Gravitons, the quantum particles of gravity, have no such limitation. Indeed, in a universe with extra dimensions, we might feel the pull of mass in those other dimensions even though they are invisible. Not long after Isaac Newton saw the apple fall in 1665, he devised the gravitational constant, G, needed to calculate the attractive force between masses at different distances. Scientists have long assumed that G is fundamental and unchanging. It has only been measured down to about a millimeter.
Nobody knows what the real force of gravity is at short distances.
In four spatial dimensions, however, gravitational force is proportional to the inverse cube of the distance. With each additional dimension, the power of the inverse law increases. These extra dimensions would have to be limited in extent, unlike the three endless dimensions we're accustomed to, or else we would have seen their effects already. Consider a performer on a high wire. To her, the wire might as well be a single dimension, along which she can travel only forward or back.