The holographic principle, rooted in connections between gravity and quantum mechanics, proposes a startling possibility: all the information contained within any region of space can be determined by studying only its surface, without accessing the interior. According to the principle, the amount of matter filling a volume is equivalent to the amount of information on its surrounding surface—effectively erasing the distinction between volume and area.
This idea emerged from the AdS/CFT correspondence, shorthand for “anti-de Sitter/conformal field theory,” which connects gravity and quantum mechanics in unexpected ways. The three foundational papers on the topic from the late 1990s have become among the most highly cited theoretical physics works of the digital era, according to the source.
The principle’s foundation traces to how gravity behaves differently from other forces. Unlike electromagnetism, where positive and negative charges can cancel each other out, mass always curves space-time in the same way—it’s always positive. This means observing distortions in space-time at a box’s surface uniquely reveals what’s inside, making holography mathematically plausible.
The concept gained traction when physicists Jacob Bekenstein and Stephen Hawking calculated black hole entropy in the 1970s. Using quantum theory, they discovered that a black hole’s entropy grows with its surface area rather than its volume—counterintuitively suggesting the interior might be redundant. Leonard Susskind at Stanford University and others built on this work in the 1990s, proposing that black holes are literally holograms where everything inside can be observed from the outside.
Since any region of space can theoretically become a black hole if compressed enough, the argument extends holographic properties to all space. As Susskind noted, this universality applies even to ordinary rooms.
However, not all physicists accept this interpretation. Latham Boyle at the University of Edinburgh questions whether the black hole entropy effect proves holography. He suggests the surface created when a black hole forms generates two distinct entropy types: one measuring particles by volume and another measuring quantum entanglement across the surface by area. These may not be the same phenomenon.
Despite disagreement about its implications for reality, the holographic principle remains influential in theoretical physics, offering a potential framework for reconciling gravity with quantum mechanics.
Key facts
- The holographic principle asserts that all information within any region of space can be determined by studying only its surface
- Gravity is unique among fundamental forces because mass always warps space-time in one direction, unlike electromagnetism where charges can cancel
- Black hole entropy, calculated by Bekenstein and Hawking, grows with surface area rather than volume, suggesting the principle applies to all space
- AdS/CFT correspondence, proposed in the late 1990s, provided mathematical support for holography and became the most cited theoretical physics work of the digital era
- Some physicists, like Latham Boyle, dispute the holographic interpretation and attribute entropy effects to entanglement rather than true holography