The principle of science, the definition, almost, is the following: The test of all knowledge is experiment. Experiment is the sole judge of scientific "truth." But what is the source of knowledge? Where do the laws that are to be tested come from? Experiment, itself, helps to produce these laws, in the sense that it gives us hints. But also needed is imagination to create from these hints the great generalizations--to guess at the wonderful, simple, but very strange patterns beneath them all, and then to experiment to check again whether we have made the right guess.
Richard P. FeynmanThere is no harm in doubt and skepticism, for it is through these that new discoveries are made.
Richard P. FeynmanYou know how it always is, every new idea, it takes a generation or two until it becomes obvious that there's no real problem. It has not yet become obvious to me that there's no real problem. I cannot define the real problem, therefore I suspect there's no real problem, but I'm not sure there's no real problem.
Richard P. FeynmanVictory usually goes to those green enough to underestimate the monumental hurdles they are facing.
Richard P. FeynmanI think it's much more interesting to live not knowing than to have answers which might be wrong.
Richard P. Feynman