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The Question
(Submitted November 07, 2007)
According to WMAP results, galaxies were seeded in the very early universe.
Is there no problem in explaining how these seeds could survive the universal
maelstrom before matter became atomic?
The Answer
The most likely seeds of galaxies are density fluctuations, which are a
fundamental property of the quantum mechanics that we believe, at least
to a good approximation, describe the Universe. The early Universe
was hot enough to ionize atoms, but not hot enough to get rid of these
fluctuations.
The bigger problem is actually how to make these fluctuations grow
large enough and fast enough to explain the large scale structure that
we see today. Most theories use the idea of mergers to grow things
quickly - the idea is that relatively small regions of matter
self-gravitate into clumps, and then these clumps aggregate into bigger
clumps, and so on.
Jay and Jeff
for Ask an Astrophysicist
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