Albert Einstein

Relativity - The Special and General Theory Albert Einstein

Book Excerpt: ...that differences of opinion are scarcely likely to arise as to its applicability in practice.*** A refinement and modification of these views does not become necessary until we come to deal with the general theory of relativity, treated in the second part of this book. SPACE AND TIME IN CLASSICAL MECHANICSThe purpose of mechanics is to describe how bodies change their position in space with "time." I should load my conscience with grave sins against the sacred spirit of lucidity were I to formulate the aims of mechanics in this way, without serious reflection and detailed explanations. Let us proceed to disclose these sins. It is not clear what is to be understood here by "position" and "space." I stand at the window of a railway carriage which is travelling uniformly, and drop a stone on the embankment, without throwing it. Then, disregarding the influence of the air resistance, I see the stone descend in a straight line. A pedestrian who observes the misdeed from the footpath notices th...