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#1




The largest thing the universe
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I don't fully understand the theoretical implications of it all though.
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kyrie eleison 
#2




Re: The largest thing the universe
So that's where Demond Wilson's career went.
Isn't the Milky Way only 150,000 light years in diameter? Gives you a good scale as to the size of this beast.
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"It always remains a scandal of philosophy and universal human reason that the existence of things outside us ... should have to be assumed merely on faith, and that if it occurs to anyone to doubt it, we should be unable to answer him with a satisfactory proof." ~~~Kant 
#3




Re: The largest thing the universe
Interesting. To say the least.
For those thus inclined (reading just the abstracts and summaries is highly recommended for mathematicaphobes ) A paper on the previously largest LQG's: http://arxiv.org/pdf/1108.6221.pdf The actual paper on the new extra large LQG: http://mnras.oxfordjournals.org/cont...97.full#ref50 And the paper that suggested the upper limit for the size of LQG's which is now apparently breached: http://mnras.oxfordjournals.org/content/405/3/2009.full I think it's a bit premature to announce the passing of the cosmological principle though. One only has to read the above articles to get an idea of how extremely complex these quasar analyses are and how many other parameters and/or assumptions might be off. 
#4




Re: The largest thing the universe
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But it would be a huge problem at another level and I think I can explain it very well with an analogy. Everyone is probably familiar with the kind of question one gets in school about finding out where or when two cars will meet when one goes from point A to point B at an average speed X and the other one from point B to point A with an average speed Y. Only a very bad teacher would mention it at the level of education these questions are asked but the answer to that question which the teacher will mark as correct does actually assume something that's very similar to the cosmological principle. Notably it assumes homogeneity of the trajectory AB. That is to say the answer is only correct if one assumes perfectly straight and perfectly level roads with no obstacles and perfect performance of the cars. That's not a real world situation of course. If this were a real world problem many more parameters would have to be calculated to come up with a correct answer. For the sake of simplicity I will introduce just one, viz. the distribution of stop signs along the road AB. Without changing the average speed of the cars, the actual real world distribution of stop signs would influence the place where the cars would meet. If there were for instance more stop signs or a cluster thereof (representing e.g. a village) on the half of the road closer to A than on the half of the road closer to B then the point of meeting would shift closer to city A. And that is almost exactly like the role the cosmological principle plays in cosmology. If one has good grounds to assume homogeneity, i.e. uniformity, throughout the universe then one can ignore the possibility of clusters of 'stop signs' or at least assume a random distribution which is easy to calculate. But if one were to find out that this homogeneity isn't the actual case then one would have to incorporate an estimate of the nonrandom, nonlinear distribution of 'stop signs'. Applied to cosmology the analogy of these 'stop signs' in fact represents a whole plethora of things. Each one of them would have to be quantified and put into an equation and these equations would substitute the hitherto simple and single parameter that represented homogeneity in the overall equations. Needless to say that would make the calculations far more complex. Every calculation that has ever been made under the assumption of the cosmological principle would have to be revisited and recalculated with the far more complex equations. The direct result would of course be a huge effort in time and resources (not to mention money). And at least temporarily many results hitherto considered accomplished would be on shaky grounds until the results of the new calculations are available. Then there are two possibilities. Either the new results would still fit in the grand scheme of things without fundamental changes or they would not. In the latter case that would be a major upheaval that could potentially likely might be a better word shake basic theoretical grounds. But this is still very much a hypothetical scheme. The cosmological principle isn't assumed for no reason or out of laziness in order to have simpler equations or on philosophical grounds but for the simple reason that until now there has never been much of an indication that the universe isn't homogeneous and there were a very great deal of reasons to assume it is. To name just one, the intensity of the cosmic background radiation is the same to 1 in 100 000 in all directions of the sky. On the bright side of things, if the universe really isn't homogeneous then the precise nature of the inhomogeneity is bound to tell us a lot more about the nature and origin of the universe. It may lead to an explanation of dark matter for instance. 
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