2018/12/21 by Alon Drory · 2 citations
Physics and Astronomy · Mathematics · #Relativity and Gravitational Theory #Mathematics and Applications #History and Theory of Mathematics
paper · doi:10.1119/1.5082535
openalex publication_date 2018/12/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/05/21
In special relativity, accelerated objects are described through instantaneous comoving frames, to which the usual transformations are then applied. This is not always possible, however. I analyze a simple example of a rod thrown from a train onto a stationary platform. The lack of absolute simultaneity implies that the rod stretches, and its points move with respect to each other. Its length, therefore, changes. Typically, the rod as a whole has no instantaneous rest length and thus no definable proper length. A fortiori, it has no instantaneous rest frame, and the (instantaneous) Lorentz contraction formula is inapplicable.