Are we, and everything around us, all projections of the cosmological horizon?

The January 15 New Scientist (I swear I’m not affiliated with them) featured a cover article titled, “Our world may be a giant hologram.” Those of you who are card-carrying nerds like Leila and me might have known about the string-theoretical concept of the insanely multi-dimensional universe for some time. While the universe might actually contain up to 26 dimensions, these extra dimensions beyond the 3 space dimensions and 1 time dimension are compacted under normal conditions, so we’re left with the 3 + 1  dimensions we know and love.

The holographic principle, however, proposes that the three space dimensions in the universe we’re used to actually exist as projections from the two-dimensional horizon of the ever-expanding universe. This is analagous to the idea that the entropy of a black hole (i.e. its information content) is proportional not to its three-dimensional volume, but its two-dimensional surface area. There’s a great, mind-blowing lecture by Raphael Bousso of UC Berkeley explaining this:

What the New Scientist article is suggesting, though, is that there might be experimental evidence that the universe we live in is actually a hologram, in effect. If I understand things correctly, and that’s a big if, according to quantum theory for a non-holographic 3-d universe, things shouldn’t get grainy until you approach the Planck length, which is about 10^-35 m. (A proton is about 100 000 000 000 000 000 000 Planck lengths in diameter, so it’s a pretty small unit.) However, if our world is holographic, things’ll get grainy at around 10^-16 m. There’s actually an instrument, the GEO 600,  which is designed to measure differences in distance down to 10^-21 m. (It was built to try to directly detect gravitational waves, which is a whole other headfuck.)  The scientists operating it, however, have had problems with noise (which might be because the gravitational force of a passing cloud overhead messed things up). According to Craig Hogan, though, this noise might very well be due to the graininess caused by the projectedness of the world we see. If we weren’t projected, the noise wouldn’t be there. Cool, eh?

~ by Mia Chen on January 30, 2009.