By: Julia Canick
Most people accept that reality has three spatial dimensions. But what if that is not true? Scientists are now considering the notion that we inhabit a holographic universe—that is, a universe in which we exist on a two dimensional surface where the information on the surface is presented in three dimensions.
The idea of a holographic universe was first conceived in the 1990s by scientists Leonard Susskind and Gerard ‘t Hooft (1), While ‘t Hooft proposed the original theory, Susskind gave it an interpretation in the context of string theory (2). The holographic principle likens the universe’s style of encoding information to that of a black hole; black holes store information in bits of area, not volume, which suggests that they need only two dimensions to hold data (3). Similarly, holographic theory suggests that the entire universe is a two-dimensional structure ‘painted’ on the cosmological horizon (4). Therefore, a mathematical description of the universe would require one fewer dimension that it may seem.
Much like a hologram on a credit card, the universe could be an image of two-dimensional information, perceived in three dimensions. This idea has been studied in complex spaces with negative curvature, called anti-de-sitter spaces; new research, however, suggests that this concept can also hold in a flat spacetime—such as the one we inhabit (5).
A recent paper published in Physical Review Letters fleshes out the mathematics behind this model.6 Researchers from the University of Southampton tested algorithms provided through holographic theory against deviations in cosmic microwave background radiation left over from the Big Bang, almost 14 billion years ago. They found that the holographic theory was a good predictor of the structure of these deviations, which supports the mathematical model’s legitimacy (1).
This doesn’t mean that there isn’t a third dimension; rather, as Raphael Bousso of Stanford University describes it, “The world doesn’t appear to us like a hologram, but in terms of the information needed to describe it, it is one.” It is a more efficient way to explain the world than the one we currently employ (3).
This idea is relatively new, but could be groundbreaking. These findings help bridge quantum mechanics and general relativity. Quantum mechanics (the study of the very small) and general relativity (the study of the cosmically large) are currently at odds when it comes to describing how the universe works at every scale. Removing a spatial dimension actually helps reconcile the theories, and could be the key to a deeper understanding of the fundamentals of the universe’s existence (1). Because gravitational relativity is described in three-dimensional space, while quantum theory is described only in two dimensions, the elimination of an entire dimension would be necessary to allow the two models to coexist harmoniously (5). Though scientists have far from proven that we live in a hologram, the holographic principle is a significant jumping-off point for human beings attempting to define the space we inhabit. As researchers uncover more elegant explanations of the puzzling workings of the universe, the holographic theory may become increasingly relevant.
Julia Canick ’17 is a senior in Adams House concentrating in Molecular and Cellular Biology.
 Mortillaro, N. Are We Living in a Holographic Universe? New Study Suggests It’s Possible. CBC News [Online], Feb. 1, 2017. http://www.cbc.ca/news/technology/ living-holographic-universe-1.3959758 (accessed Feb. 24, 2017).
 Susskind, L. J. Math. Phys. 1995, 36, 6377-6396.
 Minkel, J.R. The Holographic Principle. Scientific American [Online]. https://www.scientificamerican.com/ article/sidebar-the-holographic-p/ (accessed Feb. 24, 2017).
 Holographic Universe. ScienceDaily [Online]. https:// http://www.sciencedaily.com/terms/holographic_principle.htm (accessed Feb. 24, 2017).
 Vienna University of Technology. Is The Universe a Hologram? ScienceDaily [Online], Apr. 27, 2015. https:// http://www.sciencedaily.com/releases/2015/04/150427101633. htm (accessed Feb. 24, 2017).
 Afshordi, N. et al. Phys. Rev. Lett. 2017, 118, 041301