You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Richard_Feynman

Context:
Feynman diagrams are now fundamental for string theory and M-theory, and have even been extended topologically. The world-lines of the diagrams have developed to become tubes to allow better modeling of more complicated objects such as strings and membranes. Shortly before his death, Feynman criticized string theory in an interview: "I don't like that they're not calculating anything," he said. "I don't like that they don't check their ideas. I don't like that for anything that disagrees with an experiment, they cook up an explanation—a fix-up to say, 'Well, it still might be true.'" These words have since been much-quoted by opponents of the string-theoretic direction for particle physics.

Question:
Which quote by Feynman is often used by string theory opponents?

'Well, it still might be true.'"