We investigate a new mechanism for the cosmological QCD phase transition: inhomogeneous nucleation. The primordial temperature fluctuations, measured to be $��T/T \sim 10^{-5}$, are larger than the tiny temperature interval, in which bubbles would form in the standard picture of homogeneous nucleation. Thus the bubbles nucleate at cold spots. We find the typical distance between bubble centers to be a few meters. This exceeds the estimates from homogeneous nucleation by two orders of magnitude. The resulting baryon inhomogeneities may affect primordial nucleosynthesis.

Version to appear in Phys. Rev. Lett., 4 pages, 1 figure. Difference to heterogeneous nucleation emphasized, amplitude of temperature fluctuations analyzed in more detail, new length scale l_heat introduced, more complicated geometry of baryon number discussed shortly (relevant for low values of l_heat)