The holographic principle is a radical idea from theoretical physics proposing that all the information contained within a volume of space can be fully described by information located on its boundary. In other words, the three-dimensional contents of a region can be encoded on its two-dimensional surface, much like a hologram.
This concept originated from studies of black hole thermodynamics. Physicists found that the entropy of a black hole—which is a measure of information—is proportional not to its volume, but to the area of its event horizon. This surprising result led to the broader realization that volume-based information might be redundant.
One of the most well-known realizations of the holographic principle is the AdS/CFT correspondence, which relates a gravitational theory in a higher-dimensional “bulk” space (anti-de Sitter space) to a quantum field theory without gravity on its lower-dimensional boundary.
The holographic principle has profound implications for our understanding of space, time, gravity, and quantum mechanics. It challenges the classical notion of locality and suggests that the fabric of the universe might be fundamentally lower-dimensional than it appears.