In Maldacena paper he writes:
We start with type IIB string theory with string coupling g, which will remain fixed. Consider N parallel D3 branes separated by some distances which we denote by r.
Obviously when r=0 the branes are on 'top of each other'.
However what mechanism keeps branes parallel at exactly of a distance r? At the planck level one expects quantum effects to set in and such a position can't be, as far as I understand it, maintained given Heisenbergs uncertainty principle (the positions of the branes are precisely determined and the velocities of the branes are precisely all the same)
Is the situation, for example, being considered before quantisation?