The universe has a very high mass. So high, in fact, that all the detectable matter in the known universe cannot account for all the detectable mass in the known universe. The standard model of cosmology accounts for this with an interesting substance called Dark Matter - an invisible, undetectable particulate that has mass without being otherwise detectable in any way. The problem (to my mind), was that I could conceive of no way this could be tested. I mean, intangible mass was hard enough to swallow until I remembered that I'm continuously being bombarded with radiation that has mass and I have absolutely no way of detecting that without specialist equipment.
Someone built some specialist equipment and proved me wrong, however, and the announcement of the first direct observations of dark matter comes in the same week as the announcement of the discovery of the Higgs Boson.
I love being wrong. Hats off to everyone! I wouldn't be surprised if I dissected the experiment for Methodological Monday.