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Ken Perry
2009-Apr-18, 11:49 PM
Farthest known galaxy in the Universe discovered
(see link to article below)

"Located an estimated 13 billion light-years away, the object is
being viewed at a time only 750 million years after the big bang,
when the Universe was barely 5 percent of its current age."

Question:
Does this mean the above galaxy, Abell 2218, was very close to the
location of the Big Bang... say 750 million light-years (assuming the
speed of light is the ultimate speed limit in the universe)?

Thank for your comments.

Ken

Link to article:
http://spaceflightnow.com/news/n0402/15lens/

pzkpfw
2009-Apr-18, 11:56 PM
Post delayed, because as a defence against spam, posts from new users which contain URLs are held for moderators to look at.

Welcome Ken Perry.

Answer is basically "no".

There is no location of the big bang. It basically happened everywhere.

As the Universe expands it takes time for light to reach us from places that were once close.

BetaDust
2009-Apr-19, 12:11 AM
Answer is basically "no".

There is no location of the big bang. It basically happened everywhere.

As the Universe expands it takes time for light to reach us from places that were once close.

And it is still going on. Everywhere around us.


-- Dennis

Edit: Sorry, my mistake. Welcome to BAUT, Ken Perry.

DrRocket
2009-Apr-19, 12:35 AM
Post delayed, because as a defence against spam, posts from new users which contain URLs are held for moderators to look at.

Welcome Ken Perry.

Answer is basically "no".

There is no location of the big bang. It basically happened everywhere.

As the Universe expands it takes time for light to reach us from places that were once close.

An equally valid answer is "Yes", and the same answer applies to any other point in the universe.

pzkpfw
2009-Apr-19, 12:51 AM
An equally valid answer is "Yes", and the same answer applies to any other point in the universe.

Yes, come to think of it "yes" is a better answer than "no". Thanks.

...as long as that "and the same answer applies to any other point in the universe" (even the tip of your own thumb (and mine)) is not missed.

Ken Perry
2009-Apr-19, 12:57 AM
Your comments are sincerely appreciated!

Ken

Ken Perry
2009-Apr-19, 01:14 AM
I've always had a great interest in anything related to space. However, as an accountant, I work with black and white and try to deduce the grey. When it comes to science, I find myself working with grey trying to deduce the black and white.

Thanks again for all your comments.
Ken

matt.o
2009-Apr-19, 02:29 AM
Abell 2218 is not a galaxy. It is a cluster of galaxies. The galaxy in question is in the background of the Abell 2218 cluster, which acts as a gravitational lense, allowing said galaxy to be observed more easily.

Ken G
2009-Apr-19, 02:35 AM
What's more, the report that the galaxy is 13 billion light years away uses the standard, but misleading, press-release convention that distances should be reported in light travel times. However, that is not the standard way to measure distance in an expanding universe, because it effectively assumes that matter is shrinking, rather than the far more conventional description that space is expanding. In the latter more conventional picture, at the time the light was emitted, the distance to that galaxy was far less than 13 billion light years, and at the time the light is received (now), the galaxy is much farther than 13 billion light years. There are calculators to figure this out given various assumptions about how "space has been expanding since the light was emitted", but I'll bet the answer comes out more like the galaxy is now about 100 billion light years away. Of course, this will probably raise more questions for you than it answers, but you'll get there eventually anyway!

Ken Perry
2009-Apr-19, 04:41 AM
Abell 2218 is not a galaxy. It is a cluster of galaxies. The galaxy in question is in the background of the Abell 2218 cluster, which acts as a gravitational lense, allowing said galaxy to be observed more easily.

I went back to the article and you're right. It is a cluster of galaxies. Thanks for pointing that out.

Ken Perry
2009-Apr-19, 05:17 AM
What's more, the report that the galaxy is 13 billion light years away uses the standard, but misleading, press-release convention that distances should be reported in light travel times. However, that is not the standard way to measure distance in an expanding universe, because it effectively assumes that matter is shrinking, rather than the far more conventional description that space is expanding. In the latter more conventional picture, at the time the light was emitted, the distance to that galaxy was far less than 13 billion light years, and at the time the light is received (now), the galaxy is much farther than 13 billion light years. There are calculators to figure this out given various assumptions about how "space has been expanding since the light was emitted", but I'll bet the answer comes out more like the galaxy is now about 100 billion light years away. Of course, this will probably raise more questions for you than it answers, but you'll get there eventually anyway!

Great answer... very sobering! I'm fearful of saying I understand even on a very basic level. However, one question jumps out after reading the above:

Assuming that c is still valid, is it possible that light is stretching along with the expantion of the universe? I've never thought of light stretching while maintaining a constant speed.

The thought just occured to me that if light can bend then it had to stretch. Shortest distance between two points is a straight line... not an arc.

Thanks
Ken

pzkpfw
2009-Apr-19, 06:55 AM
I believe that the "stretching" is in effect seen - it's the redshift we note in light coming from far away (the wavelength of the light is altered (stretched) by the expansion of the universe).

Also, the thing with Gravity is that it warps space. So what might be seen as an arc to us, is the shortest line between two points. Light isn't so much "bent" by Gravity - the photons are simply following a "straight line" through space - and that space happens to be curved.

(We would have to apply energy to accelerate (-ve or +ve) Earth to alter its' curved path around the Sun).