Recent content by roberto85

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    Difference/convert between covariant/contravariant tensors

    Apologies Ray, have edited now, appreciate the pointers.
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    Contraction of a tensor to produce scalar

    Thanks Ray, i just edited the equation but can't see why its not displaying correctly? edit: i see now, sorry. Is that correct to say then that the covariant multiplied by the contravariant will reduce it to a scalar?
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    Contraction of a tensor to produce scalar

    Homework Statement Explain how it is possible to perform a contraction of the tensor ##T^{\beta \gamma}_{\delta \epsilon}## in order to produce a scalar T Homework EquationsThe Attempt at a Solution $$T^{\beta \gamma}_{\delta \epsilon}T_{\beta \gamma}^{\delta \epsilon}=T$$ Not sure if that is...
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    Difference/convert between covariant/contravariant tensors

    Homework Statement 1. Explain the difference between a covariant tensor and a contravariant tensor, using the metric tensor as an example. 2. Explain how the components of a general covariant tensor may be converted into those of the equivalent contravariant tensor, and vice versa. Homework...
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    Is there any news to Garrett Lisi theory?

    oh great thanks for letting me know
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    Is there any news to Garrett Lisi theory?

    Yes, he recently posted this paper 6 days ago: http://arxiv.org/abs/1506.08073 I would love for a technical discussion to arise from this paper like it did his last one, it was very interesting.
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    The QED experiments Feynman describes in his Auckland lectures on Vega website

    Hi all, I am looking for some more information about the experiments that Feynman describes during the lectures that he gave in Auckland which can be viewed on the vega science trust website. The first experiment is where photons are transmitted or reflected by one surface with a second similar...
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    Sphere/Atom packing - most efficient lattices?

    Brilliant, thanyou so much. I expect this pdf will answer more of my questions when i read it more fully.
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    Sphere/Atom packing - most efficient lattices?

    From wikipedia i have this quote: The fcc value is the highest theoretically possible value for any lattice, although there are other lattices which also achieve the same value, such as hexagonal close packed and one version of tetrahedral bcc What is the tetrahedral BCC which they refer...
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    Neutrinos as majorana particles or where are left handed antineutrinos?

    Cool, i had read a little about sterile neutrinos and read something about sterile neutrinos possibly being neutral heavy leptons (NHL).. oh i see where this links in with the seesaw mechanism. Okay, I'm not so dismissive of the seesaw mechanism now especially since NHL's might be a good...
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    Is there a representation diagram for fermions like the 8 fold way for mesons?

    I was wondering if there was something similar to the 8 fold way representation used on mesons for the fermions?
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    Neutrinos as majorana particles or where are left handed antineutrinos?

    Yes, to be honest i don't quite like the see saw mechanism of the majorana neutrino theory. But i still think there's something mysterious about neutrinos we have yet to discover, with the weak sector cp violation being the smoking gun. Its on my list of things to keep an eye on ;)
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    Neutrinos as majorana particles or where are left handed antineutrinos?

    In the above example it would have to be that one of the neutrinos was left handed and the other was right handed, which is what we use to distinguish them as being either a neutrino or an antineutrino respectively. But since a right handed neutrino would, i assume, look and behave exactly the...
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    Possibility to see Higgs particles at the International Linear Collider

    I do hope they build some sort of linear collider to investigate the higgs further. Perhaps plans will emerge and become more concrete once more data is accumulated at the LHC. Thanks for the info :)
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