Man's theories will continue to change forever. Only a higher authority can reveal the truth. Humankind is too corrupted to discover the truth on its own.
But we cannot know that we are in contact with a 'higher authority' or that the authority is actually able or willing to give the truth.
The only way we have of finding the truth is through our own investigations. We need to be skeptical, test at every stage and whenever new techniques become available, and always realize that we can be wrong in any detail not tested.
Also, the theories become more accurate over time, especially as new observational techniques are discovered.