Ok, so imagine observer A is moving along with a measuring rod of length L that is being slid along the ground by a rod that holds it steady by pushing it against the ground as it slides (no tilting whatsoever, the base of the rod remains firm against the ground), at a velocity comparable to c. Let's say that the velocity is such that observer B who is standing on the ground and not moving with the measuring rod will measure the length of the rod to be L/2. At some point, the measuring rod passes over a hole of length L/2. If the observer B on the ground is correct in his measurement of the length, the connecting rod will push it down into the hole when it passes over, if observer A that moves with the measuring rod is correct, the connecting rod will not be able to push it down into the hole and the rod will continue along its path. I got this question from http://www.youtube.com/watch?v=202fU9qIVK4", and the professor resolves the paradox by saying that one observer must conclude that the measuring rod was able to tilt. This is the reason for my forbidding the tilting of the measuring rod in the experiment. So what happens in this scenario? How are the two observations resolved?