Relativity and Spacetime

Abstract When it was proposed at the start of the 20th century, special relativity was revolutionary and controversial. Now, some hundred years later, the consensus in physics is that, at least in local spaces where the effects of curvature are negligible, standard special relativity will reliably predict the outcome of any experiment to which it is applied. The Lorentz transformation is considered a symmetry of nature, and new theories are crafted with Lorentz invariance as a necessary feature. This chapter introduces the ideas of special relativity with the assumption that it is an established theory whose experimental efficacy is unquestioned. The goal is to help the reader understand the theory more deeply, to see what the relativistic effects may be telling us about the world and the nature of space-time. Galileo’s principle of relativity is discussed, along with the conflict between the Galilean principle of relativity and the aether, Albert Einstein’s relativity, coordinate systems, Lorentz transformation, Lorentzian relativity, and link between mechanism and relativity.