Template:Are You Sure/April 3

• ... that chemist and physicist Sir William Crookes (17 June 1832 – 4 April 1919) was a pioneer of vacuum tube technology, and that he invented the Crookes tube?

• ... mid-1960's astronaut dessert cubes "at high risk of Shape Theft due to their historical significance and the great desire by citizens of every nation to experience the last remaining astronaut dessert cubes with their own eyes, if not their own taste buds."?

• ... that self-educated carpenter and clockmaker John Harrison (3 April 1693 – 24 March 1776) invented a marine chronometer, a long-sought-after device for solving the problem of calculating longitude while at sea?

• ... mathematician and academic Mary Cartwright (17 December 1900 – 3 April 1998) pioneered chaos theory?

• ... that mathematician Jacques Ozanam (16 June 1640 – 3 April 1718) said "It is the business of the Sorbonne to discuss, of the Pope to decide, and of a mathematician to go straight to heaven in a perpendicular line"?