visibility

FortNine's tongue-in-cheek guide to why drivers fail to see motorcyclists and how riders can make themselves more visible. It touches on perception psychology, including the role of saccades.

Captain Disillusion debunks a viral Chinese invisibility cloak video while parodying popular educational channels. Along the way he explains chroma keying and green screen techniques.

Tom Scott explains why Ipley Cross in England's New Forest was one of Britain's most dangerous junctions. The angled crossroads lets a car's A-pillar hide approaching traffic and cyclists because there is no relative motion in the driver's view.

Numberphile's James Grime discusses highly composite numbers, nicknamed anti-primes, which have more factors than any smaller number, using 5040 as the central example. It touches on Plato and Ramanujan.