Adler, Steve

My initial work on the axial anomaly was done during a six–week visit to the Cavendish Laboratory in Cambridge during April–May 1968. In early June I went to Aspen where I spent the summer working on a manuscript on the properties of the axial anomaly, which became the body of the final published version. Towards the end of my Aspen stay, Sidney Coleman arrived and told me about the related work of Bell and Jackiw. This conversation led to my writing the appendix to my anomaly paper, containing the application of the anomaly to explaining the rate of pi-zero to two-gamma decay. This calculation showed that a single triple of fractionally charged quarks leads to too small a decay rate, giving, as later interpreted by Bardeen, Fritzsch, and Gell–Mann, one of the first pieces of evidence for the “color” hypothesis.

For further details, see S. Adler, “Anomalies to all Orders,” in G. 't Hooft, ed., 50 Years of Yang–Mills Theory, World Scientific (2005).

I also enjoyed various aspects of Aspen life, skating daily at the Aspen Ice Garden, and hiking. I did the two-pass hike over Buckskin and Trailrider passes to Crystal -- the only time I've ever done that, but I have been up to Buckskin Pass and back down many summers since. In 1968, and during many summers since, I found my visit to Aspen stimulating and productive. I always look forward to my trips here.

Bagger, Jonathan

On a cool, crisp, clear summer day – even in Baltimore – I cannot help but think of Aspen, transported back much like Proust to Combray by the taste of madeleine in tea. I first visited the ACP in 1987, some 25 years ago. I feel honored and privileged to have had the Center as a part of my life ever since.

When I think of Aspen, I have nothing but the fondest of memories. I think back to long discussions about physics at the picnic tables, and lively arguments and seminars on the patio with music wafting from the tent across the meadow. I recall bicycling to Maroon Bells, bears along the Roaring Fork, and death marches in the rain with Sidney Coleman. I think of wildflowers while ascending to Buckskin, lightning while descending from Electric, and lunches while resting at Cathedral. I remember very productive afternoons spent just thinking, along with the joy of finally solving a long-standing problem. I treasure my memories of friends and colleagues, and of my children floating ducks down the "rivers" on campus during the evenings. And I think of the people who made it possible, especially Sally Mencimer, Jane Kelly, Paula Johnson and Patty Fox.

Aspen is a magical place for physics. Each time I visit, I come home renewed, and refreshed with ideas and projects to last the year. Thank you, Aspen, for all you have done for me. But more than just offering a remembrance of things past, I would also like to salute the future and wish the Center all the best for the next 50 years. Happy Birthday!

Berry, R. Stephen

I first learned of the Aspen Center for Physics in the summer of 1965, on a visit to Aspen. My sister Audrey, who was taking an art course there, had met a physicist and his wife, Martin and Beate Block. Audrey introduced us and we immediately learned that the Blocks were there because of the Aspen Center for Physics. It turned out that I knew at least one other of the participants that year, and I was intrigued by what I saw when I visited. It was easy to decide to apply to come the following summer. I'd been coming to Aspen, off and on, winter and summer from New Year's of 1946–47, for the skiing, the hiking and climbing and the music, so having a place to do science there made it as desirable a place to be as possible. My family felt as strongly attracted to Aspen as I did.

In 1966, we bought a plot of land outside the town, having decided we wanted to establish a permanent base and connection here, and in 1967–68, built a house there–the house where we still live whenever we're in Aspen. We began coming to the Center every summer we were in the United States. Our two daughters sometimes said, “We live in Aspen but we spend the fall, winter and spring in Chicago.”

Officially, I am a chemist, having learned in my early teens that chemistry was about the structure of the atom and physics was about ladders leaning against walls. But in fact, most of my research has been right on the borderline between physics and chemistry, in atomic collisions and ionization, thermodynamics, clusters and protein dynamics. Consequently I've participated in a variety of Aspen workshops, including one on molecular astrophysics, and have organized some, especially on finite–time thermodynamics. A group of people working in that area had begun holding biennial workshops on thermodynamics; the one in 1983 was such a success that the participants wanted to have another the next year, and not wait until 1985. However by then, the Center had become so popular that we couldn't get a slot at a time the participants could come, so, as a consequence of Aspen's success, we held that 1984 workshop in Telluride. And that was the beginning of the Telluride Science Research Center, in effect an offspring of the Aspen Center.

I have been involved, off and on, in the affairs of the Center, serving as a Trustee from 1979 until 1984, but, more importantly, I have found many wonderful relationships with colleagues that I would never have met, much less come to befriend, as a participant in the Aspen Center for Physics. Of course there are many others that I have known through other connections, but have linked more strongly with because of Aspen. I think, for example, of many scientists from Los Alamos who came regularly to Aspen, some no longer with us such as Dick Slansky (with whom I loved to hike, climb and ski) and George Bell (who was much too far beyond me, ever to climb together).

One important aspect of the Physics Center from its earliest days has been its capacity to involve young scientists and to bring them together in a totally informal engagement with more senior scientists. This is something that I hope the Center can continue to foster, in the variety of ways that enable postdoctorals and even graduate students to come to Aspen and be part of the Center's activities. Another aspect I would like to see made even stronger is the link between the Center and the local residents. The public lectures and the program for kids have both been important in building that link, and I would like to see us find more ways to make the Center an integral aspect of Aspen's life and character.

Goldbart, Paul

A handful of years ago, I was asked to introduce the speaker at one of the Aspen Center for Physics’ Heinz Pagels Summer Public Lectures, to be held in the Aspen Institute’s Paepcke Auditorium. As the lecture was intended for non-specialists, and thus it seemed likely that a large fraction of the audience would be unfamiliar with the Aspen Center for Physics, I thought it might be helpful if I were to spend just a few moments giving my view of the Center, focusing more on flavour than ingredients. Here is a lightly edited version of what I said that evening…

The Aspen Center for Physics is an institution truly beloved in the world of theoretical physics, which plays an extraordinary role in the lives and progress of our community of researchers. Every summer, over a fifteen-week period, some 500 leading scientists from across the globe assemble at the Center, each for a few weeks. Here, we engage with one another, discuss recent accomplishments and developments, exchange and sharpen ideas, move forward with existing collaborations and forge new ones, and try to think strategically about future research possibilities. Liberated from the normal obligations of our home institutions and superbly assisted by the Center’s devoted staff, and inspired by the presence of many researchers with whom we share common interests ─ not to mention the gorgeous Colorado scenery ─ the Center’s researchers relish the space and time to undertake the kind of intensely focused thinking that is often required to move the frontiers of science forward.
  • Part crucible of concentrated expertise that sparks creative thinking and catalyzes progress,
  • Part international hub for conversing about and sifting through the latest research ideas, and
  • Part Platonic Academy (although we do treasure visits from our experimentalist colleagues!),…
...I like to think of the Aspen Center for Physics not so much as the theoretical physicists’ spa, but rather as that most American of institutions, the summer camp, where renewal comes via opportunities to try fresh activities as well as from the shelter provided from the distractions of everyday life. The Center has a distinguished and impact-laden past, and, I say with confidence, a shining and purpose-filled future. I, for one, am extremely grateful that it exists!

Grindlay, Josh

I have been coming to Aspen and the ACP since the mid-70s, first as a young post-doc and then as a young faculty member. I remember giving a talk on the early era of understanding the newly discovered X-ray sources in globular clusters, and whether they were intermediate mass black holes or X-ray binaries. Jim Peebles was in the audience, under the grape arbor, and seemed to be taking copious notes in the front row. How exciting that Jim was listening and we were debating whether X-ray bursts, which I had recently discovered, were due to thermal instabilities in Bondi accretion on isolated BHs or thermonuclear flashes on neutron stars in low mass X-ray binaries (the latter, of course, turned out to be the answer).

David Schramm was a close friend, colleague and mentor in the early 80s and beyond. We would discuss high energy astrophysics on the trail up Buckskin Pass, the chairlift up to Highlands Peak to ski those "new" runs, or one memorable time for an overnight camp at Dinkle Lake to ski the bowl of Mt. Sopris early the next morning.

Though Aspen has many long memories for me, those at the ACP are among the best. Physics at the outside blackboard is made more clear by the muted sounds of Mozart from a morning rehearsal at the nearby tent.

Haber, Howard

I have been a regular visitor to the Aspen Center for Physics for more than 20 years now. Although there are many conferences and workshops to choose from these days, the Aspen summer workshops provide a unique and unparalleled opportunity to do physics research in a very special environment. The combination of informality, a diverse collection of physicists, and the beautiful surroundings provides an ideal location for both finishing up long-standing research projects as well as developing new directions, ideas and interests.

But, more than any one research project, the aspects of the Aspen experience that I most value are the deep personal relationships that I have developed with a number of colleagues. These relationships go beyond simple collegiality, and some have turned into some of the closest friendships of my adult life. I met Marcela Carena and Carlos Wagner in Aspen in 1993. Marcela likes to remind me that I told her on our first meeting that I was pleased to meet one of my competitors (since we were working on similar areas of MSSM Higgs physics). Nevertheless, that was the beginning of a beautiful friendship, which also led to a number of productive research collaborations. Today, I count Marcela and Carlos as two of my closest friends.

In 1994, I met Herbi Dreiner at Aspen for the first time. Within a year, it seemed that I had known him all my life. That initial meeting in Aspen eventually led to a collaboration, which resulted in a a major physics review article and hopefully soon the publication of a textbook on supersymmetry. Herbi and I have been best buds ever since, with a close friendship between our respective families. John Terning is another close friend, a fact I again attribute to Aspen. Although we never collaborated on research, we have had a close mutual interest in each other's work. Our many conversations (and hikes) from our early years at Aspen form the basis for a long and enduring friendship.

I cannot imagine any other venue for physics meetings in which such close personal relationships can develop in such a way. Aspen lends itself to this by providing space for loosely structured workshops that provide plenty of time for informal discussions and interactions. The mountains attract hikers and bicyclists and provide recreational opportunities that can be combined in a unique way with probing the fundamental questions of the universe. I am most grateful to the Aspen Center for Physics for providing me with many inspiring moments and the chance to meet some of the finest minds of our field. But I am especially appreciative of the opportunity to form new collaborations and friendships, which have enriched my life both in physics and beyond.

So, I celebrate Aspen's 50th year, with best wishes for future generations to benefit from the Aspen experience as I did.

Kauffmann, Guinevere

The first time I went to Aspen was as a young postdoc. The topic of the meeting was galaxy clusters. There were many famous astronomers that I had not yet put to faces – watching how they interacted together was a real learning experience for me. Much more recently, I returned to Aspen for another memorable workshop on galaxy clustering. This time, two postdocs in my group were admitted to the workshop, and I very much enjoyed the chance to introduce them to famous astronomers they had never met before, as well as to the music festival and the surrounding hiking trails. I also "reconnected" with Rachel Mandelbaum and we worked together on a project to understand connection between dark matter halos and galaxies using weak gravitational lensing. Aspen is a great place for us to grow up as researchers -- thank you!

Rosner, Jonathan

I owe several papers giving me great satisfaction to my summers in Aspen. These include studies of electromagnetic transitions in quarkonium with Gabriel Karl and Syd Meshkov (1975 and 1980), studies of heavy meson decay constants using the new heavy quark symmetry (1990), investigation of effects of atomic parity violation experiments on precision electroweak fits with Bill Marciano (1990), and numerous collaborations with Michael Gronau throughout the 1990s and 2000s.

I am grateful to Syd Meshkov for constant guidance on the best fishing spots, and colleagues for congenial company on many hikes. Serving as Secretary in 1978 and as a General Member for several years following that gave me valuable insight into the operation of the Physics Center, which I have always regarded as first–rate.

Stein, Dan

My first visit to the Aspen Center for Physics was in July 1979, two weeks after receiving my PhD. I was attending a workshop based on the subject of my thesis, only to find when I arrived that no one else from the workshop was there! (That was back when workshops were far less formal than they are now, and were much less emphasized.) Nevertheless, I gave a talk on my work (topological singularities in order parameter spaces in condensed matter). Marty Einhorn and Doug Toussaint were in the audience, and afterward, using similar ideas, we worked out that SU(5) grand unified theories that were popular at the time and would lead to the creation of magnetic monopoles. Moreover, these monopoles would be overproduced in the early universe, leading to a conflict between particle physics and the big bang cosmology, as both were understood at the time.

As it turned out, Alan Guth and Henry Tye (who were not at Aspen) had independently come to the same conclusion at the same time, and our papers were published at roughly the same time. The monopole problem was one of several problems with the standard Big Bang cosmology that led Guth to propose the inflationary scenario.

Since that time, I've come to Aspen almost every summer, missing a few here and there, but mostly not. I can't count the number of papers that arose from discussions at the Center, and new friendships formed there, not to mention beginning my book there in the summer of 2009. I've tried to give a little back by serving as Secretary and Treasurer of the Center in years past, but can never fully repay the Center for how it's enriched my professional (and personal) life. Here's to many more years.

Wolfenstein, Lincoln

In the winter of 1962 Michel Baranger, Michael Cohen and I sent letters to all our friends inviting them to join us in Aspen that summer. Forty–two physicists turned up staying for various amounts of time. Little did we imagine that 50 years later over 500 would be coming.

That summer I drove out with my wife and four children. We stayed at a large house at 4th and Francis. In our large living room we hosted a string quartet concert by Music School students and a talk by Jim Farmer who was visiting the Aspen Institute. The streets were nearly all dirt and in the morning we could sometimes hear the sheep coming down the hill, the hill that is now covered with condos.

I have spent many weeks in Aspen in the years since then. When I was a member of the PAC of Fermilab I would start my stay at the other end of town and then move to the Center. My daughter was so attracted to Aspen that she stayed for a whole winter commuting to Snowmass to teach nursery school.

Many of the physicists I know throughout the world I first met in Aspen. In 1972 I met Manny Paschos; we were both thinking about the detection of neutral currents predicted by the new Weinberg-Salam gauge theory of weak interactions. Together we found a formula relating the neutral–current reactions of neutrinos to those of anti-neutrinos. The Paschos–Wolfenstein relation is still sometimes used in the analysis of data.

It was at Aspen that I started a collaboration with Ernest Henley on parity violation in certain nuclear reactions. We then began a collaboration on a book, but like so many book projects it was never completed but I continue to have many discussions with Ernie. In 1977 at Aspen, Murray Gell–Mann, Pierre Ramond and Dick Slansky were discussing the origin of neutrino mass particularly in the context of SO(10) grand–unified theory. I found this work very interesting and invited Slansky to come to Pittsburgh to give a talk about it. Somehow the three of them never wrote a paper about their work but their see–saw model became very famous anyway. This may have started my long interest in the origin of neutrino mass.

Every year I am in Aspen I learn something new, from discussing the sun with Mal Ruderman in the 1970's to learning about dwarf galaxies from Rosemary Wyse in 2011.