Pebble, a smooth, rounded stone usually less than 2 inches (64 mm) in diameter. (A larger stone of this type is called a cobble, or cobblestone.) Pebbles are fragments of any kind of rock that have become worn by rubbing together in rivers or on beaches. A loose accumulation of pebbles is called gravel. Conglomerate is rock composed of pebbles cemented together.
How cool would that be to stand amongst the company of fellow laureates like Mother Teresa or Albert Einstein? We have some ideas for scoring you one (nominating yourself isn't one of them).
He's ventured to the abyss of black holes, wagered on the information paradox and floated around in zero gravity. Meet the man, the legend, the super scientist: Stephen Hawking.