Understanding galaxy ages

[LKD]

I was reading this: http://www.space.com/scienceastronomy/0 ... axies.html

And the more I hear about such things, the less I understand how these Galaxy's were made by the big bang, since they are well over 13.7 billion light years away from us. Assuming that the light is traveling slower to get to us because the Galaxy's this far away are subject to universe expansion and redshifted. Nor how they can say these Galaxies are under 1 billion years old. Conceivably, they started out a lot closer to us and had to travel to that location to be able to send the light back to us to reach us now.

Please, if there is a good basic explanation of the universe expansion and how a young galaxy could get that far away, or some resource that would give me an understanding of how these all work together, I would be beyond grateful.

 

[Saiph]

well, first the galaxies in question are only ~13 billion ly away, not 'well over' so that should help clear up some of your confusion.

But I'll run through the basic scenario with you (using approxmate figures, as I don't recall the exact ones):

Bang, universe created, expands.

Inflation, universe now the size of a basketball

Unviversal expansion slows,

~300k years later, now millions of ly across, light is free to travel.

million years more, galaxies and stars form. This is still very close to us, as nothing is very far apart.

We (the early milky way) begin seeing some of the light from nearby galaxies.

nearby galaxies are carried away from us via expansion of spacetime...but we always get their light, it's just more and more red, and the 'message' is in slow motion.

As the universe expands, the distances increase, and the galaxies receed faster and faster. The messages get dimmer due to distance, redder due to speed, and 'slower' due to time dilation...

So the really distant galaxies, that we see at only 1 billion years old, have indeed been sending us light for 13 billion years. It's just that with the expansion of the universe, most of the messages haven't arrived yet.

 

[LKD]

This is where you loose me. And I am sorry for asking. And I hope I am keeping my thoughts in line correctly.

If we are getting light from a galaxy 13.1 billion years later, it could not be 13 billion ly away when it emitted that light unless it was in uniform speed with us. I reciprocated my understanding of speed and thought it was further when it should be closer then we see. If it was blue shifted, the image we see would have been emitted from farther than 13 billion ly. When you explained light speed to me, and thank you for that, the near infrared light from that galaxy can't go light speed plus the difference of the subject's expansion speed greater then our expansion. So it has to be closer than what we are seeing because relative to us, that light is moving slower than c. Am I wrong in this thinking?

But more that is confusing me, how come there are complete galaxies so soon and so far away after the big bang. Even if adjusted for expansion, and the galaxy was say 10 billion ly away when if emitted that light, this seems to go against what the Big Bang theory explains. What am I missing? I understand the basic premise, but how come we can see galaxies so far out at such an early universe age?

 

[origin]

LKD, it is rather hard to go into detail on a forum. So this site and this site may help answer some of your questions.

 

[LKD]

Thank you for the links. I read the Astro one before. That is not terribly helpful I am afraid. The other was very interesting to say the least.

Still, I really don't quite get how the Galaxy's could have been made so quickly after the big bang, and so far away. They don't really offer postulation as to how the effect, of whatever, aligned the particles in the universe into matter and energy in a matter of such a short time over incredibly vast distances. If you place, arbitrarily, the big bang halfway between us and the oldest galaxy, that seems to imply that whatever created the universe occurred over a 6 billion ly radius of space in the course of 100 million years. Which seems incredible for any energy reaction given c as a limitation.

 

[origin]

Still, I really don't quite get how the Galaxy's could have been made so quickly after the big bang, and so far away.

Yes the galaxies and stars seemed to form relatively rapidly after the big bang - it is hard to say though since I don't really know how fast they should form. So far away from what?

They don't really offer postulation as to how the effect, of whatever, aligned the particles in the universe into matter and energy in a matter of such a short time over incredibly vast distances.

What do you mean by aligned? The energy was there at the big bang and considerable less than a second after the big bang matter was forming; as the universe expanded and cooled gravity took over matter began to coalesce.

If you place, arbitrarily, the big bang halfway between us and the oldest galaxy, that seems to imply that whatever created the universe occurred over a 6 billion ly radius of space in the course of 100 million years. Which seems incredible for any energy reaction given c as a limitation.

This statement does not make sense. The big bang did occur halfway between us and the farthest galaxies, but it also occurred at the farthest galaxy yet discovered and it occured in your kitchen. My point is there is no place where the big bang occured except that it occurred in the entire universe. The big bang happened in a very small spot, a tiny spot; and continues expanding to this day, the universe is that tiny area and it is the vast area that exists today.

100 million years is a mighty long time, by the way! What energy reactions are you talking about and what does the speed of light have to do with anything in this discussion.

 

[LKD]

I guess that is the part I can not fathom. how it happened at once all over. I wandered the internet for information and such. I can see that the mistaken understanding of it starting from a point can put me on the wrong path. That is where most of my problem is. Not that the furthest galaxy used to be a lot closer, but that the universe we see just used to be a little bit closer to us before expansion took hold after the formulation of the galaxies.

 

[origin]

I guess that is the part I can not fathom. how it happened at once all over. I wandered the internet for information and such. I can see that the mistaken understanding of it starting from a point can put me on the wrong path. That is where most of my problem is. Not that the furthest galaxy used to be a lot closer, but that the universe we see just used to be a little bit closer to us before expansion took hold after the formulation of the galaxies.

It is absolutely a difficult concept. The term big bang conjures up an image of and explosion which of course starts in one spot and expands out into the surroundings. The deal with the big bang is that there are no surroundings. There is nothing except the universe, or the universe is not expanding into anything, it is just expanding.

edited to add this link of the farthest look into the past from the Hubble