A trip to the end of the universe and the twin "paradox"

Special relativity offers the possibility of going on a trip to the center of our galaxy or even to the end of our universe within a lifetime. On the basis of the well known twin paradox, we discuss uniformly accelerated motion and emphasize the local perspective of each twin concerning the interchange of light signals between both twins as well as their different views of the stellar sky. For this purpose we developed two Java applets that students can use to explore interactively and understand the topics presented here. (c) 2008 American Association of Physics Teachers.