Experiment and Theory

Dennis Overbye:

The British astrophysicist Arthur S. Eddington once wrote, “No experiment should be believed until it has been confirmed by theory”. . . .

Eddington’s dictum is not as radical as it might sound. He made it after early measurements of the rate of expansion of the universe made it appear that our planet was older than the cosmos in which it resides — an untenable notion. “It means that science is not just a book of facts, it is understanding as well,” explained Michael S. Turner, a cosmologist at the University of Chicago, who says the Eddington saying is one of his favorites. If a “fact” cannot be understood, fitted into a conceptual framework that we have reason to believe in, or confirmed independently some other way, it risks becoming what journalists like to call a “permanent exclusive” — wrong.  

There are uncountable ways that an experiment can go awry, and the most likely explanation of an anomalous result really is that it is an error. Results that overturn decades of theorizing are very, very rare, and mistakes are legion.