Steven Weinberg, looking back 50 years, recalls cosmology and elementary-particle physics as cacophonies of competing conjectures, now replaced by standard models allowing numerical predictions of high precision that agree with observation. Up to a point, Weinberg says, the stories can be told separately, but in the end they will come together. He first traces nearly a century of cosmology, including efforts to determine the universes expansion rate, discoveries of cosmic microwave background radiation and later its temperature variations, and the mysteries of dark matter and dark energy. For particle physics he emphasizes theory. He observes that dreams of finding a more comprehensive quantum field theory that would describe all the particles and forces of nature as happily as quantum electrodynamics had already described photons and electrons have more or less turned out. He traces electroweak theory and quantum chromodynamics. But todays particle physics standard model is clearly not the final theory, he asserts; it rests in part on numbers not understood and doesnt embrace gravitation. Weinberg moves on to string theory, reporting that he has been a fan but finds it disappointing that no one so far has succeeded in finding a solution that corresponds to observations. In the end he proposes that the problems of elementary particle physics and cosmology have increasingly merged, describes consequent mysteries, and declares, Physical science has historically progressed not only by finding precise explanations of natural phenomena, but also by discovering what sorts of things can be precisely explained. These may be fewer than we had thought. This post was written by media analyst Steve Corneliussen
Posted on: Fri, 18 Oct 2013 15:52:14 +0000
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