The holographic principle is a concept in theoretical physics that suggests the information contained within a certain volume of space can be represented as a "hologram" — a theory or image encoded on the boundary of that space. In simpler terms, it proposes that the universe can be seen as a two-dimensional information structure "painted" on the cosmological horizon, such that the three-dimensional world we observe is an emergent phenomenon from this two-dimensional projection.

When applied to quantum mechanics, the holographic principle offers intriguing insights:

By applying the holographic principle, researchers are exploring how quantum information encoded at a boundary can give rise to the phenomena observed in the bulk of three-dimensional space. This approach is pivotal in the ongoing efforts to develop a quantum theory of gravity and understand the fabric of the universe at its deepest level.

It applies in the following way: Quantum mechanics is a theory with one-dimensional worldvolume, the time direction, so it’s the boundary of a two-dimensional spacetime, of classical gravity. One example is the AdS2/CFT1 correspondence.

I think David Bohm is a big fan of this

topic, you could read one or more of

his books.

Usually the topic is not considered that relevant. It does not bring out new

physical principles.

The holographic principle, emerging from string theory and black hole physics, posits that all information within a volume of space can be encoded on its boundary, akin to a hologram. This principle is exemplified by the AdS/CFT correspondence, which equates a quantum gravity theory in a higher-dimensional AdS space to a lower-dimensional quantum field theory on its boundary. It offers insights into quantum gravity, suggesting that spacetime geometry is linked to quantum entanglement, and addresses the black hole information paradox by encoding information on the event horizon. Despite its theoretical successes, experimental verification remains challenging, and extending the principle to more realistic spacetimes is an ongoing area of research. This principle fundamentally reshapes our understanding of space, time, and information in the context of quantum mechanics.