Fractional Quantum Hall Layer As A Magical Electromagnetic Medium
  At a surface between electromagnetic media the Maxwell equations are consistent with either the usual boundary conditions, or exactly one alternative: continuity of E(perpendicular), H(perpendicular), D(parallel), B(parallel). These alternative, classically inexplicable conditions applied to the top and bottom surfaces of an FQH layer capture exactly its unique low-frequency properties. 
Alfred Scharff Goldhaber