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Dark Matter

Posted: Mon Apr 06, 2015 10:06 am
by leohopkins
Perhaps someone with a greater understanding can help me out with this one - but -

(putting the observed gravitation lensing aside for one moment)...

The reason for the hypothesis of dark matter is to explain why galaxies have a more uniform rotation that say, our solar system does. (Neptune for example orbiting the sun slower than mercury)

Now the way that I understand mass and gravity to work; there seems to be a fundamental flaw with the current 'type' of dark matter proposed to explain galactic rotation:

If this proposed dark matter indeed exists, then surely it would exist also within our own solar system and therefore we should see a more uniform rotation of the planets too and neptune would orbit at the same rate as mercury due to dark matter also within our own solar system?

Re: Dark Matter

Posted: Mon Apr 06, 2015 7:27 pm
by andrewp
I think it might have to do with the fact that 100-200 billion suns is a more attractive [sic] target for the stuff than one little sun alone.

Re: Dark Matter

Posted: Mon Apr 06, 2015 7:51 pm
by DCWhitworth
@leohopkins I think your assumption is that dark matter is spread evenly through the galaxy which is not believed to be the case.

I'm not sure of the mathematics involved in the theories but I think someone would have spotted that little issue, if it was an issue ;-)

Re: Dark Matter

Posted: Wed Jun 10, 2015 1:59 pm
by CrunchBerries
Is there a correlation between dark matter and gravity?

I was watching a documentary on colliding galaxies, and there was an example where the galaxies crashed and reacted to each other, but their dark matter components continued on like nothing happened.

So I was thinking, why was dark matter there in the first place if it continued on so easily?

Then I thought maybe it interacts with gravity, which is a very weak force. The dark matter clusters together somehow, but together as a system interacts with gravity in some similar energy level?

I would like to see what happens to that dark matter longer after that collision to see if it decelerate and slowly returns towards a gravity source..

Re: Dark Matter

Posted: Wed Jun 10, 2015 7:44 pm
by DCWhitworth
I'm not quite sure I get your point, but the current theories suggest that dark matter interacts only through gravity.

Re: Dark Matter

Posted: Wed Jun 10, 2015 11:03 pm
by CrunchBerries
Sorry for the misunderstanding, I was talking about the bullet cluster. You answered my question lol.