Of course the situation is more complex that this suggests. The confidence scientists have in their collective work draws a lot from the cumulative positive evidence from varied and repeated observations and is dynamic and is not made or broken by single dramatic experiments or observations. This is what I mentioned before. To understand Physical Reality. But what we mean by understanding is very specific.
Scientists attach a very functional meaning to the word.
And now a paradox is apparent. Say the scientist proceeds to break the process into interactions of simpler and simpler pieces. Once again our sense perceptions come to the rescue. We understand the simplest block of process in terms of observations of Physical Reality. Let me try to explain this by the use of an example.