  It follows from AW1 (and reasonable assumptions) that distinct worlds do not overlap, spatiotemporally; that no spatiotemporal part  of one world is part of   another.[16]  Moreover, given   Lewis's counterfactual analysis of causation,  it follows from this that objects in distinct worlds bear no causal  relations to one another; nothing that occurs in one world has any  causal impact on anything that occurs in any other world. 