String theory,Einstein, and the identity of physics: Theory assessment in absence of the empirical

String theorists are certain that they are practicing physicists. Yet, some of their recent critics deny this. This paper argues that this conflict is really about who holds authority in making rational judgment in theoretical physics. At bottom, the conflict centers on the question: who is a proper physicist? To illustrate and understand the differing opinions about proper practice and identity, we discuss different appreciations of epistemic virtues and explanation among string theorists and their critics, and how these have been sourced in accounts of Einstein's biography. Just as Einstein is claimed by both sides, historiography offers examples of both successful and unsuccessful non-empirical science. History of science also teaches that times of conflict are often times of innovation, in which novel scholarly identities may come into being. At the same time, since the contributions of Thomas Kuhn historians have developed a critical attitude towards formal attempts and methodological recipes for epistemic demarcation and justification of scientific practice. These are now, however, being considered in the debate on non-empirical physics.     

On miracles and spacetime

What have recently been dubbed two ‘miracles’ of general relativity—(1) that all non-gravitational interactions are locally governed by Poincaré invariant dynamical laws; and (2) that, in the regime of experimental practice in which curvature effects may be ignored, the local Poincaré symmetries of the dynamical laws governing matter fields coincide with the local Poincaré symmetries of the dynamical metric field—remain unaccounted for in that theory. In this paper, I demonstrate that these two ‘miracles’ admit of a natural explanation in one particular successor theory to general relativity—namely, perturbative string theory. I argue that this point has important implications when considering both the ‘chronogeometricity’ (that is, the object in question being surveyed by rods and clocks built from matter fields) and spatiotemporal status of the dynamical metric field in both general relativity and perturbative string theory.     

WINDOWS中DBCS的解决方案

本文通过对常见的三种字符集编码原理的介绍,然后专门针对在微软操作系统下,双字节字符集中怎样求一字符串的字符数和字节数的常用方法进行讨论。     

Target space ≠ space

This paper investigates the significance of T-duality in string theory: the indistinguishability with respect to all observables, of models attributing radically different radii to space—larger than the observable universe, or far smaller than the Planck length, say. Two interpretational branch points are identified and discussed. First, whether duals are physically equivalent or not: by considering a duality of the familiar simple harmonic oscillator, I argue that they are. Unlike the oscillator, there are no measurements ‘outside’ string theory that could distinguish the duals. Second, whether duals agree or disagree on the radius of ‘target space’, the space in which strings evolve according to string theory. I argue for the latter position, because the alternative leaves it unknown what the radius is. Since duals are physically equivalent yet disagree on the radius of target space, it follows that the radius is indeterminate between them. Using an analysis of Brandenberger and Vafa (1989), I explain why—even so—space is observed to have a determinate, large radius. The conclusion is that observed, ‘phenomenal’ space is not target space, since a space cannot have both a determinate and indeterminate radius: instead phenomenal space must be a higher-level phenomenon, not fundamental.     

关于弦论的哲学分析

弦论属于当前粒子物理学的研究前沿。在理论建构上,它内含了许多非传统的特性,这些特性使它切入到科学哲学形而上的核心争论之中。本文将系统考究弦论所牵涉的经验可证实性、理论唯一性、亚决定性原理、科学实在论、科学隐喻和科学统一等哲学问题,并给出相应的哲学分析。     

一类弦的快速镇定问题

本文在控制能量受限的前提下,讨论一类具有混合边界的弦的快速镇定问题.证明了快速控制一定在控制域的边界上达到.推导出快速控制的具体表达式.     

弦宇宙中的相变动力学模型

研究了弦宇宙中的相变动力学模型，分析了极早期宇宙中的超弦相变和QCD相变．另外，计算了标度因子的膨胀比和弦耦合常数的变化比．     

String theory and general methodology: A mutual evaluation

String theory has been the dominating research field in theoretical physics during the last decades. Despite the considerable time elapse, no new testable predictions have been derived by string theorists and it is understandable that doubts have been voiced. Some people have argued that it is time to give up since testability is wanting. But the majority has not been convinced and they continue to believe that string theory is the right way to go. This situation is interesting for philosophy of science since it highlights several of our central issues. In this paper we will discuss string theory from a number of different perspectives in general methodology. We will also relate the realism/antirealism debate to the current status of string theory. Our goal is two-fold; both to take a look at string theory from philosophical perspectives and to use string theory as a test case for some philosophical issues.     

Turbopascal中字符串变量使用问题分析

本文对Ｔｕｒｂｏｐａｓｃａｌ语言中字符串变量的使用进行讨论，指出在使用字符串变量时就应注意的问题。     

水平井多封隔器管柱力学分析及安全评价

针对水平井多封隔器管柱在井下多种载荷的共同作用下易引起管柱失效的安全问题,基于力学研究中的多杆件的多次超静定结构,引入力法对多封隔器之间管柱进行受力分析,同时考虑温度效应、活塞效应、鼓胀效应和螺旋屈曲效应的影响,建立考虑多封隔器影响的轴向力数学模型;在此基础上建立多封隔器管柱力学安全强度评价准则和封隔器控制信封失效判断方法,对现场水平井多封隔器管柱进行力学分析和安全评价。研究结果表明,建立的考虑多封隔器影响的轴向力数学模型计算结果大于常规不考虑多封隔器影响时轴向力,若不考虑多封隔器的影响将低估多封隔器管柱的轴向力,而造成管柱受力危险;同时对管柱危险位置和封隔器进行安全评价,得到了酸化作业时油压和套压的综合控制参数,以期为水平井多封隔器管柱安全工作参数的优化设计提供理论依据。