“Rickey made a bold move in signing Jackie Robinson. He realizes, more than anyone eles [sic], the troubles that will beset his ‘noble experiment.'” Si Burick, “Si–ings: It Was Inevitable That Negro Would Get Contract Chance to Make Good in Organized Ball,” Dayton News, October 24, 1945, p18
NOTE: The Dictionary does not list a first use, but notes that, according to Jules Tygiel (author of Baseball’s Great Experiment: Jackie Robinson and His Legacy, published in 1983), “the terms ‘great experiment’ and noble experiment were used by Rickey, but Tygiel’s publisher (Oxford Univ. Press) preferred ‘great’ because ‘noble’ referred to Prohibition.”
Both “great experiment” and “noble experiment” appeared in print on October 24th, the day after Robinson’s signing.
No earliest use given in 2009 Dickson Baseball Dictionary