Iron weighs more after it rusts.
68
Stephen Hawking once tried to find potential time travellers by throwing a party and only sending out invitations after the party.
17
A cubic yard of air weighs about 2 pounds at sea level.
31
German chemists made a replica of a trophy the size of one molecule.
68
Stannous fluoride, which is the cavity fighter found in toothpaste is made from recycled tin.
65
The average temperature at 40,000 feet above sea level is -60 F.
56
The bark of an older redwood tree is fireproof.
65