As though there's a worldwide "scientist conspiracy." Scientists police themselves. They love to find flaws in others' findings and theories. Such things that don't pass the scrutiny of scientists in the same field are exposed in refereed publications. For example,
Pons and Fleischmann's cold fusion experiments - their research was flawed, they were exposed, and they faded into obscurity.
Probably no science is more contentious than my own field of geology. The study of how the earth works is still a young science, and new discoveries and theories are brought forward every day. Did you know that the cause of earthquakes was not known until after the San Francisco earthquake and fire of 1906? Fault mechanisms, along with plate tectonics have been studied intensely since then, and we have a deep understanding of how these things work now. However, there is still much to be learned about the underlying driving mechanism so, yes, there will be more added to the science going forward - it's a dynamic process. Nothing will be added by superstition. Superstition is static, so clinging to the ones that have not changed over thousands of years is silly.
Over time, as evidence is discovered, our knowledge is increased - there is no such thing as "perfect understanding." That's what science is about - taking the knowledge we have and refining it to move closer to perfection. Science naysayers (usually people who cling to unsubstantiated beliefs) try to use that characteristic of scientific investigation to discredit it, saying, "It changes all the time, so scientists don't really know what's going on." That is exactly the strength of science. We're not satisfied until we can get the the very bottom of what's truly behind a phenomenon.
If you want to sound really ignorant, invoke the old chestnut, "it's just a theory, not a fact." Look up the meaning of the word "theory." There are bodies of knowledge that are well-established facts (as revealed by repeated experiments, not long-held superstitions). Those bodies of knowledge are called "theories," as in the Theory of Relativity or the Theory of Evolution. Both are well-proven concepts and, as in all sciences, are growing continuously.
