h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

http://news.bbc.co.uk/1/hi/sci/tech/7774287.stm

Is it me or is this article, interesting as it is, mixing cause and effect?

They seem to be suggesting that black holes (presumably of the supermassive variety) are 'essential' for nucleating the formation of a galaxy.

I would personally think that with the concentration of matter that makes up a galaxy then the gravitational pull of all that mass will almost inevitably lead to the formation of a supermassive black hole at the centre.

In other words, it's not the formation of a black hole that cause the rest of the galaxy to form around it but the formation of a black hole at the centre is an inevitable consequence of the formation of a galaxy...

I guess that this is only inevitable with galaxy over a certain size though. The Magellanic clouds for example don't appear to have a shape indicative of them rotating around a centre of mass.

A fine point I know but I wonder what others think

Seemed reasonable at first sight - but Orcus' comments raise a question:

If not from a suitably massive accretion of matter, where did the first black hole come from?
(unless, of course, it was the *other side* of the Big Bang!)

well, galaxies aren't the only source of matter in the universe.
Black holes do not have to be massive, they can be at the size of an atom.

There is some evidence that some (maybe many) black holes formed in the very early universe. And of course there's the theories that posit naked singularities which could then develop into black holes.

I suspect it is a bit of both, as is so often the case. Some formed from collapsing stars. Others formed at the quantum level - probably from alien civilisations who attempted to build their version of the LHC and then obliterated themselves

Just adjusting the thread title

Fair enough, Ictoan - thanks.

Not eSex on uTube then, Orcus

There would presumably be a pull of gravity towards the center, but I´m not sure the centrifugal force would not counteract it. After all you need a lot of compression to cause a black hole.

hey Orcus - just been reading this:

http://www.sciencedaily.com/releases/2009/01/090106181729.htm

which seems to imply that the black holes came first. Not conclusive but the first time they have been able to check out galaxies from the first 1billion years.

Very interesting, thanks.

Yes it seems my gravitational collapse assumption in the first post was wrong wasn't it.

Good stuff.