The phrase "key unknowns" refers to important things or factors that we do not yet know or understand. They are crucial elements that are still uncertain or have not been determined yet. Full definition
The goals represent key unknowns in the arctic system and are designed to catalyze interagency and inter-disciplinary activities, with a strong focus on decision - makers» needs. (searcharcticscience.org)
They argue that two pairs of detectors would be needed to pin down two key unknown parameters: the mass of a hypothetical sterile neutrino and the characteristic distance over which the particle would oscillate. (sciencemag.org)
Lobanov's group will focus on characterizing key unknown properties of the deep Earth as well as exploring their geophysical significance. (gl.ciw.edu)