open problem
known problem or question which is thought to have an objective and verifiable solution or explanation, but which has not yet been solved
list of unsolved problems in physics
Wikimedia list article
cosmological constant problem
major unsolved problem in physics
black hole information paradox
scientific question of whether information can disappear in a black hole
gravitational interaction of antimatter
theory of gravity on antimatter
sums of three cubes
the mathematical problem of characterizing which integers are representable as sums of three cubes of integers
mystery
something secret or unexplained and peculiar
hard problem of consciousness
the problem of explaining how and why organisms have qualia or phenomenal experiences
medically unexplained physical symptom
symptoms with no known or agreed upon cause
proton spin crisis
theoretical crisis precipitated by an experiment in 1987 which tried to determine the spin configuration of the proton
Great Rationality Debate
question of whether humans are rational or not
dark proteome
category of proteins
terraforming
hypothetical planetary engineering process
cattle mutilation
killing and mutilation of cattle in unusual and anomalous ways
Gaussian moat
mathematical problem in number Theory
unsolved crime
criminal case that has not been solved
conjecture
proposition in mathematics that is unproven
philosophical problem
disputed or unresolved question in field of philosophy