What is our perpective, where did it start, and why can we see it?

  • Context: Undergrad 
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Discussion Overview

The discussion revolves around the nature of the universe's expansion, the origins of light after the Big Bang, and the implications of these concepts on our understanding of cosmic structure and position. Participants explore theoretical aspects, address misconceptions, and clarify the timeline of cosmic events.

Discussion Character

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

Main Points Raised

  • Some participants assert that light began to escape the early universe around 400,000 years after the Big Bang, while others challenge this by stating that light existed earlier but was unable to escape due to the plasma state of the universe.
  • There is contention regarding the timeline of star formation, with some stating that the first stars formed around 9 billion years after the Big Bang, while others clarify that our galaxy formed at that time, suggesting stars formed earlier.
  • Participants discuss the concept of a center in the universe, with a consensus that there is no center and that the universe expanded uniformly in all directions.
  • Some express confusion over the implications of the universe expanding faster than the speed of light, with questions raised about how this can occur and its relation to the expansion of space itself.
  • The analogy of the universe as a bubble or skin is debated, with some rejecting the notion of an "inside" or "outside" to the universe.
  • Several participants recommend reading additional resources, such as the Balloon Analogy, to better understand the expansion of the universe and our observational limitations.

Areas of Agreement / Disagreement

Participants generally agree that the universe has no edges and did not expand from a single point. However, there are multiple competing views regarding the timeline of light and star formation, as well as the implications of the universe's expansion speed.

Contextual Notes

Some claims about the timeline of cosmic events are challenged, indicating potential confusion or miscommunication regarding the formation of stars and galaxies. The discussion also highlights the complexity of understanding cosmic expansion and the limitations of observational perspectives.

Who May Find This Useful

This discussion may be useful for individuals interested in cosmology, the Big Bang theory, and the nature of the universe's expansion, particularly those seeking clarification on common misconceptions and theoretical frameworks.

Dokshifty
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Everything had it's start in the "big bang". Then light began at around 400k years after. Then 9 bil years after that the first stars formed, and we now are at 14 bil years after the big bang. Correct? Everything moved at the same rate away from centre, but not faster than light? This means light past us even though the universe expanded before light was created? Does this mean that the first light expanded out in a uniform bubble from a single start point? Could you look at this as a 2D skin like a bubble that is expanding out that we can observe from the inside? If so were does that place us inside the bubble? Also I have heard that everything is moving away from us and everything is moving away from everything else. If this is true then how can we place our position is relation to a centre if there is one. Obviously we are not the centre the same as we are not the centre of our solar system or the centre of the milky way. If we have only a limited viewing distance from our point of view how can we know where the inside of the bubble is in all directions. Assuming we are not the centre.

Edit: I just read that the Universe is expanding faster than the speed of light. Is this true? If so how is this possible? If it is true then this does answer some of my questions, but also raises many more.

If this has been discussed before link threads. I am very new to this subject. I am sorry
 
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Dokshifty said:
Everything had it's start in the "big bang". Then light began at around 400k years after.

No, light started earlier than that, but it could not escape the plasma of the early universe. At 400K years, THEN it could escape.

Then 9 bil years after that the first stars formed, and we now are at 14 bil years after the big bang. Correct?
Stars formed earlier than 9B years. OUR galaxy of stars formed at about 9B years.

Everything moved at the same rate away from centre, but not faster than light?
There IS no center. Never has been. During inflation, stuff moved away from each other MUCH faster than the speed of light but that is NOT that they were moving that fast relative to each other IN space but rather that space itself was expanding. You should read about inflation.

This means light past us even though the universe expanded before light was created?
Don't have any idea what you mean here.

Does this mean that the first light expanded out in a uniform bubble from a single start point?
NO. There IS no center. No "starting POINT". The expansion happened everywhere at once. Do not think of it as a normal explosion.

Could you look at this as a 2D skin like a bubble that is expanding out that we can observe from the inside? If so were does that place us inside the bubble?
There is no inside and outside

Also I have heard that everything is moving away from us and everything is moving away from everything else. If this is true then how can we place our position is relation to a centre if there is one.
It is true and there IS no center.

Obviously we are not the centre the same as we are not the centre of our solar system or the centre of the milky way. If we have only a limited viewing distance from our point of view how can we know where the inside of the bubble is in all directions. Assuming we are not the centre.
There is no center

If this has been discussed before link threads.
It has all been discussed THOUSANDS of times. Do a forum search. Better still, start off by reading the FAQs in the Cosmology section.
 
So the Universe has no edges, it did not expand from a single point, and we are just making observations from our position within it? If so, that explains much, and I will read about inflation. Thank you.
 
Dokshifty said:
So the Universe has no edges, it did not expand from a single point, and we are just making observations from our position within it? If so, that explains much, and I will read about inflation. Thank you.

That is correct. The part we can see is called the "Observable Universe"
 
phinds said:
OUR galaxy of stars formed at about 9B years.

I expect that was just a typo, our Solar System formed 4.5 billion years ago at a cosmic age of around 9.2 billion years, the galaxy overall is much (around 2.5 times) older.
 
Our galaxy formed not all that long after the big bang. Massive, young galaxies appear to be rare.
 
GeorgeDishman said:
I expect that was just a typo, our Solar System formed 4.5 billion years ago at a cosmic age of around 9.2 billion years, the galaxy overall is much (around 2.5 times) older.

DOH ! I knew that & got myself confused. Thanks for the correction.
 
The OP should read the Balloon Analogy sticky to get a better picture of how the universe expands and of our place in it.
 
  • #10
bapowell said:
The OP should read the Balloon Analogy sticky to get a better picture of how the universe expands and of our place in it.

I have some concerns about that, it's the last post on the thread at the moment (#238).
 

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