 As with the Zeno Dichotomy, there is a regressive version of the Thomson lamp supertask. Such a lamp has been studied by Uzquiano (2012), although as a set of instructions rather than a set of tasks. Consider a lamp that has been switched on at 2 seconds past the hour, off at 1 second past, on at ½ a second past, off at ¼ a second past, and so on. What is the state of the lamp on the hour, just before the supertask has begun? This supertask can be viewed as incomplete in the same way as the original Thomson lamp. Insofar as the mechanics of bouncing balls and electric circuits described in Earman and Norton’s lamp are time reversal invariant, it follows that the time-reversed system is a possibility as well, which is spontaneously excited to begin bouncing, providing a physical implementation of the regressive Thomson lamp. However, whether the reversed Thomson lamp is a physical possibility depends on whether or not the system is time reversible. A difficulty is that its initial state will not determine the subsequent history of an infinity of alternations.