book-summaries/universe-from-nothing/ch3_light-from-the-beginnin...

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.SECTION Light from the beginning of time
.PARAGRAPH_INDENTED
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.METAINFO1
This chapter introduces a more reliable way to determine the geometry of the universe, thanks to the cosmic microwave background radiations.
.METAINFO2
Trying to measure the universe weight by gravitational lensing galaxies and clusters is fundamentally flawed.
This could only provide a rough approximation in case the weight actually came from somewhere within clusters.
In case the weight of the universe comes from between clusters, then our method doesn't work.
Another involves observing cosmic microwave background radiations (CRBR) and actually measure see the curvature of the universe.
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.SECTION_NO_NUMBER Measuring the geometry of the universe
.PARAGRAPH_INDENTED
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Before trying to explain how to measure the curvature of the universe, let's try to answer a simpler question.
.QUESTION "How to measure the curvature of a world in two dimensions?"
.TBD
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.SECTION_NO_NUMBER Cosmic Microwave Background Radiations
.PARAGRAPH_INDENTED
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Somewhere around 300 000 years after the Big Bang, the universe became cold enough to emit radiations.
.TBD
.EXPLANATION1
Gravity is propagated at the speed of light.
.EXPLANATION2