It may sound silly to wonder if our huge, vast universe is 3D, but that's exactly what scientists are now beginning to question. According to a new study, some scientists now believe that the Universe is really just a hologram.
Holograms can be seen everywhere in real life, from credit cards to bank notes. They are two dimensional, but to us they appear 3D. The Universe could behave in much the same way.
According to the "holographic principle," a mathematical description of the universe actually requires one fewer dimensions than it seems. So what does this mean? What we perceive as 3D, could in fact just be the image of 2D processes on a huge cosmic horizon.
Until now, scientists scientists have studied the holographic principle in exotic spaces with negative curvature meaning those in which any object thrown away in a straight line will eventually return. However, for this latest study, a team at the Vienna University of Technology (TU Wien) suggests the principle could actually be applied to flat space-time such as our Universe.
"Our Universe, in contrast, is quite flat - and on astronomic distances, it has positive curvature," Daniel Grumiller from (TU Wien) said in a statement.
To test this hypothesis, the team constructed several gravitational theories, which do not require exotic anti-de-sitter spaces, but live in a flat space.
"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," Grumiller explained.
For example, when quantum particles are entangled, they cannot be described individually. They form a single quantum object, even if they are located far apart. The measure of the amount of entanglement in a quantum system is known as the "entropy of entanglement." Grumiller and his fellow researchers found that the entropy of entanglement has the same value in flat quantum gravity as it does in a low quantum field theory.
"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," said researcher Max Riegler (TU Wien).
"The fact that we can even talk about quantum information and entropy of entanglement in a theory of gravity is astounding in itself," Grumiller added, "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."
It should also be noted that these findings alone don't prove that we are definitely living in a hologram. But it does add some new compelling evidence of such and could serve as a step towards validating the correspondence principle in our own Universe.
