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This is the Cosmic Microwave Background Radiation map over the sky, redshifted by a factor of 1100 by the expansion of the universe, showing that the primordial gas (75% hydrogen, 25% helium) as it formed when the plasma cooled to 3000 K had very small applitude temperature fluctuations. These represent quantum- gravitational "turbulence" fossilized at inflation by expansion beyond the scale of causal connection ct (the horizon scale), where c is the speed of light and t is the age of the universe (10^13 seconds, or 300,000 years at this time). The horizon scale then was only 3x10^21 meters, the size of a galaxy at present, and is only 1 degree out of the 360 shown in the slide. Because the fluctuations \ delta T / T are so small at all scales, the primordial gas as it emerged from the plasma epoch could not have been turbulent. Why not? Only viscous forces or buoyancy forces or both could have prevented turbulence in the plasma epoch just before photon decoupling. The conclusion is that both were required.
astro-ph/9911264

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