Okay I've got a question about the difference between the sagnac effect in an inertial and non-inertial environment. Let me give you an example to base the info off of. I want to make a really long linear sagnac-like arrangement to factor out any cross propagation. In the following example all I want is toward and away. Put a set of 4 mirrors in space that will reflect light in a square. Bring two mirrors close together on each side to create a rectangle. Separate these two sets of close mirrors from eachother by 10 light seconds. Place a spaceship that is capable of travelling .25C in the plane of one of the 2 long optical paths (imagining that it doesn't block the other path) Ignore the small travel time in which the beams propagate perpendicularly to the ships motion so - if you're ticky - when comparing to a ring that has a circumference the same as the linear optical path, just reduce the circumference by that tiny cross propagation amount. (close enough) The purpose is to determine how the arrival time difference compares to a sagnac device. So for your non-inertial example imagine the same ship with 1 huge fiber optic cable attached to it's tail and nose. The length of the fiber cable is the same as the optical path in the first thought experiment and the ship is flying in a circle of that circumference. For the Linear experiment: Examination 1) Have the ship start at the 1/4 mark and emit a pulse forward and back simultaneously. Examine results with SR. Exam 2) Have the ship start in the middle and examine results. Questions: 1) Do both examinations arrive at the same arrival time difference? 2) Do both experiments result in the same arrival time difference in all situations of examination? Anyone got Mathematica so they can show the linear experiment visually?