Science
The Holographic Principle
The startling idea that everything inside a region of space can be described by information on its boundary, like a hologram. It grew directly from Hawking's work on black holes.
Last updated 23 May 2026 · How we research
The holographic principle is one of the most surprising ideas in modern physics: the suggestion that everything happening inside a region of space can be fully described by information stored on the boundary of that region, one dimension lower. Just as a flat hologram can encode a three-dimensional image, our three-dimensional reality may be, in some deep sense, encoded on a distant two-dimensional surface. The idea sounds outlandish, but it grew directly out of Hawking's work.
Where it came from
The seed was black hole entropy. When Hawking and Jacob Bekenstein worked out how much entropy, and therefore how much information, a black hole contains, they found something strange. For ordinary objects, the amount of information you can store grows with volume. But a black hole's information is proportional to the area of its event horizon, its two-dimensional surface, not its three-dimensional volume. The maximum information that can be packed into any region of space, it seemed, is fixed by the area of its boundary.
What it implies
In the 1990s the physicists Gerard 't Hooft and Leonard Susskind took this clue seriously and proposed it as a general principle. A concrete and astonishingly successful mathematical version followed, in which the physics of a region of space with gravity is shown to be exactly equivalent to a different physical theory, without gravity, living on its boundary. This "holographic" duality has become one of the most powerful tools in theoretical physics.
The connection to Hawking
The holographic principle matters enormously for the puzzle Hawking spent his last decades on, the black hole information paradox. If the information about everything that falls into a black hole is encoded on its horizon, then it need not be destroyed when the black hole evaporates; it could be carried away, scrambled, in the outgoing radiation. Many physicists now believe holography is the key to resolving the paradox. It is a remarkable legacy: an idea now central to the search for quantum gravity, born from Hawking's insistence on taking the thermodynamics of black holes seriously.
See the idea in action with the black hole entropy visualiser.