Posted in量子引力

LQG：Loops 11 会议视频

Posted in量子引力

会议网站：http://loops11.iem.csic.es/loops11/index.php

1. João Magueijo – Cosmology and quantum gravity: a chiral signature?
(Abstracts/Plenary Lectures)

… on matters like the inner product, the ground state (which we prove is NOT the Kodama state) and ordering issues. Download: Video (.mp4 688.3 MiB) – Slides (.ppt …

2. Yongge Ma – Extension of Loop Quantum Gravity to Metric Theories beyond General Relativity
(Abstracts/Plenary Lectures)

… quantization of the $f(R)$ theories and Brans-Dicke theory by extending the loop quantization scheme of GR. Download: Video (.mp4 497.9 MiB) – Slides (.pdf 425.9 …

3. Parampreet Singh – Physics of singularity resolution in LQC
(Abstracts/Plenary Lectures)

… while analyzing physics of models in quantum gravity. Download: Video (.mp4 604.1 MiB) – Slides (.pdf 464.6 KiB) Parampreet-Singh_Physics-of-sin …

4. Tomasz Pawlowski – Quantum dynamics and semiclassicality in LQC
(Abstracts/Plenary Lectures)

… preservation across the bounce. Download: Video (.mp4 450.2 MiB) – Slides (.pdf 911.4 MiB) Tomasz-Pawlowski_Quantum-dynamics-and-semiclassicality- …

5. Martin Bojowald – How to rule out loop quantum gravity
(Abstracts/Plenary Lectures)

… will be discussed, based on the main corrections of quantum geometry and a systematic procedure to derive effective descriptions. Download: Video (.mp4 526.9 MiB) …

6. Alejandro Corichi – The semiclassical limit of Loop Quantum Cosmology
(Abstracts/Plenary Lectures)

… theory. Download: Video (.mp4 464.5 MiB) – Slides (.pdf 464.5 KiB) Alejandro-Corichi_The-semiclassical-limit-of-Loop-Quantum-Cosmology …

7. Jorge Pullin – Quantum scalar field in loop quantum gravity with spherical symmetry
(Abstracts/Plenary Lectures)

… theory and discuss more generally how breaking Lorentz invariance at the Planck scale does not necessarily lead to problems at low energies. Download: Video (.mp4 …

8. Alejandro Perez – Black Hole Entropy and SU(2) Chern Simons Theory
(Abstracts/Plenary Lectures)

… quantum aspects of black hole systems modeled by isolated horizons and SU(2) Chern-Simons theories. Download: Video (.mp4 442.9 MiB) – Slides (.pdf 3.1 MiB)  …

9. Lee Smolin – The Principle of Relative Locality
(Abstracts/Plenary Lectures)

… laws. These are in principle all measurable by appropriate experiments, some of which will be described. Download: Video (.mp4 466.8 MiB) – Slides (.pdf 3.6 MiB)  …

10. Renate Loll – Nonperturbative Highlights on Quantum Gravity from Causal Dynamical Triangulation
(Abstracts/Plenary Lectures)

…  Download: Video (.mp4 613.1 MiB) – Slides (.pdf 4.3 MiB) Renate-Loll_Nonperturbative-Highlights-on-Quantum-Gravity-from-Causal-Dynamical-Triangulation …

Posted in量子引力

物理：圈量子引力（LQG）的发展历史大事记（节选自卡尔·罗维利的文章）

Posted in量子引力

原文全文：http://pan.baidu.com/share/link?shareid=162744&uk=3171134180

1992 Classical limit: weaves
Ashtekar, Rovelli, Smolin.
The first indication that the theory predicts Planck
scale discreteness came from studying the states
that approximate geometries flat on large scale [23].

These states, denoted “weaves”, have a “polymer”
like structure at short scale, and can be viewed as
a formalization of Wheeler’s “spacetime foam”.

……

1994 Discreteness of area and volume eigenvalues
Rovelli, Smolin.
In my opinion, the most significative result of loop
quantum gravity is the discovery that certain ge-
ometrical quantities, in particular area and vol-
ume, are represented by operators that have dis-
crete eigenvalues. This was found by Rovelli and
Smolin in [186], where the first set of these eigenval-
ues were computed. Shortly after, this result was
confirmed and extended by a number of authors,
using very diverse techniques. In particular, Re-
nate Loll [142,143] used lattice techniques to ana-
lyze the volume operator and corrected a numerical
error in [186]. Ashtekar and Lewandowski [138,17]
recovered and completed the computation of the
spectrum of the area using the connection represen-
tation, and new regularization techniques. Frittelli,
Lehner and Rovelli [84] recovered the Ashtekar-
Lewandowski terms of the spectrum of the area,
using the loop representation. DePietri and Rov-
elli [77] computed general eigenvalues of the vol-
ume. Complete understanding of the precise rela-
tion between different versions of the volume oper-
ator came from the work of Lewandowski [139].

Posted inMatlab 计算物理

编程：MATLAB实现粒子二维随机运动轨迹

Posted inMatlab, 计算物理

代码如下：

视频演示：待更新

 

运行结果图展示：

3个粒子的轨迹：

10个粒子的轨迹

50个粒子的轨迹

100个粒子的轨迹

若要查看动态图片请查看全文
Posted inFortran 计算物理

软件：G77的万能式安装使用和说明文件

Posted inFortran, 计算物理

我修改了一点G77，安装非常简单，可以任意安装，随你喜好！

请使用这个版本的G77，下载地址：G77.rar

本程序由TAHO修改，可以放在任何盘的任何文件夹里，包括U盘，不再局限于C盘，更支持中文文件夹和名字有空格的文件夹，使用非常方便。
对于学习计算物理的同学，把它放在U盘里使用也行的！

安装方法：

1. 下载压缩包G77.rar，右键点击G77.rar，选择“解压到当前文件夹”，

2. 你会看见一个名叫G77的文件夹出现了，打开这个文件夹

3. 双击打开start.bat便可以使用了（注：windows7用户如果那样打开不行，请右键选择“以管理员身份运行”）。

4. 每一次使用G77都要运行start.bat，你可以把start.bat重新命名，只要保留后缀名仍为bat便好，start改成什么都可以，不影响使用，比如命名为“运行.bat”。注意，使用时要把你的程序复制到G77文件夹里面哟~！

G77的一些简单使用方法：

1.最简单的编译方法:
G77 MYTEST1.F

2.要生成名字不是a.exe，而是自己想起的名字，比如GOOD.EXE的程序，只需要加上“-o”，后面写上GOOD.EXE便可，像这样：
G77 MYTEST1.F -o GOOD.EXE

3.纠错编译（如果程序本身就有错误，这个办法可以检查出来，编译不会通过的，会给出警告信息。即编译的时候，只要加上“-Wall”就可以了），就像这样：
G77 -Wall MYTEST1.F
4.其他用法：（不翻译了）

The g77 compiler has a large number of other command switches – a few of
the most useful are shown here:

-c Compile-only: produces .OBJ files.
-ffree-form Selects free-format source code
-fpedantic Warns of non-portable/non-standard code.
-fno-automatic Static storage for all variables, like universal SAVE
-fno-backslash Interprets “” as a normal character in strings
-fvxt Use VAX Fortran interpretation of certain syntax
-g Produces debugging information.
-Idirectory Specifies directory to search for INCLUDE files
-O Optimise code generation
-Wimplicit Warns of any names with no explicit data type
-Wuninitialised Warns of some cases of unset variables (if -O also set).
-Wall Warns of both of above cases.

献给丹儿
BY TAHO
2012.11.22
taholab.com
tahoroom.sinaapp.com

本文链接：http://tahoroom.sinaapp.com/?p=2215 欢迎分享！

Posted inFortran Matlab 计算物理

技术：G77与MATLAB接口和FORTRAN77语法概述/简单教程

Posted inFortran, Matlab, 计算物理

MATLAB与C++、G77的混合编程

《深入浅出MATLAB 7.X混合编程》 董维国 编著 电子书下载  请查看第四章内容

下面内容属于转载：来自 http://www.legalsoft.com.cn/fortran/fortran77.aspx

不过这篇文章更像是C#语言的广告，也许C#真有他说的那么好用，谁知道呢。

FORTRAN77语法概述/简单教程（G77）

FORTRAN是世界上最早出现的高级编程语言，是工程界最常用的编程语言，它在科学计算中（如航空航天、地质勘探、天气预报和建筑工程等领域）发挥着极其重要的作用。经过40多年的发展，伴随着FORTRAN语言多次版本的更新及相应开发系统的出现，其功能不断完善，最新版本的开发系统几乎具备了VC、VB的所有特点，如图形界面编程、数据库等。目前，工科院校开设的计算机编程语言课首选仍然是FORTRAN :<

说实话，从科技发展的趋势来说这不是好事。您可以设想一下，如果需要用鹅毛笔抄写大量的古籍是什么感受！
强烈建议阅读《发掘C#特性赋予科学计算项目以威力》

1 FORTRAN77四则运算符

+ – * / ** (其中**表示乘方)
在表达式中按优先级次序由低到高为： +或-→*或/→**→函数→()

2 FORTRAN77变量类型

2.1 隐含约定：I-N规则

凡是以字母I，J，K，L，M，N六个字母开头的，即认为是整型变量，其它为实型变量。

2.2 用类型说明语句确定变量类型：可以改变I-N规则

INTEGER 整型
REAL 实型
DOUBLE PRECISION 双精度实型
COMPLEX 复型，赋值形式为(实部，虚部),如D=(8.76E+0.5,-67.8E-3),C=(3.0,6.3),如果含表达式则用CMPLX,如C=CMPLX(3.0*A,6.0+B)
LOGICAL 逻辑型,逻辑常量有“T”和“F”，“T”表示“.TRUE.”,“F”表示“.FALSE.”
CHARACTER*N 字符型,N为字符串长度,可以在变量名称后重新指定长度,如CHARACTER*8 STR1,STR2*10 ,赋值形式为STR2=’I”M A BOY.’

2.3 用IMPLICIT语句将某一字母开头的全部变量指定为所需类型

如 IMPLICIT REAL (I,J)
三种定义的优先级别由低到高顺序为：I-N规则→IMPLICIT语句→类型说明语句，因此，在程序中IMPLICIT语句应放在类型说明语句之前。