 When considering the implications of spacetime singularities, it is important to note that we have good reasons to believe that the spacetime of our universe is singular. In the late 1960s, Penrose, Geroch, and Hawking proved several singularity theorems, using path incompleteness as a criterion (Penrose 1965, 1968; Hawking 1965, 1966b, 1966c, 1966d; Geroch 1966, 1967, 1968b, 1970; Hawking and Penrose 1970). These theorems showed that if certain physically reasonable premises were satisfied, then in certain circumstances singularities could not be avoided. Notable among these conditions is the positive energy condition, which captures the idea that energy is never negative. These theorems indicate that our universe began with an initial singularity, the Big Bang, approximately 14 billion years ago. They also indicate that in certain circumstances (discussed below) collapsing matter will form a black hole with a central singularity. According to our best current cosmological theories, moreover, two of the likeliest scenarios for the end of the universe is either a global collapse of everything into a Big Crunch singularity, or the complete and utter diremption of everything, down to the smallest fundamental particles, in a Big Rip singularity. (See Joshi 2014 for a recent survey of singularities in general, and Berger 2014 for a recent survey of the different kinds of singularities that can occur in cosmological models.) 