What is dark matter and whats it's purpose?

Question

Apparently black holes may hold the keys to galaxy formation.

http://richarddawkins.net/article,1819,Huge-Black-Holes-May-Hold-Keys-to-Galaxy-Formation,Marc-Kaufman-Washington-Post

Now if this is true and black holes are recycling units for the universe then:-

Where will the energy go after it's released back into the universe? Not to the already formed systems surely but to new one's, is this dark matter gravity? And does this mean that the universe is exapanding?

Answer 1

Dark matter is any matter that doesn't interact with photons and is therefore invisible. For example Neutrino's. The exact nature of the dark matter in the universe is currently unknown. As for a purpose, that suggest a creator.

Blackholes and galaxy formation. There is a link between Dark Matter Halo size and galaxy mass, The Supermassive blackholes in the centre of galaxies clearly play a part in galaxy evolution although what that is, is as yet unclear.

Where will the energy go after it's released back into the universe - Back into the universe.

Not to the already formed systems surely but to new one's, is this dark matter gravity? No

And does this mean that the universe is exapanding? No but it is.

Note

Steve B you have no way of telling if the black holes are formed after,before or with the formation of the galaxy. So unless you are a published researcher in this area (and I can see one from where I'm sitting) I wouldn't make such sweeping statements.

MS Minger.

You have a number of good points in your answer. Yes the cosmological constant was put in by Einstein to keep the universe in a steady state. However, the universe isn't in a steady state - it's expanding. As it expands we move away from a matter dominated universe to a dark energy dominated one, hence the gravitational forces become less important whilst the expansion force created by dark energy becomes more important. So no big crunch because if gravity isn't  strong enough now to stop the expansion - it will never be.

Answer 2

Wrong  = contrary to accepted cosmology theory in almost every respect ..

The massive Black Holes at the centers of galaxies are formed AFTER the galaxy forms, not BEFORE ..

Of course 'evaporating' Black Holes release energy into the physical universe ... ..

Dark Matter is a theory that explains how galaxies 'stick together' ..

It is postulated that the expansion of the universe is accelerating due to Dark Energy =  the postulated Dark Matter has normal Gravity, and Gravity slows down the expansion of the universe ...

Go take a basic astronomy course  = even evening classes will cover the basics ...

Reporters took 'art' degrees - not science degrees - so while they may be good at 'telling a story' ('lies to children') they are quite incapable of recognising the difference between fact and fiction :-)

Answer 3

Firstly, to the person above me, Richard Dawkins is not a reporter, he is an extremely emminent scientist.

But nobody truly knows what dark matter is. It doesn't appear to be made of atoms like everything else and therefore can't be contained or captured, and light doesn't reflect off it so it can't be seen. They know it exists though because of the gravitational effect it has.

But yes, we already know that the universe is expanding...whether this has anything directly to do with dark matter isn't known.

I read somewhere that dark energy and matter may be Einstein's "cosmological constant" - a device he used to try and prove steady-state theory which he later regretted and retracted. But, maybe, dark matter will actually stop the universe expanding infinitely and at some stage will bring it all back to a single point in order to start again - the big crunch.

Answer 4

Dark matter is really just what its name suggest,matter you can't see nothing else. Theoretically it just doesn't reflect light. It isn't there to balance gravity its there to balance the mass.

Answer 5

It is the matter mathematically needed to balance the equations of gravity in the universe. Mathematically there is not enough gravity to make celestial systems behave the way they do, so theoretically this “dark matter” must exist. 4% of the universes' total density is mass as you and I know it, 22% is dark matter, and 74% is dark energy.

Answer 6

it's the oppisite of antimatter and they can't get a reading on it yet ... check out the history channel they have a documentary of what scientist think of the issue..