quarta-feira, 28 de janeiro de 2015

Particle Physics and Negative Knowledge


"Negative Knowledge and the Liminal Approach

Having argued that to assure success HEP experiments turn toward the care of the self, I now want to add that they also turn toward the study of “liminal” phenomena, things which are neither empirical objects of posi­tive knowledge nor effects in the formless regions of the unknowable, but something in between. Limen means “threshold” in Latin. The term has been used in the past to refer to the ambiguous status of individuals during transitional periods of time (Turner 1969). I shall use the term to refer to knowledge about phenomena on the fringe and at the margin of the objects of interest. High energy physics incorporates liminal phenom­ena into research by enlisting the world of disturbances and distortions, imperfections, errors, uncertainties, and limits of research into its project. It has lifted the zone of unsavory blemishes of an experiment into the spotlight, and studies these features. It cultivates a kind of negative knowledge. Negative knowledge is not nonknowledge, but knowledge of the limits of knowing, of the mistakes we make in trying to know, of the things that interfere with our knowing, of what we are not interested in and do not really want to know. We have already encountered some forces of this kind in the background, the underlying event, the noise, and the smearing of distributions. All of these are limitations of the experi­ment, in the sense that they are linked to the features of the detector, the collider, or the particles used in collisions. High energy collider physics defines the perturbations of positive knowledge in terms of the limita­tions of its own apparatus and approach. But it does not do this just to put the blame on these components, or complain about them. Rather, it teases these fiends of empirical research out of their liminal existence; it draws distinctions between them, elaborates on them, and creates a discourse about them. It puts them under the magnifying glass and pre­sents enlarged versions of them to the public. In a sense, high energy experimental physics has forged a coalition with the evil that bars knowl­edge, by turning these barriers into a principle of knowing.

In Christian theology, there was once an approach called “apophantic theology” that prescribed studying God in terms of what He was not rather than what He was, since no positive assertions could be made about His essence. High energy experimental physics has taken a similar route. By developing liminal knowledge, it has narrowed down the region of positive, phenomenal knowledge. It specifies the boundaries of knowledge and pinpoints the uncertainties that surround it. It delimits the properties and possibilities of the objects that dwell in this region by recognizing the properties of the objects that interfere with them and distort them. Of course, if one asks a physicist about “negative knowl­edge” he or she will say that the goal remains to catch the (positive, phenomenal) particles at loose, to measure their mass and other (posi­tive, phenomenal) properties, and nothing less. All else is the ways and means of reaching this goal. There is no doubt that this goal is indeed what one wishes to achieve, and occasionally succeeds in achieving, as with the discovery of the vector bosons at CERN in 1983 (Arnison et 1983a,b; Bagnaia et al. 1983; Banner et al. 1983). My intention is by no means to deny such motivations or their gratification, but what is of interest as one works one’s way into a culture is precisely the ways and means through which a group arrives at its gratifications. The upgrading of liminal phenomena—the torch that is shone on them, the time and care devoted to them—is a cultural preference of some inter­est.4 For one thing, it extends and accentuates what I call HEP’s negative and self-referential epistemics. For another, the majority of fields, among them molecular genetics, does not share this preference. And, lastly, it is quite remarkable how much one can do by mobilizing negative knowledge.

There are two areas in which the liminal approach is most visible: the area of errors and uncertainties and the area of corrections. Let me start with the latter. The idea of a correction is that the limits of knowing must enter into the calculation of positive knowledge. For example, “meaningless” measurements can be turned into meaningful data by correcting them for the peculiarities and limitations of the detector. “What you really want to know,” as a physicist summed up this point, “is, given that an event is produced in your detector, do you identify it.” Corrections can be characterized as “acceptances”, or as “efficien­cies.” An acceptance tells physicists “how many events my detector sees of what it should see”; it is the number of observed events divided by the number of produced events.5 An overall acceptance calculation re­quires a detector response model: it requires that all the physics proc­esses that end up in a detector are generated, and a full detector simulation is created to ascertain what the detector makes of these processes. In UA2, the detector response model also included such components as a simulation of the underlying event and detector per­formance measures, such as its geometrical acceptance (which describes how many events are lost through the incomplete coverage of detectors with dead angles and cracks), its resolution (which refers to the smear­ing of distributions described earlier), and its response curves (which determine the reaction to energy inputs that deviate from those of the test beam used to determine the basic calibration constants)."

Karin Knorr Cetina, Epistemic Cultures: How the Sciences Make Knowledge, p.63-65.




Epistemic Cultures: How the Sciences Make Knowledge, by Karin Knorr Cetina. Cambridge, MA: Harvard University Press, 1999. xix + 329 pp.


Karin Knorr Cetina offers the reader a valuable comparative look at the “epistemic cultures” (the arrangement and mechanisms by which we come to know what we know) in two fields of science—high-energy physics (HEP) and molecular biology (MB). She believes there is a “diversity” among epistemic cultures, which reveals “disunity” within the sciences—hence the comparative approach. Her analysis is not focused on the construction of scientific knowledge, but rather the “machineries of knowledge construction”—the practices that go into the making of scientific knowl­edge—and the “cultures” that surround and give symbolic meaning to such practices. Following a chapter that examines the constitution of differing types of laboratories, Knorr Cetina offers up a series of comparative chapters that deal with the configura­tion of “reality,” the technological machinery, and the social arrangements entailed in the two fields. A final chapter in the form of an imagined dialogue between author and reader, which worked less well for me than most of the book, tries to set what has been learned about these two epistemic cultures within what Knorr Cetina sees as a broader trend toward knowledge-based societies in the Western world. A brief summary of Knorr Cetina’s analysis, which is based on many years of participant observation and interviews with selected practitioners, can hardly do justice to the complexities of her findings. Nor is the reading always easy, in part due to the science itself. Nonetheless, a review of some of the author’s key points is revealing of the richness of this impor­tant study.

Knorr Cetina views laboratories as reconfigurations of natural and social orders, ones in which scientists have also become “specific epistemic subjects” as they are shaped and transformed with regard to the kinds of technologies and techniques they use. She views HEP laboratories in terms of technologies of “correspondence” that “stage” real-world phenomena, while MB laboratories involve technologies of “treat­ment and intervention” in which the objects of research are processed partial versions of these phenomena. Thus, the detectors of particle physics laboratories are sign-pro­cessing technologies that examine particle beams within “a closed circuitry” in which measurements are inside the staged experiment, not outside as in the molecular biol­ogy laboratory, which is open to “natural” objects. Detectors mediate between the experiment and their data representation of the phenomenon. Because detectors vary widely, interact with each other, and are tied to “background” processes, HEP labora­tories often focus on negative knowledge areas of imperfection and uncertainty as ways to narrow down the region of positive, phenomenal knowledge. This also accounts for why experimental physicists often focus so much attention on analyzing the experiment itself, rather than the objects of it. By comparison, the more open MB laboratory seeks to maximize empirical contact through experimental manipulation of objects to develop positive knowledge. In contrast to the large-scale nature of HEP experiments, molecular biology is a benchwork science dealing with small objects in small laboratories. When problems arise, it adopts a “blind variation natural selec­tion” approach that tries out various alternative procedures until one is successfully found to “fit” and is hence selected. This is in sharp contrast to the more “scientific” self-analytical problem investigation of HEP experiments. Finally, MB uses the sen­sory body of the scientist as an information-processing tool in a way that has been eliminated by the HEP detector.

Knorr Cetina moves from the discussion of what goes on experimentally in the two types of laboratories to an analysis of the symbolic classifications that particular phys­icists and molecular biologists superimpose on their technical universes and that reveal relationships between objects and subjects. HEP is dominated by technology that determines what physicists can do, yet these machines turn into symbolic organisms. Thus, detectors “see” and are “in/sensitive” and can have “reactions” and “responses” while “interacting” with particles. They also “age,” “act up,” and “get sick” and can either “cooperate” or “misbehave.” Scientists blame the “background,” not the detector, which is a “friend,” while they “fight” the background, trying to “kill” it. Physicists seem less imaginative about themselves, referring symbolically to them­selves in terms of the objects with which they work—hence the “electron group” or the “top working group.”

Whereas machines are organically symbolized in HEP laboratories, in MB, living organisms are transformed into production systems and molecular machines. MB does not deal with naturally occurring plants and animals; rather, it cultures its own entities for study. Thus, mouse breeding for experiments is “standardized” and “ratio­nalized” as part of a “well-oiled production line,” and while cell lines are certainly “cared for,” it is out of concern for economy of time and resources, not a sense of morality. Mice, cell lines, bacteria, and vectors are production devices themselves— autonomous units in which biological tasks are performed not for the host’s own needs but for human objectives. Substances created by such biological machines are mass-produced, uniform, and pure. It is in this sense that the term “genetic engineer­ing” sustains the idea of biological machines and suggests a technological view of molecular biology.


Knorr Cetina’s third area of comparative analysis deals with the collective, com­munitarian structure of HEP experiments and the far more individualized nature of the MB laboratories. HEP experiments—because they depend so centrally on singular and very large experimental devices, involve hundreds of financially independent “institutes,” and whose “life” may run for upwards of twenty years—tend as a result to be cooperatively managed by content rather than by social hierarchies. Thus, funding, research work, and publication are largely divorced from individual scientists and are instead collectively focused. Because no one individual or even a small group can do all the work, “naming” and “epistemic agency” have shifted to the experiment, and publications are authored alphabetically with all the many hundreds of participants being listed. Conferences are attended by a variety of “spokespersons” who reflect the collaborative nature of the work. Horizontal “object-centered” organizational struc­tures characterize HEP experiments, as does the free flow of open “discourse” through widely circulated “status reports” and “confidence pathways” that help link people together. Knorr Cetina characterizes all this as entailing a “post-traditional communitarian structure.”

By direct contrast, MB laboratories entail a dual organizational format in which individual units focused around single researchers do the direct research, while a lab­oratory leader provides overall direction and is the focal point for the laboratory as a whole. In MB, where there is no dominating technical apparatus as in HEP, the indi­vidual scientist remains the epistemic subject, using skills and expertise in small “lifeworlds” that are largely separate from each other. The laboratory, which is a grouping of otherwise spatially and often territorially separate activities, is personi­fied in the leader who must position and represent the entity as a whole to those in the outside scientific community. Competitive tensions may evolve, for while most work is conducted by Ph.D. students, post-docs, and permanent position scientists, it is gen­erally only the laboratory leader who travels to conferences to represent the laboratory and hence reaps the benefits. There can also be tensions between those responsible for their own research projects and those who do necessary, but often unrecognized, “ser­vice” work within a laboratory. Primary authorship thus becomes much more of a competitive issue, for it is through such recognition that one advances through a more hierarchical career path than is generally evident in HEP, hopefully to become a labo­ratory leader at some point in the future. Knorr Cetina points out that there is a more well-defined “logic of exchange” in MB laboratories, in contrast to the communi­tarian principles evident in HEP experiments. Finally, she briefly notes that gender seemed to be more of an issue in MB laboratories than in HEP experiments, which she characterized as more typically being “mono-gendered,” albeit with a look more male than female.


In sum, this is a sophisticated study that because of its comparative lens provides the reader with useful insights into the two fields, insights that might otherwise be harder to discern if examined separately. Knorr Cetina’s study of the “cultures” within which scientific knowledge is constructed is a useful addition to science studies and contributes to our overall understanding of the multiple ways science is practiced. It further suggests the tight fit between techniques, technological instrumentation, and scientific knowledge creation in contemporary laboratory work. Epistemic Cultures should be a STS standard for some years to come.

—Stephen Cutcliffe Lehigh University

Science, Technology, & Human Values
Vol. 26, No. 3 (Summer, 2001), pp. 390-393

See also my interview with Prof Karin Knorr Cetina for Folha de SP, 2/5/2010, Mais!
http://urania-josegalisifilho.blogspot.de/2011/09/acelerador-de-gente-entrevista-com.html

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