222 research outputs found

    Current Algebra: Quarks and What Else?

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    After receiving many requests for reprints of this article, describing the original ideas on the quark gluon gauge theory, which we later named QCD, we decided to place the article in the e-Print archive

    Adaptive Coarse Graining, Environment, Strong Decoherence, and Quasiclassical Realms

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    Three ideas are introduced that when brought together characterize the realistic quasiclassical realms of our quantum universe as particular kinds of sets of alternative coarse-grained histories defined by quasiclassical variables: (1) Branch dependent adaptive coarse grainings that can be close to maximally refined and can simplify calculation. (2) Narrative coarse grainings that describe how features of the universe change over time and allow the construction of an environment. (3) A notion of strong decoherence that characterizes realistic mechanisms of decoherence.Comment: 11 pages, revtex

    Dick Feynman—The Guy in the Office Down the Hall

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    When I think of Richard, I often recall a chilly afternoon in Altadena shortly after his marriage to the charming Gweneth. My late wife, Margaret, and I had returned in September 1960 from a year in Paris, London and East Africa; Richard had greeted me with the news that he was “catching up with me”—he too was to have an English wife and a small brown dog. The wedding soon took place, and it was a delightful occasion. We also met the dog (called Venus, I believe) and found that Richard was going overboard teaching her tricks (leading his mother, Lucille, with her dry wit, to wonder aloud what would become of a child if one came along). The Feynmans and we both bought houses in Altadena, and on the afternoon in question Margaret and I were visiting their place. A brilliant, vital and amusing neighbor, Feynman was a stimulating (if sometimes exasperating) partner in discussions of profound issues. His sum‐over‐paths method may turn out to be not just useful, but fundamental

    Particles and principles

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    We know that there are two frontiers in the study of the basic laws of natural science: the frontier of the very large, the cosmos, and the frontier of the very small, the structure of the elementary particles out of which the entire universe is constructed, including us. The combination of these two (at the present time theoretically unrelated, although we hope that this situation won't persist) gives us the basic scientific laws that form the foundations for our discussions of science. The research in both of these fields is necessarily a close partnership of theory and observation, and the availability of numerous experiments in the study of the very small is what has made progress in that field more rapid and more exciting in recent years than progress at the other end. But, as interesting observations of the cosmos accumulate, cosmology too should flourish. One thing that makes the adventure of working in our field particularly rewarding, especially in attempting to improve the theory, is that at this basic level of science a chief criterion for the selection of a correct hypothesis, even more than elsewhere in science, seems to be the criterion of beauty, simplicity, or elegance

    How scientists can really help

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    Last fall I had the honor of speaking at the dedication of a new physics building on the University of California campus at Santa Barbara. As I arrived for the occasion, it struck me how lucky the physicists at Santa Barbara are to be living and working in such a glorious place. The day was clear and I could see the mountains, which contain the surviving frayed specimens of the majestic California condor, and the channel, with the islands on the other side. I had been sailing in the channel and had seen it sometimes sparkling in the sunlight, sometimes shrouded with fog, full of dolphins and sea lions. The campus is built on what used to be my favorite bird‐watching place in Southern California, with its curlews, godwits, and phalaropes. Now, for the males of our species, it is a favorite girl‐watching place. In any case it is bustling with young Californians presumably seeking knowledge and wisdom, and some older people who are supposed to be able to impart such things. The priority need is to develop a systems analysis with heart that society can rely on to choose between possible technologies

    ISIS Opening Address: Complexity versus Simplicity

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    There are a lot of different concepts to cover all the meanings that we attach intuitively to the word complexity, and to its opposite simplicity. There is one kind of complexity that corresponds best to what is meant by the word complexity in ordinary conversation, and in most scientific dialog. It’s what I call effective complexity. Roughly, effective complexity refers to the length of a very precise description of the regularities of an entity. Not the features that are treated as random or incidental, but the features that are treated as regularities