The Universe as it looks to us (top) and as it might really be (bottom): a flat two-dimensional space (Photo : TU Wien)
The Universe and all of everything might simply be a hologram.
Think about this maddening statement and what it means for your definition of reality. A group of very bright minds has and their conclusion might re-define what reality really is.
A new study published in the journal Physical Review Letters seems to strengthen the mind-boggling theory that everything in the Universe, and everything we believe is real, is just a three dimensional or 3D holographic illusion projected onto our limited two dimensional or 2D brains.
In other words, what we perceive as 3D might just be the image of two dimensional processes painted on a huge cosmic horizon.
Holograms as we know them are encodings of light fields rather than of images formed by a lens usually intended for displaying 3D images. The holographic recording itself is not an image but consists of an apparently random structure of varying intensity, density or surface profile. It's a very real illusion.
The "holographic principle" in physics is a controversial theory first proposed by Gerard 't Hooft, a Dutch theoretical physicist, that suggests the entire universe can be seen as a 2D information structure "painted" on the cosmological horizon.
It postulates that a mathematical description of the universe actually requires one fewer dimension than it seems. In effect, the three dimensions we observe are an effective description only at macroscopic scales and at low energies.
The holographic principle claims that a volume of space can be thought of as encoded on a boundary to it -- such as an observer-dependent gravitational horizon -- and therefore needs one less dimension than it appears to need.
By extension, since our universe seems 3D to us, it could actually be a 2D structure that's overlaid onto an endless large cosmic horizon.
Juan Maldacena first proposed the theory of a holographic universe in 1997 based on String theory, which postulates gravity arises from thin, vibrating strings that exist in 10 dimensions.
Now physicists at TU Wien (Vienna) in cooperation with the University of Edinburgh, Harvard, IISER Pune, MIT and the University of Kyoto propose the holographic principle works even in a flat spacetime, and not just in theoretical regions with negative curvature.
It must be remembered gravitational phenomena are described with three spatial dimensions. On the other hand, quantum particles are described with just two dimensions.
"If quantum gravity in a flat space allows for a holographic description by a standard quantum theory, then there must by physical quantities, which can be calculated in both theories - and the results must agree," said Daniel Grumiller of TU Wien.
That includes the appearance of quantum entanglement in the gravitational theory, meaning that the particles can't be described individually.
It turns out you can measure the amount of entanglement in a quantum system, which is called the entropy of entanglement. Grumiller shows that it has the same value in flat quantum gravity and in a low-dimension quantum field theory.
"The fact that we can even talk about quantum information and entropy of entanglement in a theory of gravity is astounding in itself, and would hardly have been imaginable only a few years back. That we are now able to use this as a tool to test the validity of the holographic principle, and that this test works out, is quite remarkable," said Grumiller.
Max Riegler, also of TU Wien, said this calculation "affirms our assumption that the holographic principle can also be realized in flat spaces. It is evidence for the validity of this correspondence in our universe".
What Riegler said is simply this: all of us live in a hologram.
