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According to special relativity, a (longitudinally) moving stick is Lorentz contracted. When it is brought to rest, it must expand to its proper length. But, exactly how this expansion unfolds depends on how the stick is stopped. If the front end hits a brick wall, the rear end must (briefly) continue moving, and the stick contracts even further before expanding; if instead the rear end is suddenly stopped, the front end (briefly) continues, and (surprisingly) the stick overexpands before settling into its proper length. These effects of overexpanding and overcontracting are independent of any classical or molecular elasticity, but are derived entirely from the limits of information travel time imposed by special relativity. I explore these phenomena, inspired by the little known ‘lock and key’ paradox. [ABSTRACT FROM AUTHOR]