The $100 million Breakthrough Starshot project, announced today by Yuri Milner, plans to use giant lasers to launch tiny spacecraft to Alpha Centauri. While using laser cannons for spacecraft propulsion might sound like science fiction, previous research suggests that "laser sailing" might be one of the only known ways to get a probe to another star within a human lifetime.

Although Alpha Centauri is the nearest star system to us, it still lies roughly 4.37 light-years away. That is equal to more than 25.6 trillion miles, or more than 276,000 times the distance from Earth to the sun.

Conventional rockets are nowhere near efficient enough to cross the enormous distance to Alpha Centauri within a human lifetime, as science fiction author and NASA physicist Geoffrey Landis once explained. For instance, at the space shuttle's maximum speed of about 17,600 mph, it would have taken roughly 165,000 years to reach Alpha Centauri.