What the arrow of time problem asks — why does time have a direction when fundamental laws are time-reversible

What Maxwell's demon thought experiment challenges — can information be used to decrease entropy

Maxwell's demon challenges the second law of thermodynamics by potentially decreasing entropy using information

Why time translation symmetry gives energy conservation — if physics doesn't change with time, energy is conserved

Time translation symmetry implies unchanging physics, thus conserving energy

What the second law of thermodynamics says — entropy of an isolated system never decreases

Entropy in an isolated system always increases or remains constant

What the information paradox asks — does information falling into a black hole disappear, violating quantum mechanics

The information paradox questions: Does information vanish in black holes, contradicting quantum theory?

What CPT symmetry is — the combination of charge, parity, and time reversal is always conserved

CP-symmetry implies charge, parity, and time reversal conservation

What the EPR paradox challenged — Einstein argued entanglement implied either hidden variables or nonlocality

EPR paradox questioned quantum mechanics' lack of locality and determinism