"Relativity: The Special and General Theory" by Albert Einstein is a popular science book published in German in 1916. Written for readers without advanced mathematical training, it explains Einstein's revolutionary theories of special and general relativity in accessible terms. Through thought experiments involving trains, light, and moving observers, Einstein reveals how time, space, and simultaneity are relative concepts rather than absolute truths. The book demonstrates how these insights unite fundamental laws of physics in unexpected ways.
See also PG #30155 which is from a later print edition. Note especially that some of the automatically-generated formats of #5001 may not display images or equations correctly. Wikipedia page about this book: en.wikipedia.org/wiki/Relativity:_The_Special_and_the_General_Theory