[jarin]

They're not saying the universe is a light hologram like the one on your credit card, they're saying it might be holographic in the sense that our 3d space could be a projection of a 2d boundary.

The idea came about as a way to resolve the black hole information paradox in a way compatible with string theory (the idea is that information can never be destroyed, but black holes appear to destroy information). One interesting consequence would be that our universe could be the result of a black hole in some other universe.

[Justen]

Last I read about holographic projection was the idea that our universe is a 3D projection of a 4D star. Is this a completely different theory or maybe just easier to test?

[snowwrestler]

Where does the idea come from that information cannot be destroyed? Is that supported by strong evidence, or is it just an assumption, axiom, or hypothesis?

My intuitive sense is that information can be created and destroyed. For example if I arrange wooden block letters to form a sentence, I have expended energy to encode information. If I scatter the blocks randomly, I have expended more energy to destroy information.

[jarin]

It's supported in both classical mechanics (Liouville's theorem, which is a vital component of the proof of Newton's second law) and in quantum mechanics (quantum unitarity).

http://van.physics.illinois.edu/qa/listing.php?id=24045

[snowwrestler]

Ah, looks like I am confused between quantum information and classical information (bits). We can create and destroy the latter.