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The universe was created 13.7 billion years ago. We are able to observe things much further than 13.7 billion light years away. This suggests that the light has been traveling for more than 13.7 billion years. What accounts for this?
I understand that the universe is expanding at everypoint and there are things many times further away from us then 13.7 billion light years, but how are we able to observe them? What am I missing?

2007-01-10 07:49:35 · 4 answers · asked by E 5 in Science & Mathematics Astronomy & Space

Maybe? When an astronomer says that they discovered a galaxy approximately 30 billion light years away they are talking about current distance calculated? The actual light that was observed was emitted 20 billion years earlier when it was much closer to earth?

2007-01-10 08:12:15 · update #1

Correction on above comment: The light could not have been emitted 20 BYA because the object did not exist then.

2007-01-10 08:13:25 · update #2

Im an idiot, i realize where I was messing up. Should have just thought about it for a few more minutes rather than post a question.

2007-01-10 08:19:28 · update #3

4 answers

Check out "comoving distance" in Wiki.

Objects that we can see today cannot have sent their light more than 13.7 billion years ago, otherwise the light would not have had time to reach us.

However, in the time that it took for that light to reach us, the universe has expanded and things that were far apart then are now even much further apart. The distance at which the object would now be from us, if we could see it where it is now (instead of then) is called the "comoving distance".

But we can't. We can observe objects that are "now" more than 13.7 billion light years away, but we see them as they were "then" when they were less than 13.7 billion light years away from us. We do not see then as they were (or are) further away than 13.7 billion years ago.

Light cones and all that.

2007-01-10 08:09:39 · answer #1 · answered by Raymond 7 · 1 0

So far astronomers don't think they have seen anything further than 13.7 billion light years. I don't even think they have seen that far away...I thought it was more like 13 billion that they have seen and are estimating the age of the universe to be 13.7 billion years old.

2007-01-10 16:11:04 · answer #2 · answered by Kelly B 2 · 0 0

What you're missing is that we haven't observed anything that's farther away than that. You got your facts wrong.

You may have read that we think the universe is much larger than that. The explanation is that we've seen 13.7 billion light years...but the universe is continuing to expand (or so we think) so we have to infer how much it expanded in the last 13.7 billion years since that light left its source.

2007-01-10 16:29:54 · answer #3 · answered by Anonymous · 0 0

The most distant know object in the universe, a galaxy brought into sight by gravitational lensing, is thought to be about 13 billion light years away.

No conflic there.

2007-01-10 15:59:04 · answer #4 · answered by minuteblue 6 · 0 0

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