The theory of the Hologram

The theory of the Hologram was launched  in 1997 by physicist Juan Maldacena who was able to prove its existence in equations that only partially explain our universe. It expression was  " We are living in a giant hologram, and everything we see around us is merely a projection of a two-dimensional surface" .

Now researchers in Austria have, for the first time, been able to show how this strange holographic principle can also work in a more realistic model of our cosmos.

The holographic principle suggests that, like the security chip on your credit card, there is a two-dimensional surface that we can't see.This surface contains all the information needed to describe a three-dimensional object - which in this case is our universe.In essence, the principle claims that data containing a description of 3D object – such as the device you're reading this on - could be hidden in a region of this flattened, 'real' version of the universe . Maldacena came to this conclusion when he discovered that mathematical descriptions of the universe actually require one fewer dimension than it seems.But up until now, this principle has only been studied in something known as 'curved anti-de-sitter spaces' – or exotic spaces with negative curvature.

Scientists came up with these spaces as way to combine describing gravity in a three-dimensional setting while predicting quantum particles in two spatial dimensions.

Anti-de-sitter spaces are negatively curved, and any object thrown away on a straight line will eventually return.

The problem is they are very different from the spaces in our own universe. 

Our universe is largely flat, and on astronomic distances, it has positive curvature.

The latest study by scientists at the Technology University of Vienna now suggests that the holographic principle holds in a flat space-time.

'Juan Maldacena proposed the idea that there is a correspondence between gravitational theories in curved anti-de-sitter spaces on the one hand and quantum field theories in spaces with one fewer dimension on the other'.

THE HOLOGRAPHIC PRINCIPLE

The holographic principle claims gravity in the universe comes from thin, vibrating strings.These strings are holograms of events that take place in a simpler, flatter cosmos.The principle suggests that, like the security chip on your credit card, there is a two-dimensional surface that contains all the information needed to describe a three-dimensional object - which in this case is our universe.The theory claims that data containing a description of a volume of space - such as a human or a comet - could be hidden in a region of this flattened, 'real' version of the universe.In a black hole, for instance, all the objects that ever fall into it would be entirely contained in surface fluctuations, almost like a piece of computer memory on contained in a chip.In a larger sense,

the theory suggests that the entire universe can be seen as a 'two-dimensional structure projected onto a cosmological horizon' - or in simpler terms, a projection.If we could understand the laws that govern physics on that distant surface, the principle suggests we would grasp all there is to know about reality.To test the theory, scientists spent three years creating gravitational equations that do not require exotic spaces and, instead, 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', says Grumiller from the Technology University of Vienna.They said one key feature of quantum mechanics –quantum entanglement – had to appear in the more realistic model of our universe.When quantum particles are entangled, they cannot be described individually.They form a single quantum object, even if they are located far apart.There is a measure for the amount of entanglement in a quantum system, called 'entropy of entanglement'.The team showed that this entanglement takes the same value in both a flat quantum gravity model and in a low dimension quantum field theory.'This calculation affirms our assumption that the holographic principle can also be realised in flat spaces,' said Max Riegler at the Technology University of Vienna.'It is evidence for the validity of this correspondence in our universe', says 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, and would hardly have been imaginable only a few years back,' added Grumiller.'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.'