The material science of building a light sail to take us to Alpha Centauri

It has been about two years since Yuri Milner announced his most audacious piece of science-focused philanthropy: Breakthrough Starshot, an attempt to send hardware to Alpha Centauri by mid-century. Although the technology involved is a reasonable extrapolation of things we already know how to make, being able to create materials and technology that create that extrapolation is a serious challenge. So much of Breakthrough Starshot’s early funding has gone to figuring out what improvements on current technology are needed.