 Loop quantum cosmology (LQC) is an approach to cosmology within the framework of the loop quantum gravity (LQG) program (Rovelli 2004), which itself starts with the idea that unifying quantum theory and general relativity will require “quantizing” the gravitational field—and hence the structures of spacetime itself. Roughly speaking, to quantize a theory means that the quantities (e.g., position, momentum, scalar curvature, etc.) are replaced by “matrices,” or more generally with “operators on a Hilbert space.” This replacement can have profound physical consequences, most particularly the spectrum of a quantity (i.e., the numerical values it can possess) can become discretized where it was previously continuous, or bounded where it was previously unbounded, and quantities can be forced to obey a Heisenberg uncertainty principle.