Eight years ago, Moses Chan of Penn State made big news by publishing experimental evidence that appeared to be consistent with supersolidity - a hypothesized state in which atomic vacancies in a solid (in this case, pressurized crystals of 4He at very low temperatures) could move without dissipation, analogous to the quantum coherent, viscosity-free flow of atoms in a superfluid. I've mentioned this before (1) (2). Now, as written up in the latest issue of Science, it seems like supersolidity (at least in the system that had been studied) is dead, and a major killer was a paper by the original authors of the first claim.
This happens sometimes. Observations and their interpretation can seem very very compelling, and yet later someone will think of some subtle issue that had not been considered previously. That's the nature of science. Unfortunately, sometimes the popular impression that gets conveyed is that because of these rare situations, science is no more trustworthy than random guesses or opinions. My own thesis advisor told me more than once that it's ok to be wrong in science occasionally, and the best outcome is to be the one who discovers your own mistake! (He and coauthors had published a PRL claiming that an effect they saw was taking place in solid 3He, when it turned out that it really was happening in the liquid, which they then also published, correcting their own mistaken interpretation. It worked out well for them.)
That reminds me: time for the annual Nobel speculation, since the physics prize comes next Tuesday. Place your bets below.... (blogging will continue to be slow due to multiple other writing constraints right now)