[ExI] Milky Way is on the outskirts of 'immeasurable heaven' supercluster

[Anders Sandberg]

Awesome. BTW, their own longer version of the film is at http://irfu.cea.fr/laniakea
One of the things I have been reading up on today (for my upcoming paper about long-term information processing in the universe) is what structures will remain gravitationally bound when the acceleration speeds up. Laniakea is estimated 160 Mpc across and has 10^17 solar masses. The criterion for remaining bound is M_{obj} / 10^{12} M_{\sun} > 3 ( r_0 / 1 Mpc)^3 (this is from http://arxiv.org/abs/astro-ph/0305211 ). So in this case the LHS is 100,000 and the RHS 1,536,000... so it is 15 times too light to keep together. Incidentally, that is the factor in the paper for how bound we are to the Virgo cluster - probably not a coincidence. 
So while we are in Laniakea right now, we will not always be. Unless we move. Or even better, move the galaxies closer together! I have been spending the afternoon estimating the mass-energy costs for large scale megascale engineering (on the K3 level): the relativistic rocket equation applies to galaxies too. There are some problems in estimating from how far away galaxies can be moved together (you need to move faster than the Hubble flow, but it is accelerating, so if you are too slow you will never reach the goal), but getting into the core of Laniakea should be fairly easy. 



Anders Sandberg, Future of Humanity Institute Philosophy Faculty of Oxford University


BillK <pharos at gmail.com> , 3/9/2014 10:09 PM:
This places the Milky Way in a vast network of neighbouring galaxies 
or "supercluster" that forms a spectacular web of stars and planets 
stretching across 520m light years of our local patch of universe. 
Named Laniakea, meaning "immeasurable heaven" in Hawaiian, the 
supercluster contains 100,000 large galaxies that together have the 
mass of 100 million billion suns. 
 
<http://www.theguardian.com/science/2014/sep/03/milky-way-laniakea-galaxy-supercluster-immeasurable-heaven> 
 
 
100 million billion suns!  And that's just our supercluster. 
 
It's a big universe out there. 
 
 
BillK 
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