狭义相对论中的几个佯谬(讲课札记)

Several paradoxes in the special relativity (Lecture notes)

真空光速c既是一个具有运动学品性的量,又是一个电磁场理论中具有动力学品性的量.因此狭义相对论中的光速不变原理不但可以给出洛伦兹时空变换,进而给出钟慢、尺缩等运动学观测效应,而且同时也对理论的动力学结构提出了在经典力学中不可能出现的约束.本文设计并详细分析了几个典型的佯谬问题,旨在说明狭义相对论的运动学如何约束其动力学结构.具体来说,运动学的观测效应要求动力学上与其协调的一定是以有限速度传播的场相互作用理论,其传播速度上限即为真空光速,而场量的变换应由洛伦兹时空变换所决定.进一步分析表明,场具有动量等物质属性,是物质存在的一种形式.

The velocity of light in vacuum has both the kinematical character and dynamical character as a prediction of the Maxwell＇ s theory. The principle of constancy of light velocity in the special relativity provides not only the Lorentz space-time transformation and some kinematical effects such as the shrink ruler effect, but also the non -trivial constraints on the dynamics structure of the theory. We devise several typical paradoxes and analyze them in detail to explain how the kinematics constrain the dynamics in the special relativity. Specifically, the dynamical theory of interaction, which can be harmonious to the relativistic kinematics, must be a field theory with a limited velocity of propagation of interactions, which is exactly the velocity of light in vacuum, and the transformation of the fields should be determined by the Lorentz space-time transformation. Further analysis makes clear that the field should have momentum, which is usual character of matter.