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.
(c) Douglas Adams
Unbelievably vast quasar cluster forces universe-sized rethink
It’s there, but it shouldn’t be: the Sloan Digital Sky Survey has found a quasar cluster so large that it demands a re-assessment of theories about the universe. The problem with the Large Quasar Group is this: it’s too big. One of the assumptions astronomers draw from Einstein’s General Theory of Relativity is that at the …
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Monday 14th January 2013 01:24 GMT SleepGuy
Buses, huh?
Well, assuming the standard London double-decker bus length of 8.4 m, then the Milky Way would measure 112,627,743,721,200,000,000 buses across! I suppose we could round this up to 113 sextillion buses...besides, sextillion has a certain ring to it! As far as the Virgo Cluster, it's 113 septillion buses across.
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Monday 14th January 2013 06:54 GMT Destroy All Monsters
Can't make sense of this article
73 quasars distributed over four billion light years is not particularly dense. As is commonly supposed, a quasar is a black holse swallowing up stuff in the center of forming galaxies. If you see 73, you are looking down the axis of rotation of those holes in 73 cases. Doesn't sound a particularly surprising surprise, there must be tens of thousands of galaxies over 4 billion lys
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Monday 14th January 2013 10:43 GMT Great Bu
Re: Can't make sense of this article
The point of the original assumption that this observation makes less likely was that mathematically for the universe to appear to be the same for all observers then the largest such 'smudge' would be 1.2 billion light years, anything bigger would produce a big enough difference in the 'texture' of the universe that it would look different to different observers.
So whilst there are random variations in the appearance of the universe, these variations reach the level of non-randomness once they grow to more than the 1.2 billion light year size - it's like looking at the random fuzz on a TV showing just static, how many black pixels would need to cluster together before you started thinking they were not random after all ? This cluster is a big block of black pixels together which suggests that either it's not random or the assumption is wrong.
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Wednesday 16th January 2013 01:23 GMT Destroy All Monsters
Re: Can't make sense of this article
Finally a good explanation:
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Monday 14th January 2013 09:33 GMT Cloud & rain model of the Universe structure
This is just fine with Car model.
"With its 73 members spanning four billion light years, the Large Quasar Group is a theoretical inconvenience, because astrophysical models have suggested that 1.2 billion light years was the upper limit for the size of a structure."
This is always fine with structure of the Universe; "Cloud & rain model". This observation gives advantages to "Car model" against "The Big bang theory".
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Monday 14th January 2013 11:53 GMT Anonymous Coward
Re: 1.2 billion light years was the upper limit for the size of a structure
Similarly, I have always refused to accept the speed of light as the upper limit of speed.
Sure it may be the speed at which we can perceive anything, but it always seemed a bit arbitrary. I don't have a degree in physics, but I would imagine that travelling at that speed, to an observer you'd be past before they see you pass, but this to me is no different from Concorde - you see it pass before you hear it.
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Monday 14th January 2013 20:06 GMT Fred Flintstone
Re: 1.2 billion light years was the upper limit for the size of a structure
Ultimately whether we like it or not, the point of physics is to make predictions and the predictions that come out of special relativity, both on a quantum and a classical level, match reality to whatever accuracy we can push it. That then implies that any theory we come up with to replace special relativity has to mimic it in these regimes so closely as to be indistinguishable.
World class summation IMHO :). Have an upvote!
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Monday 14th January 2013 15:10 GMT Martin
....I have always refused to accept the speed of light as the upper limit of speed.
I've recommended this here before, but Relativity and Common Sense (by Hermann Bondi) is a good introduction from first principles to the strange things that happen at high speeds. It makes no assumptions about your knowledge - you just need to know a bit of obvious classical mechanics and be able to follow some simple algebra and diagrams.
Excellent book. Convinced me when I was a 6th former and thought as you did. My Physics teacher recommended it to me.
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Monday 14th January 2013 15:35 GMT Destroy All Monsters
Re: ....I have always refused to accept the speed of light as the upper limit of speed.
"the foundations of special relativity look rather absurd -- they basically state, as an input assumption, that all observers will measure light travelling at the speed of light *regardless of their own speed*. So when we're travelling towards the Sun and travelling away from it, we measure exactly the same speed. Absurd."
Apparently not.
Mitch Feigenbaum thinks this is all a straightforward extension of Galilean thought... this is a paper I have yet to read though.
http://arxiv.org/abs/0806.1234
"We determine the Lorentz transformations and the kinematic content and dynamical framework of special relativity as purely an extension of Galileo's thoughts. No reference to light is ever required: The theories of relativity are logically independent of any properties of light. The thoughts of Galileo are fully realized in a system of Lorentz transformations with a parameter 1/c^2, some undetermined, universal constant of nature; and are realizable in no other. Isotropy of space plays a deep and pivotal role in all of this, since here three-dimensional space appears at first blush, and persists until the conclusion: Relativity can never correctly be fully developed in just one spatial dimension."
See also
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Monday 14th January 2013 11:16 GMT Somerset John
Group...........what group?
What makes this a group?
4 billion light years is a significant fraction of the size of the entire known universe. Given that Quasars are active galactic nuclei (I assume this is the case on current evidence) there are likely millions, if not billions, of them. 73 is a pretty insignificant number compared to the total, so insignificant that whatever common characteristic leads observers to consider them a group may be no more than coincidence.
I would not be terribly surprised if this went the way of the FTL neutrino.
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