Our cosmology course is well under way and it's a lot of fun so far! The class direction overall is towards describing the inflationary universe by means of quantum field theory, but this week we're focused on relativity. We're allowed to work on our homework together, however, I'm spending most of my time in the lab this semester, so I'll be posting my homework notes here. If you'd like to grab bits and pieces, make suggestions, or contribute, the whole shooting match will also be archived on github . Our first homework contains a problem that involves accelerating reference frames. The question is, given the transformation between the lab and the accelerating reference frame, figure out if the line element $ds^2$ is preserved. There are a few interesting aspects to this problem. First, while the transform looks similar to Rindler coordinates, it's not, (as ar as I can tell.) Second, looking into Rindler coordinates a bit, they seem to ...