Spacetime pixels probably smaller than predicted

Paul Raven @ 06-07-2011

Just because I get a deep kick of joy from being able to type out a post title like that and have it actually mean something. From Wired UK, reassurance that we’re (probably) not living in a holographic universe:

Hogan’s interpretation of results from the GEO600 gravitational wave experiment had shown a quantum fuzziness — a sort of pixellation — at incredibly small scales, suggesting that what was perceive as the universe might be projected from a two-dimensional shell at its edge.

However, a European satellite that should be able to measure these small scales hasn’t found any quantum fuzziness at all, contradicting the interpretation of the GEO600 results and indicating that the pixellation of spacetime, if it exists, is considerably smaller than predicted.

Well, I’ll be sleeping more soundly tonight.

 


Is the universe a hologram?

Paul Raven @ 25-10-2010

Wrap your head around this on a Monday morning, if you can: what we think of as the three dimensional universe we inhabit may in fact just be a holographic projection, and Craig Hogan is trying to prove it [via BigThink and Ian Sales].

The idea that spacetime may not be entirely smooth – like a digital image that becomes increasingly pixelated as you zoom in – had been previously proposed by Stephen Hawking and others. Possible evidence for this model appeared last year in the unaccountable “noise” plaguing the GEO600 experiment in Germany, which searches for gravitational waves from black holes. To Hogan, the jitteriness suggested that the experiment had stumbled upon the lower limit of the spacetime pixels’ resolution.

Black hole physics, in which space and time become compressed, provides a basis for math showing that the third dimension may not exist at all. In this two-dimensional cartoon of a universe, what we perceive as a third dimension would actually be a projection of time intertwined with depth. If this is true, the illusion can only be maintained until equipment becomes sensitive enough to find its limits.

“You can’t perceive it because nothing ever travels faster than light,” says Hogan. “This holographic view is how the universe would look if you sat on a photon.”

Coming soon to a Greg Egan short story collection near you…

I just never get tired of these existential cosmology ideas. As I’ve said before, this is the sort of stuff that makes me wish I’d actually paid attention at university and gone on to study hardcore physics… though given how much I sucked at calculus, it’s probably best that I didn’t.