Regular Journal Club:

Jim Nester talked about “Weyl’s Lagrangian in Teleparallel Form“:

1. From this paper:

• We get Weyl’s field equation from doing variation of a Weyl’s Lagrangian.

• There is a transformation between Weyl’s eqn. and its tetrad form(teleparallel form).

2.Ideas:

• We get Dirac’s field equation from doing variation of a Dirac Lagrangian.

• There is also a transmation between Dirac’s field eqn. and a special orthonormal frame gauge field.
• Then, can we find a frame Lagrangian that can describe the SOF gauge field.

Remarkables:

1. Towards the quasi-localization of conanical GR by Szabados (arXiv:0902.3199).
2. Hehl’s visiting: 12 Mar to 4 Apr.

•  L. Szabadoz will come to NCU. 
• F. Hehl — P.R.A 77, 022106.
• 2-D Gravity. (This talk will be held next week.)
• Negative Energy (by Jim Nester):

1. Take a  finite region, how to measure the mass of a galaxy?
2. Brill & Deser
3. Homogeneous Cosmology — Equation can be homogeneous but the solution can’t be.

1. Bianchi Cosmology: homogeneous (but not isotropic)

2. We need the model investigated to be isotropic.

3. Find some special cases for isotropic in Bianchi Cosmology.

4. If we classified the 9 types of Bianchi Cosmology, there are 2 classes:

    Class A: Type I, II, VIII, IX.

    Class B: Type III to VII_{h}

5. Few cases can be isoptropic:

    Bianchi I –> FLRW (k=0)

    Bianchi V(VII_{h}) –> FLRW (k=-1)

    Bianchi IX –> FLRW (k=1)

…

2008, Jan 3, NCU Relativity and Geometric Physics Group Meeting 討論的主題是由Jim Nester 主講: Spinor’s repesentation: idempotents and projections

Note: I hope I can make a Latex edition for this topic.

        2007, Dec 27, NCU Relativity and Geometric Physics Group Meeting 討論的主題是由Teofilo Vargas 主講: P. Davis 的 ”Anthropic Principle”。
        會中提到了:
           Brandon Carter: “Anthropic Principle in Cosmology“ 
           P. Davies: Cosmic Jackpot
           Barrow-Tipler: The Anthropic Cosmological Principle. Oxford Univ. Press. ISBN 0-19-282147-4. 

        這是一個很大的題目，可以用物理學、哲學、形上學各種角度切入，要列舉的參考文獻太多了…

        李淼老師在科學與信仰的博文中評論了P. Davies的文章，從這裡面可以找到很多相關文章。另外，在不只一個世界中也對M. Tegmark的平行宇宙多所著墨。

        這個題目我還沒能有什麼評論，得爬在更多的巨人身上才能看得更遠。

        2007, Dec 13, NCU Relativity and Geometric Physics Group Meeting 討論的主題是由Teofilo Vargas 主講: M. Tegmark 的 ”On the dimensionality of spacetime”。

        會中提到了3篇文章:

           Barrow-Tipler

           M. Tegmark (C.Q.G. 14 L69, (1997)): ”On the dimensionality of spacetime”

           I. M. Freeman (Am. J. Phys. 37, 1222, (1969)): “Why is space three dimensional? Based on B¨uchel …”

        這是一個有趣的題目…。 

        後來研究了一下 M. Tegmark，他寫了幾篇有趣的文章：”Shut up and calculate“、”Many lives in many worlds“、”The Mathematical Universe “、”On Math, Matter and Mind“。有機會要好好讀讀。