How we came to know the size of the Universe – and what mysteries remain

A riveting ride through the history of astrophysics, this video details how humans have climbed ‘the cosmic distance ladder’ to calculate sizes and distances in the cosmos. The second in a two-part series, this instalment begins with the fascinating story of how thinkers working across generations were able to calculate the distances between bodies in our solar system, and builds to some of the still-lingering mysteries of size and scale in the cosmos. Presented by Terence Tao, a Fields medalist and professor of mathematics at the University of California, Los Angeles, and the video essayist Grant Sanderson (aka 3Blue1Brown), the piece provides an engrossing look at how knowledge has built about itself alongside our technologies, and how we might unlock the puzzles of the Universe yet to be solved.