ASTRON 1F03 Lecture Notes - Lecture 27: Horizon Problem, Big Bang, String Theory
18 Dec 2015
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Document Summary
Light (or any physical interaction) has never connected a and b since the big bang. At 300,000 years old when the cosmic microwave background (cmb) was formed, light could only have travelled 300,000 light years, since the big bang. This corresponds to patches 1 degree in size on the cmb. All these patches are statistically the same. A flat universe is balanced on a knife-edge. Any deviation from flat is rapidly enhanced. The microwave background has small ripples the seeds of all structure in the universe. Given 14 billion years, gravity can grow these ripples into galaxies and clusters. Physicists believe the universe underwent a period of inflation for at least a tiny fraction of a second (10-33 seconds). In cosmology, inflation describes a time of extremely fast expansion. Small regions, originally in contact are stretched faster than the speed of light to be at either edge of the observable universe 30 billion light years apart or more.
