On December 2, 2014, Nature published a story headlined “European probe shoots down dark-matter claims” (link). Reading such a headline, one is inclined first to ask, What exactly are “dark matter claims”? The first thought that springs to mind is the claim that dark matter exists. And if that claim has been shot down, why, that’s actually Big News. But that can’t be true, can it? If it was, the headline would be bigger—and even CNN might have mentioned it since December 2, 2014 (or even December 11, 2014, when the article was last revised).
The article concerns a news announcement, by the European Space Agency, that a full analysis of data on the Cosmic Microwave Background (CMB), collected by the Planck spacecraft, is now being prepared for publication. Some highlights were presented on December 2.
Reading the brief-enough article, one learns that despite the “shoot down” Planck data still “confirm that 26% of the total mass-energy budget of the Universe is made up of dark matter.” Therefore dark matter is alive and well. What that dramatically announced “shoot down” means is that some conjectures about dark matter—namely that excess positrons found in the CMB is explained by dark matter—has been shown to be false. So one conjecture has been falsified, but dark matter is still in the saddle. Had the headline signaled that, I wouldn’t have bothered reading the article.
Compare that headline to another published by Phys.Org on December 4 (link). It said: “Researchers report on data analysis from Planck spacecraft.” The substance of that story is essentially the same as Nature’s. Clever headlines capture readers, but dark matter lingers on.