I've been reading in Khan academy about the formula for calculating magnetic field lines (Ampere's law). Some materials have the ability to concentrate magnetic fields, which is described by those materials having higher permeability. The permeability of vacuum is $4\pi *10^-7$ , which means it can concentrate magnetic field lines. But how can nothing—no matter, energy, or force—influence or manipulate the waves passing through it (practically through nothingness). I mean why is the permeability not 0? (This just comes out of the rigid intuition that vacuum does nothing to anything because it is nothing—ignoring the particle-antiparticle pairs or similar very distant stuff.)
As can be seen from the fuzziness of the question, I'm learning physics (not an expert) and any theoretical answer is okay but answers involving complex math like calculus or differentials are unwelcome but if it needs to be used let me be informed.