Can anyone make sense of this question.

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Discussion Overview

The discussion revolves around the timing of the emission of Cosmic Microwave Background (CMB) radiation and its implications for understanding the early universe. Participants explore the nature of CMB radiation, its historical context, and its relevance to cosmological theories.

Discussion Character

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

Main Points Raised

  • One participant expresses confusion about the question regarding the timing of emitted CMB radiation, suggesting that CMB radiation is emitted continuously from the remnants of the Big Bang.
  • Another participant clarifies that CMB radiation was emitted during a specific interval early in the universe's evolution, emphasizing the importance of this understanding for grasping Big Bang theory.
  • There is a suggestion that the answer to the timing question might be the current age of the universe, which is challenged by another participant.
  • A later reply introduces the concept of the "surface of last scattering" as a more accurate reference point for understanding when the CMB was emitted.
  • One participant states that the CMB was emitted when the universe was approximately 300,000 years old, noting the transition from opaque plasma to transparent gas.
  • Another participant questions the existence of a "previous universe," suggesting that even if it existed, knowledge of "all the things in the universe" would not be possible.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the initial question regarding the timing of CMB emission, with multiple viewpoints and clarifications presented. The discussion reflects uncertainty and varying interpretations of the CMB's nature and implications.

Contextual Notes

Participants reference concepts such as the "surface of last scattering" and the transition from opaque to transparent states of the universe, indicating that there may be underlying assumptions or definitions that are not fully explored in the discussion.

xdrgnh
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At what time was emitted CMB radiation which is detected at our time

Can anyone makes sense of this question. Isn't CMB radiation emitted all of the time from the left over the big bang. I'm not asking for a answer I just don't understand this question or don't understand something about CMB. I would post this on the homework help but no one there seems to know anything about cosmology.
 
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xdrgnh said:
Isn't CMB radiation emitted all of the time from the left over the big bang.
No. The CMB radiation was emitted during a rather short interval of time that occurred fairly early on in the evolution of the universe.

I'm being a bit oblique and incomplete with my answer because this is homework. Understanding this is critical to understanding this big bang theory.
 
Alright that clears things up enough.
 
If it's to much would the answer then just be the current age of the universe.
 
No, that is not correct.
 
xdrgnh said:
If it's to much would the answer then just be the current age of the universe.

Not quite. Look up "surface of last scattering"
 
K got it thanks guys.
 
xdrgnh said:
At what time was emitted CMB radiation which is detected at our time
The CMB was emitted when our universe was about 300,000 years old*. That's about the time when it transitioned from an opaque plasma to a transparent gas.

Regardless of the time we're looking, we see light that was emitted during that single event that happened everywhere. The light we see currently was emitted from matter that was, at the time, about 42 million light years away. In the future, we will see light from that same event that was emitted further away, and thus has taken longer to reach us.

* Bear in mind that this event did not happen instantly: it took a good amount of time for the universe to go from completely opaque to completely transparent. This has the effect of making our image of the CMB a bit blurry.
 
sir if previous universe has same law as us than can we know all the thigs in the universe?
 
  • #10
danger9 said:
sir if previous universe has same law as us than can we know all the thigs in the universe?

As far as we know, there WAS no "previous universe" so your question is pointless, but even if there were, no we would not be able to know "all the things in the universe".

By the way, you should not hijack a thread. If you have a question that is not related to the thread, start a NEW thread with your question.
 

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