In his Scientific Autobiography, Max Planck recalls that he was unable to persuade the chemist Wilhelm Ostwald that the Second Law of Thermodynamics could not be deduced from the First Law of Thermodynamics. "This experience gave me also an opportunity to learn a fact—a remarkable one, in my opinion: A new scientific truth does not triumph by convincing it opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it." Planck also wrote of his conflict with Ostwald: "It is one of the most painful experiences of my entire scientific life that I have but seldom—in fact, I might say, never— succeeded in gaining universal recognition for a new result, the truth of which I could demonstrate by a conclusive, albeit only theoretical proof. This is what happened this time, too. All my sound arguments fell on deaf ears. It was simply impossible to be heard against the authority of men like Ostwald, Helm, and Mach."
Fortunately, Planck was able to obtain universal recognition for his Radiation Law, again not by his theoretical proof, but by experimental confirmation.
There has been a tendency among theoretical physicists, particularly string theorists, to downplay the importance of experimental confirmation in recent years. Many have even claimed that Copernicus was not superior in predictive power over Ptolemy. I myself decided to check this claim, by looking at Tycho's notebooks. I discovered that between 1564 and 1601, Tycho compared Copernicus's predictions and Ptolemy's predictions with his own observations 294 times. As I expected, Copernicus was superior. So Copernicus' theory was confirmed as experimentally superior to Ptolemy long before Galileo. So I have put the Copernicus-was-no-better-than-Ptolemy idea to the (historical) experimental test, and found that it is false: Copernicus Trumps Ptolemy.
As it was in the beginning of modern science, so it should be now. We should keep the fundamental requirement that experimental confirmation is the hallmark of true science. Since string theorists have failed to propose any way to confirm string theory experimentally, string theory should be retired, today, now.