What is the holographic principle?

The holographic principle is a concept in theoretical physics that suggests that the information contained in a three-dimensional space can be entirely encoded in a two-dimensional surface. This principle was first proposed by physicist Gerard 't Hooft in 1993 and further developed by physicist Leonard Susskind.

According to the holographic principle, the universe can be thought of as a hologram, where the information about the three-dimensional world is represented on a two-dimensional surface. In other words, the entire universe can be considered a projection of information onto a lower-dimensional surface.

This principle has important implications for our understanding of black holes and quantum gravity. It suggests that the behavior of a black hole can be explained by the laws of quantum mechanics, and that information inside a black hole is not lost as previously thought.

The holographic principle is a conjecture in quantum gravity that states that the information about a volume of space can be encoded on a boundary to the region — such as a light-like boundary like a gravitational horizon. This suggests that matter itself cannot be subdivided infinitely many times and there must be an ultimate level of fundamental particles.

The holographic principle was first proposed by Gerard 't Hooft in 1993. He argued that the degrees of freedom of a particle are the product of all the degrees of freedom of its sub-particles, and that if a particle were to have infinite subdivisions into lower-level particles, the degrees of freedom of the original particle would be infinite, violating the maximal limit of entropy density. The holographic principle thus implies that the subdivisions must stop at some level.

The holographic principle was given a precise string-theory interpretation by Leonard Susskind in 1995. He combined his ideas with previous ones of 't Hooft and Charles Thorn. Susskind argued that the information about a volume of space can be encoded on a lower-dimensional boundary to the region, such as a light-like boundary like a gravitational horizon. This means that the three-dimensional world we live in may be an illusion, and that the real world is actually two-dimensional.

The holographic principle is still a very active area of research in physics. It has implications for our understanding of black holes, the early universe, and quantum gravity. It is also a possible explanation for the phenomenon of consciousness.