Freezeout And Annihilation

As particles and antiparticles collided, the material created in the Big Bang was nearly all converted back to energy, leaving a tiny excess of matter behind. The energy release sustained the universe's temperature for a while, but eventually even light particles could not be spontaneously created, and the content of the universe was fixed.

origins the early universe

After the first microsecond, falling temperatures meant that particles were no longer moving so rapidly and could bond together. The first to do so were the quarks—heavy particles that make up the protons and neutrons in the heart of all today's atoms. A small proportion of these then bonded to form the atomic nuclei of light elements. Photons bounced back and forth between particles of matter, preventing them from coalescing, and the cosmos was foggy rather than transparent. Dark matter, unaffected by the photons, began to form structure. Finally, after 300,000 years, nuclei and electrons combined into atoms. The number of particles dropped rapidly, and the universe's fog cleared.


60 billion miles (100 billion km)

600 billion miles (1,000 billion km)

10 light-years (1 light-year =


18 trillion °F (10113K /10 trillion °C)

1,800 billion °F (1012 K / 1,000 billion °C)

18 billion °F (1010K / 10 billion °C)

10-6 seconds

1 millisecond (10--3 seconds / 1 thousandth of a second)

1 second

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