After a century of relativity, a new view of gravity
ONE of the defining anniversaries in 2015 will be the centenary of general relativity. In 1915, Einstein published a set of equations that changed our understanding of the universe. Out went the Newtonian notion of gravity as a force between massive objects; in came the counter-intuitive idea that gravity is a property of the universe, with massive objects curving space-time.
A century on, gravity continues to challenge us. The equations predict that cataclysmic cosmic events should send ripples through space-time, but we have yet to observe any. This year will see two projects aimed at sorting this out: the resumption of a gravitational-wave experiment called LIGOMovie Camera and the launch of a spacecraft called LISA Pathfinder that will test technology for catching the waves in space.
We may even see progress on the biggest unresolved issue of all – the incompatibility of relativity and quantum theory. At the atomic scale, gravity is so weak we routinely ignore it. Now it seems we are wrong to do so. Gravity might play a crucial role in the quantum world. It might be the secret ingredient of reality. We won't get full answers this year, but relativity's greatest remaining puzzle looks to be on its way to being solved, at last.
A century of relativity
Perhaps gravity is electromagnetic? Perhaps it is an Electric Universe? Give it another 100 years and they might still be celebrating Albert Einstein's genius and the awesomeness of the General theory of relativity, while still waiting for the evidence to be found.