From the Weeping Angels developmental lab:
One of the oddest predictions of quantum theory – that a system can’t change while you’re watching it – has been confirmed in an experiment by Cornell physicists. Their work opens the door to a fundamentally new method to control and manipulate the quantum states of atoms and could lead to new kinds of sensors.
The experiments were performed in the Utracold Lab of Mukund Vengalattore, assistant professor of physics, who has established Cornell’s first program to study the physics of materials cooled to temperatures as low as .000000001 degree above absolute zero. The work is described in the Oct. 2 issue of the journal Physical Review Letters
Of course this doesn’t answer the real, more fundamental question: How do the atoms know we’re watching?