## Astronomers Discover Largest Structure In the Universe 143

Posted
by
samzenpus

from the biggest-there-is dept.

from the biggest-there-is dept.

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."*
## Enter Metaphysics (Score:5, Insightful)

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.

## Random distribution (Score:2, Insightful)

Random distribution means that lumps will form.

This is relatively obvious chaos theory.

Even more so when objects can grow closer due to huge centers of mass.

This might be how black holes start for all we know...

## Re:quasardilla supreme (Score:3, Insightful)

Thats what science is all about...

## Re:quasardilla supreme (Score:5, Insightful)

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.

## Re:Enter Metaphysics (Score:5, Insightful)

causalsuspicion of having arisen other than randomly; but it's still measurable."Structure" seems like a poor word, given the heavy connotations of purposeful design or systemic interaction; but choosing a statistical cut-off and taking particular interest in outcomes less probable than that, given the assumptions about the underlying distribution, is in principle sound enough(though it may simply mean that an improbable outcome happened, rather than that the assumptions about the underlying distribution were wrong).

It's like watching the payouts of N slot machines over the course of an evening: If you know, or have a hypothesis, about the odds of the game, you can tell how far a given outcome deviates from the expected distribution, though even observing an extraordinarily unlikely one cannot prove that the game was being rigged, though it can suggest it strongly enough to send you looking for clues in that direction.

## Re:Random distribution (Score:4, Insightful)

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