For decades the key goal of fundamental physics has been to unify the theory that works so well on the universe’s largest scales – Einstein’s theory of general relativity – with the theory of the subatomic world – quantum mechanics.
The BICEP2 results do not point the way to what that unified theory might be, but they provide evidence for the fact that general relativity and quantum mechanics can be made compatible.
In recent years physicists have taken a few encouraging steps toward a potential theory of quantum gravity. While Bern does not suggest that supergravity is the ultimate theory, he hopes that it may at least provide the skeleton for a more complete theory. If this double-copy-of-gluons relationship holds in general, this clue could potentially lead to a dramatic breakthrough in the search for a quantum theory of gravity. The important point is that physicists already have at their disposal a fairly successful theory – quantum chromodynamics.
One piece of the puzzle that, at the moment, appears difficult to crack is how to deal with black holes – those singularities in classical general relativity that manifestly represent a breakdown of the theory on the quantum scales.