Polar bear fur-inspired sweater is thinner than a down jacket — and just as warm

A sweater knitted from a fibre that mimics polar bear fur offers as much warmth as a down jacket, despite being one-fifth as thick, according to a study published today in Science¹. The fibre — made from a light, synthetic material known as an aerogel — maintains its heat-trapping properties even after being stretched, washed and dyed.

The proof-of-concept fibre might one day be used for clothing that need to be…