洛仑兹长度收缩佯谬

本文应用洛仑兹变换和信号的传播速度小于光速 ,解释了洛仑兹长度收缩佯谬 ,具体证明了在不同参照系上的观测者 ,观测所得结论相同 .     

洛率兹长度收绽佯谬

本文应用洛仑兹变换和信号的传播速度小于光速，解释了洛仑兹长度收缩佯谬，具体证明了在没参照系上的观测者，观测所得结论相同。     

气体分子自由程分布公式中的初始条件和2佯谬

本文用模拟实验证实了坎纳德关于自由程与平面相交的几率正比于自由程长度的假设，从而圆满解释了２λ佯谬．     

长度收缩佯谬

狭义相对论中的长度收缩佯谬,虽然没有时钟佯谬那样讨论得那么多,却也经常带来困惑,启人深思。 长度佯谬所讨论的内容也不是单一的。例如,图1中所表示的佯谬是这样的:一钢尺沿长度方向在光滑的平面上以匀速v前进,途中有一裂缝,若缝宽及尺长的静测量值都是L0,则对于相对平面为静止的观测者来说,不管v的大小如何,似乎这根钢尺总应掉进缝中,然而,在与钢尺一起以v速前进的惯性系里,又似乎只要v适当地大,这根尺子就不会掉下去,于是就呈现出表现的矛盾[1]。而图2所示的情况则是:若圆孔直径及棒尺之长的静测量值彼此相等,这根棒尺能否自由穿过圆孔…     

吉布斯佯谬

吉布斯佯谬在许多教材中都归咎于没有考虑到量子力学中微观粒子的全同性,但是考虑了微观粒子的全同性的量子理想气体混合时,还会出现更多的佯谬,如内能的佯谬等其他佯谬。显然,引起佯谬的根本原因不是没有考虑粒子的全同性。因此,有必要进一步澄清吉布斯佯谬产生的缘由,并说明实际吉布斯佯谬是由粒子数密度突变造成的。     

再论狭义相对论中“观测”与“看见”的差别──时钟佯谬的时空图表示法

本文以时钟佯谬为例，阐明了在运动时钟问题中“观测记录”与“视觉读数”之差异，再一次澄清了狭义相对论中“观测”与“看见”两个概念的区别，并在讨论中强调了用狭义相对论解释时钟佯谬的关键所在．     

物理学咬文嚼字之四十六 Oh,Paradoxes

Paradox在中文物理学文献中被翻译成悖论或者佯谬,武断了点,不足以传达paradox的真实含义.Paradox一直伴随着人类的认识进程,芝诺佯谬、孪生子佯谬、EPR佯谬、理发师佯谬等是数学和物理绕不开的话题.与paradox意义相近的词有dilemma,antinomy和catch-22等.     

物理学咬文嚼字之四十六

Paradox在中文物理学文献中被翻译成悖论或者佯谬,武断了点,不足以传达paradox的真实含义．Paradox一直伴随着人类的认识进程,芝诺佯谬、孪生子佯谬、EPR佯谬、理发师佯谬等是数学和物理绕不开的话题．与paradox意义相近的词有dilemma,antinomy和catch-22等．     

吉布斯佯谬的佯谬

吉布斯佯谬的传统的解决方法又引起另一个佯谬。本文提出对这个佯谬的解决方法。     

论M.Casper的“吉布斯佯谬的佯谬”

国内外的热力学及统计物理教科书中曾有谈到吉 布斯佯谬的问题.综合各课本的说法,大约可分为二 种不同的观点:(1)不同种气体(例如氩与氖的混合) 的混合不产生吉布斯佯谬,但同一种气体(即全同气 体)的混合产生熵的增加叫做吉布斯佯谬;(2)两个 相同体积的全同的气体的混合、用热力学方法来计算 熵与用经典统计力学来计算熵,得到不同的结果,这种差异叫做吉布斯佯谬.这二种说法,我们将分别加以讨论; M .Casper的“论吉布斯作谬的体谬”一文所作的解释(见《大学物理》1982年第12期范印哲译)亦有问题,特别是对微观制备的说法不正确.兹将本人对本…     

谈狭义相对论时空理论教学——大学物理课程讲授狭义相对论之我见

依据狭义相对论基本原理和物理事例,导出钟慢、尺缩效应和同时相对性,再以此为据导出洛伦兹变换.     

狭义相对论中同时性的研究

本文对狭义相对论中＂同时性＂的基础和＂尺缩钟慢＂效应的本质进行了深入探讨.＂绝对同时＂和＂绝对静止＂一样是不存在的,＂同时＂和＂静止＂都具有相对性.以此为出发点,本文对一个不能直接应用＂尺缩钟慢＂效应解决的物理问题进行了深入研究.结果表明只要找到与正在发生的事件始终保持相对静止的惯性参考系,我们就可以引入＂固有时间＂的概念,再结合＂尺缩钟慢＂效应得到相应事件相对于地面参考系的时间变化规律.     

Lengths on rotating platforms

The paper treats the issue of the length of a rotating circumference as seen from on board the moving disk and from an inertial reference frame. It is shown that, properly defining a measuring process, the result is in both cases 2πR thus dissolving the Ehrenfest paradox. The same holds good when considering that, for the rotating observer, the perceived radius coincides with the curvature radius of a space-time helix and a complete round trip corresponds to an angle which differs from the one seen by the inertial observer. The apparent contradiction with the Lorentz contraction is discussed.     

Irreversibility paradox revised: Onset of a center manifold in dissipative systems

A center-manifold-reduced Fokker-Planck equation is derived, starting from a time-reversible Liouville equation. The derivation is valid when there is a large separation of relaxation-time scales causing the phase-space contraction near a dynamic critical point. The paradox of breaking of time-reversal symmetry in the resulting Fokker-Planck equation at the onset of the center manifold is clarified.     

自由射流缩流机理研究

与喷到水中的水喷流(潜喷流 submerged jet)不同,喷到大气中水的喷流(自由喷流 free jet)从喷嘴喷出后会发生缩流,然后再渐渐扩散,但这种缩流的流动机理迄今都没有被非常清楚的描述。本文对喷管喷出的射流进行了详细的非定常粘性流动解析,究明了产生缩流时准自由射流区域内压能转化为动能的机理,并用数值计算方法对自由射流的缩流直径进行了预测。     

温度的相对论变换

同长度一样,热力学系统的内能增量和绝对温度也是洛仑兹收缩的．本文用相对论与热力学的方法导出了这些变换关系．     

Conventionality of Simultaneity and the Tippe Top Paradox in Relativity

In this paper we critically examine a recently posed paradox (tippe top paradox in relativity) and its suggested resolution. A tippe top when spun on a table, tips over after a few rotations and eventually stands spinning on its stem. The ability of the top to demonstrate this charming feat depends on its geometry (all tops are not tippe tops). To a rocket-bound observer the top geometry should change because of the Lorentz contraction. This gives rise to the possibility that for a sufficiently fast observer the geometry of the top may get altered to such an extent that the top may not tip over! This is certainly paradoxical since a mere change of the observer cannot alter the fact that the top tips over on the table. In an effort to resolve the issue the authors of the paradox compare the equations of motion of the particles of the top from the perspective of the inertial frames of the rocket and the table and observe among other things that (1) the relativity of simultaneity plays an essential role in resolving the paradox and (2) the puzzle in some way is connected with one of the corrolaries of special relativity that the notion of rigidity is inconsistent with the theory. We show here that the question of the incompatibility of the notion of rigidity with special relativity has nothing to do with the current paradox and the role of the lack of synchronization of clocks in the context of the paradox is grossly over-emphasized. The conventionality of simultaneity of special relativity and the notion of the standard (Einstein) synchrony in the Galilean world have been used to throw light on some subtle issues concerning the paradox.     

Formal model of internal measurement: Alternate changing between recursive definition and domain equation

We sketch a paradox generally resulting from recursivity, and propose a novel model to express evolutionary processes that requires identification of an interaction with internal measurement. In this model, a paradox is not resolved and the notion of relativity of any resolution is implicit. In a dynamical system a certain transition rule is used recursively along time. If one takes the foundation (or context) of recursivity into consideration, one obtains a fixed point or one confronts a paradox. In order to resolve this paradox, we adopt Scott's technical way to identify the form of a fixed point with a domain equation and to obtain a reflective domain, however we simultaneously show that any resolution is destined to be relative. In utilizing this notion, we construct a model of dynamical process by embedding a measurement process in one time step. Any time transition involves the process of doubting the foundation of a transition rule leading to a fixed point. Solving it and obtaining a reflexive domain is used as a new transition rule. Also, this process perpetually proceeds along time, and then the system perpetually proceeds while any solution is destined to be relative. We illustrate this type of model by using a dynamically changing contraction mapping as the interface of state and transition rule. Finally, we show that one can formalize emergent properties by using this model and discuss the relationship between endo-physics and internal measurement.     

可压缩理想等离子体柱的稳定性

本文从描述理想等离子体运动的线性化磁流体方程出发,导出了压缩量▽·ξ的一个表示式。一般情况下,它由两部分组成:第一部分与纵向惯性运动有关,第二部分与载等离子体力管的均匀运动(膨胀与压缩)有关。对于等离子体柱,我们讨论了几种可以将含有压缩量项的运动方程作某些简化的情形。利用这些结果,导出和分析了描述具有均匀分布电流的等离子体柱运动的色散关系。