Interactive Tools
Black Hole Entropy & the Holographic Principle (Interactive)
An interactive visualiser of black hole entropy. See why a black hole's information is set by the area of its horizon, not its volume, the idea behind the holographic principle.
Last reviewed 23 May 2026 · How we research
A black hole's entropy, the amount of hidden information it holds, is set by the area of its event horizon, not its volume. This is the Bekenstein-Hawking insight behind the holographic principle. Drag the mass and watch how radius, area and entropy scale differently.
Radius (~ M)
2×
grows in step with mass
Horizon area (~ M\u00B2)
4×
grows with the square
Entropy (~ area)
4×
set by area, not volume
Notice that doubling the mass doubles the radius but quadruples the area and the entropy. Because the information capacity tracks the two-dimensional surface rather than the three-dimensional interior, physicists suspect the universe itself may be "holographic": its contents describable on a lower-dimensional boundary.
One of the strangest results in physics is that a black hole's entropy, the measure of the hidden information it contains, depends on the area of its event horizon, not on its volume. This interactive tool lets you feel why that matters, and why it led physicists to the astonishing idea of the holographic principle.
Area, not volume
Drag the mass and watch the three quantities scale at different rates. Because the radius grows in step with mass but the area grows with the square of mass, doubling the mass quadruples the entropy. The information capacity tracks a two-dimensional surface, not a three-dimensional interior. This is the Bekenstein-Hawking insight that underpins black hole thermodynamics, and it hints that the universe itself may be describable on a lower-dimensional boundary.