Historical clue formulations

• ... PROPOSAL PROPOSAL PROPOSAL ... — 2021-12-05
• Violation of the first and second laws of thermodynamics — 2013-10-13
• Mechanical impossibility — 2002-08-13
• Inventor's impossible goal — 1999-11-01
• "Impossible" achievement — 1998-05-19
• Noted Paganini composition — 1995-09-23