That is the beauty of science, and why it is called a "theory". A "theory" is basically the best guess that fits the facts at hand. As we discover more facts, or learn different things about old ones, the theories can and do need revision from time to time. The better-known theories tend to last a long time, but the odds are good that they will need to be changed someday.
And, by the way, you fail to note that theologians do the exact same thing. Editing Scripture, voting on which books do and do not belong in the "official" Bible, revising terms to better fit our understanding of the world... but not before the glorious Church spends a few solid decades slaughtering some of the world's greatest scientific minds for heresy before they figure out the earth is round. Or did that not happen, because it isn't in the current King James version?