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## Astronomers Discover a Group of Quasars 4 Billion Light Years Across106

New submitter mal0rd writes "NewScientist reports a 'collection of galaxies that is a whopping four billion light years long is the biggest cosmic structure ever seen. The group is roughly one-twentieth the diameter of the observable universe – big enough to challenge a principle dating back to Einstein, that, on large scales, the universe looks the same in every direction.' For reference, Andromeda is only 2.5 million light years away."
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## Astronomers Discover a Group of Quasars 4 Billion Light Years Across

• #### Stupid (but serious) Question (Score:4, Insightful)

by Anonymous Coward on Saturday January 12, 2013 @12:45PM (#42568395)
What exactly makes this "a structure"? All linked gravitationally or what?
• #### Re:"A" reference point, sure... (Score:4, Insightful)

on Saturday January 12, 2013 @01:15PM (#42568615) Homepage
The new collection is four billion light years long. Andromeda is 2.5 million light years away. This means the collection is 1600 times the distance to Andromeda in length. What's wrong with that? (apart from the fact that either distance is pretty close to unimaginable for us day-to-day Earth-bound humans)

Using one as a reference point for the other in four-dimensional space makes little sense to me.

It's being used as a reference distance.

• #### Re:Stupid (but serious) Question (Score:5, Insightful)

on Saturday January 12, 2013 @01:37PM (#42568747)

I think what people are missing is the laws of probability. When Einstein said it looked the same in every direction, what he meant was that it's all governed by the same laws. There's no local variations in the laws of physics. But the probability of something is never either 1 or 0, but some value in between, which means that if you do it enough times (observe) you're eventually going to stumble across something highly improbable. It does not mean that the universe still isn't mostly homogenous -- it just means that there are local defects, in the same way that when you're stirring pudding every now and then you get a lump in it.

I don't find this find to be particularly interesting by itself. Science starts with "That's odd" more often than not, and this certainly is odd, but it doesn't prove anything. Not yet.

• #### The Cosmological principle will still hold. (Score:5, Insightful)

on Saturday January 12, 2013 @02:31PM (#42569155)

All this observation really implies is that the true and full size of the universe is much larger than what has been documented so far.

Currently, we can observe a bubble of space around us to a radius of about 13.5 billion light years. That's as far as we can see. This may well be analogous to being at the center of a water balloon, submerged in a swimming pool of much greater volume.

We can currently see to the inner surface of that balloon, but the far greater mass of water outside of it remains hidden for now to our instrumentation.

Complex systems will always tend to appear homogenous, given enough subjective distance.

Fun fact: The rotational period of the Milky Way is approximately 200-250 million years.

The universe we currently observe is approximately 13.5 billion years old --- there is no way a spiral of such definition could form after only 50-odd rotations, and yet still be so topographically distinct from other such bodies.

That's simply not enough time.

2c

• #### Re:Central limit theorem (Score:4, Insightful)

on Saturday January 12, 2013 @06:35PM (#42570775)

homogenous literally means "no lumps"

No, it literally means "same kind". Homo genos, the Greek words for 'same' and 'kind or type.'

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