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Why a microwave leaves cold spots: a standing wave 12.2 cm long, and a chocolate bar that measures the speed of light Microwave ovens fill a metal box with radio waves 12.2 cm long. The waves bounce off the walls and add up into a standing wave, a frozen pattern of hot spots… Food Science5 min read1 Nov Why sunflower seeds never leave gaps: the golden angle and the Fibonacci spirals Sunflower seeds are not placed in spirals on purpose. Each new seed turns a fixed angle from the last, and only one angle, about 137.5 degrees, leaves no bare… Maths4 min read28 Oct Why a dot vanishes when you look away from it: the blind spot where the optic nerve exits Close one eye, stare at a cross, and a dot a hand's width away simply vanishes. That is your blind spot: the place where the optic nerve leaves each eye, with… Mind4 min read19 Oct Why a dried coffee drop leaves a ring: the edge is stuck and the rim dries first Spill coffee, let it dry, and you get a dark ring with a pale middle, not an even stain. The pigment started out spread through the whole drop. The drop's edge… Physics2 min read8 Oct Every eye has a hole in its vision, and your brain paints over it Every one of your eyes has a hole in its vision, about ten Moons wide, and you have never seen it. It is where the optic nerve leaves the retina, a patch with… Mind3 min read3 Oct Autumn leaves don't turn yellow. The yellow was there all summer Autumn leaves don't really turn yellow. The yellow carotenoids were in the leaf all summer, hidden under green chlorophyll. In autumn the tree dismantles its… Biology5 min read27 Sep Why traffic jams appear out of nowhere Sometimes a motorway grinds to a halt and then clears up with no crash, roadworks or merge in sight. That's a phantom traffic jam, and it starts with one… Engineering4 min read26 Sep