In AdS/CFT partition functions of decoupled copies of the CFT factorize.
In bulk computations of such quantities contributions from spacetime
wormholes which link separate asymptotic boundaries threaten to spoil
this property, leading to a "factorization puzzle." Certain simple
models like JT gravity and the SYK model have wormholes, but bulk
computations in them correspond to averages over an ensemble of boundary
systems. These averages need not factorize. We can formulate a toy
version of the factorization puzzle in such models by focusing on a
specific member of the ensemble, for which partition functions will
factorize. In the bulk, these fixed members of the ensemble correspond
to "alpha states" of many closed universes. In this talk we discuss bulk
computations of partition functions in (sometimes approximate) alpha
states in three simple models: the topological model introduced by
Marolf and Maxfield (the "MM model"), JT gravity, and the SYK model, and
give an effective description of the factorization mechanism.