The growth of astrophysical understanding

Abstract

Since this symposium commemorated Galileo's discoveries and was concerned with astronomy and culture, I thought I might examine the extent to which culture affects how we view, depict, and ultimately come to understand the Universe around us. Twenty-five years ago, Andrew Pickering, wrote Constructing Quarks – A Sociological History of Particle Physics, (Pickering 1984) a book that enormously annoyed the high-energy physics community, perhaps because it contained a disquieting dose of truth. Pickering argued that the theory of fundamental particles, the particles that make up the atomic nucleus, and break up or fuse into myriad other particles when smashed into each other, was a construct that physicist had pieced together, through a process he termed a “communally congenial representation of reality”. Physicists, he claimed, had arrived at a so-called “standard theory” of particle physics that was not an inherent description of Nature, but “deeply rooted in common-sense intuitions about the world and our knowledge of it”. Instead, Pickering surmised that a better depiction of particle physics would eventually be found, which would appear unrecognizably different from what had come to be the accepted way of viewing Nature's fundamental particles. Today, many particle physicists would be more likely to agree with Pickering than they were then. Although the standard theory has successfully survived a quarter of a century of testing, its scope is known to be limited. It fails to properly accommodate gravity. And the string theories, brane theories, and other attempts of particle physicists to produce a coherent theory of all the known forces of nature have so different a structure from the standard theory, topologically, as well as in terms of numbers of spatial dimensions, that they share little recognizable resemblance. So, we may ask, was Pickering right? Are physicists and astronomers just constructing congenial representations that bear little relation to the inherent structure of the Universe we inhabit? In astronomy, we have by now embraced what we term the “concordance model” based on general relativity, which we assert has led to tremendous strides in understanding the evolution of the Universe. But we find ourselves forced to postulate a new form of matter, dark matter, the existence of which is supported by little independent evidence, and we find ourselves forced to postulate the existence of a new form of energy, dark energy, for which there is similarly little independent evidence. Perhaps both these postulates will someday soon be justified. But we may equally well find a need for viewing the Universe in a totally different way that encompasses general relativity only as a limiting case, but embraces dark matter and dark energy as a natural consequence. Such a depiction might then be just as mind-bogglingly different from what we conceive today, as Einstein's postulate was, when he first annunciated it, that the speed of light would always appear the same no matter how fast an observer was moving toward or away from its source. How could that be, it violated every conceivable human intuition?