Australian researchers say they've extended Einstein's theory of special relativity to work beyond the speed of light, but caution it only works in the math.

"Our paper doesn't try and explain how this could be achieved, just how equations of motion might operate in such regimes," Jim Hill of the University of Adelaide's School of Mathematical Sciences said.

Einstein's Theory of Special Relativity, published in 1905, explains how motion and speed is always relative to the observer's frame of reference, with an absolute limit being the speed of light.

The study, published in the Proceedings of the Royal Society A, includes mathematical formulas that extend special relativity to a situation where the relative velocity can be infinite, and can be used to describe motion at speeds faster than light.

"About this time last year experiments at CERN, the European center for particle physics in Switzerland, suggested perhaps neutrinos could be accelerated just a very small amount faster than the speed of light; at this point we started to think about how to deal with the issues from both a mathematical and physical perspective," Hill said.

"Questions have since been raised over the experimental results but we were already well on our way to successfully formulating a theory of special relativity, applicable to relative velocities in excess of the speed of light."

However, Hill said, "there is no substantial evidence to suggest that this is presently feasible with any existing transportation mechanisms."