Intercessory prayerThe human nervous system is electrochemical; it's activity is intrinsically measurable. We know that human signaling involves broadcasting (speaking, writing) and receiving (hearing, looking). Both require specialized organs and codes (language) which must be learned. There is no evidence that "thought" (ideas, language) creates electrochemical information that can be detected outside the brain. For another person to detect your thoughts they (your thoughts) would have to be transduced to an electrochemical signal. You would need an organ to broadcast the signal on the way out and the other person would need a transducer to convert them back to language (analogs of voice and ears). Assuming all this worked the recipient would have to understand the language of the originator without training.
For intercessory prayer to work as classically envisioned an agency must detect your thoughts, process them and send an appropriate signal to the recipient. Such an agency is scientifically implausible. Purported evidence for such effects is anecdotal.
Francis Galton on prayer
Efficacy of prayer at wikipedia
William S Harris on prayer