In a comment to a recent question, "LHC: Irreproducible results: when/where else have we put so much trust in one test facility?", aandreev said "formally speaking, every experiment is irreproducible because law of physics might have changed since yesterday." Apparently, I can't ask this question of aandreev directly in the comments section because I don't have the reputation points, so I'll ask it more generally here. Can someone give me an example of an experiment made irreproducible because the law of physics changed? While our understanding of the laws of physics certainly evolves, do we believe the actual laws themselves change as well? It seems to me a basic foundation of the scientific method is that if I accurately reproduce an experiment, I should expect identical results to the original, without being concerned that the laws of physics may have changed. Wouldn't changing laws undermine the value of science, to use experimental results to understand future behavior?
Correct. In as much as we sometimes postulate hypothetical changes in the known laws of physics (e.g. changing fundamental constants during the inflationary phase of the early universe), we are essentially proposing to replace our current understanding of the laws of physics with a more general (and hopefully experimentally justified) version of these laws that only look as if they were changing with time if you are stuck in a mindset only compatible with the previously prevalent understanding.