Superb new film of Great Attractor & local flow

[Weltevreden SA (Dana)]

If you've ever wanted to fly through our Local Volume to the Great Attractor region—just as our local galaxy group is doing—here's a new paper and video about the subject. It is a very pleasing example of how the technical side of our hobby can join up with the aesthetic side of our personalities. The paper adds couple of winsome new terms to the astro-jargon we love to use: the Snoopy Dog Void, and the Horse Collar. Put the video on a thumb driver and give it to all the teachers you know. It runs over 17 mins and is guaranteed to keep the little rascals quiet for awhile.

[inline_online (Dan)]

Outstanding video.
I will show it to everybody I know.
Thanks for posting.

[multiweb (Marc)]

Outstanding indeed. I found the first half is very hard to visualise with the static views and slices. Much easier with the coloured volumes and relative rotation but it all makes sense in the last few minutes with the velocity lines.

[madbadgalaxyman (Robert)]

The bulk flows of tens of thousands of galaxies are a well-known feature of the universe at the largest scale.

These are usually ascribed to the effects of gravity, but what if there is some other explanation?

[snas (Stuart)]

Way cool!
Stuart

[ZeroID (Brent)]

Wow ! Watched it at work, no sound unfortunately so have to watch it again at home on the TV, Have to be amazing on big screen.

[PeterM]

Thanks so much for posting this link Dana. Absolutely incredible. Add madbadgalaxymans thoughts and it really gets you thinking.

[ZeroID (Brent)]

Ok, watched it a few times now and on the 46" TV screen it just jumps out at you. Having some difficulty though with the heavily french accented commentator but getting the gist of it all.

[madbadgalaxyman (Robert)]

The cellular structure of Voids and shells [or equivalently, some people call the edges of the shells 'walls' and 'filaments' made up of tens of thousands of galaxies] is supposedly produced in the so-called 'cosmological simulations' of galaxy formation.

However it is not clear to me that gravity naturally produces this sort of structure. One does also wonder if a mere 14 billion years is enough time to produce supergalactic structures on the vast spatial scale that we do observe them. (individual structures that are hundreds of millions of light years across, in some cases).
I have always wondered, given the rather tight time limitation of only 14 billion years in the Big Bang model, if this is really enough time for these enormous supergalactic structures to form.

[sjastro]

....I have always wondered, given the rather tight time limitation of only 14 billion years in the Big Bang model, if this is really enough time for these enormous supergalactic structures to form.

This is a frequently used argument by Plasma Cosmology and Steady State proponents who advocate the Universe is infinitely old and therefore time is not an issue in the formation of such structures.

What isn't taken into consideration about the Big Bang model is the following.
(1) The Universe was smaller in the past compared to today hence structures would form at smaller relative distances.
(2) Since the density of the Big Bang was greater in the past gravity had a much greater influence in structure formation. Velocities relative to the Hubble flow where higher in the past compared to now.
(3) The temperature variations in the early Universe as seen by the anisotropy of the Cosmic Radiation Background would provide the "seeding points" for the formation of large structures.

Regards

Steven

[Dave2042 (Dave)]

Originally Posted by sjastro

This is a frequently used argument by Plasma Cosmology and Steady State proponents who advocate the Universe is infinitely old and therefore time is not an issue in the formation of such structures.

What isn't taken into consideration about the Big Bang model is the following.
(1) The Universe was smaller in the past compared to today hence structures would form at smaller relative distances.
(2) Since the density of the Big Bang was greater in the past gravity had a much greater influence in structure formation. Velocities relative to the Hubble flow where higher in the past compared to now.
(3) The temperature variations in the early Universe as seen by the anisotropy of the Cosmic Radiation Background would provide the "seeding points" for the formation of large structures.

Regards

Steven

Though isn't this potentially up for debate again if Webb's result about the fine structure constant turns out to be right?

For those who haven't encountered this, Webb at UNSW claims to have found a 'dipole' along which the fine structure constant is greater in one direction and less in the other. One potential implication is that the universe is much, much larger than currently assumed, and potentially infinite. Either of these would blow a large hole in the Big Bang model as I see it (disagreements from anyone?).

Link: http://arxiv.org/pdf/1008.3907v2.pdf

Of course, by Webb's own admission, this is still a pretty speculative result requiring a lot more independent confirmation. At the moment I'd still be backing the consensus as you put it, Steven.

Fascinating video, by the way, Dana.

[sjastro]

Thanks for the info Dave.

One of the criticisms of the data is where the Keck and VLT searches overlap, the combined data indicate virtually no change.
One can be tempted to think that each scope has a systematic error of almost equal and opposite magnitude.
When combining the results the errors cancel giving the null result.

Regards

Steven