Sailing has been a mainstay of human history for millennia, so it’s no surprise that scientists would apply it to traveling in space. Solar sailing, the most common version, uses pressure from the Sun to push spacecraft with giant sails outward in the solar system. However, there is a more technologically advanced version that several groups think might offer us the best shot at getting to Alpha Centauri – light sailing. Instead of relying on light from the Sun, this technique uses a laser to push an extraordinarily light spacecraft up to speeds never before achieved by anything humans have built. One such project is supported by the Breakthrough Starshot Initiative, initially founded by Yuri Milner and Stephen Hawking. A new paper by researchers at Caltech, funded by the Initiative, explores how to test what force a laser would have on a light sail as it travels to another star.