Version History and Errata

Please forward any corrections or criticisms to John O'Hanley.

May 2023

April 2023

March 2023

October 2022

May 22, 2020

Added the does-it-really questions.

May 15, 2020

Some editing and rewriting of Part I. Add a summary of important results, near the beginning. Add a list of pitfalls, near the end. Expand and improve the explanation as to why time dilation doesn't lead to a contradiction. Add a section showing why time dilation multiplies by γ, while length contraction divides by γ. Correct sloppy language for s versus s2.

May 8, 2017

Some editing and rewriting of Part I. The beginning was made more concise. Motivations for learning about the subject were added.

February 27, 2014

Added a download for a small Java tool, for generating relativistic starfield images. The tool was created mostly for generating images with a large number of stars, such as found in the Tycho-2 database.

January 28, 2014

Appearance of a sky full of stars: the diagrams showing the number of visible stars and their brightness have been updated to use the much larger Tycho-2 catalog, instead of the Yale Bright Star Catalog. Thus, these diagrams are now much closer to what a human eye would actually see.

January 25, 2014

The site was first posted to the web on this date.