a narrow street as a way of describing electrical resistance in normal metals to six-year olds)! The Science Center also collaborates with the Physics Center during winter conferences by hosting discussions with the speakers of the DeWolf Winter Public Lectures during informal “Physics Cafés” before the lecture. Physics Center members have been playing an increasingly important role in the running of the Science Center and today, more so than George and I, Mike Simmons and Steve Pinsky are in charge.

The New Generation

Another major concern I had as President was that the increasing competition for limited participant slots and the large changes in the lifestyles of the younger generation of physicists – working spouses, increasing numbers of summer commitments, decreasing funding support from Washington, and escalating costs of long summer stays in Aspen – were beginning to affect the time commitment of younger researchers to the Center. As a result, the membership of long-time active members of the Center was extended term after term, reinforcing the reputation that the Center was run as an “old boys’ club.” At the same time scientific activities were shifting towards shorter workshops and shorter stays, and the character of the Center was beginning to change towards that of a formal conference center.

After holding some hands (and perhaps breaking others) we began addressing some of these issues in a number of specific ways:

  • We revised our bylaws to limit membership terms to five years as a general member and, if active in the governance of the Center, an additional five-year term as an honorary member. Some of the key contributors to the Center can be renewed for an additional term as general member, or may be transitioned from honorary to general membership. This assured us of a constant influx of the scientifically active young members into the Center without compromising the upper limit of eighty for the total membership.
  • We eliminated the practice of allowing members to be both general members and honorary members at the same time and we limited honorary memberships to one or the other of the categories: honorary members or honorary trustees. The latter designation is now reserved for former presidents and members who have made extraordinary contributions to the Center.
  • We moved towards a broader focus and longer duration for workshops in mainstream fields; we began requiring a minimum of two-week stays for all participants, and we increased the number of researchers participating in small collaborative groups and as individual investigators with no connections to a formally scheduled workshop.
  • We reviewed and revised our support policy to increase affordability for young participants.

The other strategy I used while President was to run a number of events focused on the history of the Center, a history of which few of our younger members were aware. It seemed to me that the younger generation had little opportunity for developing an appreciation for the vision, dedication, and collaborative spirit of the founders that had made the Center possible. I thought that more exposure to those who had created this remarkable institution – many of whom were still with us – could serve to drive younger members to become more active in running the enterprise, and to preserve the uniqueness of our governance model based on high personal effort but low financial overhead.

In early August 2006 I took advantage of the exceptional dedication and enthusiasm of our staff to organize a weekend (August 5-6) focused on the history of the Center and on those who had shaped that history. The event, which I referred to as “Founders and Pillars,” brought together the founders – Michael Cohen, Robert Craig and George Stranahan – and many of the early participants and contributors to the Center. During that weekend, in the presence of his wife, Rose, his children, Henry and Monica, and his grandchildren, as well as collaborators, friends and students, we celebrated the memory of Hans Bethe, who had passed away a few months earlier, and who had donated part of his Nobel Prize to support the Center.

One year earlier the ACP trustees had approved establishment of the Block Fund, which the Block children and Bill Frazer created in honor of Marty and Beate Block’s 80th birthdays. Marty had initiated the Winter Conferences in 1985 and the Block Fund is now being used every year to award a Block Prize to a promising young participant in each of the winter conferences.

As President, I also allocated some resources towards producing additional interviews with “founders and pillars” and some of our current members in support of Bernice Durand’s Aspen Physics Center History Project. Ever an idealist, I see history as a force perpetuating and sustaining the great works of the past into the future. To quote Samartine: “History teaches everything including the future”!

Financial Sustainability

A few words on this important issue, which I regularly worried about as President. During the NSF grant renewal, referees and some of the program officers were wondering aloud whether funds would not be better spent on starting up young researchers than supporting an elitist organization being run by an “old boys’ club.” I managed to convince them that the Center had evolved away from the “old boys’ club” model but, clearly, with the increasing uncertainties in research funding at the national level, the Physics Center’s financial future remained unclear. At the time I started my term in office, the Center was in good financial shape but had no endowment and no long-term financial strategy. The first thing I did as President was to establish an endowment and an investment committee of financially shrewd physicists and some of the non-scientific members of the Center from the business community to manage this endowment. Together with the establishment of the endowment, towards the end of my term I also pushed for a long-term master plan for the Center, to be taken up by the next President, Andy Cohen. Quoting from my last report to the membership and the trustees:

“[We will need to set] up a number of committees:

  • to project our long-term financial and housing needs
  • to evaluate various options for renovations/rebuilding of the campus
  • to evaluate possible solutions to the housing problem
  • to evaluate and formulate fund raising strategies”

One other aspect we also began discussing late in 2007 was the fact that the world and all human activities, including scientific research, were becoming increasingly global. In this new world in which we live and work the US-centric character of the Physics Center is at the very least limiting. Broadening participation to other parts of the world, most notably China, India, South America, Africa and the Middle East, would enhance the diversity of the Physics Center, and would take advantage of untapped talent and resources that are currently inaccessible. In my view, in addition to creative management of the endowment, the globalization of the Physics Center is an important route to both its financial and intellectual sustainability.

Happy Anniversary!

As I hope is clear from these recollections, the Physics Center has given me a great deal, both professionally and personally. I am grateful for the exciting physics I learned, the wonderful music performances and master classes I attended, and the life-long friendships I developed since that first summer in 1985. Even though, as a life-time honorary trustee of the Center I have now been relegated to the role of “an elder statesman,” I do not yet feel I have paid my dues to the Center and I intend to continue supporting and working on behalf of this truly remarkable institution.

In closing, I want to acknowledge the tremendous dedication and personal commitment our talented staff put into creating and keeping the Aspen Physics family together for this half a century. Sally Mencimer and her late husband Bill, Pat Carey, Ann Altemus, Bryce Maple, and Heather Tharp, and more recently Jane Kelly, Paula Johnson, Patty Fox, and Kelly Thomson have been the mind and heart of the Center. Interacting with them for almost three decades has made me a better person. And let me not forget you, my Physics Center colleagues – past, present and future, physicists and non-physicists alike. I commend your passion, creativity, and genuine dedication to your work on behalf of the Center, and I thank you for your help, advice, and partnership in making the Physics Center the best it can be. Happy 50th Birthday and Many Happy Returns, Aspen Center for Physics!

This post was written in celebration of ACP’s 50th Anniversary