I think the linked blog post is right in that scientists, even though they might mention Popper a lot, don’t really believe that a theory is never verified, only falsified (strict Popperianism). First, an important element which is missing in that naive picture is the role of cumulative evidence: people are loathe to give up a theory that can already explain a lot of things, and especially in physics, they would try to restrict the theory’s domain to what has been verified instead of throwing it out completely.
Second, the Duhem-Quine thesis (i.e. you don’t know if it’s the theory that is falsified, or one of your measuring tools) is a potential problem, but physicists have had ways to deal with it, again by invoking the notion of cumulative evidence. My field of research (precision measurement) is focused on testing the most fundamental and well-accepted theories, such as whether gravity really scales as r^{-2}, whether certain new hypothetical particles exist and whether the electron’s charge is really symmetric or not. In this field, we don’t just decide arbitrarily whether an established theory is really wrong or that one of the measuring tools is defective. Instead, we try as much as we can to calculate and independently measure the precision and accuracy of our measuring tools and factor them into a systematic error “budget”. This calibration of our tools is done with techniques which are relatively simple, well-established and widely accepted. If this calibration cannot be done properly, or that it turns out that our tools are very imprecise, then sometimes we hold off judgment on the significance of our measurement until we can design a better experiment that can verify it more precisely.
The rigor of the above process is such that many experiments (including mine) in fact blind our final measured value during the entire process of running the experiment and doing the data analysis, so as to minimize human bias from interfering in the case that an established theory is really false, for example. That’s falsification in action, I would say.
An example of this happening in action is the proton radius measurement (which I’m surprised hasn’t been analyzed from a philosophy or sociology of science perspective yet). There was a new, much more precise measurement that conflicted with previous results. Instead of just rejecting the newer result, what people did is construct a number of newer, more precise experiments (utilizing very different methods of measuring the same quantity) in order to put the extraordinary result to the test.
Third is the issue of ad hoc hypotheses. The author argues that falsification is a meaningless criteria to demarcate science from non-science, as both mainstream science and pseudoscience are equally guilty of being willing to conjure up ad hoc hypotheses to rescue their theory. But this is an overly simplified picture that doesn’t take into account different types of ad hoc hypotheses, and the testability of the ad hoc hypotheses themselves. It’s common in theoretical physics to revise one’s prediction of the mass of a new, undiscovered particle in response to the latest experimental results, but people don’t just accept that blindly. They evaluate each revision to see how it fits with other parts of physics that are already well-established.
In conclusion, I would say that most scientists today (at least in most of physics) still operate on the assumption that some type of falsification is a necessary but insufficient criteria for something to constitute a legitimate scientific hypothesis. Almost every time one proposes a new, speculative hypothesis, the next thing that is asked is, “How can we test this? What experimental evidence would this theory predict?”
Now, this may not apply in the same way to some really speculative areas (such as multiverse hypotheses or string theory), but I don’t think most people regard these theories as “established” in the same way that the Standard Model of particle physics or Big Bang cosmology is established, for example. You are much freer to claim that you don’t believe in a multiverse compared to claiming that you don’t believe in the robustness of the Standard Model. (Of course everyone also agrees that the SM has to fail at some point, but that’s a different matter…)