 Arguments along these lines led ’t Hooft (1993, in  OIR)  to postulate the Holographic Principle (though the name is due to Susskind 1995). This principle claims that the number of fundamental degrees of freedom in any spherical spatial region is given by the Bekenstein entropy of a black hole of the same size as that region. The Holographic Principle is notable not only because it postulates a well-defined, finite number of degrees of freedom for any region, but also because this number grows in proportion to the area surrounding the region, not the volume. This flies in the face of the standard picture of the dynamics of all other known types of physical systems, whether particles or fields. According to that picture, the entropy is measured by the number of possible ways something can be, and that number of ways increases as the volume of any spatial region. To the contrary, if the Holographic Principle is correct then one spatial dimension of any physical system can, in a sense, be viewed as superfluous: the fundamental “physical story” of a spatial region is actually a story that can be told merely about the boundary of the region (Luminet 2016). 