nsec

Returns just the number of nanoseconds for time.

t = Time.now        #=> 2007-11-17 15:18:03 +0900
"%10.9f" % t.to_f   #=> "1195280283.536151409"
t.nsec              #=> 536151406

The lowest digit of to_f and nsec is different because IEEE 754 double is not accurate enough to represent nanoseconds from the Epoch. The accurate value is returned by nsec.