I'm confused as to how far apart the hash marks should be on a minkowski spacetime diagram that shows the rocket frame overlapped over the lab frame. Should the hash marks that represent space in the rocket frame be spaced apart exactly the same length as the hash marks that represent space in the lab frame? How do we go about determining how far apart the hash marks should be? Do we just rotate the x axis to get the x' axis and keep the hash marks space the same length apart? Any help would be greatly appreciated. Thanks in advance!