World Science: Signs of dark matter found?

Tiny Little Raven · Nov 21, 2008

World Science
Signs of dark matter found?

Telltale signs may have turned up of a mysterious substance that pervades the universe but has never been seen, astronomers say.

The “dark matter” is believed to make up five-sixths of the physical material in the universe, but has revealed no sign of its existence other than through its gravitational pull. For decades, physicists have tried to figure out just what the stuff is.

Some theories hold that signature signs of dark matter could be detected when particles of the stuff meet and annihilate each other. These events would result in emissions of electrically charged particles.

Such a sign of dark matter annihilation may have been detected high above the skies of Antarctica, according to an international research team. The group reports the findings in the Nov. 20 issue of the research journal Nature.

The investigators recorded what they said was an unexpectedly high amount of the charged particles, called electrons, at energies consistent with theoretical predictions about the dark matter.

The specific dark matter “annihilation signature” is consistent with the idea that dark matter consists of components called Kaluza-Klein particles, according to the research group. These particles emerge from theories of the universe involving extra dimensions beyond those which we can normally detect—theories that in turn have been invoked to show that the various forces of nature could possess an underlying unity.

However, the detected electrons could also come from celestial objects unrelated to dark matter, such as so-called pulsars or microquasars, the team noted.

The detections were made using a high-altitude balloon-borne device called an advanced thin ionization calorimeter.

Because, as Einstein showed, matter and energy are ultimately equivalent, dark matter would also be a part of the energy in the universe. Cosmologists estimate that dark matter comprises 23 percent of all energy in the cosmos. An equally mysterious “dark energy,” which drives galaxies apart, is thought to take up another 73 percent or so. Ordinary, visible matter is believed to represent only four percent of the total energy.

The team consisted of researchers from Purple Mountain Observatory in Nanjing, China; the Marshall Space Flight Center in Huntsville, Ala.; the University of Maryland; Moscow State University; and Louisiana State University.

freyar · Nov 21, 2008

There are actually a number of experiments, all with tantalizing hints of dark matter detection, but it's difficult to make sense of all of them at once (and, in fact, to know whether they have all been correctly analyzed). However, there has been some recent work that presents a theory consistent with the experiments. Time will tell -- if it's right, the LHC will find this stuff.

Incidentally, I've recently been working on Kaluza-Klein dark matter models myself.

Angel Tarragon · Nov 22, 2008

Very cool.

Treebore · Nov 22, 2008

When they get that particle accelerator up and running in France/Sweden they will hopefully find very solid evidence, and maybe even create some black holes while they are at it. Which I hope not. Even tiny and momentary, I rather not think about it.

Even if it does happen, and ends up safe, they'll then push the envelope on how long and how big black holes can be "safely" maintained. The question I don't want answered: What happens when we find out they were wrong about how long they could go?

At least we should know about Dark Matter before that happens.

Relique du Madde · Nov 23, 2008

If I had a band, I'll call it Annihilation Signature... that would be cool. Now if they would fix that collider..

Mustrum_Ridcully · Nov 23, 2008

Treebore said:
When they get that particle accelerator up and running in France/Sweden they will hopefully find very solid evidence, and maybe even create some black holes while they are at it. Which I hope not. Even tiny and momentary, I rather not think about it.

Even if it does happen, and ends up safe, they'll then push the envelope on how long and how big black holes can be "safely" maintained. The question I don't want answered: What happens when we find out they were wrong about how long they could go?

At least we should know about Dark Matter before that happens.

The chance of creating black holes is... slim. The energies the Collider achieves are impressive, but the truth is that cosmic radiation creates similar effects in our atmosphere all the time. Unfortunately, we don't have the kind of detectors in place there to analyze the effects happening there.

Knowing about Dark Matter will do little to affect our knowledge or control over black holes. Despite the natural connection between "dark" and "black", these two are not really related.

(Of course, more generally speaking, we might still gain insights on one field by studying the other. But I wouldn't consider at as something practical useful yet...

)

Treebore · Nov 23, 2008

Mustrum_Ridcully said:
The chance of creating black holes is... slim. The energies the Collider achieves are impressive, but the truth is that cosmic radiation creates similar effects in our atmosphere all the time. Unfortunately, we don't have the kind of detectors in place there to analyze the effects happening there.

Knowing about Dark Matter will do little to affect our knowledge or control over black holes. Despite the natural connection between "dark" and "black", these two are not really related.

(Of course, more generally speaking, we might still gain insights on one field by studying the other. But I wouldn't consider at as something practical useful yet... )

Well, the collider will be looking at a lot of different things. Possibly Black Holes, if they are created, and definitely dark matters existence, and many other questions of Physics. Including the various particles that make up atoms, etc....

So I, at least, know there is no direct connection between dark matter and black holes, other than the same research facility/collider might be able to research both areas.

Personally I do not want man kind knowing how to create black holes. Even small ones. If they learn how to do so, they will try to create bigger and bigger ones. Either on this planet or in this solar system. Losing control of one, that remains in existence after control is lost, would be the end of our planet and solar system.

That is research that we can wait on doing when we are able to travel to other solar systems, or galaxies, to do such research.

Umbran · Nov 23, 2008

Treebore said:
Well, the collider will be looking at a lot of different things. Possibly Black Holes, if they are created, and definitely dark matters existence, and many other questions of Physics. Including the various particles that make up atoms, etc....

Well, let's get something clear - the LHC will look at black holes if they are created, but it is not designed, intended, or expected to create them.

The subject of black holes entered into the discussion by way of people who do not understand the science in full, and who are thus fearful and want the collider shut down.

freyar · Nov 24, 2008

Umbran said:
Well, let's get something clear - the LHC will look at black holes if they are created, but it is not designed, intended, or expected to create them.

The subject of black holes entered into the discussion by way of people who do not understand the science in full, and who are thus fearful and want the collider shut down.

To be absolutely fair, about 10-11 years ago there was a model proposed in which you would expect the LHC to create mini-black holes. However, it is also absolutely true that the recent discussion of black holes at the LHC has been driven by a few fanatics who don't know the science. In fact, I spoke to one of the people who invented that model about a week and a half ago, and he really doesn't believe it to be correct. So, yes, it's certainly not expected to create black holes.

Treebore, I don't know if this will be reassuring or not, but, on the extremely off chance that the LHC does create black holes, it would be very difficult to tell them apart from any of the other possible particles it could create. In particular, as we know from cosmic rays (as Mustrum mentioned above), they either decay extremely rapidly (which is what one would expect from all theoretical considerations) or interact with normal stuff very weakly -- to the point that they'd just go flying off into space pretty much completely unimpeded by the earth or anything on it. There wouldn't be any way to try to capture them, grow them, or control them. They'd just be gone.

Another point is the human one: none of the people involved in particle physics, either theory or experiment, want to destroy the earth or civilization. I know and/or have met a number of these scientists, and these are people with kids, hobbies, and all kinds of attachments. There has been an extreme amount of care taken with this experiment.

megamania · Nov 24, 2008

Umbran said:
The subject of black holes entered into the discussion by way of people who do not understand the science in full, and who are thus fearful and want the collider shut down.

and thus why the Mayan calendar ends at 2012...... silly sciencetists

Joking aside it is both amazing and frieghtening where science is going these days. It doesn't sound like much learning if the energy exists and what it does but IF if exists and we can harness it somehow I'm sure some good will come of it.

Neat. Keep us up to date.