What is this close-up picture? (WotsThat: glass fibre insulation)

Question

What object is shown in this zoomed-in close-up photo?

Accepted Answer

glass fibre insulation. Glass fibre insulation was actually developed during World War II as a way to use recycled glass waste, and it became so good at trapping air that manufacturers realized they could make it thinner and lighter than mineral wool while keeping the same insulating power. The tiny glass fibres are so fine that they're actually invisible to the naked eye, yet they create an incredibly effective barrier against heat transfer by essentially freezing pockets of air in place.

Answer: glass fibre insulation

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