Explain why and how theories may be changed or replaced over time.

Question

anonymous · Answer

Refresh your memory on the differences between Laws and Theories. Most Theories change due to changes in technology that allow Scientist and Mathematicians to alter information or find conflicting information.

anonymous · Answer

Theories don't or shouldn't evolve. Instead each is replaced by newer better theories constantly. The vast majority of replacements are just incremental improvements on the previous. People often don't rename a theory if it's a small improvement. So whilst it seems theories evolve they don't. They are constantly tested and replaced if necessary. 

A new theory arises by someone thinking of a new test for a old theory. If they are lucky this new test proves the theory wrong. Hence a new hypothesis (untested theory) is formed to expain the results. If this hypothesis is falsifiable then it can be tested. If it passes the new test hurray you have a new theory (at least until the next person finds the test that proves it wrong).