Introduction
Dark Matter, according to hypothesis, is a
kind of matter that accounts for a large part of the total mass in the
universe. It cannot be seen with telescopes, simply because it does not emit or
absorb light or any electromagnetic radiation. Its existence is inferred from
its gravitational effects on visible matter, radiation and the large-scale
fabric of the universe. Dark matter is
estimated to constitute more than 90% of the matter in the universe.
The dark matter hypothesis
arises from calculations concerning the Big Bang theory. There is insufficient
observed matter to account for the current stability of the universe. If the
Big Bang happened as postulated, and the universe contained only observable
matter, then it should by now have spread itself into complete dissociation.
Therefore, astrophysicists propose that there must be much greater gravity
caused by matter, which cannot be detected by any current method. This is the
dark matter proposed, and Big Bang astrophysicists assume that 84% of all the
matter in the universe is dark matter.
Scientists know dark matter exists
by its gravitational pull but, unlike regular matter and antimatter, it's so
far been undetectable. Regular matter accounts for about 4 percent of the
universe's mass, and dark matter makes up about 25 percent. The rest is dark
energy, which is also a mystery.
Case Study
What's regarded
as the world's most sensitive dark matter detector was lowered into a
70,000-gallon water tank nearly a mile (1.6 kilometers) beneath the earth's
surface, shrouding it in enough insulation to isolate dark matter from the
cosmic radiation that makes it impossible to detect above ground.
The search in
South Dakota began in 2003 after the Homestake Gold Mine in the Black Hills'
Lead, South Dakota, shuttered for good. Scientists came to know about the site,
and in July, after years of fundraising and planning, the LUX detector was
moved into the Sanford Underground Research Facility, 4,850 feet (1,478 meters)
below the earth's surface. It took two days to ease the phone booth-sized
detector down the once-filthy shaft and walkways that originally opened for
mining in 1876 during the Black Hills Gold Rush. There, the device was further
insulated from cosmic radiation by being submerged in water that's run through
reverse osmosis filters to de-ionize and clean it.
Scientists are
currently working to finish the plumbing needed to keep the xenon as clean as
possible. The xenon, in both liquid and gas form, will fill the detector and be
continuously circulated through a purifier that works much like a dialysis
machine, pulling the substance out to remove impurities before pushing it back
into the detector.
