Although the ongoing public debate on string theory has captured the limelight and the public's attention (at least, the interested public's attention) leaving dark matter in the dark (pun intended), chances are my readers have heard/read about the latter.
Together with the slightly more recent dark energy (and the even more recent and highly controversial dark flow), dark energy is another hot topic in contemporary physics.
But, what is dark matter? How was it discovered? More importantly for my own purposes: how does it fit in the great Popperian scheme? The following video clip, accessible to the wider public, provides an overview as useful as it is entertaining:
As with the discovery of Neptune (and the recently announced search for Planet X) dark matter is an inferred answer to an empirical anomaly detected when testing a hypothesis: the universe is expanding at an increasing rate, but it shouldn't be. To the astrophysicists' credit, unlike the Queen of Hearts in "Alice in Wonderland", they did not go all "off with your head"; no heads prematurely rolling. On the floor, oh! You don't hear a single word about falsification in that video: astrophysicists -- it seems -- have a lot more sense than Sir Karl (or Joan Robinson, her disciple).
But that wouldn't surprise Bridgman.
Popper's fans won't enjoy reading this, but nothing in this episode seems to fit their master's scheme (anomalies falsify hypotheses? adjusting hypotheses is taboo?); but it does fit mine just fine: see my post on the subject of inference to the best explanation.
Yeah Yeah Yeahs' 2009 "Heads will Roll", with the mega cool Karen O:
----------The short video on dark matter comes from a really cool website (Physics Girl) by young MIT graduate physicist Dianna Cowern. Check it out: plenty of amazing stuff there and in her YouTube channel.