The universe and dark matter

The universe is made mostly of dark matter and dark energy," says Saul Perlmutter, leader of the Supernova Cosmology Project headquartered at Berkeley Lab, "and we don't know what either of them is." He credits University of Chicago cosmologist Michael Turner with coining the phrase "dark energy" in an article they wrote together with Martin White of the University of Illinois for Physical Review Letters.

In the May 28 Science article, Perlmutter and Neta Bahcall, Jeremiah Ostriker, and Paul Steinhardt of Princeton use the concept of dark energy in discussing their graphic approach to understanding the past, present, and future status of the universe. The Cosmic Triangle is the authors' way of presenting the major questions cosmology must answer: "How much matter is in the universe? Is the expansion rate slowing down or speeding up? And, is the universe flat?"
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What are your thoughts on the questions posed? I�ve also hear that our matter only makes up about 20 %. So what is this dark matter and on what level does it exist?

[edit on 27-6-2004 by DaTruth]

what do you mean "on what level does it exist?"

Dark matter is the same stuff as normal matter, it's just that we cant see it.

I often wonder about this one from a non expert point of view. I kind of think dark matter is like water [non expert bit showing me up] but not, if you know what I mean. The deeper you get the darker it appears. As no one has ever been that far out in space. Who knows the further out you get the lighter the universe might become, depending on how deep in the universe earth is.

Dark matter does exist, we just are trying to find out WHAT it is comprised of.
Whether it is a particle that violates the Standard model or not..
It's not like a uniform distribution of dark matter throughout the universe, it's clustered, much like galaxies.. Infact, from my understanding, it is part of galaxies, like a circle/sphere around the galaxy, just like stars on the edge of the galaxy and well pretty much anywhere but the centre, that we just cannot see.

Dark matter and energy, sounds complicated. If anyone has any info, please share. You never know the us is probly already trying to make a bomb out of it. lol

lol
dark energy as it is commonly called is in fact vacuum energy. There is a strange energy that continues to suck and it is unaccounted for (I'm not at all sure on the specifics), it's something to do with the rate of expansion of the universe (E.g. the rate of expansion continues to increase, indicating there is something sucking it to make it grow faster).
Dark matter is pretty straight forward, it's pretty much definitely exists, we just need to find out what it's made of..
It has been speculated that dark matter is actually gravity waves travelling from other branes onto our brane (see M-Theory).
On the other hand, it could just be a bunch of black gooey stuff =p

Originally posted by browha
Dark matter is the same stuff as normal matter, it's just that we cant see it.

No, the results of big bang nucleosynthesis calculations contradict this. Only 10% of the matter can normal, baryonic, matter (source).

To be honest, I don't like dark matter and dark energy. Add in the amazingly accurate results of MOND and I think maybe we have to take a step back and look at everything critically again. What we have here now is a theory that worked pretty well, but some observations didn't work with the theory, so we fixed it with invisible matter and energy. Maybe there really is dark matter and energy, but the fact is that we can't verify our theories until we detect it. Maybe the dark matter is really normal matter and we screwed up big bang nucleosynthesis. Maybe we find out that there are supersymmetric versions of particles, or that monopoles or cosmic strings really exist. I don't know, but I doubt that many cosmologists are really comfortable with dark matter and dark energy.

Until we have a better theory, I say we stick to this one, with its problems.

I haven't studied dark matter for a long time, but my take was that they were just the anti-particles with opposite orientations of their repective "light" matter particles. So that the charges are opposite allowing for annihilation.

Originally posted by Jamuhn
I haven't studied dark matter for a long time, but my take was that they were just the anti-particles with opposite orientations of their repective "light" matter particles. So that the charges are opposite allowing for annihilation.

No, I think you're talking about antimatter here. Antimatter annihilates normal matter. Dark matter is basicly all the matter we can't see, but that seems to be there, because we can record its gravitational influence. Dark matter can be a lot of things: dark normal matter like planets, neutrino's, unknown (maybe supersymmetric) particles or topological defects (like magnetic monopoles or cosmic strings).