In fact, the effects of prayer on others can be scientifically investigated. Indeed, it has been. In a huge Templeton funded study!
In 2006 Harvard professor Herbert Benson performed a "Study of the Therapeutic Effects of Intercessory Prayer (STEP)" It used 1,802 coronary artery bypass surgery patients at six hospitals. Using double-blind protocols, patients were randomized into three groups. The members of the experimental and control Groups 1 and 2 were informed they might or might not receive prayers, and only Group 1 received prayers. Group 3, which served as a test for possible psychosomatic effects, was informed they would receive prayers and subsequently did. Complications of surgery occurred in 52 percent of those who received prayer (Group 1), 51 percent of those who did not receive it (Group 2), and 59 percent of patients who knew they would receive prayers (Group 3). There were no statistically significant differences in major complications or thirty-day mortality.
What if the study had shown strong evidence for the effects of prayer (which it might have done)? Then, as Dawkins points out, this would have been hailed as a scientific and theological breakthrough - it would have been 'trumpeted from the rooftops'. But Templeton didn't get the result they were after. Now they declare such studies are a waste of time - a scientific and theological dead end. Why, then, did they fund it?
Of course, the study wasn't a dead end. This was good science, properly done. And Templeton should get credit for that.
This and other research has revealed not only an absence of evidence for the beneficial medical effects of intercessionary prayer, it's also revealed pretty good evidence for the absence of any such effect.