Scientists are said to be closing in on detecting 'waves' in inter-stellar gravity.
Predicted by Einstein as a consquence of his general theory of relativity, gravitational waves are suspected to be a form of curvature in the fabric of reality.
The theory of relativity describes gravity as the visible result of curvatures in space-time which are caused by mass.
Heavy objects cause space time to 'bend', and attract other objects towards them. This is often explained with the metaphor of a heavy ball on a sheet of rubber, bending the surface towards the source of the weight.
Even light has been shown to 'bend' as it passes along the curves created by very heavy objects in space - a key proof of Einstein's theory.
But Einstein also theorised that objects would be able to generate short-term changes in space time in the form of waves, expelled from a source of intense mass or energy. These waves would essentially be 'ripples' in the curvature of space time, and experienced as distortions in space-time by an observer.
It is thought that very dense objects like neutron stars or black holes orbiting in pairs - so called binary systems - might create gravitational waves that could be detected by very delicate instruments on Earth.
In August 2012 it was reported that the waves' existence had been given weight after a small change in the orbits of two white dwarf stars was detected some 3,000 light years from our Solar System.
Two experiments designed to do exactly that are due to start in just a few years, raising hopes that gravitational waves might finally be detected.
They include the Advanced LIGO (Laser Interferometer Gravitational Wave Observatory) and Advanced Virgo experiments, which will come online in 2017.
Space.com has an interesting and readable description of how these experiments work - essentially stretching lasers in thin, kilometer-long beams and waiting for ripples in the light to be detected.
So while we're not there yet, it might not be too long until Einstein is proven right yet again.