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A visualization of particles jets in the CMS. Yellow is the path of the particles, while blue and red represent energy detected from the particles.  (Source: CERN/Imperial College of London)
Discovery of dark matter's behavior would solve many outstanding mysteries in physics

Dark matter makes up five times more of the universe's mass than visible matter (~25% vs ~5%), yet scientists have yet to directly observe this ultra-abundant substance.  Scientists also have yet to observe dark energy, which may well beat out normal energy in universal abundance.  This lack of direct observations means that scientists know precious little about two of the most important physical components of our universe.

That could soon change.  CERN's Large Hadron Collider, a 17-mile long circular underground track that is chilled to almost zero degrees Kelvin, is recording incredibly violent collisions, the likes of which haven't been seen since billions of years ago.  Those collisions will likely produce exotic substances like dark matter, which will be analyzed by the LHC's instruments, unlocking long debated mysteries of physics.

Scientists think they are making progress in the hunt for the SUSY – also known as supersymmetric particle, or 'sparticle'.  Scientists believe the sparticle may be the mysterious dark matter, given its theoretical stability.

In order to detect sparticles, scientists must probe the matter resulting from the collision for the absence of energy and momenta signals -- the sign that a sparticle was produced, rather than a standard particle.  This lack of energetic emissivity is the reason why dark matter is dark -- it does not transfer energy to photons, like standard particles.

More specifically, the researchers are trying to detect a "jet" of particles traveling in the same direction, post proton-beam collision, that lack a significant amount of detected energy and momentum.  

Professor Oliver Buchmueller [profile], a faculty member at the Department of Physics at Imperial College London who is doing research at CERN, describes the LHC team's findings, stating [press release], "We need a good understanding of the ordinary collisions so that we can recognise the unusual ones when they happen. Such collisions are rare but can be produced by known physics. We examined some 3-trillion proton-proton collisions and found 13 'SUSY-like' ones, around the number that we expected. Although no evidence for sparticles was found, this measurement narrows down the area for the search for dark matter significantly."

The CMS (compact muon solenoid) detector was co-designed by faculty at the Imperial College, one of Europe's best physics schools.  

Professor Geoff Hall [profile], another Imperial College physics faculty member working at CERN, describes the recent detection of "SUSY-like" streams of particles, stating, "We have made an important step forward in the hunt for dark matter, although no discovery has yet been made. These results have come faster than we expected because the LHC and CMS ran better last year than we dared hope and we are now very optimistic about the prospects of pinning down Supersymmetry in the next few years."

Later this year, physicists will run more trials, which they hope will verify the existence of dark matter in the stream.  They also hope that the theory of supersymmetry will be verified as an accurate description of dark matter, allowing the Standard Model of particle physics to be officially extended.

Looking ahead there's also much hope that the higher-energy collisions might yield a legendary Higgs boson, which would offer much more insight into the behavior of the universe.  The LHC's other major detector -- ATLAS (A Toroidal LHC ApparatuS) -- was designed to search for the Higgs boson.

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RE: Wait
By JediJeb on 2/2/2011 1:38:28 PM , Rating: 2
You're also basically saying go detect something that interacts with nothing but gravity, without using gravity.

Doesn't the fact they are using the LHC and its detectors to try to observe dark matter particles say the best physicists on earth are trying to do just that, observe something that only interacts with gravity by using something other than gravity to detect it?

Which solves the problem of the spin of galaxies - galaxies spin just as fast at the center as they do at the tip of the spiral. If you think of a crane, if the base turns, the tip of the crane doesn't go really fast but lags behind twisting the metal. The visible mass in galaxies is about 1/10th what is needed for this to occur. The OBSERVED mass of dark matter through gravitational lensing is exactly the amount needed to counter this.

But if you think of a CD or LP, the whole disk spins at the same rotational rate, though linear velocity is faster at the outer edges. Also the stars in the galaxy are not connected by a hard physical link as the crane is in your metaphor so they are being propelled by different forces.

We know dark energy is there because the universe is expanding, and the rate of expansion is expanding. That's the same as throwing a ball in the air, and instead of it comming back down, it goes up and into space faster and faster. Something is pushing the galaxies away from eachother, despite the huge gravitational pulls.

This one also gives me pause when thinking about it. We say the rate of expansion is increasing because we observer greater red shifts in the galaxies that are farther away. But that seems counter to what we should observe, since a greater red shift means something is moving away at a higher velocity. If galaxies were moving away from us at higher velocities 10 billion years ago, while other galaxies we observe are moving away as slower velocities millions of years ago,(closer galaxies have less red shift), wouldn't that say the expansion is slowing down? We can not take a snapshot and say look these farther galaxies are moving faster and the closer ones are moving slower and extrapolate that expansion is increasing because of the temporal displacement of the data being used( every point of data is taken from a different time as well as place).

Oh and we have observed black holes. Through gravitational lensing, through watching the stars at the center of the galaxy orbit at an incredible speed around a supermassive object we cannot see in any way, and watching a super nova blow up then that part of space going dark.

This goes back to the first, seems we are observing the center of the galaxy moving faster than the outer edges, or were the first comments wrong in that the outer edges are not actually moving as fast as the inner parts? IF the laws of gravity break down at the very small scale, how do we know without a doubt that they do not also vary at the very large scale. We observe it in almost all galaxies, that they seem to not follow what we have set as our laws of gravity, but instead of questioning the laws of gravity we have postulated, we instead say the laws can not be wrong therefore something else must be causing it. If we never prove dark matter exists, will we then have to say the laws of gravity could be wrong or do we have to make up some other explanation?

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