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
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
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
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.
quote: until it can be concretely disproven, it really is the best avenue of progress.