Faculty of Science and Technology

Dr Richard Hayley

Low-temperature physicists at Lancaster University may have found a laboratory test of the 'untestable' string theory.

The test - which uses two distinct phases of liquid helium - is reported online this week in Nature Physics (published 23 December). Their paper will also be published as the cover article in the paper edition of Nature Physics in January.

String theory is a multidimensional theory based on vibrating strings, as opposed to the point particles described in the Standard Model.

Within string theory, a brane is a large surface embedded in higher dimensional space — our Universe could occupy such a brane.

A collision between a brane and an antibrane can leave behind topological defects, including perhaps the Big Bang itself. But however elegant this theory, it makes no falsifiable predictions, or at least none using current technology.

Richard Haley and the ULT Group have taken a lateral step to address this barrier. They cool the helium-3 isotope to a superfluid state — that is, a quantum fluid with non-classical properties such as completely frictionless flow. Adding a magnetic field creates a second superfluid phase, and the interface between these two phases behaves like a two-dimensional brane.

Fri 21 December 2007

Associated Links

• Lancaster Ultra Low Temperature Physics - part of Lancaster university's Physics Department