Project Poltergeist documents a 40-year endeavor to understand the neutrino, a fundamental particle in the structure of the present universe—and the early cosmos. After a concise introduction to Wolfgang Pauli’s neutrino theory, the program focuses on John Bahcall’s controversial struggle to detect accurate neutrino quantities and confirm the calculations of his colleague Ray Davis. Featuring the massive underground facilities used to measure neutrino influx, including the SNO laboratory at which the Davis/Bahcall collaboration triumphed, the program concludes with the cosmological implications of their findings. Original BBCW broadcast title: Project Poltergeist. (50 minutes)