= Rod containment and simultaneity
A moving rod can have both ends inside a shorter shed on a single constant-time slice of the shed frame. <Lorentz transformation> sends the two simultaneous endpoint events to different times in the rod frame; it does not imply simultaneous containment there. Entrance and first collision can be spacelike separated and occur in reversed time order. After impact, length changes must propagate through the rod causally; a perfectly rigid instantaneous stopping model is not relativistically admissible.
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