A uniformly accelerated observer in anti-de Sitter spacetime is known to de
tect thermal radiation when the acceleration exceeds a critical value. We i
nvestigate the holographic interpretation of this phenomenon. For uniformly
accelerated trajectories transverse to the boundary of the AdS space, the
hologram is a blob that expands along the boundary. Observers on the bounda
ry comoving with the hologram become observers, in cosmological spacetimes.
For supercritical accelerations one gets a Milne universe when the hologra
phic screen is the boundary in Poincare coordinates, while for the boundary
in hyperspherical coordinates one gets de Sitter spacetimes. The presence
or absence of thermality is then interpreted in terms of specific classes o
f observers in these cosmologies.