As a scientist and a man of reason, Jeffrey Rosenthal has long considered the value of luck, good and bad, seeking to measure chance and hope in formulas scratched out on chalkboards. In Knock on Wood, Rosenthal, with great humour and irreverence, divines the world of luck, fate and chance, putting his considerable scientific acumen to the test in deducing whether luck is real or the mere stuff of superstition.