D. G. Cory

In 1946, Felix Bloch predicted that even without an external magnetic field, a fluctuating magnetic moment exists in an ensemble of spins. It grows as the square root of the number of particles, and in small samples this noise can exceed thermal polarization.

A stone falls into water, and ripples spread in all directions. Throw a handful of stones at once, and the ripples overlap: you can no longer tell which ripple came from which stone. A neutron beam hitting a detector looks much the same: a bright spot blurred by many causes.