All children are born scientists, innately curious about the world. We then desiccate their enthusiasm with an arid and false notion of science as a passionless activity, one stereotypically pursued by social misfits. We then wonder why Science, Technology, Engineering and Math (STEM) careers do not excite more students.
Far too much of what we teach primary and secondary school students about the motivations, methods, and practice of science is little more than a well-meaning falsehood that does as much harm as good. Why is that, you say? Isn't the rote quartet of observation, hypothesis, experiment, and theory the scientific method's analog of the journalist's five Ws: Who, what, where, when and why?
Yes, they are, but they do not tell the entire story. The scientific quartet focus on the deductive (drawing necessary conclusions) and the inductive (inferring generalizations from samples or examples), but neglect the creative and exciting abductive (making guesses) elements. Abduction is about discovering (guessing) the simplest and most likely explanation.
Guessing the Theory
Now I'm going to discuss how we would look for a new law. In general, we look for a new law by the following process. First, we guess it (audience laughter). No, don't laugh, that's the truth. Then we compute the consequences of the guess, to see what, if this is right, if this law we guess is right, to see what it would imply and then we compare the computation results to nature or we say compare to experiment or experience, compare it directly with observations to see if it works.
The very fact that the audience laughed when Feynman said, "we guess it," speaks volumes about how we teach the scientific method. It ignores the inspirational, creative aspect of science and reinforces the stereotype of a scientist as an emotionless automaton. This early cultural imprinting does a deep disservice to science and discourages many children from expressing their creativity via science, to our societal detriment.
Nor is this stereotype restricted to non-academics. To my open-mouthed astonishment, I have personally witnessed professors debating whether science is beautiful. Let me state categorically that science and mathematics are beautiful. Symmetry, simplicity, elegance, universality, and yes, beauty are all words scientists use regularly and without hesitation.
Because science is a human endeavor, the creative passions inspiring scientists to "guess" are no different from those impelling artists to paint, musicians to compose, or authors to write. It is about creativity and creative expression. Like all scientists, I have looked at a scientific theory with the same reverence and awe that a great work of art inspires in me. It touches something deep and fundamental in the human psyche.
Testing the Prediction
In the same 1964 public lecture, Feynman also succinctly summarizes the leitmotif of science:
If it [the guess] disagrees with experiment, it's WRONG. In that simple statement is the key to science. It doesn't make any difference how beautiful your guess is, it doesn't matter how smart you are, who made the guess, or what his name is… If it disagrees with experiment, it's wrong. That's all there is to it.
Equally importantly, the experiment can be repeated by others – friends, enemies, competitors, doubters – to independently verify or disprove the claim. In this brief statement, Feynman captures the essence of what may be one of humanity's greatest conceptions – the systematic, repeatable testing and public validation of ideas. It gives no pride of place to the rich, powerful, dogmatic, or ideological.
It also explains why science calls well-tested ideas "theories" rather than facts or truths. A single negative experiment (i.e., one where the experiment fails to yield the predicted result) is sufficient to disprove the theory, but no number of experiments can prove with absolute certainty that the theory always holds. However, that does not mean repeated experiments do not establish high confidence. When a scientist calls something an established theory, he or she means the "guess" has withstood repeated observation and testing by an international community.
In this spirit, gravity is just that, a theory, but you can test it yourself, either the Newtonian approximation or Einstein's general relativity. If you have a better guess for a Theory of Everything that integrates quantum field theory and general relativity, no matter how beautiful, you'd better test it with an experiment.
Science rocks! That's how we roll.