5B light years across–the largest feature in the universe

http://phys.org/news/2015-08-billion-years-acrossthe-largest-feature.html

by dnetesn • 11 years ago

11 11 11 years ago

thecabinet• 11 years ago

What clickbait pointlessness. We don't even really understand what causes GRBs, but they're calling this as feature? Why not call the ring much farther out in the picture a feature to? That seems only slight sillier.

DanBC• 11 years ago

They appear to be at very similar distances from us – around 7 billion light years – in a circle 36° across on the sky, or more than 70 times the diameter of the Full Moon. This implies that the ring is more than 5 billion light years across, and according to Prof Balazs there is only a 1 in 20,000 probability of the GRBs being in this distribution by chance.

I'd be interested to hear how they get this 1 in 20,000 figure.

wereHamster• 11 years ago

Hint: it's in the paper.

4.2 Verification of the ring structure

skwosh• 11 years ago

It's considered a feature I think not just because it's a ring but because it's an area of higher than expected density of Gamma Ray Bursts (GRBs).

madaxe_again• 11 years ago

They've identified a new largest structure - your high horse. Get off it.

wcoenen• 11 years ago

xarchiv link to paper:

http://arxiv.org/abs/1507.00675

anti-shill• 11 years ago

so if the universe is homogeneous on a large scale, and they keep finding ever larger and larger structures that qualify as the largest structure discovered, then the apparent size of the universe keeps getting larger and larger...so the question is whether the universe is infinite...and that leads to another question: if it is infinite, how can it ever end? The next question is, if an infinite universe can never end, how can human life ever be extinguished?

46Bit• 11 years ago

The next question is, if an infinite universe can never end, how can human life ever be extinguished?

Heat death. If the universe grows infinitely we'll eventually run out of stars - but I'd worry far more about how we're treating Earth than such things.

fsloth2• 11 years ago

What is a definition of a "feature" in this instance? Does it just mean the current state of a system that could be modeled as a single phase-space (i.e. location plus momentum space for the non-physicists)?

fsloth2• 11 years ago

No, really, I have MSc in physics but I have no idea what a thing being 'a feature' specifically means in the cosmological sense - quick googling also fails to find specification for the term.

If it's significant then it is significant within a specific model and elements of said model should be able to be specified with logical precision - otherwise the said model is kinda pointless.

Clearly what they are seeing is a large scale anisotropy - so what's the treshold for an anisotropy to be considered to be 'a single structure' and how is it measured?

eevilspock• 11 years ago

It's implied by his equating "feature" to "structure" and his references to a "Cosmological Principle" that "indicate that the structure of the cosmos is uniform on the largest scales" and that "this new discovery challenge the principle, which sets a theoretical limit of 1.2 billion light years for the largest structures."

Think of it in terms of the Second Law of thermodynamics. Local increases in order (decreases in entropy), such as there formation of stars or the emergence and spread of life, apparently violate the law, but in fact do not when you look at a greater scope. Order is decreases at "the largest scales".

So by "feature" and "structure" he means a local violation of this principle of uniformity. Apparently this arrangement of GRB's cannot be random non-uniformity, thus implying it is some kind of structure. For example if you flip a coin a million times you will get some clumsiness, periods with far more heads or far more tails. But if clumpy periods exceed a certain size, you would start to suspect that the coin is biased or rigged. It would be violating your expectations given truly random coin tosses.

Or as skwosh said in another comment, "It's considered a feature I think not just because it's a ring but because it's an area of higher than expected density of Gamma Ray Bursts (GRBs)."

5B light years across–the largest feature in the universe

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