SOMETIMES, perceiving something as real doesn’t cut it. With the shimmering image of a hologram, the illusion is clear enough. That 3D representation is a trick of the light, a projection of information encoded in just two dimensions. But it would be a bit of a shocker if we found out that the entire universe were made that way.
We’re not close to proving that, still less working out the implications. But a groundswell of work in theoretical physics suggests it’s a
distinct possibility.
The story really begins in the 1990s. Physicists were struggling to tame the intractable mathematics of string theory – our best stab at forcing gravity to play nicely with the other three forces of nature –
when they discovered a cunning trick. Under certain circumstances, by subtracting one from the number of dimensions in the universe you were dealing with – in other words, treating it like a hologram – gravity could be made to disappear.
The best-researched instance of this “holographic principle”, known as the AdS/CFT correspondence, only works in a complex 5D space-time bent back on itself rather like the surface of a Pringle.
The trick has proved surprisingly useful, not just in string theory but also to elucidate the workings of practical things
like superconductors, and explain such stubborn problems as why particles have mass.