Dark Matter Discovered Near Solar System? 179
gpronger writes "The ATIC (Advanced Thin Ionization Calorimeter) has potentially discovered the presence of dark matter close (only 3000 light-years) to our solar system. The system detected a large-amount of high energy cosmic rays which match the theoretical signature of dark matter annihilating itself. The universe is believed to be composed of about 25% dark matter, but there has been little evidence of it. This discovery, if correct, would be the first."
The paper was published in Nature , but it requires a subscription to see beyond the abstract.
Re:25%? Wait a minute.. (Score:2, Interesting)
I believe you're thinking of dark energy - it's currently thought to be about 74% of the universe's mass/energy. Roughly 22% is guesstimated to be dark matter, and about 4% is "normal" matter.
Re:math hosers. (Score:3, Interesting)
...They have an energy dependent signal....
So there is a signal, but what produces it is still only a conjectural speculative interpretation of an observation. From experiments here at home, such radiation is ONLY and ALWAYS produced by charged particles. Instead of dark matter, the radiation could be produced by naturally occurring interstellar or intergalactic particle acceleration. It could even be some space alien's giant version of the LHC. All we observe is lots of radiation, but then they are guessing what produces it. If it is dark matter, then there should also be dark antimatter.
We know from measurements that the sun produces or is involved with an enormous amount of electrical current we call the solar wind. Even though the earth intercepts only a minute fraction of this, some strong outburst of solar electricity has shut down power grids and communication systems.
Even if there is an interstellar electric field of only millvolts per kilometer, the vast distances of space can still accelerate charged particles, mostly electrons, to immense energies. These could produce much radiation when they encounter intense magnetic fields we have observed. Annihilation of any sort is only one other, far less likely possibility.
Re:Kinda Reminds Me of the Face on Mars (Score:2, Interesting)
I bet you believe in creationism too, huh?
I understand the argument you're making, it's the old 'if it's a horse, it's a horse; not a zebra' argument. However, physicists are not willy-nilly declaring stuff dark matter because that's what they want to find. There is actually a lot of hard-core science to support what you call
outlandish conclusions(black holes, wormholes, dark matter, dark energy, big bang, parallel universes, etc.)
The fact that YOU don't understand it is more a statement about yourself, not the science.
Re:There is no such thing (Score:3, Interesting)
Well *something* is warping spacetime this way and that, and that's what they call dark matter and dark energy respectively. Now the question is what does the warping.
Re:math hosers. (Score:4, Interesting)
http://en.wikipedia.org/wiki/Technetium-99m [wikipedia.org]
There are lots of reactions that produce EM radiation. This one is used in medical imaging. Positron-electron annihilation also creates gamma rays. Yes, those are charged particles, but the gammas are not produced by the charges moving. That reaction is also used every day in medical imaging.
All these resources available on the Internet and you can't even educate yourself. Such a waste.
Re:Common doublespeak! (Score:3, Interesting)
OK, so scientists look at how galaxies behave and notice that they are behaving as if they had more mass than we can observe them having. Now there are two options: either 1. galaxies contain mass that hasn't been observed or 2. the theories of how the gravity works need to be revised. Both of these options are being studied, and so far the 'unobserved mass' hypothesis seems to explain obsrvations pretty well.
According to you, however, option 1 should have been discarded in the first place, for some ideological reason.
Re:Common doublespeak! (Score:3, Interesting)
Scientists looked at the data and saw it didn't fit, so they made up some goofy theories that "explained" why their calculations didn't match reality.
Yeah, uh, DUH. That's what science IS. You make up a theory to describe what you observe. If it doesn't fit, it's wrong, so you make up a new one and see if that works.
As another poster said, you seem to have some kind of ideological prejudice against the particular theory they came up with. But it's foolish to criticize them merely for coming up with a new theory in the first place. That's what they're SUPPOSED to do.
No! My theory isn't WRONG! It's ... err... invisible matter that can't be detected in any manner!! Yeah! That's the ticket!
So you're mocking the idea that there can be particles out there which don't interact with light, despite the fact that we know such particles exist, e.g., neutrinos? The main difference between neutrinos and dark matter is that dark matter needs to be heavier than neutrinos. And dark matter particles have been PREDICTED to exist for entirely independent reasons in order to explain other mysteries in particle physics; indeed, the Standard Model itself arguably already contains dark matter candidates (axions). According to you, this is an insane idea to be derided, despite the fact that its predictions agree with numerous observed phenomena including galactic rotation curves, galactic cluster orbits, large-scale structure formulation, cosmology and the CMBR, gravitational lensing, galaxy collisions, etc.
Re:math hosers. (Score:3, Interesting)
I can't get past the paywall to see how many sigmas they put on the detection event, but I seriously doubt the situation is as simple as you claim. I personally find it unlikely they would get published in Nature with a signal that is statistically indistinguishable from background noise. Unfortunately, I can't read the paper to see what they did. I'm not a particle astrophysicist, but you don't mention at all what the error bars are; a 150 GeV difference can be big or small depending on how precise the measurement is. The location of the peak is also not the only factor which you can use in detection; the height and shape of the I(E) curve matters, as well as the time signature (light curve). Quite possibly they found a real source. Whether that source is dark matter is another issue.