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Brave New Universe: Illuminating the Darkest Secrets of the Cosmos
physicists, it is only now that philosophers have also come to recognize his innovative way of thinking.
Often emphasizing that he was not a solipsist, Eddington clearly stated that he believed in the existence of an external world. Nevertheless, he was convinced that our way of viewing it is limited by our biology. This conviction led him to the conclusion that science is, at least partly, subjective. His most memorable defense of this unpopular view was an analogy involving the meshsize of a fishnet.
Eddington imagined an ichthyologist investigating ocean life. He casts a net, with gaps two inches wide, into the water. When he retrieves his catch, he finds it full of fish, each more than two inches long. This leads him to generalize that no sea creature is smaller than two inches. By analogy, we retrieve from the sea of knowledge only what the mesh of our methodology allows. Other (smaller) things pass through. As Eddington pointed out, scientists are often boxed in by the boundaries of physical observation. They tend to discount what they can’t directly perceive. Eddington emphasized this view when, continuing the tale of the ichthyologist, he related how difficult it can be to challenge improper scientific assumptions:
An onlooker may object that the first generalization is wrong. “There are plenty of sea creatures under two inches long, only your net is not adapted to catch them.” The ichthyologist dismisses this objection contemptuously. “Anything uncatchable by my net is ipso facto outside the scope of ichthyological knowledge and is not part of the kingdom of fishes…. In short, what my net can’t catch isn’t fish.” Or—to translate the analogy—“If you are not simply guessing, you are claiming a knowledge of the physical universe discovered in some other way than by the methods of physical science, and admittedly unverifiable by such methods. You are a metaphysician. Bah!
In Eddington’s day, labels for various physical phenomena were starting to break down. As the Copenhagen interpretation of