Doing Physics by Martin H. Krieger

Doing Physics by Martin H. Krieger

Author:Martin H. Krieger
Language: eng
Format: epub
Publisher: Indiana University Press
Published: 2012-07-14T16:00:00+00:00


THE DIALECTIC OF FINDING A GOOD VACUUM: A PHENOM ENOLOGY

As we discuss in chapter 5, a good vacuum allows physicists to observe phenomena in terms of that vacuum’s orderly Somethings, Somethings which are simple and recognizable. For when one pokes properly at a vacuum, with the right kind and level of intrusiveness and gentleness, the response is just those Somethings, the rest of the degrees of freedom still being tamed and hidden and held in. Conversely, that the effects of poking are simple and reproducible is taken as a sign of our having achieved a good enough vacuum for this particular physical situation. (That a piece of theater works well suggests we have set the stage properly.) Now, effects will be reproducible if we have swept up enough degrees of freedom so that we have sufficient control over all the rest – for otherwise, untended-to degrees of freedom could arbitrarily affect what we see. (We do not want strangers wandering onto the set.) And if reproducible, the disturbances of the vacuum will then be seen as “effects,” as consequences of our own interactions with the world. (In classical theater, we want a sense of causation and agency.) Observation now becomes possible because we know how to generate robust phenomena and what kind of signals to look for.38

Now a good orderly vacuum is, in fact, overdetermined in that the actual achievement of any one of the goals seems to give the physicist the rest by the way. To repeat: Degrees of freedom are tamed, an emptiness is created, a new orderliness is found, and some formal procedure (formal mathematics, or a formal analogy to another situation) or some experimental setup does all of this work automatically. These are both grammatical and practical demands. Taming degrees of freedom means there is emptiness, which means there is a residual orderliness, and this work is done by formal sleights of hand or through the design of experiments. However, the experience of the physicist is rather more contingent, the work of creating or setting up or conceiving of the vacuum rather more subtle, than any grammatical identities would imply. And that wondrous overdetermination is only apparent after a good vacuum is found. A good vacuum is in essence those right degrees of freedom that Weinberg speaks of. The commitments to the various constraints and their deeper features might be likened to a faith, their eventual automatic effectiveness being seen as its miraculous confirmation.

Now, in the end, the story of constraints and deeper features proves to be insufficiently satisfying. For example, that an optimization principle works does not say just how and why it works.39 So scientists also demand an account of how orderliness sets in, just how the sweeping up of the irrelevant degrees of freedom takes place, just how the constraints are actually fulfilled. Such a mechanism is taken as the sign of a real explanation. Note as well that such an account is ironic in its effect, since creation is no longer a



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