by Alex Vikoulov
"The world is a mirror of ourselves.” - Dayth Banger
My favorite Greek philosopher Plato has left a great legacy in the series of written “Dialogues” which summarized parables which he had learned from his mentor, philosopher Socrates. One of the better known of these Dialogues is the “Allegory of the Cave”. In this allegory, people are chained from birth in a cave so that they can only see the shadows which are cast on the walls of the cave by a fire. To these people, the shadows represent the entirety of their existence — it is impossible for them to imagine a reality which consists of anything other than the blurry shadows on the wall. However, one prisoner escapes from the cave, goes out into the light of the sun and beholds true reality. When he tries to go back into the cave and tell the other captives the truth, he’s mocked as a madman.
In Plato’s time, this story symbolized to him mankind's struggle to reach enlightenment and understanding through critical thinking and open-mindedness. Initially, we all are captives in the "cave" of our material world. Just as a prisoner may escape out into the sun, so may some people attain knowledge and ascend to the higher truth. What’s equally astonishing is the literal interpretation of Plato's tale: The idea that reality could be represented completely as “shadows” on the walls. To many people, the Holographic Principle, which is reminiscent of Plato's Allegory of the Cave, seems strange and counterintuitive: How could all of the physics which takes place in a given room be equivalent to some physics defined on the walls of the room? Could all of the information contained in your body actually be represented by your “shadow'?
In fact, the Holographic Principle appears in M-theory in similar ways. In M-theory we are the shadows on the wall. The “room” is some larger, extra-dimensional spacetime and our four-dimensional world is just the boundary of this larger space. If we try to move away from the wall, we are moving into extra dimensions of space (what one might call probabilistic space, phase space, and so on, see my essay The Unified Field and Quantum Nature of Consciousness). In modern scientific terms, a helpful visualization of the Holographic Principle would look like a fisheye space-time geometry of the Universe known as “anti-de Sitter” (AdS) space. As you move away from the center, spatial increments get shorter until eventually the spatial dimension from the center extends to nothing — smacking into a boundary. This boundary has one less spatial dimension than its interior, referred to as the “Bulk,” wherein is projected the Holographic Universe — with all its mass and energy, as well as space-time, bending and curving as described in General Relativity.
The idea that our world may be a hologram comes from black hole physics. In the 1970s researchers knew that when an object falls into a black hole, all the detailed information about that object is lost. This was dubbed the Black Hole Information Paradox, and it turned out to be a “battleground” debate between renowned physicists Stephen Hawking and Leonard Susskind that lasted for decades. The Information Paradox seemed to contradict the Second Law of Thermodynamics, because one of the lost details was the object's entropy, or the information describing its microscopic parts. Susskind insisted that no information that goes into a black hole can be lost. What eventually offered a resolution to the Information Paradox was the fact that the surface area of the black hole's event horizon (the point of no return for infalling matter and energy) always grows. If entropy must grow, and a black hole's surface area must too, perhaps for the black hole they are one and the same, and information is somehow stored on the horizon.
Physicists also began to wonder: what if the Universe itself stores information in a similar fashion? One of the starting assumptions of Quantum Mechanics was that information could be stored in every volume of space. But any patch of space can potentially become a black hole, nature's densest file folder, which stores information in bits of area. Perhaps, then, all that's needed to describe a patch of space, black hole or otherwise, is that surface area's content of information. The idea was named the Holographic Principle, after the way that a hologram encodes 3D information on a 2D surface.
Video: World Science Festival - What is the Holographic Principle?