Holograms are perhaps among the most interesting "Flat" objects that humans can create. As a fully three-dimensional set of information encoded on a two-dimensional surface, holograms can change their appearance depending on your point of view. And although scientists claim that we can only perceive three spatial dimensions, there can actually be many more.
Hence, the intriguing possibility arises that we may be a holographic projection of a multidimensional universe, in a sense.
A holographic universe could explain a lot. So, assuming that the holographic point of view is correct, what would be the relationship between a two-dimensional surface and a three-dimensional manifestation? How useful is a hologram in general in understanding the universe?
We've all seen holograms, but most people don't know how they actually work. Their scientific side is fascinating. Photography is simple: you take the light emitted or reflected from an object, focus it in a lens, and record it onto a flat surface. It's not just photography that works: your eye works the same way. The lens of your eyeball focuses the light, and the rods and cones at the back of your eye record it, sending signals to your brain, which converts it into a picture.
However, using a special emulsion and coherent (i.e. laser) light, you can create a map of the entire light field of an object, i.e. a hologram. Variations in density, texture, transparency, and more can be accurately recorded. When properly illuminated, this flat 2D map displays a full set of 3D information that changes with your perspective, and most interestingly, it does so for any possible perspective from which you can look at it. Print it on metal film and you have a simple, traditional hologram.
Our universe, as we perceive it, has three spatial dimensions available to us. But what if there are many more? Just as an ordinary hologram is a two-dimensional surface that encodes a complete set of information about our three-dimensional universe, can our three-dimensional universe encode information about a fundamentally four - or - more - dimensional reality in which we are trapped? In principle, this is possible, and a number of fun possibilities follow from this. True, these possibilities also have their limitations, which are important to understand.
The idea that our universe could be a hologram came from the concept of string theory. String theory emerged from the assumption - the string model - that would explain the strong interactions that protons, neutrons, and other baryons (and mesons) have a composite structure. She made a bunch of nonsensical predictions that did not fit the experiments, including the existence of a spin-2 particle, but people realized that if the energy scale was shifted up toward the Planck scale, the string model could combine known fundamental forces with gravity. This is how string theory was born. The plus or minus (depending on which side you look at) this model is that it requires more measurements. The next serious question was how we can extract our universe with three spatial dimensions from theory,in which there are many more of these dimensions. And which of the string theories (and there are a great many) will be the most correct?
Perhaps the many different models and scenarios of string theory are just different aspects of the same fundamental theory viewed from different angles. In mathematics, two systems that are equivalent to each other are known as "Dual" (duals), and one unexpected discovery pointed towards the hologram - in the dual system, each side has a different number of dimensions. In 1997, physicist Juan Maldacena suggested that our three-dimensional universe (plus time), with its quantum field theories describing elementary particles and interactions, is dual to a more multidimensional space-time (anti-de Sitter space), which has implications for quantum theories of gravity …
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So far, the only dualities we have found link the properties of multidimensional space to its one-dimensional lower boundary: decreasing dimensions by one. It is not yet clear if we can deduce from ten-dimensional string theory a three-dimensional universe like ours so that they are dual. We can create two-dimensional holograms by encoding only three-dimensional information; we cannot encode four-dimensional information in a three-dimensional hologram; we cannot encode our three-dimensional universe in one-dimensional.
Another interesting reason that two spaces with different dimensions are dual is the following: less information is available on the surface of a low-dimensional boundary than inside the volume of total space that this boundary contains. So if you change.