 Finally, there are a number of conceptual pitfalls regarding what would count as an adequate “explanation” of the origins of the universe. What is the target of such explanations, and what can be used in providing an explanation? The target might be the state defined at the earliest time when extrapolations based on the SM can be trusted. The challenge is that this state then needs to be explained in terms of a physical theory, quantum gravity, whose basic concepts are still obscure to us. This is a familiar challenge in physics, where substantial work is often required to clarify how central concepts (such as space and time) are modified by a new theory. An explanation of origins in this first sense would explain how it is that classical spacetime emerges from a quantum gravity regime. While any such proposals remain quite speculative, the form of the explanation is similar to other cases in physics: what is explained is the applicability of an older, less fundamental theory within some domain. Such an explanation does not address ultimate questions regarding why the universe exists—instead, such questions are pushed back one step, into the quantum gravity regime.