A few years ago, the experiments at the LHC were getting started. Decades of thirst for the new experimental data – started especially by the sour 1994 U.S. Congress' decision to abolish the 40 TeV Superconducting Supercollider – were superseded by a new era producing lots of data.
The 126 GeV Higgs boson is the most concrete new result coming from this recent exciting activity. But we shouldn't forget that the LHC's confirmation of hundreds of predictions by the good old Standard Model is incredibly impressive, too.
The first anthem of students of high-energy physics, Russian chanson Marsh fizikov (The March of the Physicists), was composed in 1964 (the year of the Higgs boson papers) and sung by Vladimir Vysotsky, an unofficial yet immensely famous Soviet songwriter with some dissident links. Paradoxically enough, we received a book with his lyrics in 1988, when we were 15, as a gift to guarantee that we would join the Socialist Youth Union, SSM. I took the book but didn't join because I was not obliged to obey unwritten rules of corruption despite its being common in the criminal organization.
The expectation of the meaningful experimental activity was reflected in the job market, too. Experimental groups hired new people and they assured everyone that there was some work for them to do. Among the non-experimenters, almost all the new hires went to phenomenology – they hired people who were able to professionally analyze the data coming from the LHC (and other ongoing experiments).
Just to be sure, people in particle physics or high-energy physics (HEP) may be loosely divided to three groups – experimenters, phenomenologists, theorists. The boundaries are not sharp; you may consider these three labels to be specific colors on a continuous rainbow. But a quantity loosely dividing people into these groups surely exists and the classification above is widely used by the high energy community itself.
The classification was invented in the early 1990s by Paul Ginsparg when he was creating his famous archive of electronic preprints, xxx.lanl.gov – today, we use the modern URL, arXiv.org. Ginsparg wanted to make fun out of several things. So when he moved his activities to the web around 1994, WWW in the URL was replaced by a funnier acronym XXX. This funny acronym made it impossible for many physicists to access papers from the airports because many airports simply don't allow you to open XXX websites.
Ginsparg, a very well-defined formal theorist or string theorist at that time, also wanted to make fun out of those theorists who wanted to stay away from formal theory and string theory and from very deep and ambitious questions and from unification of all forces and who primarily wanted to remain as close to experiments as possible.
In other disciplines than high-energy physics, people would still use the term "theorist" both for what we call theorists and phenomenologists in high-energy physics. If you're a scientist but you're not the guy who actually performs the experiments, you're a theorist, they would say in other fields. But because the polarization of "theorists" and "phenomenologists" looked rather strong in high-energy physics, Ginsparg simply created two archives, hep-th and hep-ph, and this Velvet Divorce was a wise choice (despite many people working near the boundary and many papers crosslisted to both archives). He also invented the funny name, "phenomenologists", for those theorists who don't really want to develop new theoretical concepts and who are more concerned with the application of existing theoretical concepts to the experiments. Model builders are a subset of phenomenologists who work on the construction of new models (the rest works on not-quite-understood manifestations of well-known theories) – but they're not supposed to be models that are "totally conceptually new" or "theories of everything". They're supposed to be "just another possible step". All phenomenologists work in the framework of quantum field theory; once you really take string theory seriously and use its mathematical framework as well, you're a full-fledged theorist.
If you look at the Wikipedia's definition of phenomenology, you may start to laugh and appreciate how witty Ginsparg's naming scheme was. Why? While the word "phenomenology" is derived from "phenomena" so that particle physicists may naturally imagine that it's connected with tangible, material things, the word "phenomenology" has actually been used exactly with the opposite connotations in many other fields of human activity.
In philosophy, "phenomenology" is linked to Edmund Husserl who thought that the most important thing for philosophers to study are "phenomena". But he didn't mean natural phenomena; instead, what he had in mind were phenomena (as well as "noumena") resulting from consciousness. This stuff is full of occult references to sensibilities, emotions, and their existence that is supposed to be independent of the material carriers.
In theology and psychology, "phenomenology" is all about the subjective perceptions, too. I don't know what all those people study but it's clearly some spiritist flapdoodle whose intersection with scientifically meaningful entities is almost certainly empty. In architecture and archaeology, "phenomenology" is a related weird theory about places' having their own spirits that are correlated with ill-defined mixtures of the physical properties of the places. I won't even try to understand what these people could be talking about. ;-)
But let me return to the main topic.
I believe that the redirection to experiments and phenomenology has already been overdone. It's really great that the Higgs boson has been discovered but one didn't really need 10,000 experimenters for that. Moreover, one must be ready for the possibility that the Higgs boson is the last new thing that the LHC will observe. This scenario surely can't be ruled out. If this scenario turns out to be true, we will quickly see that there are way too many people employed to study certain particular aspects of Nature that are modest or don't exist.
And in this context, I mean both experimenters and phenomenologists. The phenomenologists' preference for questions that may be addressed by contemporary experiments may look very intriguing – many people like tangible things – but it has an obvious flip side. If you're focusing on things that are accessible and hot in 2012, chances are high that they will no longer be hot and important in 2013 or later. Whether you like it or not, most of the work in phenomenology has a lower lasting value. The fact that those ideas are partially "fads" that quickly fade away (at least most of them) is completely inseparable from their being relevant for currently doable experiments.
So a vast majority of the particular models with some preferred choices of parameters that had been proposed as a solution to the hierarchy problem has already been falsified. Almost all others – with at most one exception – will be falsified in the coming months and years. If you assign a price to a model builder's paper, this really means that the price drops to zero once the model is falsified. Unless the person finds the right new model; no one has succeeded in this task after the fathers of the Standard Model.
Only if a paper transcends some particular technicalities that are identified as valid or invalid by experiments, it may have a lasting value. A paper with a lasting value must contain some new and intriguing enough ideas or methods or theorems or new tools or new concepts that are independent of a particular technical implementation of these ideas – implementation that is usually quickly shown not to be relevant for Nature around us.
Needless to say, the concentration of such ideas and insights is much higher in the formal theoretical papers – in papers on string theory and perhaps also some others. The amount and the penetration factor of deep insights with a lasting value that were found by string theorists in recent decades is staggering.
Even though we are in the middle of the exciting LHC era, everyone should start to appreciate the simple and self-evident fact that the LHC won't give us the answers to all open questions in physics. High-energy physics will keep on living after the LHC and a thread of its life that will probably regain its dominance in a few years is firmly rooted in theory.
That's why I think it's important for places not to become giant LHC bubbles and to start to hire many theorists again.
And that's the memo.