Are You Real, Or Are You a Hologram?

The principle of a holographic universe, not to be confused with the Holographic Universe, an album by swedish death metal rock band Scar Symmetry, continues to hold serious sway among a not insignificant group of even more serious cosmologists.

Originally proposed by noted physicists Gerard ‘t Hooft, and Leonard Susskind in the mid-1990s, the holographic theory of the universe suggests that our entire universe can described as a informational 3-D projection painted in two dimensions on a cosmological boundary. This is analogous to the flat hologram printed on a credit card creating the illusion of a 3-D object.

While current mathematical theory and experimental verification is lagging, the theory has garnered much interest and forward momentum — so this area warrants a brief status check, courtesy of the New Scientist.

[div class=attrib]From the New Scientist:[end-div]

TAKE a look around you. The walls, the chair you’re sitting in, your own body – they all seem real and solid. Yet there is a possibility that everything we see in the universe – including you and me – may be nothing more than a hologram.

It sounds preposterous, yet there is already some evidence that it may be true, and we could know for sure within a couple of years. If it does turn out to be the case, it would turn our common-sense conception of reality inside out.

The idea has a long history, stemming from an apparent paradox posed by Stephen Hawking’s work in the 1970s. He discovered that black holes slowly radiate their mass away. This Hawking radiation appears to carry no information, however, raising the question of what happens to the information that described the original star once the black hole evaporates. It is a cornerstone of physics that information cannot be destroyed.

In 1972 Jacob Bekenstein at the Hebrew University of Jerusalem, Israel, showed that the information content of a black hole is proportional to the two-dimensional surface area of its event horizon – the point-of-no-return for in-falling light or matter. Later, string theorists managed to show how the original star’s information could be encoded in tiny lumps and bumps on the event horizon, which would then imprint it on the Hawking radiation departing the black hole.

This solved the paradox, but theoretical physicists Leonard Susskind and Gerard ‘t Hooft decided to take the idea a step further: if a three-dimensional star could be encoded on a black hole’s 2D event horizon, maybe the same could be true of the whole universe. The universe does, after all, have a horizon 42 billion light years away, beyond which point light would not have had time to reach us since the big bang. Susskind and ‘t Hooft suggested that this 2D “surface” may encode the entire 3D universe that we experience – much like the 3D hologram that is projected from your credit card.

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[div class=attrib]Image courtesy of Computerarts.[end-div]