Cosmologist Dr Bart Pindor explains gravitational lensing, in which the curvature of space by gravity allows us to investigate galaxies and other astral bodies. Presented by Dr Shane Huntington.
"Because the dark matter doesn't feel electromagnetic forces so it doesn't feel pressure, it doesn't participate in this giant conflagration." -- Dr Bart Pindor -
See more at: http://upclose.unimelb.edu.au/episode/298-curve-your-expectations-observing-planets-and-galaxies-help-gravity#sthash.CYhAoTCO.dpuf