‘Once in a Century’ Proof Settles Math’s Kakeya Conjecture

Consider a pencil lying on your desk. Try to spin it around so that it points once in every direction, but make sure it sweeps over as little of the desk’s surface as possible. You might twirl the pencil about its middle, tracing out a circle. But if you slide it in clever ways, you can do much better. “It’s just a problem about how straight lines can intersect one another…

Source