Probing spacetime foam with extragalactic sources.

Because of quantum fluctuations, spacetime is probably "foamy" on very small scales. We propose to detect this texture of spacetime foam by looking for halo structures in the images of distant quasars. We find that the Very Large Telescope interferometer will be on the verge of being able to probe the fabric of spacetime when it reaches its design performance. Our method also allows us to use spacetime foam physics and physics of computation to infer the existence of dark energy or matter, independent of the evidence from recent cosmological observations.