Is our universe a hologram?
Probably not, but a hypothesis along these lines has been suggested.
There are two variations of this idea: 1) that the universe is giant hologram related to black holes and multiple universe, and 2) that the universe is giant computer simulation being run by aliens.
The reasoning for the second variant goes something like this...if we humans can create a simple computer simulation. like SimCity or 2nd life, then why couldn't/wouldn't vastly superior aliens create an even more sophisticated version, ie. our world as a sim?
Most physicists are very skeptical of either of these variations as there is very little to no evidence for these ideas. See: