Why is the CMB relatively uniform?

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Discussion Overview

The discussion centers around the uniformity of the Cosmic Microwave Background (CMB) radiation and the implications of the Big Bang theory. Participants explore concepts related to cosmology, including inflation, the nature of the Big Bang, and common misconceptions about its singularity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why the CMB is uniform across the sky, suggesting that if the Big Bang originated from a point, one side should have higher readings due to proximity.
  • Another participant emphasizes the importance of the question and introduces the idea of an inflationary period shortly after the Big Bang, which may explain the uniform distribution of the CMB.
  • There is a discussion about the nature of the Big Bang, with a participant noting that it occurred everywhere simultaneously rather than from a single point.
  • A participant raises a concern about whether the rapid expansion during inflation would require objects to move faster than the speed of light.
  • Another participant clarifies that there is no cosmic speed limit on the expansion of the universe, only on how fast objects can move through space.
  • A later reply challenges the common misconception that the Big Bang was a singular point, explaining that the term "singularity" refers to a breakdown in the mathematical model rather than a physical point in space.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the Big Bang and the nature of its singularity. While some agree on the concept of inflation, there is no consensus on the interpretations of the singularity or the implications of expansion speed.

Contextual Notes

There are limitations in the discussion regarding the definitions of key terms like "singularity" and the assumptions underlying the inflationary model. Some mathematical aspects remain unresolved, and the scope of the discussion does not cover all aspects of cosmological theories.

hewiiitt-
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This might be a stupid question due to a simplistic under standing of the Big Bang. But why is the CMB uniform across the sky. Why is it not sognificantly higher on one side from the other. Surely if the Big Bang was a point then everything would eminate from that point resulting in one side that was closer having higher reading. Thanks for any answers. Sorry if it is a stupid question.
 
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It's not just a good question, but an exceedingly important one in cosmology.

One popular notion is that very shortly after the birth of the universe, it entered an inflationary period of unimaginably rapid expansion so that by the time gravity could have a significant effect, things were already spread out pretty uniformly.

As far as where the big bang happened, it kind of happened everywhere. Space itself just got really big really quickly.
 
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jfizzix said:
It's not just a good question, but an exceedingly important one in cosmology.

One popular notion is that very shortly after the birth of the universe, it entered an inflationary period of unimaginably rapid expansion so that by the time gravity could have a significant effect, things were already spread out pretty uniformly.

As far as where the big bang happened, it kind of happened everywhere. Space itself just got really big really quickly.

Thanks for the quick response
 
jfizzix said:
It's not just a good question, but an exceedingly important one in cosmology.

One popular notion is that very shortly after the birth of the universe, it entered an inflationary period of unimaginably rapid expansion so that by the time gravity could have a significant effect, things were already spread out pretty uniformly.

As far as where the big bang happened, it kind of happened everywhere. Space itself just got really big really quickly.

Just thinking though for this to out run gravity wouldn't things have had to move faster than the speed of light.
 
Yes, but there's no cosmic speed limit for the expansion of the universe. The only speed limit is on how fast things can move through space.
 
hewiiitt- said:
Surely if the Big Bang was a point ...
This is by far the most common misconception is the early study of cosmology and is promulgated by pop-science making exactly that false statement. The "big bang singularity" was NOT a point. It happened everywhere at once. The "big bang theory" doesn't even include the singularity but instead is a discussion of what happened from about one Plank Time after the singularity to today. Contrary to the totally incorrect statements you see everywhere in pop-science, "singularity" does not mean "point" it means "the place where our math model breaks down and gives nonphysical results and we don't know WHAT is/was going on"
 

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