<p>Time is kind of funny when you look at such distances. Let's imagine that you are running away from a person throwing a ball at you. The ball will travel further to hit you, based on your speed, than the distance that was present when you started to run. </p>

<p>The universe is expanding. The early Universe expanded very quickly, giving large deviations from the expected position today than what we see through a telescope. Something that we see that is 12 billion years old is actually quite a bit further away today, although we can't know exactly where it is. As I understand, this hypothetical object would be around 40 billion light years away today (See <a href="https://astronomy.stackexchange.com/q/3635/182">this question</a>), given current theories.</p>

<p>But yes, if you looked at a galaxy that appears in today's distance to be 13 billion light years away, then the universe was 800 million year old, roughly speaking. Galaxies took about a billion years to form, however, so you probably wouldn't see such a galaxy.</p>

CC BY-SA 3.0
2016-01-27T17:43:39.563Z
2016-01-27T19:55:22.143Z
2017-04-13T12:59:07.017Z
PearsonArtPhoto
<p>I understand that we can observe far away galaxies to get an idea how the universe looked like in the past. </p>

<p>Assuming the universe is 13.82b years old, would it be correct to say that if we looked at a galaxy that was 13.82b ly away, we would see whatever happened just after the big bang? If this is correct, what would we have observed had we looked at the same point 1b years ago? </p>

<p>Is this an application for special relativity?</p>

CC BY-SA 3.0
2016-01-26T23:57:40.260Z
A Galaxy 12.8 billion light years away (more or less).
ProfRob
CC BY-SA 3.0
2016-01-27T00:07:54.073Z
Not a full answer, but maybe it helps to find a full answer: There are several notions of "distance" https://en.wikipedia.org/wiki/Distance_measures_(cosmology)
Gerald
CC BY-SA 3.0
2016-01-27T19:44:53.893Z
cross-posted, answered and accepted at http://physics.stackexchange.com/questions/231974/observing-a-point-13-82b-ly-away-1b-years-ago
ProfRob
<special-relativity>
Observing a point 13.82b ly away, 1b years ago
Nickpick
# Observing a point 13.82b ly away, 1b years ago

(Asked by: username_0 on 2016-01-26)

I understand that we can observe far away galaxies to get an idea how the universe looked like in the past.

Assuming the universe is 13.82b years old, would it be correct to say that if we looked at a galaxy that was 13.82b ly away, we would see whatever happened just after the big bang? If this is correct, what would we have observed had we looked at the same point 1b years ago?

Is this an application for special relativity?

**Tags:** special-relativity

> **Comments:**
> **username_1**: A Galaxy 12.8 billion light years away (more or less).  
> **username_2**: Not a full answer, but maybe it helps to find a full answer: There are several notions of "distance" https://en.wikipedia.org/wiki/Distance_measures_(cosmology)  
> **username_1**: cross-posted, answered and accepted at http://physics.stackexchange.com/questions/231974/observing-a-point-13-82b-ly-away-1b-years-ago  

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## 1 answers

### Answer by username_3 on 2016-01-27. Score: 4 | Accepted answer

Time is kind of funny when you look at such distances. Let's imagine that you are running away from a person throwing a ball at you. The ball will travel further to hit you, based on your speed, than the distance that was present when you started to run.

The universe is expanding. The early Universe expanded very quickly, giving large deviations from the expected position today than what we see through a telescope. Something that we see that is 12 billion years old is actually quite a bit further away today, although we can't know exactly where it is. As I understand, this hypothetical object would be around 40 billion light years away today (See [this question](https://astronomy.stackexchange.com/q/3635/182)), given current theories.

But yes, if you looked at a galaxy that appears in today's distance to be 13 billion light years away, then the universe was 800 million year old, roughly speaking. Galaxies took about a billion years to form, however, so you probably wouldn't see such a galaxy.


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