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  1. T

    Spin connection vs. Christoffel connection

    My knowledge in this field is limited but there are all sorts of quantum gravity theories that choose different variables as "basic" quantities. As for the relation between spin and Christoffel connections, you can think of the Christoffel connection as the connection on an associated bundle...
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    Would a partner be a good idea?

    Having a pair of ears that are ready to listen to you (or your nonsense sometimes) is good.
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    Gauging Discrete Groups.

    You try to construct a continuous (and nonconstant) function from [0,1] to {-1,1}.
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    Gauging Discrete Groups.

    My point is that you cannot have continuous (nontrivial) spatial dependence with discrete groups. The lattice gauge theory above mentioned is not a theory with discrete gauge group, rather it is a theory with discrete spacetime.
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    MSc in Theoretical Physics as mature student

    That is remarkable!
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    Gauging Discrete Groups.

    If I understood your question correctly, you cannot "gauge" discrete groups because your want the gauge to be continuous and the only continuous function (whatever that means) having values from a discrete group on a connected space is a constant function, so it is just same as having "global...
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    Neutron-only nuclei

    I heard that something like 3000 neutrons would make a stable nucleus.
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    Learning (advanced) geometry

    Start with basic differential geometry, matrix Lie groups etc.
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    How do you ask a professor for possibility of publication

    In any case publication is not a must.
  10. T

    How do you ask a professor for possibility of publication

    I don't get your point. I mean, who would expect publications from an undergrad student who is applying for a grad program?
  11. T

    How do you ask a professor for possibility of publication

    If you are an undergrad student planning to go for grad study, publication is not important. Just do research without insisting on publication and get experience, you will get a strong recommendation letter. If your research is good your professor will suggest you to publish anyways.
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    Other Should I Become a Mathematician?

    People will give better answers than mine, but it should depend on what you want to do with your degree after graduation. For instance if you want to do actual computation and so a lot of programming, a CS minor would be good. But if you want to do research in applied math, like designing or...
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    Penrose's take on QM and QG?

    If I understood correctly, Penrose says that in QM wave function collapse there is no undeterminism is going on, it is just a way the information disappeared in black holes showing up again. So it seems that for him the information loss is important and the theory (if there is any) is...
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    Meaning of diffeomorphism invariance?

    When you move points around you also have to 'bring' the geometry along with you, so everything is ok. It just means that there is no absolute location (or the absolute coordinate system) in spacetime. Suppose the spacetime is a plane, and suppose you have chosen some coordinate system on this...
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    General Coordinate transfos vs Lorentz transfos in GR

    The fact that GR is invariant under arbitrary reparametrizations of the coordinates is not void of physical content, it has very much physical content. One that strikes me is that points on the mathematical manifold modeling the phyisical spacetime does not have physical meaning. Points can be...
  16. T

    Road to Reality

    You can just start reading it and then read other sources if you encounter something you don'd understand. Instead of distraction of reading other long books (since you don't know when you will finish them and finally get to the Road to Reality), at the first read you can just skip the...
  17. T

    GR Textbooks

    I would recommend Carroll as the absolute best for beginners. Dirac tries to simplify things by using embedding into higher dimensional Euclidean space. Straumann is a bit "mathematical" I guess.
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    Central Asia - Scythians, Tatars, . . .

    Timur means iron also in mongolian.
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    Differential forms and divergence

    In functional analysis one would say that the transpose here is actually the Riesz map (or the inverse?) acted pointwise.
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    Isometric immersion

    I don't think so. Take for example a sphere inside R^3.
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    Differential forms and divergence

    Cool. Is the transpose notation common?
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    If such an object does exists

    I meant that in near future we cannot build a (controllable) instrument that generates frame dragging. What we are observing now is frame dragging caused by massive astronomical objects.
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    Mathematics of string theory?

    I think there is a difference between mathematical physics and theoretical physics. Witten is for sure not theoretical physicist, if anything, he is a mathematical physicist.
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    If such an object does exists

    Of course, anything with energy/momentum/angular momentum will affect spacetime. But observable effects are technologically not achievable in near future since they are very weak.
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    On the Notations of Length Contraction and Time Dilation

    Remember that the lenght contracts and time slows down. Also remember that g>1. Then you can write down the equations immediately.
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    E=mc2 without SR

    In the original 1905 paper Einstein has exactly the same formula, E=mc^2, only he wrote it as m=L/c^2.
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    Christoffel Symbols homework

    I think the element in G is R^2, not R^-2. Once you find the metric, you can calculate the Christoffel symbol by using the direct formula (which involves derivatives of Gab). Or you can use the change of coordinate formula for the Christoffel symbol.
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    GR Textbooks

    Caroll's book is nice. Probably you can finish it very quickly then you will be able to read Wald. Did you consider Straumann?