Although the seasonal equinoxes and solstices seem to divide the year into four equal parts, when you count the days of what we officially call winter, spring, summer and fall, each season is different, says Bing Quock, acting chairman of the Morrison Planetarium at the California Academy of Sciences.

NPR: Not All Seasons Are Created Equal

It is for this reason that you need a device, such as Dr Shields's, which can detect and count individual photons as they come out of different parts of the beam-splitter.

ECONOMIST: Quantum information technology