The Golem: What Everyone Should Know About Science by Harry Collins Trevor Pinch

Author:Harry Collins, Trevor Pinch
Language: eng
Format: epub
Publisher: Cambridge University Press
Published: 2013-03-03T16:00:00+00:00

The experimenter’s regress

By 1972 several other laboratories had built or were building antennae to search for gravitational radiation. Three others had been operating long enough by then to be ready to make tentative negative reports. Now we must imagine the problems of a scientist attempting to replicate Weber’s experiment. Such a scientist has built a delicate apparatus and watched over it for several months while it generated its yards and yards of chart recorder squiggles. The question is: are there peaks among the squiggles which represent real gravity wave pulses rather than noise? If the answer seems to be ‘no’ then the next question is whether to publish the results, implying that Weber was wrong and that there are no high fluxes of gravity waves to be found. At this point the experimenter has an agonising decision to make; it could be that there really are gravity waves but the negative experiment is flawed in some way. For example, the decision about the threshold for what counts as real peaks might be wrong, or the amplifier might not be as sensitive as Weber’s, or the bar might not be appropriately supported, or the crystals might not be well enough glued to allow the signals to come through. If such is the case, and if it turns out that there are high fluxes of gravity waves, then in reporting their non-existence, the scientist will have revealed his own experimental incompetence.

Here the situation is quite unlike that of the school or university student’s practical class. The student can have a good idea whether or not he or she has done an experiment competently by referring to the outcome. If the outcome is in the right range, then the experiment has been done about right, but if the outcome is in the wrong range, then something has gone wrong. In real time, the question for difficult science, such as the gravity wave case and the others described in this book, is, ‘What is the correct outcome?’. Clearly, knowledge of the correct outcome cannot provide the answer. Is the correct outcome the detection of gravity waves or the non-detection of gravity waves? Since the existence of gravity waves is the very point at issue, it is impossible to know this at the outset.

Thus, what the correct outcome is depends upon whether there are, or are not, gravity waves hitting the earth in detectable fluxes. To find this out we must build a good gravity wave detector and have a look. But we won’t know if we have built a good detector until we have tried it and obtained the correct outcome. But we don’t know what the correct outcome is until … and so on ad infinitum.

This circle can be called the ‘experimenter’s regress’. Experimental work can only be used as a test if some way is found of breaking into the circle of the experimenter’s regress. In most science the circle is broken because the appropriate range of outcomes is known at the outset.

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