Gravitational Waves and Spacetime

The recent detection of gravitational waves by the LIGO team has rightly been hailed as “the crowning achievemen of classical physics” (Holst et al. in Bull Am Math Soc 53:513–554, 2016). This detection, which came at the end of a decade-long quest, involved 950 investigators, and cost around one billion US dollars, was the scientific star of the year 2015. What, if any, is the philosophical impact of this scientific breakthrough, which Albert Einstein had anticipated one century earlier? To answer this question we start by examining the central equations of Einstein’s theory of gravitation, also known as general relativity. Subsequently we analyze the special case of a hollow sphere, in an attempt to answer the question of the reality and even materiality of space or, rather, spacetime. As well, the view that gravitation is a manifestation of the curvature of spacetime is discussed, and the reality of gravitational waves is regarded as the coup de grâce to that view.     

引力波——来自宇宙深处的弦音

文章以历史发展的顺序,分别介绍了牛顿的绝对时空及其万有引力定律,麦克斯韦的场方程及其电磁波理论,以及爱因斯坦的相对论及其预言的引力波,并对引力波的探测及其可能引领的新时代做了展望。     

The Collapse of Supertasks

A supertask consists in the performance of an infinite number of actions in a finite time. I show that any attempt to carry out a supertask will produce a divergence of the curvature of spacetime, resulting in the formation of a black hole. I maintain that supertaks, contrarily to a popular view among philosophers, are physically impossible. Supertasks, literally, collapse under their own weight.     

Cosmological Black Holes and the Direction of Time

Macroscopic irreversible processes emerge from fundamental physical laws of reversible character. The source of the local irreversibility seems to be not in the laws themselves but in the initial and boundary conditions of the equations that represent the laws. In this work we propose that the screening of currents by black hole event horizons determines, locally, a preferred direction for the flux of electromagnetic energy. We study the growth of black hole event horizons due to the cosmological expansion and accretion of cosmic microwave background radiation, for different cosmological models. We propose generalized McVittie co-moving metrics and integrate the rate of accretion of cosmic microwave background radiation onto a supermassive black hole over cosmic time. We find that for flat, open, and closed Friedmann cosmological models, the ratio of the total area of the black hole event horizons with respect to the area of a radial co-moving space-like hypersurface always increases. Since accretion of cosmic radiation sets an absolute lower limit to the total matter accreted by black holes, this implies that the causal past and future are not mirror symmetric for any spacetime event. The asymmetry causes a net Poynting flux in the global future direction; the latter is in turn related to the ever increasing thermodynamic entropy. Thus, we expose a connection between four different “time arrows”: cosmological, electromagnetic, gravitational, and thermodynamic.     

de Broglie Waves as the “Bridge of Becoming” Between Quantum Theory and Relativity

It is hypothesized that de Broglie’s ‘matter waves’ provide a dynamical basis for Minkowski spacetime in an antisubstantivalist or relational account. The relativity of simultaneity is seen as an effect of the de Broglie oscillation together with a basic relativity postulate, while the dispersion relation from finite rest mass gives rise to the differentiation of spatial and temporal axes. Thus spacetime is seen as not fundamental, but rather as emergent from the quantum level. A result by Solov’ev which demonstrates that time is not an applicable concept at the quantum level is adduced in support of this claim. Finally, it is noted that de Broglie waves can be seen as the “bridge of becoming” discussed by (2005).     

Leibniz’s Theory of Space

In this paper I offer a fresh interpretation of Leibniz’s theory of space, in which I explain the connection of his relational theory to both his mathematical theory of analysis situs and his theory of substance. I argue that the elements of his mature theory are not bare bodies (as on a standard relationalist view) nor bare points (as on an absolutist view), but situations. Regarded as an accident of an individual body, a situation is the complex of its angles and distances to other co-existing bodies, founded in the representation or state of the substance or substances contained in the body. The complex of all such mutually compatible situations of co-existing bodies constitutes an order of situations, or instantaneous space. Because these relations of situation change from one instant to another, space is an accidental whole that is continuously changing and becoming something different, and therefore a phenomenon. As Leibniz explains to Clarke, it can be represented mathematically by supposing some set of existents hypothetically (and counterfactually) to remain in a fixed mutual relation of situation, and gauging all subsequent situations in terms of transformations with respect to this initial set. Space conceived in terms of such allowable transformations is the subject of Analysis Situs. Finally, insofar as space is conceived in abstraction from any bodies that might individuate the situations, it encompasses all possible relations of situation. This abstract space, the order of all possible situations, is an abstract entity, and therefore ideal.     

“Who” is a “Topical Measuring” Postphenomenologist and How Does One Get That Way?

Gert Goeminne’s paper is primarily concerned with “the politics of sustainable technology,” but for good reasons he does not start with this topic. He knows that technology studies as he conceives it must clear a space for itself in a philosophical atmosphere that discourages its pursuit. He therefore begins with a critique of this objectivistic and technocratically defined atmosphere, before moving on to embrace a postphenomenology of technological multistabilities, and then further to introduce what he calls (in an adaptation of Rudolf Boehm) the “topical measure” of technoscientific life. The problem I raise is not about Goeminne’s aims, with which I mostly agree, but with his presentation of how to achieve them. I argue that if one were actually to follow his advice—that is, start with critique, move on to postphenomenology, and end with “political” evaluation of technoscientific life, the project would be doomed to failure. For in our world, no one Understands this pluralizing vision. According to the understanding we actually live through and speak from, some of postphenomenology’s multiple disclosures already arrive in our experience with significantly greater ontological power than others, and sincerity about topical measure notwithstanding, the very identification of something as an interest or “value,” especially if it allegedly comes from a “layperson,” already condemns it to secondary status.     

On the Construction of Mental Objects in Third and in First Persons

This paper deals with some formal properties of objects that are supposed to be internal to persons, that is, mental structures and mental functions. Depending on the ways of talking about these internal objects, they will appear different. Two types of discourse will be presented, to be called the realist and the nominalist discourses, and for eachdiscourse I will focus upon the construction of `self'.The realist discourse assumes an identity between the person and his construction of himself. I will illustrate this discourse in terms of Descartes' ideas on himself as a `thinking substance'. The nominalist discourse assumes an impossibility to attain this identity, and instead to imply a complementarity between the person and his self-construction. I will illustrate this discourse in terms of the problems both William James and Sartre discerned when a conscious person chases after his own consciousness (termed `judging thought' and `pour-soi' respectively).     

Can the Causal Paradoxes of QM be Explained in the Framework of QED?

Attemts to explain causal paradoxes of Quantum Mechanics (QM) have tried to solve the problems within the framework of Quantum Electrodynamics (QED). We will show, that this is impossible. The original theory of QED by Dirac (Proc Roy Soc A117:610, 1928) formulated in its preamble four preliminary requirements that the new theory should meet. The first of these requirements was that the theory must be causal. Causality is not to be derived as a consequence of the theory since it was a precondition for the formulation of the theory; it has been constructed so that it be causal. Therefore, causal paradoxes logically cannot be explained within the framework of QED. To transcend this problem we should consider the following points: Dirac himself stated in his original paper (1928) that his theory was only an approximation. When he returned to improve the theory later (Proc Roy Soc A209, 1951), he noted that the new theory “involves only the ratio e/m, not e and m separately”. This is a sign that although the electromagnetic effects (whose source is e) are magnitudes stronger than the gravitational effects (whose source is m), the two are coupled. Already in 1919, Einstein noted that “the elementary formations which go to make up the atom” are influenced by gravitational forces. Although in that form the statement proved not to be exactly correct, the effects of gravitation on QM phenomena have been established. The conclusion is that we should seek a resolution for the causal paradoxes in the framework of the General Theory of Relativity (GTR)—in contrast to QED, which involves only the Special Theory of Relativity (STR). We show that causality is necessarily violated in GTR. This follows from the curvature of the space-time. Although those effects are very small, one cannot ignore their influence in the case of the so-called “paradox phenomena”.     

用磁悬浮陀螺探测引力波的方案——类比方法的一个应用

运用科学方法论中的类比方法,把无线电接收技术的“调谐”原理移植到引力波探测领域,避免现有主流方法对各种频率的引力波信号不加选择地兼收并蓄,造成波与波之间互相干扰的弊病。利用磁悬浮陀螺作为探测引力波的天线,在旋转的陀螺减速过程中,可能与某一频率相近的引力波共振,使信息得到放大;有效地提高灵敏度并避免地面杂散信号的干扰。     

休谟可以区分自我与他人吗?——论休谟的个人同一性困惑

休谟在《人性论》的附录中承认,自己之前对个人同一性问题的说明存有缺陷,他不知道该如何解决,因此陷入困惑。这个反省引发了一个问题:休谟的困惑究竟指的是什么?一种解释认为,困惑的根源是休谟意识到自己在说明个人同一性问题时无法区分自我与他人。本文将对这种解释作出修正,指出休谟对个人同一性的说明为什么需要区分自我与他人,他又在多大程度上无法区分自我与他人。本文将表明,休谟的困惑并不在于他完全无法区分自我与他人,而在于更弱一点的困难:他有资源在大多数情况下作出这个区分,但是仍然留下无法区分的情况。     

A Non-Aristotelian Model: Time as Space and Landscape in Postmodern Theatre

In his Poetics, Aristotle articulated certain ideas on the structure of drama that dominated both dramatic literature and theatre practices for the centuries to come. In this article I show how the thorough analysis of his statements leads us to believe that he endorses causality, narrativity, and temporal linearity as primary factors in the organization of dramatic and stage texts. Tracing various modifications of causality throughout theatre history, I use the work of the two prominent contemporary directors, Eimuntas Nekrosius and Anatoly Vasilyev, to demonstrate how postmodernist theatre has arrived at non-Aristotelian theatrical model based on the unity of a time–space continuum rather than temporal development.     

Which Wisdom Can Change the World?

The thoughts that Michel Puech formulates on wisdom, technology and the art of living are timely at a moment when social, ecological and economic problems are pressing upon our societies and the speed of technological development seems to overwhelm our ability to integrate and adapt new technologies in our lives and societies. However, he restricts his concept of wisdom too much to a personal endeavor and overestimates the relevance of non-confrontation. I argue that his project can only be of value when it is embedded in a broader societal and political strategy for change.     

Planck-Scale Physics: Facts and Beliefs

The relevance of the Planck scale to a theory of quantum gravity has become a worryingly little examined assumption that goes unchallenged in the majority of research in this area. However, in all scientific honesty, the significance of Planck’s natural units in a future physical theory of spacetime is only a plausible, yet by no means certain, assumption. The purpose of this article is to clearly separate fact from belief in this connection.     

专名的意向性分析和语境——评塞尔的专名理论

随着塞尔意向性理论的发展,塞尔对专名的研究由前期的"簇摹状词"理论转到"簇意向内容"理论,其研究方向也由语言哲学转向心灵哲学。塞尔认为专名的含义就是意向内容,指称是由一根意向内容的,因果历史链条决定的。本文指出,由于塞尔忽略语境因素,且意向内容本质上是心理的因而是私人性的,这使专名的意义在其理论中失去公共性。本文对塞尔、克里普克和陈晓平三人的因果历史理论作了比较和评价,进而指出,在语境中两种因果历史链条相结合的必要性。     

终结与拯救——维特根斯坦论哲学的性质及出路

维特根斯坦终其一生都在坚持哲学不是理论而是种活动,在他思想的前期哲学是种对思想和语言的逻辑澄清活动,后期则是对日常语言的观察描述活动。这种视哲学为活动而非理论的观点对传统哲学进行了釜底抽薪式的批判,以致人们普遍的认为维特根斯坦"终结"了哲学,但实际上他不是在终结哲学而是在拯救哲学,并为哲学的复兴找到了希望。     

对脉冲双星PSR1913＋16引力辐射计算的一个注解

本文在牛顿的万有引力定律与爱因斯坦的狭义相对论之间找到一个理论结合点,使质电类比更具理据,以此对陈永明的脉冲双星PSR1913＋16引力辐射的计算提供一个注解。     

Dwelling In-Between Walls: The Architectural Surround

The title of this paper might evoke claustrophobic associations. In other words, architecture in a very immediate sense can affect our behavior and feelings. In more mediated ways, architecture is also capable of influencing humans and putting their environment into perspective. Consider, for example, how a penthouse apartment can literally elevate people??s emotions and unfold a new perspective on city life, which some people are willing to pay millions of dollars to attain. In this paper I will explore how architecture frames human experience from a philosophical point of view. My aim is to offer key elements of a new typology of architecture. For that purpose I am going to reflect and expand on key insights into technology of one of the funding fathers of contemporary philosophy of technology, Don Ihde. Through a life time, Ihde has been probing and investigating the relation between humans and their world as it is mediated through technology. In doing so he has concentrated on examining and understanding the role of scientific instruments. This paper is dedicated to showing how Ihde??s significant postphenomenological concepts not only can be translated to another domain and serve a better understanding of architecture, but also how his work can help us to relate to architecture in multiple constructive ways. The succeeding experimental translations of Ihde??s understanding of technology to architecture are also meant as a guide to design more adequate and fascinating built environments. I will begin with a broad overview of Ihde??s postphenomenological project; subsequently I shall endeavor to translate this work onto architecture through a number of case-studies, some of which are detailed and others less so.     

What is Applied Mathematics?

A number of issues connected with the nature of applied mathematics are discussed. Among the claims are these: mathematics "hooks onto" the world by providing models or representations, not by describing the world; classic platonism is to be preferred to structuralism; and several issues in the philosophy of science (reality of spacetime, the quantum state) are intimately connected to the nature of applied mathematics.