A few promising prospects exist

Dec 29, 2008 22:21 GMT  ·  By

The strive to find the mysterious dark matter has been an undertaking that no one returned from successfully, because of the intricate nature of the stuff. In other words, no one can see it, smell it, taste it or touch it, although it resides everywhere around us, and inside us as well. Particle physicists hypothesize that this matter makes up a large part of our universe, alongside dark energy. Visible matter, such as galaxies, stars, all the planets and other celestial bodies only compose some 4 percent of the matter the entire universe is made of.

Astrophysicists say that the dark matter has to be out there, because otherwise all the galaxies would fly apart, as would all the planets in every solar system. Gravity can only do so much, they say. According to their speculations, as-of-yet undiscovered particles must make up this strange form of matter, particles that are somehow electrically neutral and do not interact with light, therefore being invisible to any human detection method, including infrared and ultraviolet scans.

"There is no consensus actually at all as to what dark matter is," says Gerard Gilmore, a University of Cambridge astronomer, and author of an essay on the quest for discovering dark energy.

The WIMP (Weakly Interacting Massive Particles) is one of the most embraced hypotheses of the moment. It stipulates that massive particles, roughly 100 times heavier than currently-known protons, and neutral in charge, make up the enormous amount of dark matter that is believed to exist everywhere around us.

If so many assumptions seem disconcerting, think about the fact that most forces governing the world, including gravity, were at some point or another taken for granted, and it took revelations by brilliant scientists to identify and catalog them.

"The assumption is, there will be whole families of new types of particles. The challenge then is to say, well OK, we now then have a new set of ingredients in our recipe for how nature is put together, but what is the recipe that uses this set of ingredients? I.e., what mix of these particles does nature actually use to create the universe, and how?" Gilmore told Science, referring to the potential success of the Large Hadron Collider (LHC), the largest particle smasher in the world.

The European Space Agency (ESA) also has a plan for determining the presence of dark energy, namely the Gaia satellite, which will observe the positions of some 1 billion stars, as it moves away from our solar system.

"What Gaia will do is measure the distances of stuff and measure how they're moving in three dimensions around space to much better precision than we've had before, which will allow us to weigh things on all sorts of scales down to the smallest scales we can find. They will tell us to exquisite precision how the dark matter is distributed in space, which is the recipe we need to determine its properties," Gilmore added.