army intelligence: an agency of the United States Army responsible for providing timely and relevant and accurate and synchronized intelligence to tactical and operational and strategic level commanders
social group: people sharing some social relation
planck's law: (physics) the basis of quantum theory; the energy of electromagnetic waves is contained in indivisible quanta that have to be radiated or absorbed as a whole; the magnitude is proportional to frequency where the constant of proportionality is given by Planck's constant