Physics of Reality – 7: Are We Living in a Hologram?
by Charles Phelan
In prior segments reviewing the work of Leonard Susskind on Black Hole Complementarity, we saw how modern physics is pointing toward an observer-dependent reality rather than a single objective universe. In discussing the black hole information loss paradox first identified by Stephen Hawking in the 1970s, and the subsequent battle in physics eventually won by Susskind, I omitted an important development that happened along the way, and will return to it now. This is the Holographic Principle, first proposed by Susskind in the 1990s as a consequence of his work on string theory.
One of the weirdest results of all the research on black hole entropy and information loss was a mathematical calculation that determined how much "information" could be stored in a black hole. If the event horizon – the point of no return – can be visualized as the surface of a hollow sphere surrounding the singularity at the center, then logically we would expect the calculation to yield a volume result since any sphere is three dimensional. However, the bizarre outcome was that the information capacity of a black hole is limited to the area of the surface of the event horizon, a two-dimensional result instead of three-dimensional! It is difficult to convey how truly strange this is!
Think of it this way. Let's say the Earth was hollow except for a tiny diamond at the center, so the surface of the Earth is like the event horizon, and the diamond takes the place of the singularity at the center. Let's be quaint and take information in the form of computer printouts filled with ones and zeroes, and then use all that paper to fill up the hollow sphere between the crust and the center. If you were to calculate how much paper (information) could be held inside of the hollow sphere, the result would be based on a volume calculation for a sphere the size of Earth, taking into account the size and thickness of the paper used for printing the data and how much information could fit on one sheet.
Yet the result calculated by Jacob Bekenstein – work that Susskind later built on to develop his Holographic Principle – showed that it doesn't work that way for black holes. Again, instead of a volume result, the equations produce an area result. It's as though no matter how many sheets of paper with information on them are poured into the sphere, the result for maximum information capacity will always be the surface of the sphere and not its volume. It would be like dumping papers into the hollow sphere but never being able to fit more than would cover the surface of the Earth. For all practical purposes, an entire dimension is lost, and 3D becomes 2D.
Translating this astonishing finding back to black holes, it is as though there is no “inside” of the event horizon, that as far as anything outside the event horizon is concerned, nothing on the other side actually exists. So from the view outside the horizon, the information available is limited to the area of the surface of the horizon's sphere. If this does not boggle your mind, then you're not quite grasping the strangeness of it.
So far I haven't touched on the issue of how information capacity could actually be calculated in the first place, as this leads into difficult territory like Shannon entropy and the Planck length limitation, which are beyond the scope of this article. But the short version is that there is a smallest possible size for a single bit of information, which allows an immense but finite amount of information to be stored on the surface of a black hole's event horizon. But why only an area? Why not a volume? Susskind's answer is the Holographic Principle. Consider a simple hologram, where three-dimensional information is inscribed in two dimensions on the surface of a plastic card or other material. A three-dimensional projection appears at a distance from the two-dimensional substrate and any one portion of the substrate contains information about the whole.
Susskind's work involved analyzing the mathematics of a special type of theoretical universe called an anti deSitter universe. Anti de-Sitter space has a negative curvature, which results in strange anomalies compared to a universe like our own, which is flat and positively curved by comparison. For example, an object thrown with sufficient velocity along a straight line in anti de-Sitter space would eventually return to its original starting point!
As it happens, a universe made from anti de-Sitter space is an ideal universe in which to do certain complex calculations. Within the specific framework of the anti deSitter space, Susskind was able to show that the total information capacity was equivalent to the area of the cosmic boundary, and this led to his application of the term “holographic." It is as though any apparent 3D events are really just projections from the distant 2D information field encoded on the cosmic boundary.
It has not been proven yet that our universe is holographic, but there has been considerable momentum in that direction, in terms of thousands of physics papers supporting the principle, and not just for anti deSitter space but also for regular space like our own. At this point in the progress of modern theoretical physics, there are still critics taking aim at potential flaws in the Holographic Principle. But it remains a solid theory that probably deserves to be called a consensus. It really does appear that our apparently 3D universe is just a projection from a 2D information matrix encoded on the distant cosmic boundary horizon.
How does the Holographic Principle pertain to Advaita, or further our understanding of the nondual perspective? Advaita teaches that the apparent creation is not actually real, that it is mithyA, a dependent reality. The Upanishads teach that the apparent reality we observe with our senses, and even the mental world we observe with our minds, is all just a trick by mAyA. It is all just a magic show where things appear to be one way but are not actually as we observe. Science is beginning to tease out how some of mAyA's tricks work. Drill down into matter with a microscope and mathematics, and the result is nothing. Molecules contain atoms, which contain particles like electrons or protons, which in turn contain quarks and other members of the quantum zoo of particles, which contain – what? Tiny one-dimensional vibrating strings that change depending on one's frame of reference?
Drill down far enough and there is only speculative mathematics and nothing more, nothing that is ever unchanging or actually solid. I believe we can fairly describe all of this as mithyA, the snake in the rope, or the ghost in the post. If it can ultimately be proven with certainty that our 3D universe is actually just a hologram projected from a distant 2D cosmic horizon, this would mean that the mithyA nature of creation, known to Vedic sages for millennia, had actually been demonstrated and accepted by modern science.
Further from the perspective of the student of Advaita, it is fascinating to observe that modern physicists often dance very close to discussing the role of Consciousness, but never quite go there. Yet if reality is observer dependent, then where does the observer come from? This is not a question addressed by physics, let alone answered by it. Yet in result after result, modern physics seems to be converging to a view that reality is indeed observer dependent. No observer means no universe. If we jettison the God's eye view of reality and accept that each so-called individual has their own reality cone, then the apparent paradoxes drop away and all becomes much clearer. So perhaps it is only a matter of time before some young physicist gets the bright idea to propose that Consciousness is primary and that all else arises within it!