These particles, if they exist, do not generally associate
with ordinary atoms, but they occasionally collide anyway, producing some secondary effects.
The leading theoretical candidates are weakly interacting massive particles, or WIMPs, which should occasionally collide
with ordinary atoms and create a telltale signal.
Not exact matches
Dark energy accounts for most of its mass, exotic dark matter comes in second place, and
ordinary matter — the
atoms we are made of — lands in a distant third place,
with just 4.4 percent.
Dark
atoms and molecules could perhaps clump together into galactic disks that overlap
with the
ordinary matter disks and spiral arms of galaxies such as Andromeda.
Created by essentially strapping a hacked Kinect to an iRobot Create (a sort of blank Roomba platform used by robotics developers) along
with a gutted Intel
Atom computer, the KinectBot uses the Kinect bar's 3D sensors in ways that'd make an
ordinary Roomba hopelessly jealous.
If it all sounds too radical, that may be a good thing: most direct detection experiments, which wait for an
ordinary WIMP to collide
with the nucleus of a heavy
atom like germanium or xenon, have seen nothing (see «Going underground in search of dark matter strikes «-RRB-, for example.
A new measurement by RHIC's STAR collaboration reveals that the force between antiprotons (p
with bar above it) is attractive and strong — just like the force that holds
ordinary protons together within the nuclei of
atoms.
So, Chapman proposed that as soon as one of these oxygen
atoms («free radicals») collided
with an
ordinary diatomic oxygen molecule, they would react together to form a single triatomic ozone molecule (Figure 18).