On the vorticity of the Universe
  Recent analyses of the first-year WMAP data claim large-scale asymmetry and anisotropy of the CMBR fluctuations. We argue that the covariant and gauge invariant treatment of density fluctuations formulated by Ellis and Bruni can explain the asymmetric and anisotropic WMAP data by including the vorticity of the Universe. It appears that the spatial gradients of the density contrast are proportional to the vorticity of the Universe, thus allowing measurements and quantifications of the magnitude and axis of the possible cosmological rotation. 
D. Palle (Rugjer Boskovic Institute, Zagreb, Croatia)