NASA Discovers Most Distant Galaxy In Known Universe

An anonymous reader writes with this snippet from cbc.ca: "'NASA's Hubble and Spitzer space telescopes (not to be outdone by the Kepler Space Telescope) have discovered the most distant galaxy identified so far in the universe... the galaxy is 13.3 billion light years away and only a tiny fraction of the size of the Milky Way. Due to the time it takes light to travel through space, the images seen from Earth now show what the galaxy looked like when the universe was just 420 million years old, according to a press statement released from NASA. The newly discovered galaxy (is) named MACS0647-JD."

Comments

I don't get it

[symes]

Apologies for the ignorance - So I understand that the further an object is the longer it takes for light to reach us. So what we observe is effectively light that has been traveling for a long time and we are looking back in time. But surely the Universe is expanding and is we go back in time then at some point we were in fairly close proximity to this galaxy. Light back then would have taken only a few moments to reach us. Moving forward from this point, for us to be able to see the past now surely we must have moved away from this galaxy at a relative speed that is considerable. What I don't get is how fast we need to be hurtling away from this galaxy for us to see the relative past now. As surely any speed below the speed of light would only slow time, rather than reverse it as implied here. Can anyone explain?

Re:I don't get it

[wvmarle]

I think the point of OP is different: the light from this galaxy took 13.3 bln years to reach us; so this implies the light has been travelling for that distance (13.3 bln light-years) before it reached us. Otherwise it should have reached us earlier.

However 420 mln light years after the Big Bang, was the universe already that big? If the universe was smaller (say 1 bln light-years across) the light of that star system should have reached us long time ago.

And, on the same note, there must be a lot of our universe that we can not see, simply because it is now so far away from use that the light from those places can not have reached us yet.

Or are OP and me missing something? If so, what?

Re:I don't get it

[Anonymous Coward]

This is explained thoroughly on http://en.wikipedia.org/wiki/Observable_universe

Re:I don't get it

[gshegosh]

The speed limit of c only applies to matter inside of the spacetime. The spacetime itself can expand faster than light and in fact there might be galaxies that we'll never be able to reach or see because they move away from us faster than light. Moreover, the idea of inflation stage of universe growth seems to explain well some problems with standard "big bang" theory and is widely accepted. Inflation means that there was a shot period in universe history when it expanded very quickly, faster than light speed in fact.

Re:I don't get it

[Kergan]

I think the point of OP is different: the light from this galaxy took 13.3 bln years to reach us; so this implies the light has been travelling for that distance (13.3 bln light-years) before it reached us. Otherwise it should have reached us earlier. (...)

Or are OP and me missing something? If so, what?

I suspect you're misunderstanding space inflation. The big bang wasn't so much an explosion in space than it was an explosion of space. Picture a balloon with dots on it. Roughly speaking, our 3d space would correspond to the balloon's surface. (The balloon's volume corresponds to nothing physical.) There isn't such a thing as a center of the balloon's surface any more than there is a center of the universe, and the big bang corresponds to a huge initial blowing into the balloon. Crunchy details if needed.

Re:I don't get it

[rgbatduke]

Just to actually answer your question, the original inflation of space (supposedly) took only a very, very short time, so even if the two points were "close together" at the instant of the big bang itself, they ended up very far apart (and moving farther apart) at the end of a second or so. The parts of the universe in question did not exceed the speed of light because speed is distance over time in spacetime and it is the latter that was inflating. Think of a very small balloon with a picture of the Universe printed on its surface being suddenly blown up -- when the balloon is small, everything is compact, but when it is inflated it is much further apart. Then make it a balloon with a three dimensional "surface" and no interior...

There is a lot more to learn about this, much of it in e.g. wikipedia pages as noted in the thread or in astronomy textbooks, and it is actually a lot of fun to learn. One very interesting thing, for example, is to follow the scientific argument from parallax, blackbody radiation, and our knowledge of how radiation intensity drops off with distance, through the discovery of the Hubble constant, out to how we estimate/compute the size and age of the Universe. Another interesting thing is to learn about "the Great Dark" that followed the big bang up until the formation of the earliest stars some 200 million years later, the chain of nucleosynthesis within those starts and the supernovae that ended them, and the gradual accumulation of "metals" (elements heavier than hydrogen and helium) in the ashes of those stars. The entire planet Earth and we ourselves are composed of stardust, the ash of ancient stars that gave rise to the elements that make up our bodies in their dying explosions.

It's well worth it to take a course in astronomy at some point if this sort of thing interests you, although a lot of it is covered in discovery channel stuff and shows you can probably find on netflix if that's too time or money consuming for you.

rgb (who occasionally teaches astronomy and hasn't lost his sense of wonder at how it all works out)

Re:I don't get it

[wvmarle]

That part I get; I also checked the wikipedia link provided by a helpful AC.

The issue I don't understand: this galaxy must have been some 13.3 bln light years away from us, as the light took that long to reach us. Anything closer we'd see "nearer in time". This means the galaxy must have been at least that big already at that time. Sounds pretty big to me, considering it has been expanding since and expansion is accelerating.

Re:I don't get it

[nthcolumnist]

Again with this? There is no theory stage. 'Theory' is not a precursor to absolute knowledge. If you think gravity is just a theory I invite you to test it via the nearest window.

Re:I don't get it

[History's Coming To]

It's a perfectly good question, and a tricky one to fully explain. The first thing to look at is how you measure distances - because we're talking about light here we're firmly in the realm of relativity, so there's no such thing as "space" and "time", you have to bundle them together in spacetime. And talking of x-light-years or y-million-years doesn't actually make much sense, you have to measure both at once, so instead of distances or times things are measured in "spacetime intervals" which account for all four dimensions.

Now this is the tricky bit - for any "light-like" path (more technically called a "null geodesic") the spacetime interval is zero. So the light that we're receiving from the galaxy here and now has a spactime interval of zero. The light that this galaxy emits all travels the same spacetime interval of zero - some of those photons would have been aimed at (as you suggest) "our galaxy" when it was "closer" - although in fact "our galaxy" was just a wisp of hydrogen at the time. Other photons (the ones we see today) were essentially aimed at a point that was also 13Bn years IN THE FUTURE, and those are the ones we see hitting us today.

Long story short, you don't just aim light at a point in space, you also aim it at some point in the future, and the further away in space it's aimed then the further into the future it's aimed. In a million years we'll still be able to see this galaxy (assuming it doesn't slip over the cosmic horizon), and the photons we'll detect then are currently still in transit, aimed at when/wherever we will be then, just as the photons we detect today were still in transit last week, last year and 13Bn years ago.

Re:I don't get it

[Runaway1956]

The guy coming at you in the other lane gets blinded by your high beams.

NASA doesn't discover galaxies: astronomers do

[Trapezium Artist]

I realise that the title of this article was carried over from the CBC article, but could we at least try to remember that it's astronomers that discover things like this high-redshift galaxy, not an administration like NASA in isolation? I don't mean to diminish the absolutely central role played by NASA in both Hubble and Spitzer, of course, but at the same time, a whole range of people, institutions, and organisations come together to make scientific discoveries like this possible, and I think it's important that we recognise that science is often a highly collaborative and international endeavour.

For example, there are 23 astronomers who co-authored the paper on this galaxy: 11 are from US institutions, 11 from European institutions, and 1 from a Chinese one. Note, I didn't say that they were (necessarily) American, European, and Chinese: in the list of co-authors, there are at least some Europeans working in the US and vice versa.

Also, the Hubble Space Telescope is a collaboration between NASA and ESA, the European Space Agency, albeit with NASA in this instance contributing the majority. There are other space missions including Herschel and Planck which are led by ESA, but in which NASA plays a minority role. Many space missions are collaborative in this way, in essence underpinning the mix of US-based, Europe-based, and other international astronomers who've written this paper.

In more detail, it can get even more complicated when you realise that NASA, ESA, and other space agencies themselves employ astronomers and other space scientists, so in that sense, discoveries can be made by those organisations too.

Speaking of which, it might have been more appropriate to give the links to the original US and European press releases from the Space Telescope Science Institute, NASA, and ESA to get the full story.

Anyway, despite the (important, I believe) pedantry, this is is an interesting discovery :-)

Re:13.3 billion in one direction?

[meetpi]

It's also worth pointing out that in the context of the universe, there is no edge. By default we tend to think of the universe as being like an explosion in space where the first particles ejected are at the edge of the explosion radius.

However, when we're discussing the universe, this explosion is actually creating space, so the expansion is not from the core to the edges, it's happening through all of space - everything is moving away from everything else. Think of it like the surface of a balloon that is being blown up. In 2d terms, all points on the surface of the balloon are moving away from each other, but none of them are at the 'edge' of the balloon.

Someone standing on the surface of a sufficiently large balloon would look around and see everything receding from them - it would be reasonable for them to feel they were at the centre of the surface of the balloon and that therefore somewhere there was an 'edge' - but they'd be wrong.

Re:13.3 billion in one direction?

[aneroid]

Would the distance between the two galaxies be 26.6 billion years and longer than the age of the universe?

Good point: Yes and No.

Would it happen, yes, already has: If the universe is 93 billion light years in diameter, it is obviously possible to to find a galaxy 26.6 billion light years away but it should not be older than 13.7 billion years.

Because 13.3 billion light years away vs 13.3 billion years ago are not the same in the "Expanding universe" theory. The summary says "the galaxy is 13.3 billion light years away" - which makes it not as old as that statement implies --- imagine an early universe 1 billion light years across, with 2 galaxies forming near the edge diametrically opposite each other. They could now be 93 billion light years apart from each other but they would still be slightly younger than this one (MACS0647-JD). Similarly, it's possible that this galaxy could have been formed 12 billion years ago and has since moved relatively or "apparently" further away to 13.3 billion light years. 1.3 billion light years in 1.3 billion years in an expanding universe doesn't seem impossible since the universe is already larger (93 billion light years) than it is old (13.7 billion years).

The article didn't explain how they've correlated distance with age. Doppler shift?

The "No" part to your question, and the part which makes some of my answer wrong, is for observable:
There would also be the implication that what is "observed" can not be older than 13.7 billion years so you would need to wait another 13.3 billion years to observe the 13.3 billion year-old galaxy **at** 26.6 billion light years away.

Ummm,

[u64]

I love to hear more about this 'big bag' theory.

Re:Very young galaxy

[History's Coming To]

It's exactly at the point of the Big Bang. As are you. As is Jupiter, Spica, and an empty bit of space a billion lightyears from our galaxy. The Big Bang happened everywhere, it's just that "everywhere" was all in one place at the time.