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>> Dr Massimo Stiavelli, from the Space Telescope Science Institute, in Baltimore, US, believes the populations seen may well have been able to re-ionise the Universe, provided the stars were bigger and possessed much fewer heavier elements than those we see today.<br /><br />Those should be big fat Gen1 stars in the image, right?<br />
The image is supposed to be 'only' 100 million years after the big bang. So I'd assume you are right. Right?<br /><br />Douglas
In the 1800s, the general belief was that the ether permeated the entire universe and allowed light to flow through it. In addition, scientists had no good theory regarding why the sun continued to burn and hadn't used up all its energy. As the scientists had a very good handle on the mass of the sun and the amount of energy it produced, there was no substance on earth that could burn for any significant amount of time and produce the amount of energy the sun produced. I often wonder if our current theories, especially about such things as dark matter and dark energy, which is really no different than the 1800s "theories" regarding how the sun could continue to burn, won't prove to be as wrong as these previously discredited theories. All well, we can only work with what we got (in the same way that prior to E=Mc2, there was no way to come up with good theories for what the sun burned).
>> Another exciting possibility is that physics was very different in the early Universe; our understanding of the recipe stars obey when they form is flawed." <br /><br />Do you think he's talking about maybe a difference in the strngth of the nuclear strong or weak force relative to gravity? Maybe the Higgs field had different properties? Or is this a more mundane comment about maybe the cycle of early generation stars not bing understood?
<i>Buried in the image are objects that shone not long after the Big Bang</i> <div class="Discussion_UserSignature"> </div>
RobNissen:<br /><br />Different possibilites for dark matter:<br /><br />Axions, neutrinos, or (my favorite) exotic WIMPs in the halo of gallaxies. Some of these have been or can be detected.<br /><br />Another possibility is the existence of a shadow universe with matter in it in a nearby brane. If one of the extra dimensions is extremely large or infinite a brane could exist. Everything not involving gravity would be confined to our brane, but gravity would permeate the higher dimension space time. Light is confined to the branes, so the gravity would come from a truely dark mass (in another brane).<br /><br />Another possibility is if our brane is infinite but highly curved (shaped like a hyperbolic paraboloid). The high curvature would act like a second brane and gravity would be confied to a small regieon of the brane and would not spread out. Gravity would vary more at short distance.<br /><br />These two might be testable by observational astronomy or perhps collider and even two body small-scale measurements.<br /><br /><br />
This also calls into question [assuming its true about a lower rate of star formation in the early universe] - supermassive black holes.<br /><br />You know those 1 billion Sun mass, 12.7 l.y. black holes - how could they have been formed with so little available material to crunch ?
borman- Hi! I'm paulharth6.<br /><br />So, what do you think caused the reionization?<br /><br />Can we assume that the cosmic symphony produced at the big bang was not involved?<br /><br />What about the cause of inflation as in inflation theories?<br /><br />I'll study the black hole possibility meanwhile.
The Early Universe had about as much material as the present Universe, but the density was much higher, so very massive black holes likely formed more easily. Neil
Even supermassive black holes evaporate less than one earth mass per century, and recapture much of the evaporated suff in less than a billion years.<br /> The least massive black holes only have about one Earth mass, so evaporatated stuff has little inpact on the Universe, unless there are many more black holes than generally supposed. My guess is we are seriously under estimating the number of black holes.<br /> If there are a billion blackholes within one hundred light years, but no large or medium mass black holes within one light year could we detect them, if they had very thin accreation disks? Neil
Apparently I missed the whole topic of re-ionization. I assume most all matter was ionized until most of the Universe cooled below 10,000 degrees c. It may have taken another billion years for half of the nuclii to capture enough free electrons to fill their shells. Nuclii that enter dense atmospheres would quickly capture enough free electrons to fill their shells, bt only about a trillionth of the universe is presently dense atmosphere, likely much less. Please explain why we need re-ionization. Neil
What about a fuselade of exploding primordial black holes? Each would release high-energy gamma ray bursts as it evaporate. Perhaps an inflationary change might trigger an onslaught of evaporations rather than a random distribution. For a few microseconds the universe would be awash in 10**20 GEV photons.
In the link below is the new full size complete HUDF!!!<br /><br />http://www.aoas.org/gallery/album03/hubble_ultra_deep_field_1?full=1<br /><br /><br />after all is said and done it still makes a nice wallpaper 
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<br />Very nice! Thanks trevz6! <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>
The full size image is 6200 x 6200 pixels across at 110 meg in size, available here:<br /><br />http://hubblesite.org/newscenter/newsdesk/archive/<br /><br />And it is stunning beyond belief. You can find even larger detailed views of many galaxy's as well as detailed views of various nebuli and other objects:<br /><br />http://hubblesite.org/newscenter/newsdesk/archive/releases/ <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>
I have a version of that picture on my other computer. It's not quite 6,200 x 6,200 pixels; it's more like about 4,000 x 3,000 or something like that. It's honkin' huge though. Scrolls left to right several times on my 19 inch monitor.
Looking at all those gaudy little galactic lights, realizing how very small a patch of sky that image represents, it gives me a very peculiar feeling. Like all the parties in world are going on out there, and I'm not invited.<br /><br />Awe. <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>
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