The question of demarcation is an interesting and important one in the philosophy of science. It is, essentially: What is science? Where do we draw the line between science and pseudoscience? I think that question is based on a false premise, namely that a sharp division exists. I don’t think there is a sharp line but rather a gray area. On the other hand there are clearly some things that are pseudoscience and others that are science. So, in the cases where the distinction exists, how do we tell them apart?
David Koepsell, in the adjacent article, has given one suggestion: The pursuit of a claim moves from science to pseudoscience when the claim has been falsified. So far, so good. Clearly, if the claim is capable of being shown false and then has been demonstrated to be false, any continued pursuit is problematic at best. But does this test always work? Alas, the answer is no.
Let’s take the EmDrive as an example. Looking at the most recent publication mentioned by Koepsell from the group in Germany (http://arc.aiaa. org/doi/abs/10.2514/6.2015-4083), we see in their abstract an observed thrust of about twenty micronewtons (μN). This is the force of gravity on a mass of about two milligrams, or the weight of a small mosquito. In the abstract of the paper we read: “. . . we do observe thrusts close to the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena.” Looks good, doesn’t it? But take another look at that excerpt from the abstract. We’ll start with the preceding sentence, which says: