what does theory mean in science
There’s an important difference between a scientific theory and the fanciful theories of an imaginative raconteur, and this quirk of semantics can lead to an all-too-common misconception. In general conversation, a ‘theory’ might simply mean a guess. But a scientific theory respects a somewhat stricter set of requirements. When scientists discuss theories, they are designed as comprehensive explanations for things we observe in nature. They’re founded on strong evidence and provide ways to make real-world predictions that can be tested.
While scientific theories aren’t necessarily all accurate or true, they shouldn’t be belittled by their name alone. The theory of natural selection, quantum theory, the theory of general relativity and the germ theory of disease aren’t ‘just theories’. They’re structured explanations of the world around us, and the very foundation of science itself.
Part of the Darwin exhibition.
But for scientists, a theory has nearly the opposite meaning. A theory is a well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses and facts. The theory of gravitation, for instance, explains why apples fall from trees and astronauts float in space. Similarly, the theory of evolution explains why so many plants and animals–some very similar and some very different–exist on Earth now and in the past, as revealed by the fossil record.