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(io9)   Astronomers discover galaxy far, far away   (io9.com ) divider line
    More: Cool, galaxies, astronomers, light-years away, solar masses, Hubble Space Telescope, redshifts, Milky Way  
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3113 clicks; posted to Geek » on 23 Oct 2013 at 9:38 PM (2 years ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2013-10-23 11:18:48 PM  
5 votes:

sgnilward: if light speed is the fastest speed there is, how can a galaxy outpace it?


Okay, first of all it's important to understand what the Universe is doing when it expands. I explained this in the other thread:

Think of it like this: The Big Bang wasn't an explosion but rather an expansion of space-time. The galaxies aren't moving away from each other or from some central point. Rather, the space between the galaxies is filling up with more space. Because of this, the things furthest away from us are moving away faster than things closer to us. Basically, the more space that exists between us and a distant object, the more space there is that can fill up, so the gap gets bigger faster.

Moreover, wherever you are in the Universe, you will observe this exact same phenomenon, so it looks like you are the center with everything moving away from you, and the farthest things moving away the fastest.

Here's a 2D example to show what that looks like:

img.fark.net

In other words, there is no center of the Universe because everywhere is the center.

Secondly, you must understand that there is no such thing as any objective standard time. Time is relative and predicated on gravity and velocity. Things move at different rates in relation to other things, so while we say that the Universe is 13.72 billion years old, that is a metric that only means something to us, from our vantage point. That is not a Universal Standard Time index. The Universe doesn't have one. So light only travels at light-speed in relation to things not traveling at light-speed. Things behave very strange at relativistic speeds. If you were traveling at the speed of light, you could traverse the entire Universe in about 56 years. But the Universe itself will age 13.72 billion years during that time. And it will be much bigger.

If you don't understand any of this, don't worry about it. The Universe is a very weird place. It's not only stranger than we imagine, it's stranger than we CAN imagine.
2013-10-23 08:36:14 PM  
4 votes:
Sentences like this drive me crazy: "It's less than 2% the mass of the Milky Way, but it's producing stars at a rate that's confounding scientists. " No, it was producing stars 13.1 billion years ago. We have no idea what's happening there now.
2013-10-23 08:38:55 PM  
2 votes:
And I'm not going to start on the 30 billion light years away.
2013-10-24 12:08:47 PM  
1 vote:

Kerr Avon: SevenizGud: sgnilward: if light speed is the fastest speed there is, how can a galaxy outpace it?

Light is the fastest thing through space. But space does not travel through space when it expands. Space can expand faster than light can travel through space. As a result, in the end, nobody will be able to see anything because it will be too far away.

That makes sense, thanks. Other than Wiki, any recommendations of places to look for similar information for someone that can handle the concepts, but who's O Level maths isn't up to the squiggly bits?


Much recommended, a very good read with minimal reliance on math.  There are a few equations but the concepts are simply yet brilliantly explained.

ecx.images-amazon.com
2013-10-24 09:01:54 AM  
1 vote:

sxacho: It's less than 2% the mass of the Milky Way, but it's producing stars at a rate that's confounding scientists.

...

It has a mass of one billion suns, which is 40 to 50 billion times less than the Milky Way.

Well, 40-50 billion times less is less than 2%. Nice job, article.


If the mods insist on greening links to "science" stories on io9, that's the quality of article you're going to get.
2013-10-24 07:48:24 AM  
1 vote:

Dibikad: Oh, one day we will get to these astoundingly distant galaxies. We just need to get around to building one of these


We already did.

upload.wikimedia.org

Welcome to the future.
2013-10-24 05:26:25 AM  
1 vote:

sgnilward: if light speed is the fastest speed there is, how can a galaxy outpace it?


Light is the fastest thing through space. But space does not travel through space when it expands. Space can expand faster than light can travel through space. As a result, in the end, nobody will be able to see anything because it will be too far away.

In other words, astronomers have no farking idea what they are doing, and this fudge factor will finally be revealed for the charade it is when people come up with a paradigm that shows the error in current thinking.

And all of this is exactly as predicted by the computer models and included in the IPCC report in diagram 5.
2013-10-24 05:09:42 AM  
1 vote:
Oh, one day we will get to these astoundingly distant galaxies. We just need to get around to building one of these www.geekenfreude.com
2013-10-24 02:28:32 AM  
1 vote:
Last Contact, a short story by Stephen Baxter, based on the Big Rip. This is the scariest thing I've read in a long time.
2013-10-24 02:03:58 AM  
1 vote:

dobro: simplicimus: And I'm not going to start on the 30 billion light years away.

Right? I noticed that too. The numbers here make no sense.


Great question! It does make no sense. But the Universe expanded really, really, unimaginably fast.

http://curious.astro.cornell.edu/question.php?number=387
How can the Universe expand faster than the speed of light during inflation?
Some sources indicate that the big bang caused an expansion which traveled faster than the speed of light. How can this be?

You ask a good question, one whose answer lies in the subtle difference between expansion that is faster than the speed of light and the propagation of information that is faster than the speed of light. The latter is forbidden by fundamental physical laws, but the former is allowed; that is, as long as you are not transmitting any information (like a light pulse), you can make something happen at a speed that is faster than that of light. The expansion of the Universe is a "growth" of the spacetime itself; this spacetime may move faster than the speed of light relative to some other location, as long as the two locations can't communicate with each other (or, in terms of light rays, these two parts of the Universe can't see each other). According to the theory of inflation, the Universe grew by a factor of 10 to the sixtieth power in less than 10 to the negative thirty seconds, so the "edges" of the Universe were expanding away from each other faster than the speed of light; however, as long as those edges can't see each other (which is what we always assume), there is no physical law that forbids it.
2013-10-24 01:05:00 AM  
1 vote:
Ishkur, that was an awesome explanation!
2013-10-23 11:19:44 PM  
1 vote:

sgnilward: if light speed is the fastest speed there is, how can a galaxy outpace it?


You're looking at it from a fixed frame of reference, which doesn't apply in this case. Individual galaxies are moving away from each other at a small fraction of the speed...about 1000 km per second in the case of our home galaxy, the Milky Way. At the same time space itself is inflating at all scales, from the quantum to the intergalactic, so that galaxies at the edge of visibility are much further away after 13 billion years than can be explained by our relative motions, even though they are not moving faster than light.

http://en.wikipedia.org/wiki/Inflation_(cosmology)
2013-10-23 10:50:13 PM  
1 vote:

Suckmaster Burstingfoam: How does a galaxy that old, when the whole universe was new, have a high metallicity?


Maybe its unusually high rate of star formation is producing lots of short-lived, high mass stars that subsequently produce and, er...distribute said metals.

And by distribute I mean explode violently.
2013-10-23 10:06:15 PM  
1 vote:

Suckmaster Burstingfoam: How does a galaxy that old, when the whole universe was new, have a high metallicity?


Left over from the previous big bang.
 
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