# Leonard Susskind on The World As Hologram

Leonard Susskind of the Stanford Institute for Theoretical Physics discusses the indestructability of information and the nature of black holes in a lecture entitled The World As Hologram.

# The World as a Hologram

*(Submitted on 15 Sep 1994 (**v1**), last revised 28 Sep 1994 (this version, v2))*

According to 't Hooft the combination of quantum mechanics and gravity requires the three dimensional world to be an image of data that can be stored on a two dimensional projection much like a holographic image. The two dimensional description only requires one discrete degree of freedom per Planck area and yet it is rich enough to describe all three dimensional phenomena. After outlining 't Hooft's proposal I give a preliminary informal description of how it may be implemented. One finds a basic requirement that particles must grow in size as their momenta are increased far above the Planck scale. The consequences for high energy particle collisions are described. The phenomena of particle growth with momentum was previously discussed in the context of string theory and was related to information spreading near black hole horizons. The considerations of this paper indicate that the effect is much more rapid at all but the earliest times. In fact the rate of spreading is found to saturate the bound from causality. Finally we consider string theory as a possible realization of 't Hooft's idea. The light front lattice string model of Klebanov and Susskind is reviewed and its similarities with the holographic theory are demonstrated. The agreement between the two requires unproven but plausible assumptions about the nonperturbative behavior of string theory. Very similar ideas to those in this paper have been long held by Charles Thorn.

Comments: SU-ITP-94-33, phyzzx, 33 pages and 5 figures (Some typos fixed and one reference added.)

**Subjects:** High Energy Physics - Theory (hep-th)**Journal reference:** J.Math.Phys.36:6377-6396,1995

**DOI:**10.1063/1.531249

**Cite as:**

**arXiv:hep-th/9409089**

**(or**

**arXiv:hep-th/9409089v2**for this version)

## Submission history

**From:** Leonard Susskind [view email] **[v1]** Thu, 15 Sep 1994 23:14:18 UTC (0 KB)**[v2]** Wed, 28 Sep 1994 01:12:55 UTC (39 KB)

# Holographic principle

From Wikipedia, the free encyclopedia

The **holographic principle** is a principle of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a lower-dimensional boundary to the region—preferably a light-like boundary like a gravitational horizon. First proposed by Gerard 't Hooft, it was given a precise string-theory interpretation by Leonard Susskind[1] who combined his ideas with previous ones of 't Hooft and Charles Thorn.[1][2] As pointed out by Raphael Bousso,[3] Thorn observed in 1978 that string theory admits a lower-dimensional description in which gravity emerges from it in what would now be called a holographic way. The prime example of holography is the AdS/CFT correspondence.

The holographic principle was inspired by black hole thermodynamics, which conjectures that the maximal entropy in any region scales with the radius *squared*, and not cubed as might be expected. In the case of a black hole, the insight was that the informational content of all the objects that have fallen into the hole might be entirely contained in surface fluctuations of the event horizon. The holographic principle resolves the black hole information paradoxwithin the framework of string theory.[4] However, there exist classical solutions to the Einstein equations that allow values of the entropy larger than those allowed by an area law, hence in principle larger than those of a black hole. These are the so-called "Wheeler's bags of gold". The existence of such solutions conflicts with the holographic interpretation, and their effects in a quantum theory of gravity including the holographic principle are not yet fully understood.[5]

# Holographic Cosmology with Leonard Susskind

Documentary HD 2017 Stanford Lectures.

Leonard Susskind of the Stanford Institute for Theoretical Physics discusses the indestructability of information and the nature of black holes in a lecture entitled The World As Hologram.

NOTE: Audio clears up at the 8:20 mark Part 1 of a conference lecture given by Leonard Susskind on Holographic Cosmology. The holographic principle provides an extraordinary new picture.

According to Leonard Susskind (Bad Boy of Physics), our reality is much stranger than it appears to be and life, the universe, EVERYTHING, might just be a holographic projection! Is the universe.