Quote by Felix Alba-Juez
The objective and merit of Einstein's theory is to identify those physical magnitudes which are absolute, i.e. common for all Inertial Frames, distinguishing them from those which are a mere perspective, only shared by those observers in repose within a given Inertial Frame.
Summary
This quote highlights the purpose of Einstein's theory, which is to determine the physical quantities that are the same for all observers in inertial frames. These quantities are considered absolute, implying that they do not change based on an observer's perspective or frame of reference at rest. On the other hand, there are measurements that are only relevant to observers within a specific inertial frame and are therefore considered as mere perspectives. By distinguishing between these absolute and perspective-dependent quantities, Einstein's theory aims to provide a unified understanding of the physical world.