Toward A Philosophy of Physical Instruments

TOWARD A PHILOSOPHY OF PHYSICAL INSTRUMENTS T HE instruments of physics, like Gothic architecture, Roman roads, and the pyramids, are among the most admirable of man's exterior achievements. Galileo, at the dawn of modern science, measuring the fall of bodies, seems almost among the ancients by contrast with the decimal points in the physics of today. Micromicrovolts and micromicrofarads are common expressions in the ordinary textbook. The electronmicroscope has extended man's eyes to the molecular level. The weights and charges of even sub-atomic particles have flashed across films and meters. By radar techniques, measuring time lapses down to the millionths of a second, man has bounced electromagnetic energy off the moon. Long before Hiroshima, atoms had been smashed in laboratories; and since the end of the war, physics has disclosed the synthesis of at lea~t four new man-made elements. A German scientist claimed, after the war, to have devised a thermopile to detect temperature differentials of a millionth of a degree. In the region of the very large, a new giant telescope to be assembled on Mount Wilson, will make the stars, the fine print of night, seem as near and as clear as the morning headlines. On every side, the vistas of modern physics are stretching even farther toward the very large and the very small. As spectacles improve weak vision, the instruments of physics have focused on the metrical aspects of the universe with a sharpness that excites as much amazement as it imparts knowledge. An instrument does not stand isolated, even though in some aspects of positivism, it is viewed as a sheer detached and passive register of actual laboratory events. The betatron, the cathode-ray oscilloscope, and other such devices seem at first sight to be as self-sufficient and as self-revealing as the Moses of 307 808 VINCENT EDWARD SMITH Michelangelo or a symphony. But they are not. Instruments, whatever be their purpose, have relations without which they lose their meaning-the tide without the ocean. These relations , not only with a view to clarifying physics but also with reference to various forms of positivism and pragmatism, stand in need of philosophical assessment. Measurement, like everything else that the physicist deems meaningful, is an interaction between facts or physical events. As Lenzen has written, " The fundamental physical concept is that of the space-time coincidence of two points-the similarity of the two points with respect to spatial position and temporal position." 1 In nature, there is no hierarchy between measure and the measured. Whatever priority be accorded to the instrument is thus not owed to it in its own right. Evident by a philosophical analysis, the equivalence of measure and the measured is endorsed by both the special and general theories of relativity which make it permissible when A is moving relative to B, to say simultaneously that B is moving relative to A; relativistically , for example, it can be said that the sun moves around the earth just as truly as a helio-centric view may be accepted. Being in physics does not stand alone with intrinsic nature and intrinsic dignity. Scientifically, it makes no difference whether man bites dog or dog bites man.2 Instruments acquire their logical rank from the physicist. In the scientific method, man is thought to be a merely passive observer-a photosensitive plate exposed to external events. But in a global view, scientific method, or more accurately the scientist, cannot be so regarded. Scientific method is not selfsu ~cient. In openir;g, closing, directing, and focusing its camera, this method is truly and totally dependent on the larger, vital, active, and non-inertial power of the human spirit. Here at the very onset of measurement, man thus intervenes with a qualita1 The Nature of Physical Theory, New York, 1931, p. 43. •" Nun ist es klar, dass ... der Akt der Messung nichts anderes ist als ein physikalisches Ereignis, dessen Ausgang sich rein empirisch beobachten liisst." Wind, E., Das Experiment und die Metaphysik, Tubingen, 1934, p. 4. TOWARD A PHILOSOPHY OF PHYSICAL INSTRUMENTS 309 tive judgment, according at least a logical priority to his meter as opposed to the measured object. Whatever be...