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Astronomers Discover Largest Structure In the Universe
KentuckyFC writes "Until now, the largest known structure in the Universe was the Huge-LQG (Large Quasar Group), a cluster of 73 quasars stretching over a distance of 4 billion light years. Now astronomers say they've spotted something even bigger in data from gamma ray bursts, the final explosions of energy released by stars as they die and the universe's most energetic events. Astronomers have measured the distance to 283 of these bursts and mapped their position in the universe. This throws up a surprise. At a distance of ten billion light years, there are more gamma ray bursts than expected if they were evenly distributed throughout the universe. This implies the existence of a structure at this distance that is about ten billion light years across and so dwarfs the Huge-LQG. What's odd about the discovery is that the Cosmological principle--one of the fundamental tenets of cosmology--holds that the distribution of matter in the universe will appear uniform if viewed at a large enough scale. And yet, structures clearly emerge at every scale astronomers can see. The new discovery doesn't disprove the principle but it does provide some interesting food for thought for theorists."
Maybe we're at the bottom of the turtles after all?
The real importance of such observations and discoveries lies not in their ability to test existing hypothesis but in furthering our ability to form new ones.
Scruting the inscrutable for over 50 years.
Probably because they're Hungarian
1989
http://en.wikipedia.org/wiki/CfA2_Great_Wall
The Great Wall (also called Coma Wall), sometimes specifically referred to as the CfA2 Great Wall, is one of the largest known superstructures in the Universe, (the largest being the Huge-LQG). It is a filament of galaxies approximately 200 million light-years away and has dimensions which measure over 500 million light-years long, 300 million light-years wide and 16 million light-years thick, and includes the Hercules Supercluster, the Coma Supercluster and the Leo Cluster.[1]
It was discovered in 1989 by Margaret Geller and John Huchra based on redshift survey data from the CfA Redshift Survey.
work in progress
Thank God we have people on Slashdot to tell us things like this. Where would we have been if generations of cosmologists were entirely ignorant of statistics or gravitational physics? The mind boggles!
Sorry, but the problem isn't that there are lumps - if there weren't our existence would be a bit suspect since we live on the edge of a reasonably large lump (the Virgo supercluster) ourselves. The problem (if you want to call it a problem; it's more an interesting question) concerns the *size* of the lumps. We can predict with reasonable certainty the probability of a bound structure of such and such a size appearing in the universe. That's quite straightforward in principle. And structures this big are pushing the bounds of the standard cosmological model quite hard; basically, they shouldn't really be there. I don't know the actual probability but it's extremely low, and low enough that we would not expect to see it. That there are now three structures that are rather too large (this one, if it comes to be accepted as a genuine structure; the Sloan great wall, if it turns out to actually be a structure; and the CfA great wall) is getting interesting.
Thats what science is all about...
Science is the systematic observation of everything in our world and universe; it is the best and most successful way we have discovered for determining what is true and what is not. That does not mean that it cannot make mistakes, but it does mean that mistakes can be noticed, making it a self-correcting process, trudging ever forward towards greater accuracy and understanding. Pointing out that science makes mistakes is pointing out a part of how the scientific process works and achieves progress; it's not a bane, it's a boon.
Isn't Kareem of Wheat what Buckwheat changed his name to after converting to Islam?
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Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
- Douglas Adams, The Hitchhiker's Guide to the Galaxy.
One mind numbing possibility is that the laws of physics may change depending upon location in the universe. Drawing conclusions by observation of remote objects and events may it self be irrational.
In the big bang theory there is no outside, so it isn't a lump. Indeed, it's exactly the opposite. In a true "big bang" theory the universe is totally smooth and featureless, and evolving. It's built on "homogeneous and isotropic surfaces". The main observational motivation for this is the microwave background, which to one part in 1000 is identical everywhere we look. That 1/1000 discrepency is a pure dipole -- nothing but a Doppler shift. What *causes* that is mildly debatable, but the effect has to mimic the Earth's motion with respect to the microwave background so closely that an alternative is liable to fall to Occam's razor. In any event, no matter what its source, we know how to remove pure dipoles, so we remove it. And we're left with something that is identical everywhere we look to one part in ten thousand!
So the microwave background is "isotropic" around Earth - everywhere we look it is identical, for all practical purposes. Any model of cosmology has to be able to explain that, and as a bonus also explain what those tiny fluctuations are doing on there and where they came from, and predict their statistical nature. (The big bang theory, plus inflation, does this as perfectly as we could ever ask. No-one seriously suggests that inflation is other than, at best, an effective field theory that describes a more fundamental underlying theory. Well, no-one except people who believe they can boil a moduli inflation out of one string theory or another, but those are still somewhat contrived. But the success of inflation tells us something that acted exactly like it had to happen. (The answer is easy: so-called R^2 inflation. The first inflationary model is believed in the West to be due to Alan Guth, of MIT. This isn't, strictly speaking, true, and Guth would never claim it was. Guth - and Tye - presented the first quantum field theoretical model of inflation, which they based on the Higgs. The first actual inflation came a few years earlier, behind the Iron Curtain, and due to Starobinsky who is a big name in cosmology but deserves to be bigger. Starobinsky was examining what happens when you look at the 'low-energy' limits of a wide variety of modified gravities. General relativity can be described by the equation L=R. Here L is the "Lagrangian density" from which the equations of the theory can be derived while R is the "Ricci scalar" which describes the curvature of spacetime; for comparison, the Lagrangian of normal classical mechanics is L=K-V where K is the kinetic energy and V the potential energy. I'm brushing over the difference between a Lagrangian and a Lagrangian density but it's exactly what it sounds like... Anyway, Starobinsky started from the observation that virtually any modification of gravity will end up reducing, at energies beginning to approach sanity, to something of the form L=R + alpha * R^2 +... where the dots include a wide variety of grotesquely ugly terms alongside the expected R^3. The interesting thing here is that when R gets very large, as would happen in the very early universe, the Lagrangian becomes L=alpha R^2. Solve this and you find you have an exponentially growing universe -- inflation. Study it in more detail, and you find it acts exactly like a more normal inflation (with a potential V proportional to phi^2, I think; it may be phi^4, I forget which), including exactly predicting the form of the perturabtions on the CMB. Actually, if you look at the recent Planck results, R^2 inflation is still stubbornly by *far* the best result... if you judge by eye. Its nearest widely-known competitor is only excluded at the one sigma level, which you'd be laughed at if you seriously tried to say that excluded it, but R^2 lies slap in the middle of every contour and will never be budged from there as long as we live, unless there is a significant detection of cosmological gravitational waves.)
Anyway, I digress.
There are two conclusions we can draw from the CMB:
1) The Earth is at the centre of the Universe. I don't know why religious crazies ne