The Hierarchy problem

It might seem strange, but gravity is a lot weaker than the other basic forces of nature. Let's take a look at this chart. It shows how the strength of each fundamental force changes when the energy increases, or the distance over which the force operates decreases. We've only been able to study these forces at relatively low energies, but we can guess what might happen at higher energies. And when we do, we find a point where the electromagnetic, weak and strong forces all become equally powerful. We call this unification. However, gravity seems to be late to this party. Its path to unification appears to be much further out. This is where the elusive theory of everything comes into play. But what if some of the gravitational force escaped into, for example, a fourth spatial dimension? In that case, its strength could reduce more quickly, and it might reach unification with the other three forces earlier. Advanced experiments like LIGO are on the lookout for this phenomenon, but as of now, they haven't detected any signs of it.