Counterfactual History is Consistent with Physics

Counterfactual histories (CFHs) are histories that did not ``happen'' [1, 2]. For this concept to be meaningful, CFHs must correspond to states of the physical universe for which none of the laws of physics are violated. We present arguments to show that CFHs are realizable. Several of their critical features are: (i) their past states (histories) are uniquely determined from any given ``present state''; (ii) the future evolution from any given ``present state'' is non-predictable; and (iii) different trajectories, evolving from a given ``present state'' do not communicate with each other. We demonstrate the validity of these propositions by means of a toy universe that has these features. The general conclusion reached is that CFHs may exist. References: [1] ``The Counterfactual History Review'' ( research journal). [2] E. H. Carr, What is History (Cambridge University Press, 1961).