Recent content by ccdantas

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    Lecture of Edward Witten and 2nd Dutch-IFT School (BRAZIL)

    The 2nd Joint Dutch-IFT School on Theoretical Physics will be held from February 14-18 at the IFT-UNESP in Sao Paulo. The opening lecture "String Theory and the Universe" will be given by Prof. Edward Witten (IAS, Princeton) at 10:15 on Monday Feb 14, followed by minicourses of Prof. Eric...
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    Laws of Nature workshop: what can we tell from the program?

    Finally, only now I was able to watch this video. Very interesting. Lots of material to think about, and potential points of convergence with other ideas. I am curious on how far the idea of time as a "change of change" is connected with H. Bergson's idea of "duration". Hopefully, the book...
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    Bojowald's upcoming book

    Marcus, Most physics undergraduate courses do not offer even general relativity (not even a basic introduction to it), so Hamiltonian GR is out of question. This is so in Brazil, and as far as I can see, also true elsewhere. http://arxiv.org/abs/gr-qc/0506075 Undergraduate physics has...
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    Bojowald's upcoming book

    I apologize if this has been posted before. https://www.amazon.com/dp/0521195756/?tag=pfamazon01-20 Martin Bojowald Hardcover: 304 pages Publisher: Cambridge University Press (January 31, 2011)
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    Book Ideas

    I strongly advice *against* this book, since it is for advanced undergraduates and beginning graduate students, which is evidently not the case here. If you are really interested to work hard and the right way in other to have a good basic understanding of these matters, so that you can...
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    Doubly Special Relativity

    See Sabine H.'s latest blog entry http://backreaction.blogspot.com/2010/08/update-on-status-of-dsr.html" [Broken].
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    Why I am REALLY disappointed about string theory

    http://egregium.wordpress.com/2007/05/24/is-there-more-to-gravity-than-gravitons/" [Broken]
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    Why I am REALLY disappointed about string theory

    There is no misunderstanding :smile: It's just that it's really more appropriate to read how professional string theorists will address your questions than I write/question anything general for the moment. My concern with negru's comments is somewhat outside this thread.
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    Why I am REALLY disappointed about string theory

    Just one thing: I wonder who are really professional string theorists known to contribute at PF??
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    Why I am REALLY disappointed about string theory

    Yes, thanks, I know. I was just questioning negru in order that he would clarify his rationale. But since I am not a string theorist and do not wish to contribute diverging from your interesting thread, I will just be following with no further comments. Thanks.
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    Why I am REALLY disappointed about string theory

    You mean then that those features are not necessarily physical, and hence their eventual non-observation has no impact whatsoever on corroborating or not the theory? Then what is your criteria for considering a feature physical within a theory, or in other words, what would make it "important"...
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    What's Ed Witten up to?

    Hi atyy, I cannot tell from the more recent papers (the last two), but I'd say that, yes, the first three examples above involve model building and calculations on it, at varying degrees. The last one appears to use computations from other works, but I'd have to read it some time. Best...
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    What's Ed Witten up to?

    Here are some dictionary definitions of the word "calculation": - problem solving that involves numbers or quantities - determining something by mathematical or logical methods [syn: computation, computing] - to determine by mathematical processes [ex: calculate the rate of...
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    What's Ed Witten up to?

    In a sense you corroborate with my impressions. Generally one does calculations aiming at something specific, an application, for instance. Not the general solution or result. It's not a question of calculations being good/bad, elegant/cumbersome, but required or not.
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    What's Ed Witten up to?

    I would say "equations" or "mathematical expressions", instead of "calculations". Most string theory papers that I have seen do not have "calculations" in the sense of the word, that is, with concrete numbers put into formulas.
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