If we could see 13.7 Billion lyears away?

  • Context: Undergrad 
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Discussion Overview

The discussion revolves around the concept of observing distant astronomical objects and the implications for understanding the early universe, particularly in relation to the Big Bang. Participants explore theoretical limits of observation in cosmology, the nature of cosmic background radiation, and the potential of different observational technologies.

Discussion Character

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

Main Points Raised

  • One participant questions whether observing something 13 billion light years away would allow us to see the Big Bang, suggesting this is an interesting thought experiment.
  • Another participant clarifies that while looking at distant objects means looking back in time, the universe was opaque to electromagnetic radiation for the first 380,000 years, limiting observations to that time frame.
  • A different participant states that we cannot see the Big Bang itself but can observe the state of the universe approximately 380,000 years after the event, referencing cosmic background radiation.
  • One participant mentions the potential of using a neutrino telescope to observe events closer to the Big Bang, though notes the practical challenges involved in achieving useful resolution.
  • A question is raised about whether it is possible to see further than the age of the universe in any part of the electromagnetic spectrum, and whether the expansion of the universe plays a role in this.
  • Another participant discusses the terminology surrounding the Big Bang, explaining its dual meaning in cosmology and the observations related to it.

Areas of Agreement / Disagreement

Participants generally agree that there are limitations to observing the Big Bang directly due to the universe's early opacity, but there are differing views on the implications of these limitations and the potential of different observational methods.

Contextual Notes

There are unresolved questions regarding the definitions and implications of the Big Bang, as well as the technical feasibility of observing events close to it with current or theoretical technologies.

RCulling
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The age of the universe is approx 13billion years right?
(if not, sub the correct value for everytime i say 13billion)


I was wondering.. if we could, in theory, see something 13billion light years away
we would see it how it was that long ago right?
So would we not see the big bang?

This may well be impossible, just an interesting thought.. i thought..
If we could see something that far away, would we see the big bang?

I posted this on here in hope of a more educated answer?

Thanks
 
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You're right that when we look at very distant objects we look very far back in time. However early on the universe was opaque to electromagnetic radiation and it took approximately 380,000 years for the universe to become transparent to electromagnetic radiation. That means we can't look further back than 380,000 years after the big bang. Not by detecting photons anyway.
 
If we could see something that far away, would we see the big bang?
Yes, it looks like http://en.wikipedia.org/wiki/File:WMAP_2010.png" .
For a disclaimer (actually, we can't see exactly the big bang, but the state of the universe 380000 years later), see https://www.physicsforums.com/showthread.php?t=401866".
 
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Ah so this IS the cosmic background radiation i hear about in lectures :)
Thank you very much guys!
 
With a neutrino telescope, we could theoretically see back almost to the main event. Unfortunately, such a telescope would require an aperature of many light years to achieve useful resolution.
 
Can we see further than -age of the universe- light years away?
(in any part of the electromagnetic spectrum?)
Does the exapansion of the universe enable this?
 
I think it would be helpful to have a better understanding of the terminology used for "Big Bang" since the OP RCulling asked, "So would we not see the big bang?" Briefly, here are the observations that have been made.:biggrin:

In physical cosmology, the term Big Bang has two related meanings. It is a cosmological model in which the universe has been expanding for around 13.7 billion years (13.7 Ga), starting from a tremendously dense and hot state. The term is also used in a narrower sense to describe the fundamental 'fireball' that erupted at or close to time t=0 in the history of the universe.
http://observing.eu/big_bang_en.html
 
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