By Duncan Geere, Wired UK

An astrophysicist’s attempt to measure quantum “fuzziness” to find out if we’re living in a hologram has been headed off at the pass by results suggesting that we’re probably not.

In October 2010, we reported on Craig Hogan’s experiments with two of the world’s most precise clocks, which he was using to try and confirm the existence of Planck units — the smallest possible chunks of space, time, mass and other properties of the 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.

By examining the polarisation of gamma-ray bursts as they reach Earth, we should be able to detect this graininess, as the polarisation of the photons that arrive here is affected by the spacetime that they travel through. The grains should twist them, changing the direction in which they oscillate so that they arrive with the same polarisation. Also, higher energy gamma rays should be twisted more than lower ones.

However, the satellite detected no such twisting — there were no differences in the polarisation between different energies found to the accuracy limits of the data, which are 10,000 times better than any previous readings. That means that any quantum grains that exist would have to measure 10^-48 metres or smaller.

“This is a very important result in fundamental physics and will rule out some string theories and quantum loop gravity theories,” says Philippe Laurent, a physicist at France’s Atomic Energy Commission who analysed the data, in a press release.

Source: Wired UK/em>

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Image: Gamma ray burst. (ESA/SPI Team/ECF)