Compressibility of a quantum Hall system at $\nu = 1/2$
  Despite the fact that composite fermions may be regarded as electrically neutral objects at Landua-level filling factor $\nu=1/2$, carrying only an electric dipole moment, we argue that the long-wavelength compressibility of the system is finite. 
B.I. Halperin (Harvard) and Ady Stern (Weizmann)