Dark Matter.. Dark energy .. the more I find out about it

[Ichingcarpenter]

the less I understand about our existence.

Since Dark Matter is invisible and intangible.

Can someone give some links and some better understanding of it?

I just watched this

http://www.youtube.com/watch?feature=player_embedded&list=PL0F38DB3BC840E5D5&v=muTaKcA3toQ#!

blew my mind

[patrice]

1. The last thing I saw about it was that there are serious DM/E skeptics now. nt

[bananas]

2. They are two different things. nt

[hue]

3. It looks like Cold Dark Matter (CDM) is made up of amixture of particles...

Indeed most matter does not interact with light and what we think of as "our world".

One of the prime candidates for CDM is the Higgsino which is the super partner for the Higgs Boson. This is one very important reason why the discovery of the Higgs boson is so important. In fact the energy level at which it's signal/signature was picked up id exactly where the Super Symmetry theorists predicted it would be. It is within a narrow range which is different from what the Standard Model predicted. Axions are also thought of as part of the CDM mix. The fact that Super Symmetry(SUSY) is congruent with the energy levels at which the Higgs will be found means the universe is quite elegant in its design.
Super Symmetric particles will most likely not be seen or detected at the Large Hadron Collider. But Japan is thinking of building a linear collider that will have the capability to produce them and detect or "see" them.
New papers are being released as we speak that describe what makes up CDM.

http://arxiv.org/abs/hep-ph/9701219

http://arxiv.org/abs/1107.5581

[longship]

4. That's a difficult one, but I'll try

First, there are few serious skeptics about dark matter. It's pretty much settled that it is the real deal. After all, dark matter was basically discovered in the early 1930's by Oort and Zwicky.

The science is pretty simple. They both observed that there didn't seem to be enough mass in galaxies given their speed of rotation. So galaxies have some mass we don't observe which helps them hold together gravitationally. Without this hidden mass, the galaxies would fly apart.

It's only recently that imaging technology has advanced to the point that we can detect it by mapping the positions and velocities of stars in the galaxies to map the dark matter by inference. This is really cutting edge stuff.

The one image that puts dark matter in your face is the imaging of the Bullet Cluster. I recommend that you go to Phil Plait's Bad Astronomy blog at Discover Magazine. He's talked quite a bit about it. Also, Sean Carroll is another good source. Of course, there's Wikipedia.

The leading candidates are WIMPs and Axions. See the Wiki page. Whatever the stuff is, it interacts gravitationally but not electromagnetically, which is why it can't be seen. It has been suggested that it interacts via the weak nuclear force (WIMP).

Dark Energy is not so simple. We have no idea what is causing the expansion of the universe to be accelerating, but apparently this is also a fact. Speculations are that it may be the "cosmological constant" in Einstein's theory of gravity (general relativity). It could be something else, though. It acts like an opposite force to gravity (no, not anti-gravity as in the scifi sense). Rather this is a force that likely permeates all of space, possibly a characteristic of empty space itself.

That's it in a very small nutshell.

Anybody skeptical about dark matter has pretty much been shown to be wrong. It exists, we see its behavior, we can map it out, and its behavior is consistent with existing gravitational theory. Pretty much a done deal.

Dark Energy is less sure, but the data is mounting. We have lots of big eyes on it and it, too, will likely be validated. The one thing we pretty much know is that the expansion of the universe is speeding up. Probably wouldn't do you much good to deny that.

Sorry this is so long, typed on an iPhone, no less.

[Eddie Haskell]

8. It's not a done deal

Anybody skeptical about dark matter has pretty much been shown to be wrong. It exists, we see its behavior, we can map it out, and its behavior is consistent with existing gravitational theory. Pretty much a done deal.

http://blogcritics.org/scitech/article/septillion-new-stars-found-dark-matter/

[longship]

9. Whoa! Hold on for a sec

First of all, this is just one paper. It will take more than that to falsify the accumulated data for dark matter. These measurements are going to have to be repeated and astronomers are going to have to comment on these findings before anybody can state that this is a done deal. I have a problem with the claim that they are seeing red dwarfs at all in these distant galaxies. Red dwarfs are very, very dim. If you don't like that situation that's tough. Welcome to the world of science.

Second, apparently, the paper describes data only for elliptical galaxies. It may be telling that the picture in the article which the author claims to be an elliptical, is not an elliptical, it's a spiral galaxy.

Third, there are some things In the article that are just plain wrong. It's been known for a century that red dwarfs are the most numerous stars. Look up Herzsprung-Russell. Also, it is completely wrong to say that spirals don't have red dwarfs, since that's where they were discovered to be the most numerous stars in the universe.

Third, I do not like the hyperbole in the article. No scientist would use such strong language. And it's no wonder, the cited source in the article is the fucking Daily Mail. The article's author might as well have cited the Weekly World News. Needless to say the Mail is not a reliable source.

There are competing theories to dark matter. The main one is called MOND, modified Newtonian dynamics. Look it up; it's interesting stuff. Could discovery of more red dwarfs eliminate the need for dark matter? Not bloody likely as there is many times more dark matter in the universe than normal, baryonic matter. I'm sorry if some people don't like that fact. It very much seems that it's true. There are still some cosmologists adhering to MOND, but at this time it doesn't look like MOND is going to pan out.

But don't believe me. Check it out for yourself.

I think I'm done here.

[Eddie Haskell]

10. I didn't imply it was a done deal, you did.

The existing weight of evidence is on the dark side, but we don't even know what dark matter is: http://www.physorg.com/news/2012-03-dark-core-defies-explanation.html

There are well respected scientists who are skeptical of its existence: http://www.physorg.com/news/2011-08-dark-illusion-quantum-vacuum.html

I didn't like the artical either and I'm not claiming dark matter doesn't exist, but there are many questions left to be answered and I'm simply pointing out that we have much to learn.

[longship]

11. Okay, no prob

The article is horrible, and it cites the Daily Mail. So I mistakenly took the position of the article for your position. My bad, there.

However, maybe you should have vetted the article better. But I can't complain too much about that either since part of the purposes of these forums is to do precisely that.

At least there was no chair throwing about the issue.

[tama]

5. A tongue in cheek theory

Goddess Platonia found Einstein's theory mathematically beautifull so it granted it empirical verification, but being also a great jester Platonia also empirically supported the cosmological constant aka "Einstein's biggest mistake" in the form of dark matter and dark energy, so now we are stuck in trying to solve that riddle.

From what I hear, number theoretically scalable values of hbar is the so far most pleasing idea to Goddess Platonia to solve this riddle.

[eppur_se_muova]

6. How about a book rec ?

http://www.powells.com/biblio/95-9780393071337-0

This was out a few years ago, so your local library may have it.

[Gore1FL]

7. Here are a few things

This talks about it a little bit and speaks of the Cosmological Constant in the Theory of relativity. I'll warn you the guy is snarky.

&fb_source=message

Brian Cox talks about it very briefly here:

at 9:39

Though if you want a background on the standard model, start at 3:40.

It's well worth watching the whole thing in it's entirety--but not necessarily focused on what you are looking for.

[didact]

12. Check out The 4 Percent Universe by Richard Panek

The 4 Percent Universe: Dark Matter, Dark Energy, and the Race to Discover the Rest of Reality [Hardcover]
Richard Panek (Author)

http://www.amazon.com/The-Percent-Universe-Discover-Reality/dp/0618982442

[DreamGypsy]

13. Some resources for general astronomy and cosmology information

My favorite book for astronomy and cosmology topics is The Cosmos : Astronomy in the New Millennium, Third Edition, by Alex Filippenko and Jay Pasachoff It's expensive, but worth it. The book is a college level textbook and has associated online course materials. Filippenko is an Astronomy professor and researcher at Berkeley; Pasachoff at Williams College.

The book has a good 4 page explanation, including just enough mathematics, about how galactic rotation curves can be used to determine mass and why flat rotation curves of spiral galaxies indicate the presence of additional mass that is now termed Dark Matter.

Filippenko was on one of the teams credited with the Dark Energy discovery...his car license plate N DARK G.

For a good, entertaining introduction to Dark Energy and to Filippenko's engaging and entertaining teaching style I recommend viewing Dark Energy and the Runaway Universe on YouTube - a lecture he gave at the University of Santa Barbara. (for some reason my attempt to link to the lecture is working - just search for the title and Filippenko, sorry). The video is about 2 hours long so sit down with a beer to enjoy it.

If you really get hooked on Filippenko, as I did, I also highly recommend his Teaching Company course Understanding the Universe: An Introduction to Astronomy, 2nd edition. The course starts with very introductory material, so it's a little slow to start, but covers basically all of the interesting topics of The Cosmos text book, but not in as much depth. Lecture 92 on the Big Bang is astounding. There are ninety-six 30 minute lectures in the course so set aside some time. I did the lectures 2 or 3 every evening when my wife was away in Australia for 3 weeks. I affectionately think of the course as "The Universe in 96 beers". (A note on the Teaching Company pricing: The courses have very high list prices, but go on sale frequently, often 70% off. During a year, almost every course will be on sale at least once. I think I paid about $150 for Introduction to Astronomy)

Hope you find these resources useful!