For as long as humans have looked southward at the night sky, Alpha Centauri has represented both the nearest and most unreachable of destinations — a neighbor separated by 4.2 light-years and, until recently, by the hard ceiling of conventional propulsion. Breakthrough Starshot's proposal to sever the bond between engine and spacecraft — driving a gram-scale sail with ground-based lasers to one-fifth the speed of light — reframes that distance not as a barrier but as a 20-year journey. The physics is sound; the engineering remains unbuilt. Humanity stands at the edge of a concept that is neit