时间、距离、速度、红移基本物理概念的演变简史

为了尝试回答“我们能否观测到退行速度超过光速的星系”这一问题,重新考察了在牛顿物理学、狭义相对论、广义相对论和宇宙学中的时伺、距离、速度和红移等概念．揭开了一些错误观念的实质,发现只要摆脱狭义相对论先入为主的束缚,上述问题即可迎刃而解．强调了宇宙学并不是纯粹的广义相对论,而是该理论在服从宇宙学原理的条件下的一个特例,其中一系列基本物理概念都因此得到新的内涵。

Time, Distance, Velocity, Redshift:a brief history of changes in the basic physical concepts

An attempt to answer the puzzling question, "Can we observe galaxies that recede faster than light ? ", has led to a re-examination of the notions of time, distance, velocity and redshift as they occur in Newtonian Physics, Special Relativity, General Relativity and Cosmology. It is found that these basic notions have different meanings in the different contexts, that once the differences are recognized, particularly those between Special Relativity and Cosmology, the above question becomes straightforward and easily answered. It is pointed out that what is interesting to physics is not individual events, but intervals between specified events. Pairs of equations are selected to illustrate the changing meaning of time interval and distance from one theory to the next. A number of common misconceptions are pointed out. It is underlined that modern cosmology is not pure General Relativity; rather, it is an application of General Relativity under the Cosmological Principle, thanks to which quantities relating to large distances at given times become well-defined and calculable.