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Author Topic: One of the first galaxies to form in the young Universe?  (Read 2940 times)

Offline thedoc

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A team of astronomers have successfully looked back about 13 billion years to pinpoint one of the first galaxies to exist after the Big Bang.

Read the whole story on our website by clicking here

  
« Last Edit: 24/10/2010 10:56:36 by _system »


 

Offline Bill S

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One of the first galaxies to form in the young Universe?
« Reply #1 on: 24/10/2010 16:28:56 »
Fascinating story, but it raises a question for which I need a simple answer - if there is one - please.


The light seen by the astronomers left that galaxy 13billion years ago.
They are seeing the galaxy in the position it was in 13 billion years ago.
I feel sure that this cannot mean that when the Universe was only 0.7 billion years old, that galaxy was already 13 billion L Y away from Earthís present position, but I canít sort out an explanation.  On the other hand, if it was not 13billion L Y away when the light left it, why has it taken 13billion years to reach us?

Help!
 

Offline Mirkin

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One of the first galaxies to form in the young Universe?
« Reply #2 on: 31/10/2010 08:37:53 »
The light takes so long to get here because the universe is expanding. As time passes the light needs to travel further and further to get to where we are. If the Universe was expanding faster than the speed of light it would never arrive.
 

Offline Bill S

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One of the first galaxies to form in the young Universe?
« Reply #3 on: 27/01/2011 23:00:49 »
Quote from: Mirkin
The light takes so long to get here because the universe is expanding. As time passes the light needs to travel further and further to get to where we are. If the Universe was expanding faster than the speed of light it would never arrive.

Thanks Mirkin, I had forgotten about this thread until I found a reference to it on another thread.  I understand your explanation, but it still leaves me with this thought: If we look from the Earth, in opposite directions, at objects that are 13 billion LY away, they are 26 billion LY apart.  We are seeing them as/where they were 13 billion years ago, so they must have been 26 billion LY apart then.  No?
 

Offline yor_on

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One of the first galaxies to form in the young Universe?
« Reply #4 on: 28/01/2011 03:08:45 »
Yep, the lightsphere we see is double any one singly picked distance from Earth Bill. And I think you have a point in your first observation too.

Assume that there is a certain distance, at any point of 'time', from where we won't see any more light reach us, due to a 'expansion'. What hinders that point from having existed one million years ago, two millions years ago? Thirteen millions years ago? The expansion might have been 'slower' as we see it, but what proves that there isn't that possibility?
==

I'm sorry, my keyboard is falling apart :)
Have to correct my spelling constantly.

==

Ah, rereading you, no, you have to remember the 'balloon' in where all points move away from each other equally. The 'time' measured will still only be thirteen millions 'light years' to reach us from any point of observation, even though the accumulated 'size' will be the 26 millions light years.
« Last Edit: 28/01/2011 03:19:20 by yor_on »
 

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One of the first galaxies to form in the young Universe?
« Reply #4 on: 28/01/2011 03:08:45 »

 

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