  Spacetime is composed of a fluctuating arrangement of bubbles or loops called
spacetime foam, or quantum foam. We use the holographic principle to deduce its
structure, and show that the result is consistent with gedanken experiments
involving spacetime measurements. We propose to use laser-based atom
interferometry techniques to look for spacetime fluctuations. Our analysis
makes it clear that the physics of quantum foam is inextricably linked to that
of black holes. A negative experimental result, therefore, might have
non-trivial ramifications for semiclassical gravity and black hole physics.
