the first galaxies

Time Line of the Universe

This diagram shows a short timeline of the universe. At very early times (< 10-32 seconds), it is thought that the universe had this very rapid inflationary phase, where quantum fluctuations were blown up to macroscopic scales. After this brief period of exponential growth, the universe then transitioned into a more gradual phase of expansion and cooling. At a time of 400,000 years after the Big Bang, protons first recombined with the available electrons in an event known as recombination, leaving photons to wander the universe freely. The universe then entered a dark age for a period of several hundred million years, until the first stars and galaxies formed. Subsequent to this time, galaxies have been merging and coalescing to become larger and more mature systems.

Credit:NASA/WMAP Science Team

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