NS: Cosmic bubble made cold spot in big bang afterglow

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NS: Cosmic bubble made cold spot in big bang afterglow

Post by bystander » Sat Jul 03, 2010 4:56 am

Cosmic bubble made cold spot in big bang afterglow
New Scientist | Space | 01 July 2010
A BUBBLE of space that expanded differently to the rest of the early universe could explain a strange "cold spot" in the afterglow of the big bang. Such bubbles might have formed just fractions of a second after the universe came into existence, when it grew dramatically in size.
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Much of our insight into the early universe comes from light emitted when it was just 380,000 years old, the oldest light we can still detect. In 2001, the Wilkinson Microwave Anisotropy Probe (WMAP) was launched to map this cosmic microwave background (CMB). Data collected in the probe's first year revealed something unexpected: an anomalous cold spot, which cosmologists have struggled to explain.

Perhaps the spot is a hint of another universe, or maybe just an artefact of analysis. A large void that sits between our galaxy and the CMB might also explain the cold spot, but hunts for such cosmic holes have come up dry.

Now there's another option. What if the expansion of the universe was not uniform, contrary to the prevailing theory? Bubble-shaped regions could have expanded out of sync with the rest of the universe ...

Such bubbles would have a lasting effect on the density distribution of the universe. While their centres would look the same as the rest of the universe, the density of regions near their edges would vary from the average. Afshordi's team calculate that had such a bubble wound up between the CMB and Earth, it would interact with the photons from the CMB to create the appearance of a cold spot ...
A Theory of a Spot

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