A Hologram?

Ok before I get labelled a nutter (what do you mean too late!) I had better explain this bold question. For the past 7 years German Scientists have been conducting an experiment (called the GEO600) to look for gravitational waves - ripples in space-time thrown off by super-dense astronomical objects such as neutron stars and black holes. These have been predicted since 1916 by Albert Einstein but so far never directly observed.

To accomplish this they have built a 600 meter long detector in Hanover. They have yet to find any evidence of Gravitational waves but they might inadvertently have made the most important discovery in physics for half a century.

The Discovery

For quite a few months the german scientists have been scratching their heads over inexplicable noise that is plaguing their giant detector. Then, a physicist at the Fermilab particle physics laboratory in Batavia apprached them out of the blue with a possible, and highly plausible explanation. Not only that, but he even predicted the noise before he knew it was being detected at GEO600.

Craig Hogan, the physicist in question thinks that GEO600 has stumbled upon the fundamental limit of space-time - the point where space-time stops behaving like the smooth continuum Einstein described and instead dissolves into "grains", just as a newspaper photograph dissolves into dots as you zoom in.

"It looks like GEO600 is being buffeted by the microscopic quantum convulsions of space-time," says Hogan.

The Cosmic Hologram

Even more astounding though is the fact that If the GEO600 result is what Craig suspects it is, then we are all living in a giant cosmic hologram!.

Ok so this may sound totally crazy but it is very a natural extension of our best understanding scientists have of black holes, and something that has a pretty firm theoretical footing. It has also been surprisingly helpful for physicists wrestling with theories of how the universe works at its most fundamental level.

The Theory

So how does this work then?, well imagine a hologram like you see in everyday life, on money or credit cards for example. These holograms are 2 dimensional stickers that are produced in such a way that when light bounces off them they create the appearance of a 3 dimensional image. Way back in the 1990's it was suggested by physicists Leonard Susskind and Nobel prizewinner Gerard 't Hooft that the same principal might apply to our universe, everything could be a holographic projection of proccesses that take place on a distant, 2D surface. The more we may think about this the more astounding and unbelievable it sounds, but many theorists have good reasons to believe that many aspects of the holographic principle are true.

The ground breaking work into Black Hole theory by Stephen Hawking and Jacob Bekenstein have been the founding ideas behind Susskind and 't Hooft's theory.

Way back in the 1970's Stephen Hawking showed that black holes are in fact not entirely "black" but instead slowly emit radiation, which causes them to evaporate and eventually disappear. This poses a puzzle, because Hawking radiation does not convey any information about the interior of a black hole. When the black hole has gone, all the information about the star that collapsed to form the black hole has vanished, which contradicts the widely affirmed principle that information cannot be destroyed. This is known as the black hole information paradox.

The Work done by Jacob Bekenstein has helped to solve this paradox by suggesting that a black hole's entropy - which is synonymous with its information content - is proportional to the surface area of its event horizon. This is the theoretical surface that cloaks the black hole and marks the point of no return for infalling matter or light. Since this time theorists have shown that microscopic quantum ripples at the event horizon can encode the information inside the black hole, so there is no mysterious information loss as the black hole evaporates.

More Evidence

This provides a deep insight and strong evidence into the Hologram theory as it shows that all the 3D information about a precursor star can be contained in a 2D horizon of the subsequent Black Hole, in a similair way Holograms are made.

This insight is extended even further by Susskind and 't Hooft on the basis that the universe as a whole has a horizon too - the boundary from beyond which light has not had time to reach us in the 13.7-billion-year lifespan of the universe.

When you then take into account the work done by several leading String theorists, studies have shown that the physics inside a hypothetical universe with five dimensions and shaped like a Pringle is the same as the physics taking place on the four-dimensional boundary.

Back to these Cosmic Grains

Ok so at the beginning I described that the fundemental limit of space time where things start to get fuzzy, this is essentially the smallest unit of space-time where it becomes grainy and is made of tiny units rather like pixels, or grains of sand. These units are smaller than you could possibly imagine 10-35 metres and are known as the Planck length. Being so small has meant that no experiment or detector could possibly begin to record a Planck but if the Hologram theory is true, it means that a Planck is actually much bigger than anyone thought.

If space-time is a grainy hologram, then you can think of the universe as a sphere whose outer surface is papered in Planck length-sized squares, each containing one bit of information. The holographic principle says that the amount of information papering the outside must match the number of bits contained inside the volume of the universe.

Since the volume of the spherical universe is much bigger than its outer surface, how could this be true? Hogan realised that in order to have the same number of bits inside the universe as on the boundary, the world inside must be made up of grains bigger than the Planck length. So inside the Hologram this Planck would be much bigger, say 10-16 meters. Living inside this hologram would also allow you to measure this Planck blurring.

But What will it all mean?

So what does this all mean then?, well if true this could radically change the way we think about space-time, and using the GEO600 detector, they may be able to prove that this interference is in fact Holographic "noise" and if this turns out to be the case then we may have our first indication of how space-time emerges out of quantum theory. As discoveries go, it's hard to get more ground-breaking than that.