People are usually surprised at how many theories try to explain comet origins. Ironically, most theories explain the facts better than the theory currently in vogue—the Oort cloud theory. Having only one theory popularized or taught, usually as a fact, leads to its dominance and continuation as the only theory taught—despite a growing number of scientific problems.
Thomas Kuhn wrote the preeminent book on how science works.136 In it, he shows that such monopolies continue in science, often for centuries, until startling new evidence arises along with a theory that better explains all the evidence. Then, a slow reeducation process begins, accompanied by hostility from those whose income, power, pride, and prestige are rooted in the old theory or paradigm.
If, as you drove across the country, you found more and more details contradicting your map, you might suspect that you made a wrong turn somewhere. Admitting a mistake may be difficult, and backtracking and finding the correct road can consume time and fuel. In science, paradigm shifts are costly and slow, damage some reputations and businesses, and even destroy major worldviews of certain segments of society. Fundamental changes in thinking are strenuously resisted by some, but are inevitable if the scientific evidence supports those changes.
New evidence spawns new theories, and the testing cycle begins again. However, when only one explanation is taught and seldom questioned, the cycle stops. In science, we should never think we have a final or proven answer.