2 September 2009

13 more things: Noise from the edge of the universe

Are dud signals from a gravitational wave detector evidence that the universe is a holographic projection?

The GEO600 gravitational wave detector in Hanover, Germany, has not yet detected any gravitational waves. As a consolation prize, it may instead have uncovered the ultimate nature of reality.

In 2008, physicist Craig Hogan at the Fermi National Accelerator Laboratory in Batavia, Illinois, was trying to work out how we might test the idea that everything we see as physical reality is the result of a kind of projection from the boundary of the universe. This is known as the holographic principle.

The information held at the boundary is not smooth, but composed of “bits”, each one occupying an area that corresponds to the most fundamental quanta of distance in the universe. This is the Planck length, around 10-35 metres – far too small for us to see the individual bits. When this information is projected into the volume of the universe, however, each bit gets magnified. That means we might just be able to see pixellation in space-time.

The kinds of scales involved still mean it would only be detectable in the most sensitive instruments we have – such as the gravitational wave detectors looking for the ripples in space-time caused by violent cosmological events such as the collision of two black holes. Hogan worked out how the pixellation might manifest itself for GEO600 and sent his result to the researchers there.


By strange coincidence, the GEO600 team had been having problems with “noise” in their detectors. But here’s the kicker: the noise had uncannily similar characteristics as Hogan’s anticipated signal. Is it indeed the result of information that resides at the edge of the universe? “The issue is still unresolved,” says Karsten Danzmann, principal investigator for GEO600. “The noise is still there and we have no explanation.”

The answer may only come after the instrument is upgraded to make it even more sensitive, a step that is due to be completed this time next year.

Read more: 13 more things that don’t make sense