During this intermezzo, we will try to entertain the reader by analyzing some of the sociological aspects of the high-energy physics group, and in particular the string theory community. We will point out some of the surprising features that seem interesting, and typical to the community of stringy researchers.
Conferences and WorkshopsAt any point in time, there is a string theory workshop or conference taking place somewhere on the planet. It might be in Colorado, Korea or California -- there is always a city or remote village that attracts a particular sub-community of the one or two thousand string theorists on earth. Workshops usually have a mathematical or physical theme of interest to a large class of string theorists, or to a strong sub-community. The theme can range from as general a theme as M-theory to as particular a theme as two-dimensional quantum gravity or non-commutative geometry.
The yearly "Strings" conference is the largest in the field. There are usually around four hundred people attending the Strings conference. Each year it is held at a different place, on a different continent. (2001 India, 2002 Europe, 2003 Japan, 2004 Europe, 2005 North-America -- check out the web sites.) There will be many faculty members present, an army of postdocs, and a number of graduate students. Those are the three biggest groups of people that make up the stringy circus. Of course, the circus-tent would collapse if it weren't for administrators, money providers and the omnipresent and omniscient secretaries.
We can roughly describe the group of string theorists as follows. (Note: the following will be experienced as some as a caricature.) The faculty are those members of the string community that have a permanent position at one or another university: the professors. Most of them published excellent papers that earned them their distinguished status. They are 35 to 105 years old. As in any field, there are professors of all kinds, but it is surprising how non-hierarchical the average stringy professor is, how open to criticism and discussion, how jovial and down-to-earth. (As an example, not in every field authors are put in alphabetical order on papers published. In string theory this is almost always the case, without distinction between professors, postdocs or grad students.)
The postdocs are those PhD's that have a temporary position (usually of two to five years) at a university. Their age varies from 25 to 35 years old. They are young investigators that travel the world for five to ten years to learn skills at different universities around the globe. They try to make an outstanding contribution to string theory during that period. Some become professors afterwards, some find a job outside physics, as math teachers, stock market analysts, high tech advisers, computer wizards, or some other unpredictable trade.
The graduate students are young physicists, usually Bachelors in Science. During their grad studies they acquire even more background knowledge then they got in their undergraduate studies, to be able to make their first original contributions to the vast field of string theory. Sometimes they teach recitations, or correct exams (mostly to supplement their grant money).
SchoolsAround the globe, whether in Italia, the USA, Korea, India or elsewhere, the string community organizes spring, summer, autumn and winter schools for everybody interested in high level string theory courses. They are usually directed at advanced graduate students, and are taught by invited distinguished faculty members (who usually have some new and exciting development to share -- sometimes in pedagogical terms). They are excellent places for young grad students to make their first contacts with their foreign colleagues, or to get to know the different fields of expertise of different centers around the globe.
SeminarsIn the US, Europe and East-Asia (and elsewhere), there is a tradition of an exchange of information between professors and researchers at different universities in the form of seminars. Researchers (whether faculty, postdocs or grad students) that published interesting results can be invited by friendly people from other universities to give an hour-long presentation of their work. During the presentation there usually is some debate on subtler issues, important implications, or matters of interpretation, mostly pertaining to the work presented. The debate can be heated, or lame. The presentations are very useful to gauge the impact of research, the general opinions present in the community, and in general, to see the interaction of researchers that operate on a daily basis in a different research environment. The traveling circus of string theorists makes sure the separate nodes of research stay in close contact, such that the community may benefit from close cooperation, and can make maximal use of the complementarity of the different nodes.
DiscussionsOften times, the most interesting discussions take place at a small scale. Visitors talk to hosts one on one, little collaborations start in a workshop or conference and grow into large collaborations as they go along. A postdoc discusses with a faculty member and they find a common point of interest and intrigue, or a grad student comes up with a crazy suggestion that turns out to make sense. In the corridors of universities, the personal opinions on the latest papers, the narrow minded interpretations of the newest developments can often be heard in an unabbreviated, impolite, but very useful form. All the small scale interactions are of the utmost importance to do work of interest to colleagues, and the string theory community as a whole. Some people even manage to do most of their work merely by talking, and weaving a web between results of people who hardly communicate with each other. Both the solitary, original and beautiful mind behind the desk at two o'clock in the morning, and the gossiping-type scientist, do equally important work. The community works best if a large variety of scientific methods are present. In the colorful stringy community, luckily, there is plenty of variety.
GlobalizationString theory, like most trades, has gone global. To a large part thanks to the internet, the whole of the research community has grown closer and stronger, with as a happy side-effect that it has become possible to provide for useful exchanges of information and people between more-favored and less-favored regions of our planet. Most members of our community dutifully concentrate on the acquisition and spreading of new knowledge, independent of credo, color or ideology. It is no exception to see a Harvard trained scientist teach in Iran. While internal scientific politics is high on the agenda of everyday lunch-conversation, and is taken very seriously, external large scale politics is discussed freely, without much consequence.
In the late sixties and seventies (starting with the work of Veneziano in 1968), a stringy description of the strong force was attempted, by writing down models (or scattering amplitudes) that incorporated manifestly the Regge behavior of strong resonances, and crossing symmetry. Scherk and Schwarz noted in 1974 that the spin two massless particle appearing in closed string theory could be interpreted as a graviton and that therefore string theory could be put forward as a candidate theory of quantum gravity, and, in fact, of all interactions. In 1984 Green and Schwarz showed that a crucial condition for consistency of the quantum theory, anomaly cancellation, was satisfied in string theory. That was a crucial step in the popularization of string theory in the scientific community. In 1994 (hep-th/9510017) Polchinski realized that a microscopic description of non-perturbative objects, D-branes, was the right interpretation of the conformal field theory constructions, and supergravity solutions that had been available for quite a while. In 1994/5 (hep-th/9410167) Hull and Townsend and (hep-th/9503124) Witten realized surprising connections between all known string theories, thus making the theory fairly unique. In 1997 (hep-th/9711200) Maldacena realized the idea of holography in quantum gravity in a concrete gauge theory/quantum gravity correspondence. In 1996 (hep-th/9601029) Strominger and Vafa demonstrated that the microscopic degrees of freedom of a supersymmetric black hole could be correctly counted using string theory, thus providing the first example of the successful counting of black hole microstates, and the suggestion that the evolution of quantum gravity in the presence of black holes might be unitary.