On the other hand, the motion of the solar system is essentially why we may be able to measure dark matter at Earth. If dark matter is made up of WIMPs, then our ability to observe its direct (non-gravitational) effects depends heavily on the velocity distribution function of dark matter at Earth.<p>Because the non-dark matter component of the galaxy formed a disk while the dark matter halo will likely have remained roughly spherical, we expect that Earth is moving through the dark matter halo at O(230 km/s). This has a few important impliciations. First, it increases the expected kinetic energy of WIMPs in our frame, thus resulting in more energetic WIMP-nucleon interactions, making direct detection (which essentially consists of having a bunch of material and waiting for an unexplained interaction within it) significantly more feasible. Secondly, it leads to an annual modulation effect (as reportedly, controversially. observed by DAMA or COGENT) related to the Earth's motion around the sun. Thirdly, it means that recoils from interactions with WIMPs will have a preferred direction away from the direction of the Earth's propagation through the galaxy. Because no potential terrestrial background can have this signature, a number of groups, including the one I work with, are trying to develop detectors sensitive to the direction of low-energy recoils in order to potentially unambiguously detect WIMPs.
I have a question--please let me know if I'm way off base here. Gravity distorts space and we postulate the existence of dark matter from the distortion of space without corresponding mass/matter. Why must space without matter/mass be non-distorted to begin with?
Interesting article, I was hoping that dark matter would prove to be observable in our solar system.<p>I'm more curious about dark energy though. Hopefully in my lifetime, we can figure out what dark energy is. I'm curious what dark energy does to time since it accelerates the expansion of space. The next golden age of science resides in our understanding of the unknown matter and energy that we are currently observing.