The primary impediment to the scientific acceptance of psi is the fact that most psi experiences cannot be replicated in the laboratory and tested to see if there are other possible explanations for the phenomena. Most psychic phenomena are fleeting; they do not last long enough for scientists to be summoned, set up their equipment, and begin testing for psi. In addition, many experiments on psychic phenomena are filled with errors, sloppy procedures that permit leakage, and sometimes even fraud, in which the researchers manipulate the results to support their theories. Author Upton Sinclair studied psychic phenomena extensively with his wife, Mary Craig, who believed she had telepathic powers. "The factor which makes psychic phenomena so hard for the scientific world to accept," he wrote, "is cheating." However, Sinclair voiced the opinions of many when he wrote, "There is...