A Conversation for Dark Matter

Fried Brains.

Post 1


I've been trying to figure out this dark matter thing and being a comlete novice at most science and astronomy it's fried my brains. But heres how far I've got and hope someone can fill me in with the gap I'm at so i can start making stuff up again. And to top it off my printers just broke so I can't look at my notes properly.
OK so what we think we know about dark matter is that it acts much like a neutrino. So on the basis of neutrinos they have very teeny little mass or none at all, are stable, and travel if not at the speed of light then almost. Which could account for a large mass at the end of it all.
So my problem arose when i read an article about WIMP and it suggested that the movement of dark matter seems to be in a constant direction (from a linnear point of view) and that the Earth is moving against the dark matter flux in June and with the flux in December. So there would be a slightly higher bombardment in June for experimental purposes.
So this got me thinking. Taking our North as the North half of the galaxy and South as South ect. Then in relation to the actual galactic orbit is the Earth traveling with the flow in December and against it in June as well?
What I'm trying to ask, if the above theory on dark matter flux was correct, is dark matter orbiting our galaxy with the flow, against the flow or is it's flux directly away or towards the centre of the universe?
I know it's a lot to ask and is getting more confusing every time i think about it ( I don't find it easy thinking in such awsome terms I suppose) but basically it would give me an idea of how dark matter would work on a basic level and if it had stimulus just to use as a starting reference point.

Is there anyone who knows where I'm trying to go?

Cheers. Baobhan Jex

Fried Brains.

Post 2

Mammuthus Primigenius

I'll try not to fry any more brain cells smiley - winkeye

WIMPs are like neutrinos as they only interact very rarely with other particles. But unlike neutrinos they are heavy particles and more slowly (about the same speed as the earth).

As the interaction rate is so low, WIMPs behave quite differently from other particles. A typically WIMP has not met another particle since it was created shortly after the big bang. They are drawn to our galaxy by gravity and establish random orbits around the galactic centre.

Therefore the dark halo of the galaxy is just a cloud of WIMPs moving in random orbits, there is no net flow of dark matter. However ordinary matter (like the Earth) tends to all orit the galaxy in the same direction - i.e. the galactic disk is rotating.

Therefore the average velocity of the earth relative to the dark halo is given by the speed at which the earth orbits the galaxy, which varies depending on the time of year as the earth orbits the sun.

However this is just the most popular theory. There are other theories which suggest the dark halo is rotating, either in the same direction, or the opposite direction as the visible galaxy.

Fried Brains.

Post 3


Excellent. Cheers for that info. I guess maybe all of the above could exist but it's best to jsut focus on finding anything to start with. I also didn't know that WIMPs moved so slowly. Is a neutralino an example of a possible WIMP?

Right time to get my thinking cap back on start from scratch again.smiley - puff. If you've got any more info and can be bothered I'd like to read up on it. Cheers.

Fried Brains.

Post 4


Well here is some more info on potential ideas of dark matter. Firstly don't fry another brain cell.
Well in the early universe, conditions were so hot that laws of physics didn't operate. So when matter was created by compressing high amounts of energy, very often the result wasn't of equal produce. This is because the law of conservation of mass states that what goes in must come out (basically), so when matter went through the reactions in high temperatures, most of the mass would often go missing creating unconventional matter, which left matter alone, but due to its unconventional properties it was invisible to the naked eye.
This was dark matter. I hope it helped.smiley - winkeye

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