Most Distant Galaxy Gives Clues to Early Universe

NinjaT writes "From CNN, 'Scientists said on Wednesday that they have found the most distant galaxy yet, nearly 13 billion light-years away, in a discovery that could help explain how stars were formed at the dawn of time. The galaxy, named IOK-1, is so far away that the light waves that reached Earth depict it as the system of stars existed shortly after the Big Bang created the universe 13.66 billion years ago. That period, known to astronomers as the Dark Ages, saw the formation of the first stars and galaxies from elementary particles. Scientists had been unable to directly observe that time period until now.'"

Re:What I find difficult to understand

[Oizoken]

I think this will answer your questions:

http://en.wikipedia.org/wiki/Star#Massive_stars [wikipedia.org]

Re:I know cosmology is an inexact science but

[HuguesT]

From very far away they are not so easy to tell apart. Essentially these are two objects that emit extremely red-shifted light.

Re:What I find difficult to understand

[KitsuneSoftware]

Helium fuses into heavier elements, in a cycle which ultimately leads to carbon for Sun-mass stars, and ultimately to iron for heavier stars. IIRC, elements heavier than iron are only produced in significant quantities by supernova. Such heavy stars are all over the place, and are fairly easy to see because they are so bright; on the other hand, they are also fairly short-lived, lasting only a few million years instead of about ten billion like our sun or the hundred-billion odd years predicted for stars much lighter than the sun.

Re:What I find difficult to understand

[FirienFirien]

Fusion reactions in stars will combine everything up to iron. Hydrogen - being the most abundant - will be the major fusion to form Helium; there's so much of it that that's pretty much all you'll see. However as the amount of He goes up, it'll become combined with H and other He to form Li and Be, and so on - all the way up to iron. Past that the energy of fusion required is simply too high, and with a normal star you'll never see anything with a higher atomic mass. Your iron star going supernova is a little misleading, as the supernova star won't be made of iron - at that mass it'll very likely have a good amount of iron compared to other stars, but in general the greatest part of its mass will still be H and He. Only from that supernova energy, (and the occasional cosmic ray collision, but I think those are negligible in comparison to the amount of matter in a supernova) do you get the energy required to fuse higher elements.

So - the elements above Helium come from normal fusion in a star; they don't have their own phases, everything just bumps into everything else at once. All your elements above iron have a greater fission energy than fusion energy, and with the amount of trigger radiation inside a star they don't generally last long. When they get ejected from a supernova, there's less to trigger them, so they stay stable for longer; that's why we have everything higher than iron, though even on earth they're in relatively minute quantities.

One last thing to point out is that your question about carbon seems odd - bear in mind that a carbon atom only has an atomic mass of 12, while iron has an atomic mass of 56. Carbon is relatively abundant compared to iron. To hazard a guess, if you laid the periodic table in a straight line you would probably see an approximately logarithmic amount of each element, up to iron and beyond; it'll be a little complicated since some elements are more likely to decay back to lighter elements faster than others, but that's the gist.

Disclaimer: this is all out of what I remember from courses; it may not be 100% accurate, though I believe it should clarify things enough.

Abundance of elements

[Roy Ward]

> To hazard a guess, if you laid the periodic table in a straight line you would probably see an approximately logarithmic amount of each element, up to iron and beyond; it'll be a little complicated since some elements are more likely to decay back to lighter elements faster than others, but that's the gist.

Not quite right:

http://www.seafriends.org.nz/oceano/abund.htm [seafriends.org.nz]

Some elements (Oxygen, Carbon, Neon) seem to form more easily than Lithium, Beryllium etc.

Re:What I find difficult to understand

[$RANDOMLUSER]

That's here [wikipedia.org].

Re:Question for the cosmologists

[donaggie03]

I believe the short answer to that question is that you have to distinguish between objects moving in space and space itself moving. The speed of light is the limit that objects are able to move through space. Space itself has no such limitation and can expand at a greater pace than the speed of light.

Re:Question for the cosmologists

[brunascle]

i dont think that's right. i dont know the math exactly, but i dont think 2 objects can be moving apart faster than the speed of light (unless space itself is expanding).

there's no difference between 2 objects moving in opposite directions and only 1 moving and the other standing still. if that were true, it would be the same as if one object stood still and the other moved at 160% the speed of light, which is impossible.

remember, as you move, time itself changes (relative to whatever object youre moving relative to). the faster you move, the slower time gets. that's the reason you cant break the speed of light, because at that speed time stands still.

Re:Question for the cosmologists

[qeveren]

That's incorrect, since at these velocities Special Relativity takes over from Classical Mechanics.

The relative velocity between two objects (in the case of parallel or antiparallel velocities) is given by:

v(rel) = ( w - v ) / ( 1 - ( ( w * v ) / c^2 ) )

Which means two objects, travelling in opposite directions at 0.80c, will have a velocity relative to each other of 0.98c.

Re:How long was this light travelling?

[wanerious]

I agree, but I didn't feel like taking on this assumption. I was simply stating that if something were indeed seen from 13 billion ly away, it would mean they were 13 billion ly away 13 billion years ago, when the light began travelling, as opposed to being 13 billion ly away right now. On the other hand, if the other galaxy is calculated to be 13 billion ly away now, it was much closer when the light we are now seeing had left it. I addressed the former possibility because it related to the parent post.

I understand, and forgive me for pressing a point that you may not care about, but neither of the possibilities you outline above are correct: The statements (a) "The galaxy was 13 billion light years away when the light was emitted" and (b) "The galaxy is now 13 billion light years away" are both not only wrong, but meaningless. The expansion of the universe renders all such distance and time estimates subject to a particular cosmological model in which they are evaluated; and it's only the redshift number, indicating the scale factor of the expansion, that carries any real meaning.

Here's the short version: It is well known that relativity is flawed.

I'd assert that it is far from well-known. Among physicists, to my knowledge, there is no known thought experiment or demonstration that cannot be reconciled with special relativity. The usual suspect in such "paradoxes" is to wrongly assume some simultaneous measurements in two frames in relative motion.

There's a common demonstration used to introduce people to relativity: a ship, a planet, and a light exist in space. The light blinks in a regular pattern. The ship starts next to the planet and flies to the light and back at a relativistic speed. In the process, we see that the ship has experienced less time than the planet. I'm not explaining this here; I assume you are familiar. If not, there are demonstrations available on the web.

Nope, not familiar with that one so much. What's the purpose of the blinking light?

So, once that is shown, take it one step farther. Four ships in a line; two have blinking lights on them. The two without lights start next to each other, the other two are the same distance from them (on opposite sides) that the light was from the planet in the previous example. Each of the outer ships flies inward, while the other two fly outward in opposite directions; for simplicity, make the speed of each be half the speed of the ship in the previous example. When the outer and inner ships meet, they turn around and return to their original positions. So now you can see that by removing either of the outer ships, you have a model equivalent to the first example. Thus, each of the middle ships experiences less time than the other! Nothing in relativity can account for this contradiction (yet).

Are you certain? I'm having trouble diagramming the setup, but I'd be glad to look at some kind of picture to make it more clear.

Relativity is wrong. We don't know the exact nature of what is wrong. Most of us, myself included, do not discount it altogether, but some do. Thus I say again, relativity is much less certain than many people believe.

These people must not be physicists, or at least this ground-shaking refutation of special relativity has not gotten the publicity your bald assertion would seem to warrant. I'd be glad to believe you, but as a teacher of relativity, color me skeptical.