2.3 Dark Matter Evidence Summary

summary

Evidence for dark matter includes Einstein’s (gravitational) lensing, by which mass bends light.
By looking at background bright objects, we can learn how much mass is present between the stars and us.
The distribution of galaxy clusters shows mass between galaxies.
Dark matter does not interact electromagnetically or via the strong nuclear force.
We would not exist without dark matter because ordinary atoms would not clump together without dark matter; in fact, dark matter jumpstarts the formation of galaxies.
Scientists believe that dark matter is comprised of a new kind of elementary particle.
Ordinary neutrinos were a candidate for that particle, but they are too light and would stream away.
The two best candidates are axions and WIMPs because they play an important role in current particle theories independent of their candidacy for dark matter.
WIMPs are “weakly interacting massive particles” that weigh about one ten-thousandth the mass of a proton and do feel the “weak” fundamental force.
Axions are very light (100-billionth the mass of the proton) but are slow-moving.
Ways to search for WIMPs include collider rings at CERN in Switzerland and underground laboratories such as the DAMA experiment in Italy.